NATL: HUMBERTO - Advisories

[AJC3]

Tropical Storm Humberto Advisory Number 1
NWS National Hurricane Center Miami FL AL082025
500 PM AST Wed Sep 24 2025

...TROPICAL STORM HUMBERTO FORMS IN CENTRAL TROPICAL ATLANTIC...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...20.1N 54.9W
ABOUT 550 MI...885 KM ENE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...WNW OR 300 DEGREES AT 15 MPH...24 KM/H
MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES


WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.



Tropical Storm Humberto Discussion Number 1
NWS National Hurricane Center Miami FL AL082025
500 PM AST Wed Sep 24 2025

Satellite data indicates that Invest 93L over the central tropical
Atlantic has now developed into Tropical Storm Humberto. Visible
satellite imagery shows that throughout the day, the low-level
center has become well-defined, with persistent and organized deep
convection mainly located over the eastern side of the system.
Subjective Dvorak intensity estimates from TAFB and SAB were both
data-T/2.5 35 kt. DPRINT and DMINT Objective intensity estimates
from UW-CIMSS range from 31 to 35 kt. Using these data, the
initial intensity is set to 35 kt.

The system is estimated to be moving west-northwestward at 300/13
kt, but this is of low confidence since the center has only recently
formed. A west-northwestward to northwestward motion is
anticipated through the next several days along the southwestern
periphery of a mid-latitude ridge. Towards the end of the forecast
period, an approaching trough moving offshore the east coast of the
United States will erode the ridge and allow the system to turn more
northward. However, there is quite a bit of uncertainty with the
forward speed and cross-track spread of the system. This is
increasingly apparent beyond day 3 as there are complex steering
components with timing differences in the global models, including
the approaching trough and potential binary interaction with Invest
94L. The NHC track forecast lies near the consensus aids given some
of these uncertainties, and there is lower than normal confidence in
the track forecast.

The storm is within a favorable environment for strengthening with
warm sea surface temperatures near 29C and moist mid-level RH
values. The system will be dealing with some moderate westerly wind
shear for the next day or so that will likely cause an asymmetric
storm structure. EC and GFS SHIPS guidance depict the shear slightly
weakening in the day 2 to 4 time frame, and with increasing
divergence aloft, a slightly greater rate of strengthening is shown
at that time. The latest NHC forecast follows these trends and lies
near the consensus intensity aids.


FORECAST POSITIONS AND MAX WINDS

INIT 24/2100Z 20.1N 54.9W 35 KT 40 MPH
12H 25/0600Z 20.9N 56.0W 40 KT 45 MPH
24H 25/1800Z 21.6N 57.0W 45 KT 50 MPH
36H 26/0600Z 22.0N 57.5W 50 KT 60 MPH
48H 26/1800Z 22.5N 58.2W 55 KT 65 MPH
60H 27/0600Z 22.9N 59.0W 60 KT 70 MPH
72H 27/1800Z 23.6N 60.6W 70 KT 80 MPH
96H 28/1800Z 26.0N 64.3W 90 KT 105 MPH
120H 29/1800Z 29.1N 67.1W 95 KT 110 MPH

[cycloneye]

BULLETIN
Tropical Storm Humberto Advisory Number 2
NWS National Hurricane Center Miami FL AL082025
1100 PM AST Wed Sep 24 2025

...HUMBERTO EXPECTED TO STRENGTHEN DURING THE COMING DAYS...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...20.7N 55.8W
ABOUT 505 MI...815 KM ENE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...WNW OR 300 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...1007 MB...29.74 INCHES





Tropical Storm Humberto Discussion Number 2
NWS National Hurricane Center Miami FL AL082025
1100 PM AST Wed Sep 24 2025

The cloud pattern of Humberto has changed little in organization
over the past several hours. Some rudimentary convective banding
features are evident but the cold cloud tops are rather fragmented
at this time. Upper-level outflow is being restricted over the
western portion of the circulation, at least partially due to the
outflow from disturbance 94L located near Puerto Rico. The current
intensity estimate is set at 40 kt in agreement with a recently
received scatterometer pass.

The storm center is not yet very well-defined so the initial motion
is a rather uncertain 300/10 kt. Over the next few days, Humberto
should be steered generally west-northwestward to northwestward on
the southwestern side of a subtropical mid-level high pressure area.
The steering scenario for the tropical cyclone will likely become
more complicated in 2-3 days due to the interaction with the
developing system 94L to the west. The official forecast track is
quite similar to the previous one, and roughly in the middle of the
guidance. However, due to the likely complications in the evolution
of the steering flow, there is lower than normal confidence in this
track forecast.

Global models suggest that there will be some relaxation in westerly
vertical wind shear over Humberto in the coming days. This, along
with very warm ocean waters and a moist mid-level air mass, should
lead to strengthening. The system will probably become a hurricane
in a couple of days, and then strengthen into a major hurricane.
The official intensity forecast is in reasonable agreement with the
simple and corrected model consensus, including the latest FSU
Superensemble forecast.


FORECAST POSITIONS AND MAX WINDS

INIT 25/0300Z 20.7N 55.8W 40 KT 45 MPH
12H 25/1200Z 21.4N 56.7W 45 KT 50 MPH
24H 26/0000Z 21.9N 57.3W 50 KT 60 MPH
36H 26/1200Z 22.4N 57.9W 55 KT 65 MPH
48H 27/0000Z 22.9N 58.8W 60 KT 70 MPH
60H 27/1200Z 23.4N 60.1W 70 KT 80 MPH
72H 28/0000Z 24.0N 62.0W 85 KT 100 MPH
96H 29/0000Z 26.3N 66.0W 100 KT 115 MPH
120H 30/0000Z 30.1N 68.9W 100 KT 115 MPH

$$
Forecaster Pasch/Blake

[cycloneye]

BULLETIN
Tropical Storm Humberto Advisory Number 3
NWS National Hurricane Center Miami FL AL082025
500 AM AST Thu Sep 25 2025

...HUMBERTO FORECAST TO STRENGTHEN IN THE COMING DAYS...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...21.2N 56.4W
ABOUT 480 MI...775 KM ENE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...1007 MB...29.74 INCHES



Tropical Storm Humberto Discussion Number 3
NWS National Hurricane Center Miami FL AL082025
500 AM AST Thu Sep 25 2025

Humberto is still a shear tropical storm this morning. Deep
convection is wrapped around the eastern side of the circulation
with the low-level center mostly exposed to the west of the coldest
cloud tops. Objective and subjective satellite Dvorak
classifications have held steady this cycle, ranging from 33 to 41
kts. The initial intensity remains at 40 kt based on the
scatterometer data mentioned in the previous discussion.

The estimated motion is northwestward at 9 kt. Humberto is expected
to be steered along the southern and southwestern side of a
subtropical ridge centered over the western Atlantic. The track
forecast becomes more complicated in the next few days due to the
proximity of the tropical storm to 94L, the developing system to the
west. Global models generally show Humberto moving around the
western periphery of the subtropical high by the end of the forecast
period, however there is quite a bit of uncertainty in the timing
and location at which the storm will make that turn. The GFS and
UKMet show a much faster and farther east track while the ECMWF
predicts a slower and more westward track. The latest official
track forecast is slower and a bit west of the previous prediction,
near the center of the guidance envelope.

Humberto is expected to gradually strengthen during the next couple
of days, despite the strong-to-moderate vertical wind shear. When
the westerly shear relaxes over the storm in 2-3 days, more
signification intensification is expected over the warm ocean
waters. Most model guidance predicts Humberto will reach hurricane
strength over the weekend and become a major hurricane by early next
week. Few changes have been made to the NHC intensity forecast,
which still lies near the FSU Superensemble prediction.


