NATL: HUMBERTO - Advisories

[cycloneye]

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

...HUMBERTO A LITTLE STRONGER AND 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 800 AM AST...1200 UTC...INFORMATION
----------------------------------------------
LOCATION...27.5N 67.3W
ABOUT 365 MI...585 KM SSW OF BERMUDA
MAXIMUM SUSTAINED WINDS...145 MPH...230 KM/H
PRESENT MOVEMENT...NW OR 320 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...938 MB...27.70 INCHES

[cycloneye]

BULLETIN
Hurricane Humberto Advisory Number 20
NWS National Hurricane Center Miami FL AL082025
1100 AM AST Mon Sep 29 2025

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


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...28.0N 67.6W
ABOUT 340 MI...550 KM SSW OF BERMUDA
MAXIMUM SUSTAINED WINDS...145 MPH...230 KM/H
PRESENT MOVEMENT...NW OR 325 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...940 MB...27.76 INCHES




Hurricane Humberto Discussion Number 20
NWS National Hurricane Center Miami FL AL082025
1100 AM AST Mon Sep 29 2025

Air Force Reserve Hurricane Hunter aircraft found Humberto has
strengthened this morning. The aircraft depicted that the system has
completed an eyewall replacement cycle, with the outer eyewall as
depicted on earlier microwave imagery now dominant, and the old
inner eyewall has collapsed. The aircraft however did depict that
the eyewall is open on the southwest side which is likely due to the
impacts of increasing wind shear. Maximum flight level winds in the
northeast quadrant were 138 kt, which supported the increased
intensity to 125 kt at the intermediate advisory. Using the latest
hurricane hunter and scatterometer wind data, the wind radii have
been slightly adjusted and the intensity is held at 125 kt for this
advisory.

Humberto is moving northwestward at an estimated motion of 325/ 11
kt, along the southwestern periphery of a mid-level subtropical
ridge. A gradual turn to the north then northeast over the next day
or so is anticipated as the system rounds the western periphery of
the ridge, and the NHC forecast has been shifted slightly to the
left closer to the consensus aids in the short term. The system will
then begin to move northeast to east-northeastward as the system is
picked up by a trough moving into the north Atlantic. The NHC
forecast is similar to the previous through the end of the forecast
period, with a slight nudge towards the latest consensus aids.

Some fluctuations in intensity are possible over the next 12 h or
so. Thereafter, increasing wind shear and cooling sea surface
temperatures should induce a weakening trend. The wind shear will
also cause Humberto become quite asymmetric with most of the
convection displaced to the eastern side of the circulation. In
about 60 h, global models depict that the system should merge with
the previously mentioned trough digging across the north Atlantic
and develop frontal features. As the system becomes extratropical
across the north Atlantic, the wind field is anticipated to grow in
size. The latest NHC intensity forecast lies on the higher end of
the guidance envelope given the latest increase in intensity, and
then shows weakening throughout the period. By 96h, the system is
expected to dissipate and merge within the larger trough.

Along the forecast track, Humberto is expected to move to the west
and north of Bermuda, although there is a possibility of
tropical-storm-force winds occuring over the island late Tuesday and
Wednesday within outer rainbands.

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 29/1500Z 28.0N 67.6W 125 KT 145 MPH
12H 30/0000Z 29.6N 68.5W 115 KT 130 MPH
24H 30/1200Z 32.1N 69.0W 105 KT 120 MPH
36H 01/0000Z 34.4N 67.9W 95 KT 110 MPH
48H 01/1200Z 36.1N 64.5W 90 KT 105 MPH
60H 02/0000Z 37.4N 58.5W 80 KT 90 MPH...POST-TROP/EXTRATROP
72H 02/1200Z 40.6N 49.0W 75 KT 85 MPH...POST-TROP/EXTRATROP
96H 03/1200Z...DISSIPATED

$$
Forecaster Kelly

[cycloneye]

BULLETIN
Hurricane Humberto Intermediate Advisory Number 20A
NWS National Hurricane Center Miami FL AL082025
200 PM AST Mon Sep 29 2025

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


SUMMARY OF 200 PM AST...1800 UTC...INFORMATION
----------------------------------------------
LOCATION...28.5N 67.9W
ABOUT 320 MI...515 KM SW OF BERMUDA
MAXIMUM SUSTAINED WINDS...140 MPH...220 KM/H
PRESENT MOVEMENT...NNW OR 330 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...942 MB...27.82 INCHES

[cycloneye]

BULLETIN
Hurricane Humberto Advisory Number 21
NWS National Hurricane Center Miami FL AL082025
500 PM AST Mon Sep 29 2025

...HUMBERTO PRODUCING DANGEROUS SURF AND RIP CURRENTS FOR BERMUDA
AND MOST OF THE U.S. EAST COAST...
...GUSTY WINDS AND HEAVY RAINFALL FROM OUTER RAINBANDS ARE POSSIBLE
ACROSS BERMUDA TUESDAY INTO WEDNESDAY...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...29.1N 68.1W
ABOUT 295 MI...475 KM SW OF BERMUDA
MAXIMUM SUSTAINED WINDS...140 MPH...220 KM/H
PRESENT MOVEMENT...NNW OR 330 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...942 MB...27.82 INCHES