FORECAST POSITIONS AND MAX WINDS

INIT 25/0900Z 21.2N 56.4W 40 KT 45 MPH
12H 25/1800Z 21.7N 57.0W 45 KT 50 MPH
24H 26/0600Z 22.1N 57.6W 50 KT 60 MPH
36H 26/1800Z 22.6N 58.4W 55 KT 65 MPH
48H 27/0600Z 23.0N 59.4W 60 KT 70 MPH
60H 27/1800Z 23.5N 61.0W 75 KT 85 MPH
72H 28/0600Z 24.3N 63.0W 90 KT 105 MPH
96H 29/0600Z 26.7N 66.8W 100 KT 115 MPH
120H 30/0600Z 30.6N 69.3W 95 KT 110 MPH

$$
Forecaster Bucci

[cycloneye]

BULLETIN
Tropical Storm Humberto Advisory Number 4
NWS National Hurricane Center Miami FL AL082025
1100 AM AST Thu Sep 25 2025

...HUMBERTO GAINING STRENGTH...
...EXPECTED TO BECOME A HURRICANE IN A DAY OR SO OVER THE CENTRAL
ATLANTIC...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...21.4N 56.8W
ABOUT 465 MI...750 KM ENE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 8 MPH...13 KM/H
MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES




Tropical Storm Humberto Discussion Number 4
NWS National Hurricane Center Miami FL AL082025
1100 AM AST Thu Sep 25 2025

Deep convection has been increasing near and to the east of the
center of Humberto during the past several hours, but the storm
remains asymmetric due to the effects of wind shear and dry air
entertainment. The initial intensity is increased a little to 45
kt, which is near the high end of the latest satellite estimates.

The tropical storm is expected to continue to battle shear and dry
air associated with a nearby mid- to upper-level trough for another
day or so. However, by the weekend, the models show the upper-level
wind pattern becoming notably more favorable for strengthening.
Based on the current trends and expected conducive conditions, the
NHC intensity forecast has been nudged upward and shows Humberto
becoming a hurricane in a day or so and then rapidly strengthening
to a major hurricane over the weekend. This prediction is roughly
in line with the latest HCCA and IVCN consensus models.

Humberto is currently embedded in weak steering currents on the
south side of a narrow and weak subtropical high over the central
Atlantic. This pattern should keep the storm moving slowly to the
west-northwest or northwest during the next day or two. After that
time, Humberto is expected to become primarily steered by a much
stronger high over the western Atlantic, which should cause the
storm to speed up. The models have trended south and west this
cycle, and the NHC track forecast has been nudged in those
directions. This forecast keeps Humberto over the open central
and western subtropical Atlantic during the next several days.


FORECAST POSITIONS AND MAX WINDS

INIT 25/1500Z 21.4N 56.8W 45 KT 50 MPH
12H 26/0000Z 21.8N 57.3W 50 KT 60 MPH
24H 26/1200Z 22.1N 57.9W 55 KT 65 MPH
36H 27/0000Z 22.4N 58.8W 65 KT 75 MPH
48H 27/1200Z 22.8N 60.1W 75 KT 85 MPH
60H 28/0000Z 23.4N 61.9W 90 KT 105 MPH
72H 28/1200Z 24.2N 64.0W 105 KT 120 MPH
96H 29/1200Z 27.0N 67.8W 105 KT 120 MPH
120H 30/1200Z 30.7N 69.7W 95 KT 110 MPH

$$
Forecaster Cangialosi

[cycloneye]

BULLETIN
Tropical Storm Humberto Advisory Number 5
NWS National Hurricane Center Miami FL AL082025
500 PM AST Thu Sep 25 2025

...HUMBERTO CONTINUES TO STRENGTHEN OVER THE CENTRAL ATLANTIC...
...EXPECTED TO BECOME A HURRICANE ON FRIDAY...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...21.9N 57.0W
ABOUT 470 MI...760 KM NE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/H
PRESENT MOVEMENT...NW OR 320 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...1000 MB...29.53 INCHES



Tropical Storm Humberto Discussion Number 5
NWS National Hurricane Center Miami FL AL082025
500 PM AST Thu Sep 25 2025

Humberto continues to gradually gain strength over the central
Atlantic. Deep convection has been increasing over the center, and
the cloud pattern is more symmetric than it was earlier today. This
is an indication that the wind shear around the storm is lessening.
Recent microwave images indicate that an inner core appears to be
forming, and an earlier ASCAT pass showed maximum winds of about 45
kt. Based on the improving satellite presentation, the initial
intensity is increased to 50 kt. This value is also near the
average of the latest satellite intensity estimates. The 34-kt wind
radii have been adjusted based on the ASCAT data.

Steady to rapid strengthening is expected during the next few days
as the storm moves into a more favorable environment of light winds
aloft and high moisture. Given that Humberto is relatively compact
and an increasingly symmetric system, these conditions should cause
it to become a hurricane on Friday and a major hurricane over the
weekend. Less favorable environmental conditions should cause some
weakening early next week. This prediction remains in line with the
latest HCCA and IVCN consensus models.

The storm has jogged a little to the north today, but the overall
motion is northwestward at 5 kt. Humberto remains embedded in weak
steering currents on the south side of a narrow and weak subtropical
high over the central Atlantic. This pattern should keep the storm
moving slowly to the west-northwest or northwest during the next day
or two. After that time, Humberto is expected to become
increasingly steered by a much stronger high over the western
Atlantic, which should cause the storm to accelerate. The NHC track
forecast is a little slower than the previous one, trending toward
the latest consensus and Google Deep Mind models. This forecast
keeps Humberto over the open central and western subtropical
Atlantic during the next several days.


FORECAST POSITIONS AND MAX WINDS

INIT 25/2100Z 21.9N 57.0W 50 KT 60 MPH
12H 26/0600Z 22.3N 57.4W 60 KT 70 MPH
24H 26/1800Z 22.5N 58.0W 70 KT 80 MPH
36H 27/0600Z 22.7N 59.1W 80 KT 90 MPH
48H 27/1800Z 23.0N 60.8W 90 KT 105 MPH
60H 28/0600Z 23.6N 62.7W 100 KT 115 MPH
72H 28/1800Z 24.6N 64.7W 105 KT 120 MPH
96H 29/1800Z 28.0N 68.2W 105 KT 120 MPH
120H 30/1800Z 31.6N 69.9W 90 KT 105 MPH

$$
Forecaster Cangialosi

[cycloneye]

BULLETIN
Tropical Storm Humberto Advisory Number 6
NWS National Hurricane Center Miami FL AL082025
1100 PM AST Thu Sep 25 2025

...HUMBERTO CONTINUES TO STRENGTHEN OVER THE CENTRAL ATLANTIC...
...EXPECTED TO BECOME A HURRICANE TOMORROW...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...22.2N 57.1W
ABOUT 475 MI...765 KM NE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...65 MPH...100 KM/H
PRESENT MOVEMENT...NW OR 320 DEGREES AT 3 MPH...6 KM/H
MINIMUM CENTRAL PRESSURE...998 MB...29.47 INCHES


Tropical Storm Humberto Discussion Number 6
NWS National Hurricane Center Miami FL AL082025
1100 PM AST Thu Sep 25 2025

Humberto continues to gain strength while moving slowly over the
central Atlantic. The system is exhibiting a growing CDO feature
with cloud tops to near -70 deg C, along with some convective bands
over the eastern portion of the circulation, where most of the
lightning flashes are currently occurring. The advisory intensity
is increased to 55 kt, in agreement with subjective Dvorak
classifications from both TAFB and SAB and a blend of objective
satellite estimates from UW-CIMSS.

The storm's forward speed is quite slow with a motion estimate of
only 320/3 kt. Steering currents are not strong at this time since
the subtropical ridge to the north of Humberto is quite weak.
Global model forecasts show the ridge strengthening with time and in
a few days the cyclone should move somewhat faster toward the
northwest and turn northward in the vicinity of 70 W longitude. By
the end of the forecast period, after Humberto passes north of the
ridge, the system should begin accelerating northeastward.