Hurricane Humberto Discussion Number 21
NWS National Hurricane Center Miami FL AL082025
500 PM AST Mon Sep 29 2025

After some brief re-intensification this morning, satellite imagery
depicts that Humberto has started to feel the impacts of wind shear.
The ring of deep convection has become a little more broken on
infrared imagery, particularly on the western side of the system.
Earlier Hurricane Hunter aircraft data depicted that the eyewall was
open on the southwest side, and recent microwave imagery shows that
the eyewall may be completely open on the western side. As the
previous aircraft was departing, the pressure had come up a couple
millibars which also suggests the system may have begun to weaken,
and thus that trend is followed in this advisory. Using the latest
satellite trends, and a combination of intensity estimates with
previous aircraft data, the intensity is lowered to 120 kt for this
advisory. Another Air Force Reserve Hurricane Hunter aircraft is
scheduled to investigate the system late this evening to help
evaluate the intensity and structure of the system.

Humberto is moving north-northwestward at an estimated motion of
330/11 kt. The system should continue to round the western
periphery of the mid-level ridge and gradually turn to the north
then northeast over the next day or so. A trough moving into the
northern Atlantic will then pick up the system, and cause Humberto
to accelerate to the northeast to east-northeast over the next
several days. There is slightly more along-track spread with the
forward speed towards the end of the forecast period in the latest
guidance envelope. The NHC track forecast is near the previous one,
however slightly slower at long range, and lies near the consensus
track aids.

A weakening trend has started with Humberto, as wind shear appears
to have started to disrupt the circulation. Wind shear is forecast
to continue increasing over the system, and sea surface temperatures
will also cool along the forecast track. Model simulated IR images
depicts that Humberto will become more asymmetric with most of the
convection displaced to the eastern side of the circulation due to
the shear. In about 60 h, both the GFS and ECMWF guidance depict
that the system should merge with the previously mentioned trough
digging across the north Atlantic and develop frontal features. As
the system becomes extratropical across the north Atlantic, the wind
field is anticipated to grow in size. The latest NHC intensity
forecast lies on the higher end of the guidance envelope given the
latest increase in intensity, and then shows weakening throughout
the period. By 96h, the system is expected to dissipate and merge
within the larger trough.

Along the forecast track, Humberto is expected to move to the west
and north of Bermuda, gusty winds and heavy rainfall are possible
within outer rainbands late Tuesday and Wednesday.

KEY MESSAGES:

1. Gusty winds and heavy rainfall are possible within outer
rainbands of Humberto. The Tropical Storm Watch has been replaced
with a Hurricane Watch, due to the forecast of Imelda. Please follow
local updates from Bermuda Weather Service for impacts from
Humberto.

2. Dangerous marine conditions, including high surf and
life-threatening rip currents, are affecting beaches of the northern
Caribbean, Bahamas, Bermuda, and much of the east coast of the
United States.


FORECAST POSITIONS AND MAX WINDS

INIT 29/2100Z 29.1N 68.1W 120 KT 140 MPH
12H 30/0600Z 30.8N 68.8W 105 KT 120 MPH
24H 30/1800Z 33.4N 68.6W 90 KT 105 MPH
36H 01/0600Z 35.4N 66.4W 85 KT 100 MPH
48H 01/1800Z 36.8N 61.8W 75 KT 85 MPH
60H 02/0600Z 38.4N 54.9W 65 KT 75 MPH...POST-TROP/EXTRATROP
72H 02/1800Z 41.5N 46.0W 60 KT 70 MPH...POST-TROP/EXTRATROP
96H 03/1800Z...DISSIPATED

$$
Forecaster Kelly

[cycloneye]

BULLETIN
Hurricane Humberto Advisory Number 22
NWS National Hurricane Center Miami FL AL082025
1100 PM AST Mon Sep 29 2025

...DANGEROUS SURF AND RIP CURRENTS EXPECTED ACROSS BERMUDA, THE
NORTHERN CARIBBEAN, THE BAHAMAS, AND THE U.S. EAST COAST THROUGH
THE WEEK...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...30.1N 68.5W
ABOUT 265 MI...430 KM SW OF BERMUDA
MAXIMUM SUSTAINED WINDS...115 MPH...185 KM/H
PRESENT MOVEMENT...NNW OR 335 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...963 MB...28.44 INCHES





Hurricane Humberto Discussion Number 22
NWS National Hurricane Center Miami FL AL082025
1100 PM AST Mon Sep 29 2025

Northwesterly vertical wind shear is causing Humberto to lose
strength tonight. Geostationary satellite and microwave images
indicate that the cloud pattern has become asymmetric with the
inner core now fragmented and located near the western edge of the
cloud mass. The Air Force Hurricane Hunters have been investigating
the hurricane over the past few hours and have found that the
minimum pressure has increased to around 963 mb. The aircraft data
also indicate that the maximum winds have lowered to around 100 kt.