Cirrus motions indicate that the vertical wind shear over Humberto
has lessened, and the SHIPS model output does not show the shear
increasing much through 72 hours. Sea surface temperatures are
expected to be very warm along the projected path of the cyclone,
and the system should remain embedded in a moist air mass. The
official forecast continues to call for significant strengthening
during the next few days. This is consistent with the latest
corrected consensus, HCCA, forecast which also shows Humberto
intensifying into a major hurricane this weekend.


FORECAST POSITIONS AND MAX WINDS

INIT 26/0300Z 22.2N 57.1W 55 KT 65 MPH
12H 26/1200Z 22.4N 57.6W 65 KT 75 MPH
24H 27/0000Z 22.7N 58.5W 75 KT 85 MPH
36H 27/1200Z 22.9N 59.9W 90 KT 105 MPH
48H 28/0000Z 23.4N 61.8W 105 KT 120 MPH
60H 28/1200Z 24.3N 63.8W 110 KT 125 MPH
72H 29/0000Z 25.4N 65.7W 110 KT 125 MPH
96H 30/0000Z 29.0N 69.0W 100 KT 115 MPH
120H 01/0000Z 32.6N 69.7W 90 KT 105 MPH

$$
Forecaster Pasch

[cycloneye]

BULLETIN
Hurricane Humberto Advisory Number 7
NWS National Hurricane Center Miami FL AL082025
500 AM AST Fri Sep 26 2025

...HUMBERTO BECOMES A HURRICANE...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...22.2N 57.3W
ABOUT 465 MI...750 KM NE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H
PRESENT MOVEMENT...NW OR 320 DEGREES AT 3 MPH...6 KM/H
MINIMUM CENTRAL PRESSURE...990 MB...29.24 INCHES




Hurricane Humberto Discussion Number 7
NWS National Hurricane Center Miami FL AL082025
500 AM AST Fri Sep 26 2025

Humberto has become better organized during the past several hours.
Conventional satellite imagery has shown a growing central dense
overcast, with hints of an eye-like feature near the center.
Microwave imagery revealed a well-defined rain band wrapping around
a vertically-aligned vortex, suggesting the developing of an
eyewall. Satellite classifications have risen notably on this
cycle and the initial intensity is set to 65 kt, closest to the
TAFB Dvorak and SATCON estimates.

The hurricane is drifting slowly in weak steering currents with an
estimated motion of 320/3 kt. Model guidance is in relatively good
agreement, showing Humberto gradually increasing speed while moving
west-northward to northwestward along the southern side of a
subtropical ridge during the next few days. By early next week, the
hurricane is expected to turn northward around the westward
periphery of the high and begin accelerating northeastward. Only
minor adjustments have been made to the latest official track
forecast.

Humberto is showing signs of steady-to-rapid intensification. The
hurricane is over warm waters and seems to be experiencing less
vertical wind shear than the global models are currently suggesting.
Statistical rapid intensity indicators, such as DTOPS, are showing
elevated probabilities of a 25 to 30 kt increase in the next 24
hours. Given these probabilities and the recent increase in initial
intensity, the NHC intensity forecast has been increased,
particularly in the near-term forecast, and lies above most of the
guidance. By the middle of the forecast period, it is closer the
the corrected consensus aid, HCCA, and still shows Humberto becoming
a major hurricane this weekend.


FORECAST POSITIONS AND MAX WINDS

INIT 26/0900Z 22.2N 57.3W 65 KT 75 MPH
12H 26/1800Z 22.3N 57.8W 80 KT 90 MPH
24H 27/0600Z 22.6N 59.0W 90 KT 105 MPH
36H 27/1800Z 22.9N 60.5W 100 KT 115 MPH
48H 28/0600Z 23.5N 62.5W 110 KT 125 MPH
60H 28/1800Z 24.5N 64.2W 115 KT 130 MPH
72H 29/0600Z 26.0N 66.0W 115 KT 130 MPH
96H 30/0600Z 29.7N 68.8W 100 KT 115 MPH
120H 01/0600Z 33.7N 67.8W 85 KT 100 MPH

$$
Forecaster Bucci

[cycloneye]

BULLETIN
Hurricane Humberto Advisory Number 8
NWS National Hurricane Center Miami FL AL082025
1100 AM AST Fri Sep 26 2025

...HUMBERTO RAPIDLY STRENGTHENING OVER THE CENTRAL ATLANTIC...
...EXPECTED TO BECOME A MAJOR HURRICANE LATER TODAY OR ON
SATURDAY...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...22.3N 57.7W
ABOUT 450 MI...725 KM NE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...90 MPH...150 KM/H
PRESENT MOVEMENT...NW OR 315 DEGREES AT 5 MPH...7 KM/H
MINIMUM CENTRAL PRESSURE...979 MB...28.91 INCHES




Hurricane Humberto Discussion Number 8
NWS National Hurricane Center Miami FL AL082025
1100 AM AST Fri Sep 26 2025

Humberto continues to rapidly strengthen this morning. Infrared
satellite images show a ring of deep, cold inner core convection
wrapping around an eye that has recently emerged in conventional
satellite imagery. Objective satellite intensity estimates are
quickly climbing, and the initial intensity is raised to 80 kt for
this advisory, in best agreement with recent UW-CIMSS ADT and AiDT
estimates. A recent ASCAT-B pass over the hurricane was used to
update the 34- and 50-kt wind radii of Humberto.

The rapidly improving satellite structure, along with conducive
environmental and oceanic conditions, suggest that significant to
rapid intensification (RI) is likely to continue in the short term.
In fact, the latest DTOPS guidance shows a greater than 80 percent
chance of Humberto strengthening by 30 kt in the next 24 h. Thus,
rapid intensification is explicitly forecast here, and the NHC
intensity forecast has been raised during the first 48-72 h of the
forecast period. This forecast most closely follows the regional
hurricane models and the HFIP corrected consensus (HCCA), on the
higher end of the guidance envelope. By early next week, there are
indications that deep-layer shear will increase over Humberto, and
some weakening is shown beyond 72 h. Note that as Humberto gains
latitude, the wind field is forecast to expand while the hurricane
curves around Bermuda at days 4-5.

The hurricane is moving slowly northwestward at about 4 kt.
Humberto should move toward the west-northwest and northwest during
the next couple of days along the southern periphery of a
subtropical ridge over the western and central Atlantic. As this
ridge slides eastward, the hurricane is forecast to recurve around
this feature, turning northward and then accelerating northeastward
early next week. The models are in very good agreement on this
sharp recurvature over the western Atlantic, and only minor
adjustments were made to the latest NHC track forecast.


FORECAST POSITIONS AND MAX WINDS

INIT 26/1500Z 22.3N 57.7W 80 KT 90 MPH
12H 27/0000Z 22.5N 58.3W 95 KT 110 MPH
24H 27/1200Z 22.9N 59.6W 105 KT 120 MPH
36H 28/0000Z 23.3N 61.3W 115 KT 130 MPH
48H 28/1200Z 24.1N 63.3W 125 KT 145 MPH
60H 29/0000Z 25.3N 65.2W 125 KT 145 MPH
72H 29/1200Z 26.8N 66.9W 120 KT 140 MPH
96H 30/1200Z 30.6N 68.8W 105 KT 120 MPH
120H 01/1200Z 34.5N 66.0W 90 KT 105 MPH

$$
Forecaster Reinhart

[cycloneye]

BULLETIN
Hurricane Humberto Advisory Number 9
NWS National Hurricane Center Miami FL AL082025
500 PM AST Fri Sep 26 2025

...HUMBERTO RAPIDLY STRENGTHENS TO A MAJOR HURRICANE...
...FURTHER INTENSIFICATION EXPECTED OVER THE CENTRAL ATLANTIC...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...22.3N 58.1W
ABOUT 430 MI...690 KM NE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...115 MPH...185 KM/H
PRESENT MOVEMENT...WNW OR 295 DEGREES AT 5 MPH...7 KM/H
MINIMUM CENTRAL PRESSURE...962 MB...28.41 INCHES



Hurricane Humberto Discussion Number 9
NWS National Hurricane Center Miami FL AL082025
500 PM AST Fri Sep 26 2025

Satellite data indicate Humberto has strengthened into the third
major hurricane of the 2025 Atlantic hurricane season. The eye of
the hurricane has cleared out this afternoon and is surrounded by a
ring of deep, cold convective cloud tops. Based on these
developments, the latest subjective Dvorak classifications and
objective intensity estimates have risen to 90-102 kt. The initial
intensity of Humberto is set at 100 kt for this advisory. NOAA buoy
41044, located about 50 n mi southwest of the center, has reported
falling pressures and tropical-storm-force gusts this afternoon.

Humberto remains in a low shear environment over very warm
sea-surface temperatures, and its well-defined inner core structure
appears conducive to further intensification unless an eyewall
replacement cycle occurs. The latest intensity guidance favors
continued strengthening, and this is reflected in the updated NHC
forecast. There are differences noted in the upper-air pattern of
the global models later in the period, likely related to the
evolution and future path of Potential Tropical Cyclone Nine. But in
general, increasing deep-layer shear over the hurricane should
induce at least gradual weakening by early next week. Although the
peak winds are forecast to decrease, the wind field is expected to
expand as Humberto gains latitude and curves around Bermuda at days
3-5.

The hurricane is moving slowly northwestward (295/4 kt). A slow
westward to west-northwestward motion should continue through the
next day or so, followed by a turn toward the northwest later this
weekend with a gradual increase in forward speed as a subtropical
ridge slides eastward over the central Atlantic. A slight southward
adjustment was made to the near-term NHC track forecast based on
today's trends, but otherwise this portion of the forecast is
similar to the previous one. Later in the period, the models are
fairly consistent on a sharp recurvature of the hurricane between
the ridge and an upper trough digging over the northwestern
Atlantic, though there are larger along-track speed differences
noted. This part of the forecast generally lies between the
multi-model consensus aids and the Google DeepMind solution.


FORECAST POSITIONS AND MAX WINDS

INIT 26/2100Z 22.3N 58.1W 100 KT 115 MPH
12H 27/0600Z 22.4N 59.0W 115 KT 130 MPH
24H 27/1800Z 22.8N 60.5W 125 KT 145 MPH
36H 28/0600Z 23.4N 62.4W 130 KT 150 MPH
48H 28/1800Z 24.6N 64.3W 125 KT 145 MPH
60H 29/0600Z 26.0N 66.0W 120 KT 140 MPH
72H 29/1800Z 27.7N 67.5W 115 KT 130 MPH
96H 30/1800Z 31.7N 68.8W 100 KT 115 MPH
120H 01/1800Z 35.5N 63.5W 90 KT 105 MPH

$$
Forecaster Reinhart

[cycloneye]

BULLETIN
Hurricane Humberto Advisory Number 10
NWS National Hurricane Center Miami FL AL082025
1100 PM AST Fri Sep 26 2025

...HUMBERTO BECOMES A POWERFUL CATEGORY 4 HURRICANE...
...RAPID STRENGTHENING SHOULD CONTINUE OVER THE CENTRAL ATLANTIC...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...22.1N 58.7W
ABOUT 390 MI...630 KM NE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...145 MPH...230 KM/H
PRESENT MOVEMENT...W OR 265 DEGREES AT 7 MPH...11 KM/H
MINIMUM CENTRAL PRESSURE...940 MB...27.76 INCHES




TCDAT3

Hurricane Humberto Discussion Number 10
NWS National Hurricane Center Miami FL AL082025
1100 PM AST Fri Sep 26 2025

Humberto has continued to intensify rapidly this evening. The eye
temperature has increased to 15C and the eyewall white ring (-73C)
is nearly closed. A 2137 UTC WSFM-1 HiRes microwave pass indicated
that a concentric ring was developing about 65 nm from the eye. The
initial intensity is raised to 125 kt and is close to the UW-CIMSS
ADT of T6.4 and above the constrained subjective Dvorak intensity
estimates from TAFB and SAB.

All intensity contributions, low shear, warm waters, and ample
mid-level moisture, appear conducive for Humberto to intensify
rapidly during the next 12-24 hours. DTOPS guidance indicates
a high probability of RI during the next 12-24 hours, and the latest
official intensity forecast follows suit, bringing Humberto to a
peak intensity of 140 kt Saturday night. By the 36 hour period,
however, inner-core fluctuations as a result of eyewall replacement
cycles (ERC) are possible, and it's difficult to forecast the exact
timing. It's worth mentioning, however, that the UW-CIMSS M-PERC
(Microwave-based Probability of Eyewall Replacement Cycle)
statistical model is predicting a 61 percent of onset. By mid-next
week, increasing vertical shear spreading over Humberto should
induce a gradual weakening trend. At the same time, while it passes
west of Bermuda, a significant expansion in the surface wind field
will likely occur. The NHC intensity forecast is just above the
previous forecast through the 36 hour period, and closely follows a
blend of the HCCA consensus and the HAFS/HWRF/HMON hurricane models.

Humberto has taken a trochoidal jog to the left of the track this
evening, likely due to the rapid intensification event. The initial
motion is estimated to be slightly south of due west, or 265/6 kt.
Humberto is expected to move slowly toward the west or
west-northwest during the next day or so in the easterly steering
flow provided by mid-tropospheric high pressure located to the north
of the cyclone and just east of Bermuda. Around the 48 hour period,
or Sunday evening, a northwestward turn with some reduction in
forward speed is forecast while the above-mentioned high pressure
weakens and shifts eastward. By day 4, Humberto should commence a
rather abrupt turn northward and northeastward in response to a
major shortwave upper-level trough amplifying and moving out of
northeastern Canada and into the northwestern Atlantic. The
official track forecast is located just to the left of the previous
advisory, primarily due to the initial motion left of track, and
lies between the HCCA corrected consensus and the Google DeepMind
ensemble model.

NOAA buoy 41044, located about 38 n mi southwest of the center, has
reported falling pressure,sustained tropical-storm-force winds,
gusts just below hurricane-force and 17 ft seas.


FORECAST POSITIONS AND MAX WINDS

INIT 27/0300Z 22.1N 58.7W 125 KT 145 MPH
12H 27/1200Z 22.2N 59.8W 135 KT 155 MPH
24H 28/0000Z 22.7N 61.6W 140 KT 160 MPH
36H 28/1200Z 23.6N 63.5W 135 KT 155 MPH
48H 29/0000Z 24.8N 65.3W 130 KT 150 MPH
60H 29/1200Z 26.2N 67.0W 125 KT 145 MPH
72H 30/0000Z 27.9N 68.2W 115 KT 130 MPH
96H 01/0000Z 32.1N 68.2W 100 KT 115 MPH
120H 02/0000Z 36.0N 62.0W 90 KT 105 MPH

$$
Forecaster Roberts

[cycloneye]

Hurricane Humberto Discussion Number 11
NWS National Hurricane Center Miami FL AL082025
500 AM AST Sat Sep 27 2025

Humberto seems to have paused its meteoric rise for the moment.
The eye has become smaller and more distorted based on GOES
satellite imagery. An AMSR2 microwave pass showed some evidence
that the concentric rings mentioned in the previous discussion have
contracted, indicating an ongoing eyewall replacement cycle. The
microwave images also displayed classic hurricane structure, with
curved banding in all quadrants and no signs of dry air intrusions.
The satellite intensity estimates have leveled off overnight, and
the initial intensity is held at 125 kt, closest to the UW-CIMSS ADT
of T6.3.

While internal dynamics may have interrupted Humberto's
strengthening, the hurricane still has about a day of conducive
environmental and oceanic conditions to intensify. Some of the
regional hurricane models show slight strengthening, though most of
the model guidance suggests Humberto will hold generally steady for
the next couple of days. By next week, the vertical wind shear is
expected to increase and induce a gradual weakening trend. As
Humberto gains latitude, a significant expansion in the surface wind
field will likely occur while it passes west of Bermuda.
Phase-space analyses of global model forecasts by day 5 show
Humberto as an extratropical cyclone, or close to one. The latest
NHC intensity forecast is very similar to the previous prediction
and lies on the high end of the guidance in the short-term.

The hurricane is moving westward at 5 kt. A subtropical ridge
centered over the western Atlantic should slowly steer Humberto to
the west or west-northwest during the next day or so, then turn the
cyclone to the northwest and north-northwest by early next week. By
day 4, an amplifying upper-level trough moving out of the Canadian
Maritimes is expected to rapidly steer Humberto northeastward. The
NHC track forecast shifted slightly eastward this cycle and is a
little quicker at days 4 and 5. It lies between the Google DeepMind
ensemble mean and the previous prediction.

FORECAST POSITIONS AND MAX WINDS

INIT 27/0900Z 22.3N 59.3W 125 KT 145 MPH
12H 27/1800Z 22.6N 60.5W 135 KT 155 MPH
24H 28/0600Z 23.3N 62.3W 140 KT 160 MPH
36H 28/1800Z 24.4N 64.3W 135 KT 155 MPH
48H 29/0600Z 25.8N 66.0W 130 KT 150 MPH
60H 29/1800Z 27.3N 67.3W 125 KT 145 MPH
72H 30/0600Z 29.1N 68.1W 115 KT 130 MPH
96H 01/0600Z 33.4N 66.5W 100 KT 115 MPH
120H 02/0600Z 37.7N 56.4W 90 KT 105 MPH...POST-TROP/EXTRATROP

$$
Forecaster Bucci

[cycloneye]

BULLETIN
Hurricane Humberto Advisory Number 12
NWS National Hurricane Center Miami FL AL082025
1100 AM AST Sat Sep 27 2025

...DANGEROUS SURF FROM MAJOR HURRICANE HUMBERTO EXPECTED TO
AFFECT CARIBBEAN AND BERMUDA SHORES LATER THIS WEEKEND...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...22.7N 60.2W
ABOUT 365 MI...585 KM NNE OF THE NORTHERN LEEWARD ISLANDS
ABOUT 720 MI...1160 KM SSE OF BERMUDA
MAXIMUM SUSTAINED WINDS...145 MPH...230 KM/H
PRESENT MOVEMENT...WNW OR 295 DEGREES AT 8 MPH...13 KM/H
MINIMUM CENTRAL PRESSURE...938 MB...27.70 INCHES




Hurricane Humberto Discussion Number 12
NWS National Hurricane Center Miami FL AL082025
1100 AM AST Sat Sep 27 2025

Since the last advisory, Humberto's eye has once again become better
defined and recent WSF-M microwave imagery at 1001 UTC did not
indicate the presence of concentric eyewalls. Together, these data
suggest Humberto completed its eyewall replacement cycle. Recent
objective and subjective intensity estimates range from near 120 kt
to just below 130 kt, so the initial intensity remains 125 kt.

With the previous eyewall cycle completing, Humberto may resume
strengthening today, and this is still indicated in the official
forecast. Fluctuations in intensity, up or down, will be possible
with with any additional eyewall replacement cycles, and the
predictability of the specific timing of such events is quite low,
even as the SHIPS secondary eyewall prediction indicates a 2 in 3
chance that another one will occur in the next two days. With the
environment otherwise expected to be favorable for strengthening,
the NHC forecast continues to show strengthening and maintains
Humberto at or above its current strength through the weekend. Next
week, Humberto should begin to interact with a mid-latitude trough
and undergo a transformation resulting in a significant expansion of
its surface wind field and eventual extratropical transition. While
Humberto's peak winds should decrease as a result, the spread of its
impacts will likely increase as the cyclone grows in size.

The hurricane has accelerated a little, with a forward speed now
near 7 kt. Humberto will move around the subtropical ridge for the
next few days and then accelerate northeastward as it interacts with
the aforementioned mid-latitude trough. The official forecast is
very similar to the previous one, but with a slightly faster
forward speed. The NHC forecast remains closest to a blend of the
Google DeepMind and NOAA AIGEFS ensemble means, and the previous
official forecast.


FORECAST POSITIONS AND MAX WINDS

INIT 27/1500Z 22.7N 60.2W 125 KT 145 MPH
12H 28/0000Z 23.1N 61.5W 135 KT 155 MPH
24H 28/1200Z 24.1N 63.4W 135 KT 155 MPH
36H 29/0000Z 25.5N 65.3W 135 KT 155 MPH
48H 29/1200Z 27.1N 66.8W 125 KT 145 MPH
60H 30/0000Z 29.0N 67.9W 120 KT 140 MPH
72H 30/1200Z 31.3N 68.2W 105 KT 120 MPH
96H 01/1200Z 35.4N 64.4W 95 KT 110 MPH
120H 02/1200Z 40.8N 50.3W 85 KT 100 MPH...POST-TROP/EXTRATROP

$$
Forecaster D. Zelinsky

[cycloneye]

BULLETIN
Hurricane Humberto Advisory Number 13
NWS National Hurricane Center Miami FL AL082025
500 PM AST Sat Sep 27 2025

...HUMBERTO QUICKLY STRENGTHENS TO A CATEGORY 5 HURRICANE...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...22.9N 61.1W
ABOUT 350 MI...560 KM NNE OF THE NORTHERN LEEWARD ISLANDS
ABOUT 685 MI...1105 KM SSE OF BERMUDA
MAXIMUM SUSTAINED WINDS...160 MPH...260 KM/H
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...925 MB...27.32 INCHES




Hurricane Humberto Discussion Number 13
NWS National Hurricane Center Miami FL AL082025
500 PM AST Sat Sep 27 2025

Humberto has quickly strengthened during the past several hours. A
very symmetric ring of cloud tops colder than -70 deg C now
surrounds the clear eye of the hurricane. At 1800 UTC, the TAFB
subjective Dvorak analysis was 7.0/140 kt. Most of the objective
techniques like the UW-CIMSS ADT and AIDT, as well as the SAB
subjective Dvorak fix supported a slightly lower intensity, closer
to 130 kt. However, since that time, cloud tops around Humberto
have gotten colder and the objective estimates have increased.
Therefore, the intensity has been set at 140 kt, making Humberto the
second category 5 hurricane of the 2025 Atlantic hurricane season.

Some additional strengthening is possible tonight. Internal factors
like eyewall replacement cycles will likely dominate Humberto's
intensity for the next day or two, so fluctuations in maximum wind
speeds are expected. All of the intensity guidance indicates that
some slow weakening is expected to begin by Monday, before Humberto
begins to interact with a mid-latitude trough on Tuesday. The
cyclone should then begin its extratropical transition shortly
thereafter, resulting in a quicker decrease in maximum winds but an
expansion of the overall wind field. Overall, little change was
needed to the official forecast aside from showing a higher
intensity for the first day or two.

Only a slight westward adjustment was made to the track forecast.
Humberto is moving slightly faster, but westward, near 9 kt. The
hurricane is still forecast to move around the subtropical ridge for
the next few days before it interacts with the aforementioned trough
and accelerates quickly northeastward. The spread in the model track
guidance has increased since the last advisory, particularly with
regard to how fast Humberto will accelerate northeastward in 4 or 5
days. Confidence in that aspect of the forecast has therefore
decreased, even though little change was made to the official
forecast. The NHC forecast remains generally based on a blend of the
GDMI, the AIGEFS and HCCA.


FORECAST POSITIONS AND MAX WINDS

INIT 27/2100Z 22.9N 61.1W 140 KT 160 MPH
12H 28/0600Z 23.5N 62.7W 145 KT 165 MPH
24H 28/1800Z 24.7N 64.6W 140 KT 160 MPH
36H 29/0600Z 26.2N 66.1W 135 KT 155 MPH
48H 29/1800Z 28.0N 67.5W 125 KT 145 MPH
60H 30/0600Z 30.0N 68.5W 115 KT 130 MPH
72H 30/1800Z 32.1N 68.5W 105 KT 120 MPH
96H 01/1800Z 36.1N 62.4W 95 KT 110 MPH
120H 02/1800Z 42.5N 46.5W 85 KT 100 MPH...POST-TROP/EXTRATROP

$$
Forecaster D. Zelinsky/Bookbinder

[cycloneye]

BULLETIN
Hurricane Humberto Advisory Number 14
NWS National Hurricane Center Miami FL AL082025
1100 PM AST Sat Sep 27 2025

...CATEGORY 5 HUMBERTO NOW MOVING NORTHWESTWARD OVER THE
SOUTHWESTERN SUBTROPICAL ATLANTIC...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...23.4N 62.1W
ABOUT 365 MI...585 KM N OF THE NORTHERN LEEWARD ISLANDS
ABOUT 635 MI...1025 KM SSE OF BERMUDA
MAXIMUM SUSTAINED WINDS...160 MPH...260 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...924 MB...27.29 INCHES


Hurricane Humberto Discussion Number 14
NWS National Hurricane Center Miami FL AL082025
1100 PM AST Sat Sep 27 2025

Humberto remains a large, powerful hurricane this evening, with a
spectacular satellite presentation. The hurricane has a clear,
19C, symmetric 25 nm wide eye that is surrounded by a white ring
of very, cold (-73C) cloud tops. The most intense deep convection
associated with the eyewall appears to be just east of the surface
center, where -78C (CMG) tops are discernible. Impressive
ventilation aloft is provided by dual outflow channels located over
the north semicircle of the cyclone. The latest subjective Dvorak
data-T numbers from TAFB and SAB, and the various UW-CIMSS objective
estimates support holding the initial intensity at 140 kt.

Humberto could undergo inner core structural changes, which will
likely cause intensity fluctuations during the next 12-24 hours.
In fact, an earlier GPM/GMI overpass revealed a hint of concentric
outer ring development, and the UW-CIMSS MPERC is indicating up to
a 78hance of another ERC event. Afterward, the statistical and
skilled consensus intensity models point toward a gradual weakening
trend beginning around Monday. Through the remaining period,
further weakening at a faster pace is expected while the cyclone
becomes embedded in the strong upper-level westerly flow.

By the 60 hour period, Humberto should continue moving around
the southwestern periphery of a mid-tropospheric ridge located to
the northeast of the cyclone and east of Bermuda. By Tuesday
night, Humberto is forecast to turn north-northeastward while the
ridge mentioned above weakens and shifts eastward. By mid-next
week, Humberto should turn quickly toward the northeast to
east-northeast in response to a major shortwave upper-level trough
amplifying and moving out of the Canadian Maritimes and into the
northwestern Atlantic waters. There remains quite a bit of
along-track spread beyond day 4, which is typically seen when
tropical cyclones move within the mid-latitude upper-westerlies and
commence a structural transition to an extra-tropical cyclone.
The NHC forecast is nudged toward the TVCA simple consensus and the
HCCA corrected aid, and is close to the previous advisory.


FORECAST POSITIONS AND MAX WINDS

INIT 28/0300Z 23.4N 62.1W 140 KT 160 MPH
12H 28/1200Z 24.1N 63.5W 140 KT 160 MPH
24H 29/0000Z 25.4N 65.3W 135 KT 155 MPH
36H 29/1200Z 27.1N 66.9W 130 KT 150 MPH
48H 30/0000Z 29.1N 68.1W 120 KT 140 MPH
60H 30/1200Z 30.9N 68.7W 110 KT 125 MPH
72H 01/0000Z 33.2N 67.8W 100 KT 115 MPH
96H 02/0000Z 37.0N 58.7W 95 KT 110 MPH
120H 03/0000Z 44.7N 41.4W 85 KT 100 MPH...POST-TROP/EXTRATROP

$$
Forecaster Roberts

[cycloneye]

BULLETIN
Hurricane Humberto Advisory Number 15
NWS National Hurricane Center Miami FL AL082025
500 AM AST Sun Sep 28 2025

...EXTREMELY DANGEROUS CATEGORY 4 HUMBERTO MOVING WEST-NORTHWESTWARD
OVER THE SOUTHWESTERN SUBTROPICAL ATLANTIC...
...COULD BRING HAZARDS TO BERMUDA IN A FEW DAYS...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...23.9N 63.3W
ABOUT 585 MI...945 KM S OF BERMUDA
MAXIMUM SUSTAINED WINDS...155 MPH...250 KM/H
PRESENT MOVEMENT...WNW OR 300 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...929 MB...27.44 INCHES


Hurricane Humberto Discussion Number 15
NWS National Hurricane Center Miami FL AL082025
500 AM AST Sun Sep 28 2025

Humberto continues to display a clear, circular eye about 10-15
miles in diameter. Although the eye temperatures are still fairly
warm around 15C, the area of cloud tops colder then -70C has shrunk
a bit in the southwest quadrant, and data-T numbers have
continuously been lower than 7.0 for about 8 hours now. The latest
subjective CI numbers range from 127-140 kt, and the latest
objective intensity estimates range from 125-135 kt. Based on the
above analyses and data, the initial intensity is nudged down to 135
kt.

The initial motion estimate is west-northwestward, or 300 degrees
at 11 kt. Over the next couple of days, Humberto will round the
southwestern periphery of a mid-tropospheric subtropical ridge
located northeast of the cyclone. Humberto will turn northward by
early Tuesday in between the ridge and Tropical Depression Nine,
which should be located to the west-southwest of Humberto. By
Tuesday night, Humberto is forecast to turn north-northeastward
while the aforementioned ridge weakens and shifts eastward.
Humberto should turn quickly toward the northeast to east-northeast
by mid-week in response to a large, amplifying upper-level trough
moving out of the Canadian Maritimes and into the northwestern
Atlantic waters. There remains quite a bit of along-track spread
at days 4 and 5. The new NHC forecast is slightly faster toward
the northwest through 48 h, then lies to the northwest, or left of,
the previous official forecast at 60-72 when it makes its closest
approach to Bermuda. In other words, the new forecast shows the
center passing a bit farther from Bermuda, however, Bermuda still
has roughly a 50 percent chance of getting tropical-storm-force
winds, most likely on Tuesday night and Wednesday.

There have been no recent microwave passes over Humberto in the
last 6 h, but infrared imagery suggests there could be a partial
outer ring trying to become more dominant. SHIPS predictors and
the UW-CIMSS Microwave-based Probability of Eyewall Replace Cycle
(M-PERC) guidance indicate a high likelihood of an eyewall
replacement cycle commencing within the next 12 h. Otherwise,
environmental conditions are pretty favorable for the next 12 h, so
the forecast will show Humberto maintaining its current intensity
for 12 h despite the potential for fluctuations. Thereafter, all
of the intensity guidance points toward gradual weakening as there
is potential for gradually increasing vertical wind shear during
the 36 to 60 hour time frame. By hour 72, Humberto should
encounter significantly stronger upper-level westerly flow and begin
the process of extratropical transition. Extratropical transition
should be complete around 96 h, after Humberto crosses the 26
degree C sea-surface temperature isotherm, as all global models
show a warm front extending northeastward from Humberto by that
time.


FORECAST POSITIONS AND MAX WINDS

INIT 28/0900Z 23.9N 63.3W 135 KT 155 MPH
12H 28/1800Z 24.9N 64.7W 135 KT 155 MPH
24H 29/0600Z 26.4N 66.4W 130 KT 150 MPH
36H 29/1800Z 28.3N 67.8W 120 KT 140 MPH
48H 30/0600Z 30.3N 68.7W 115 KT 130 MPH
60H 30/1800Z 32.5N 68.7W 105 KT 120 MPH
72H 01/0600Z 34.5N 67.1W 95 KT 110 MPH
96H 02/0600Z 38.2N 56.0W 85 KT 100 MPH...POST-TROP/EXTRATROP
120H 03/0600Z 46.4N 37.5W 65 KT 75 MPH...POST-TROP/EXTRATROP

$$
Forecaster Hagen

[cycloneye]

BULLETIN
Hurricane Humberto Advisory Number 16
NWS National Hurricane Center Miami FL AL082025
1100 AM AST Sun Sep 28 2025

...HUMBERTO FORECAST TO REMAIN A POWERFUL MAJOR HURRICANE FOR THE
NEXT SEVERAL DAYS...
...EXPECTED TO PRODUCE DANGEROUS SURF ACROSS THE WESTERN ATLANTIC...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...24.6N 64.3W
ABOUT 450 MI...720 KM N OF THE NORTHERN LEEWARD ISLANDS
ABOUT 535 MI...855 KM S OF BERMUDA
MAXIMUM SUSTAINED WINDS...150 MPH...240 KM/H
PRESENT MOVEMENT...WNW OR 300 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...934 MB...27.58 INCH



Hurricane Humberto Discussion Number 16
NWS National Hurricane Center Miami FL AL082025
1100 AM AST Sun Sep 28 2025

Humberto has weakened slightly, likely the result of an ongoing
eyewall replacement cycle, but it remains a powerful hurricane. The
initial intensity of 130 kt is based primarily on a blend of Final-T
and CI Dvorak values from TAFB. That value is on the high end of the
various objective estimates, but the 1210 UTC UW-CIMSS DPRINT Vmax
value was also 130 kt. For the next day or two, Humberto's intensity
will likely be determined largely by internal dynamics like
additional eyewall replacement cycles, and by how large of an eye it
develops. GPM microwave data from earlier this morning showed the
presence of a very large outer ring of deep convection around
Humberto's center. If that larger ring ultimately replaces
Humberto's eyewall, it could result in the hurricane having a lower
intensity in the short term than currently forecast, but a rapidly
larger extent of hurricane-force winds.

Consequently, the main concern for Humberto going forward is not how
strong it will be, but how large. In addition to the expected
expansion of Humberto's hurricane-force inner core, the
tropical-storm-force wind radii are also expected to expand quickly
in the next few days. As a result of this, even though the core of
Humberto is forecast to move west and then north of Bermuda,
tropical-storm-force impacts appear increasingly likely and tropical
storm watches could be required there later today. Humberto is also
expected to produce swells that affect most of the western Atlantic,
with dangerous surf conditions starting along the U.S. East Coast on
Monday.

Humberto's initial motion hasn't changed, and the track forecast
reasoning is very similar to previous forecasts. Humberto should
move around the southwest periphery of the subtropical ridge for
the next couple of days, moving west of Bermuda on Tuesday. The
hurricane should then accelerate east-northeastward as it becomes
post-tropical. Humberto's winds should expand further as its
intensity gradually decreases through the middle of the week, but it
is forecast to remain a very powerful hurricane-force low, even
after it becomes post-tropical.

KEY MESSAGES:

1. There is an increasing risk of tropical-storm-force winds
affecting Bermuda by late Tuesday. Interests there should monitor
the progress of Humberto and watches could be issued later today.

2. Dangerous marine conditions, including high surf and
life-threatening rip currents, are affecting beaches of the northern
Caribbean, Bahamas, and Bermuda. The dangerous surf conditions are
expected to begin affecting the U.S. East Coast on Monday.

FORECAST POSITIONS AND MAX WINDS

INIT 28/1500Z 24.6N 64.3W 130 KT 150 MPH
12H 29/0000Z 25.7N 65.7W 125 KT 145 MPH
24H 29/1200Z 27.3N 67.2W 120 KT 140 MPH
36H 30/0000Z 29.3N 68.4W 110 KT 125 MPH
48H 30/1200Z 31.6N 69.0W 100 KT 115 MPH
60H 01/0000Z 33.7N 68.3W 95 KT 110 MPH
72H 01/1200Z 35.6N 65.0W 90 KT 105 MPH
96H 02/1200Z 39.7N 51.0W 80 KT 90 MPH...POST-TROP/EXTRATROP
120H 03/1200Z...DISSIPATED

[cycloneye]

BULLETIN
Hurricane Humberto Advisory Number 17
NWS National Hurricane Center Miami FL AL082025
500 PM AST Sun Sep 28 2025

...HUMBERTO EXPECTED TO BRING TROPICAL STORM
CONDITIONS TO BERMUDA ON TUESDAY...
...DANGEROUS SURF WILL AFFECT BERMUDA AND MOST OF THE U.S. EAST
COAST THIS WEEK...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...25.5N 65.4W
ABOUT 525 MI...845 KM NNW OF THE NORTHERN LEEWARD ISLANDS
ABOUT 470 MI...760 KM S OF BERMUDA
MAXIMUM SUSTAINED WINDS...145 MPH...230 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...937 MB...27.67 INCHES



Hurricane Humberto Discussion Number 17
NWS National Hurricane Center Miami FL AL082025
500 PM AST Sun Sep 28 2025

Humberto continues to have a small inner core, surrounded by a much
larger ring of deep convection. This structure is evident in visible
and IR satellite imagery, in which a moat of warmer cloud tops
outside of the inner eyewall has been noted at times during day.
This structure has likely caused Humberto's intensity to decrease
today, and the 125-kt intensity estimate is on the high end of
recent objective and subjective estimates. However, this has also
caused the wind field to increase, which was confirmed by ASCAT data
that arrived shortly after the issuance of the previous advisory. An
Air Force Reserve Hurricane Hunter aircraft is scheduled to
investigate Humberto this evening, which should provide more
information about the strength and structure of the hurricane.

Overall, no significant changes were made to the NHC track,
intensity, or radii forecasts for Humberto. The hurricane should
move west and then north of Bermuda over the next few days while it
slowly weakens but grows in size. Confidence in the forecast through
that period is fairly high, with the model spread being smaller than
normal. The forecast uncertainty is higher after that, but Humberto
is subsequently expected to become a post-tropical frontal low
between 72 and 96 h. Regardless of its exact strength or forward
speed, Humberto will be a strong and large hurricane-strength low
throughout the forecast period, even as its surface circulation will
likely become ill defined by the end of the week. The NHC forecast
is close to a blend of the multi-model consensus and the Google
DeepMind Ensemble Mean at all times.

The primary concerns for Humberto continue to be its production of
dangerous surf which will affect Bermuda and the U.S. East Coast
for the next several days, and the growth of its wind field,
which could result in tropical-storm-force winds
affecting Bermuda by late Tuesday.

KEY MESSAGES:

1. Tropical-storm-force winds could begin to affect Bermuda by late
Tuesday. The Bermuda Weather Service has issued a Tropical Storm
Watch for Bermuda. Interests there should continue to monitor the
progress of Humberto.

2. Dangerous marine conditions, including high surf and
life-threatening rip currents, are affecting beaches of the northern
Caribbean, Bahamas, and Bermuda. The dangerous surf conditions are
expected to begin affecting the U.S. East Coast on Monday.


FORECAST POSITIONS AND MAX WINDS

INIT 28/2100Z 25.5N 65.4W 125 KT 145 MPH
12H 29/0600Z 26.8N 66.6W 120 KT 140 MPH
24H 29/1800Z 28.7N 67.9W 115 KT 130 MPH
36H 30/0600Z 30.8N 68.8W 105 KT 120 MPH
48H 30/1800Z 33.3N 68.7W 95 KT 110 MPH
60H 01/0600Z 35.2N 67.1W 90 KT 105 MPH
72H 01/1800Z 36.4N 62.9W 85 KT 100 MPH
96H 02/1800Z 41.5N 47.0W 80 KT 90 MPH...POST-TROP/EXTRATROP
120H 03/1800Z...DISSIPATED

$$
Forecaster D. Zelinsky

[cycloneye]

BULLETIN
Hurricane Humberto Advisory Number 18
NWS National Hurricane Center Miami FL AL082025
1100 PM AST Sun Sep 28 2025

...AIR FORCE HURRICANE HUNTERS INDICATE HUMBERTO REMAINS A
CATEGORY 4 HURRICANE...
...DANGEROUS SURF WILL AFFECT BERMUDA AND MOST OF THE U.S. EAST
COAST THIS WEEK...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...26.2N 66.2W
ABOUT 585 MI...945 KM NNW OF THE NORTHERN LEEWARD ISLANDS
ABOUT 430 MI...690 KM SSW OF BERMUDA
MAXIMUM SUSTAINED WINDS...140 MPH...220 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...928 MB...27.41 INCHES



Hurricane Humberto Discussion Number 18
NWS National Hurricane Center Miami FL AL082025
1100 PM AST Sun Sep 28 2025

Humberto remains a powerful category 4 hurricane over the
subtropical western Atlantic. The Air Force Hurricane Hunters have
been investigating Humberto this evening and found that the major
hurricane has concentric eyewalls, with a double wind maximum noted
in all quadrants. Based on the flight-level wind data, the initial
intensity is set at 120 kt. Dropsonde data from the aircraft suggest
that the minimum pressure is quite low at 928 mb.

Humberto is moving northwestward at 12 kt in the flow on the
south-southwest side of a subtropical high. The major hurricane is
expected to gradually turn to the north by late Monday and Tuesday
as the high shifts to the east and weakens. After that, a trough is
expected to amplify over the north Atlantic, and that should cause
Humberto to turn sharply and accelerate east-northeastward Tuesday
night and Wednesday. The models are in good agreement, and only
minor changes were made to the previous track forecast. While there
is high confidence that the core of Humberto will miss Bermuda,
there is a possibility of tropical-storm-force winds occurring there
late Tuesday and Wednesday in Humberto's outer bands.

The intensity of Humberto will likely fluctuate over the next 12 to
24 hours, but gradual weakening is expected after that due to
increasing shear and decreasing SSTs. Extratropical transition is
now forecast to be complete by 72 hours when the system is expected
to merge with the aforementioned mid- to upper-level trough and
develop frontal features. The NHC intensity forecast is near the
middle of the guidance envelope. The hurricane is expected to grow
in size as it gains latitude during the next few days, which will
result in a large area of rough seas. See Key Messages below for
more information.

KEY MESSAGES:

1. Tropical-storm-force winds could begin to affect Bermuda by late
Tuesday, and a tropical storm watch is in effect for the island.
Interests there should continue to monitor the progress of Humberto.

2. Dangerous marine conditions, including high surf and
life-threatening rip currents, are affecting beaches of the northern
Caribbean, Bahamas, and Bermuda. The dangerous surf conditions are
expected to begin affecting much of the east coast of the U.S. on
Monday.


FORECAST POSITIONS AND MAX WINDS

INIT 29/0300Z 26.2N 66.2W 120 KT 140 MPH
12H 29/1200Z 27.5N 67.3W 120 KT 140 MPH
24H 30/0000Z 29.5N 68.5W 115 KT 130 MPH
36H 30/1200Z 31.9N 68.9W 105 KT 120 MPH
48H 01/0000Z 34.2N 68.0W 95 KT 110 MPH
60H 01/1200Z 35.9N 64.8W 90 KT 105 MPH
72H 02/0000Z 37.3N 58.7W 85 KT 100 MPH...POST-TROP/EXTRATROP
96H 03/0000Z 43.5N 41.5W 75 KT 85 MPH...POST-TROP/EXTRATROP
120H 04/0000Z...DISSIPATED

$$
Forecaster Cangialosi

[AJC3]

BULLETIN
Hurricane Humberto Intermediate Advisory Number 18A
NWS National Hurricane Center Miami FL AL082025
200 AM AST Mon Sep 29 2025

...CATEGORY 4 HUMBERTO WILL PRODUCE DANGEROUS SURF FOR BERMUDA
AND MOST OF THE U.S. EAST COAST THIS WEEK...


SUMMARY OF 200 AM AST...0600 UTC...INFORMATION
----------------------------------------------
LOCATION...26.7N 66.6W
ABOUT 400 MI...645 KM SSW OF BERMUDA
MAXIMUM SUSTAINED WINDS...140 MPH...220 KM/H
PRESENT MOVEMENT...NW OR 315 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...928 MB...27.41 INCHES

[cycloneye]

BULLETIN
Hurricane Humberto Advisory Number 19
NWS National Hurricane Center Miami FL AL082025
500 AM AST Mon Sep 29 2025

...CATEGORY 4 HUMBERTO EXPECTED TO PRODUCE DANGEROUS SURF FOR
BERMUDA AND MOST OF THE U.S. EAST COAST THIS WEEK...
...TROPICAL STORM CONDITIONS POSSIBLE IN BERMUDA ON TUESDAY...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...27.2N 66.9W
ABOUT 375 MI...600 KM SSW OF BERMUDA
MAXIMUM SUSTAINED WINDS...130 MPH...215 KM/H
PRESENT MOVEMENT...NW OR 320 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...933 MB...27.55 INCHES





Hurricane Humberto Discussion Number 19
NWS National Hurricane Center Miami FL AL082025
500 AM AST Mon Sep 29 2025

Humberto has gone through some inner-core structural changes.
Earlier aircraft data indicated that the hurricane had a double
eyewall structure, but a 29/0546 UTC AMSR2 microwave pass indicates
that the inner eyewall is starting to get overtaken by the outer
eyewall. Given the the apparent continued weakening of the inner
eyewall as inferred from GOES-19 imagery since the time of the
microwave pass, Humberto's maximum sustained winds are probably near
the lower end of the recent objective and subjective estimates, so
the initial intensity is nudged downward slightly to 115 kt.
Another Air Force plane will be in Humberto in a few hours to better
assess the intensity.

Humberto is still moving northwestward, or 320 degrees at 12 kt in
the flow on the south-southwest side of a subtropical high. The
major hurricane is expected to gradually turn to the north over the
next 24 hours as the high shifts to the east and weakens. After
that, a trough is expected to amplify over the north Atlantic, and
that should cause Humberto to turn sharply and accelerate
east-northeastward Tuesday night and Wednesday. The NHC forecast is
similar to the previous one through 24 h, but then has been shifted
slightly to the northwest, or left, of the previous forecast after
that time, close to the latest model consensus. Confidence in the
track forecast is high through 48 h. While there is high confidence
that the core of Humberto will miss Bermuda, there is a possibility
of tropical-storm-force winds occurring there late Tuesday and
Wednesday in Humberto's outer bands.

The intensity of Humberto will likely fluctuate over the next 12 h
or so, but gradual weakening is expected after that due to
increasing shear and decreasing SSTs. Extratropical transition is
expected to be complete in 60-72 hours when the system is forecast
to merge with the aforementioned mid- to upper-level trough and
develop frontal features. The NHC intensity forecast is between the
middle and higher end of the guidance envelope. The hurricane is
expected to grow in size as it gains latitude during the next few
days, which will result in a large area of rough seas. See Key
Messages below for more information.

KEY MESSAGES:

1. Tropical-storm-force winds could begin to affect Bermuda by late
Tuesday, and a tropical storm watch is in effect for the island.
Interests there should continue to monitor the progress of Humberto.

2. Dangerous marine conditions, including high surf and
life-threatening rip currents, are affecting beaches of the northern
Caribbean, Bahamas, and Bermuda. The dangerous surf conditions are
expected to begin affecting much of the east coast of the U.S.
today.


FORECAST POSITIONS AND MAX WINDS

INIT 29/0900Z 27.2N 66.9W 115 KT 130 MPH
12H 29/1800Z 28.6N 68.0W 115 KT 130 MPH
24H 30/0600Z 30.9N 68.9W 105 KT 120 MPH
36H 30/1800Z 33.3N 68.7W 95 KT 110 MPH
48H 01/0600Z 35.4N 66.7W 90 KT 105 MPH
60H 01/1800Z 36.9N 61.7W 85 KT 100 MPH
72H 02/0600Z 39.0N 54.5W 80 KT 90 MPH...POST-TROP/EXTRATROP
96H 03/0600Z...DISSIPATED

$$
Forecaster Hagen