Humberto is moving north-northwestward at 12 kt on the southwest
side of a subtropical ridge. The hurricane should turn northward on
Tuesday as the ridge shifts east and weakens. On Wednesday, a mid-
to upper-level trough is expected to amplify over the north
Atlantic, causing Humberto to turn sharply to the northeast or
east-northeast and accelerate. The models are in good agreement,
and no significant changes were made to the previous forecast.
This track takes the core of Humberto well west and then north of
Bermuda.

Continued steady weakening is expected as northwesterly vertical
wind shear and intrusions of dry air persist over the next day or
two. By late Wednesday, Humberto is expected to merge with a mid-
to upper-level trough, and that should cause the system to develop
frontal features and complete extratropical transition. Humberto is
expected to grow significantly in size as it becomes extratropical.
The large extratropical low in combination with Imelda will cause
rough marine conditions over a large portion of the western and
central Atlantic. See Key Messages below for more information.

KEY MESSAGES:

1. Humberto's outer rainbands could produce gusty winds and heavy
rainfall over Bermuda on Tuesday and Wednesday. Please follow
local updates from the Bermuda Weather Service for impacts from
both Humberto and Imelda.

2. Dangerous marine conditions, including high surf and
life-threatening rip currents, will continue to affect beaches of
the northern Caribbean, Bahamas, Bermuda, and much of the east coast
of the United States through the week.


FORECAST POSITIONS AND MAX WINDS

INIT 30/0300Z 30.1N 68.5W 100 KT 115 MPH
12H 30/1200Z 32.0N 68.8W 85 KT 100 MPH
24H 01/0000Z 34.4N 67.7W 75 KT 85 MPH
36H 01/1200Z 36.1N 64.5W 70 KT 80 MPH
48H 02/0000Z 37.4N 58.6W 70 KT 80 MPH...POST-TROP/EXTRATROP
60H 02/1200Z 39.8N 50.4W 65 KT 75 MPH...POST-TROP/EXTRATROP
72H 03/0000Z 43.4N 40.1W 60 KT 70 MPH...POST-TROP/EXTRATROP
96H 04/0000Z...DISSIPATED

$$
Forecaster Cangialosi

[cycloneye]

BULLETIN
Hurricane Humberto Advisory Number 23
NWS National Hurricane Center Miami FL AL082025
500 AM AST Tue Sep 30 2025

...DANGEROUS SURF AND RIP CURRENTS EXPECTED ACROSS BERMUDA, THE
NORTHERN CARIBBEAN, THE BAHAMAS, AND THE U.S. EAST COAST THROUGH
THE WEEK...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...31.6N 69.4W
ABOUT 275 MI...440 KM W OF BERMUDA
MAXIMUM SUSTAINED WINDS...100 MPH...155 KM/H
PRESENT MOVEMENT...NNW OR 340 DEGREES AT 17 MPH...28 KM/H
MINIMUM CENTRAL PRESSURE...972 MB...28.71 INCHES




Hurricane Humberto Discussion Number 23
NWS National Hurricane Center Miami FL AL082025
500 AM AST Tue Sep 30 2025

Humberto is a highly sheared hurricane. Strong westerly vertical
wind shear has caused the cyclone to continue its weakening trend.
This is well-demonstrated by a recent AMSR2 microwave image, which
shows that the convection has been sheared off from the western half
of Humberto's circulation. Although the low-level center is still
underneath the convective area in GOES-19 imagery, it's close to the
western edge of the convection. The cyclone has taken on an
elongated comma shape, with deep convection extending well off to
the southeast. Subjective intensity estimates range from 77-90 kt,
and objective intensity estimates from UW-CIMSS range from 70-85 kt.
The advisory intensity is adjusted downward to 85 kt based primarily
on this data, and also taking into account ASCAT and Air Force
Hurricane Hunter data from 8-9 hours ago.

Humberto is moving toward the north-northwest, or 340 degrees at 15
kt, in between a subtropical ridge to its east and Tropical Storm
Imelda to its west. Humberto has tracked farther west than the
previous NHC track forecast. A northward turn is expected over the
next few hours as the ridge shifts east and weakens. On Wednesday,
a very large mid- to upper-level trough is expected to amplify over
the north Atlantic, causing Humberto to turn sharply to the
east-northeast and accelerate. The NHC track forecast has been
adjusted well to the left of the previous forecast at the 12 and 24
hour points, and is a bit slower than the previous forecast at 36-48
hours. The new NHC forecast is very near the various consensus
aids. This track takes the core of Humberto well west and then
north of Bermuda.

Steady weakening is expected over the next 12 h as northwesterly
vertical wind shear and intrusions of dry air persist, followed by
more gradual weakening over the next day or two. By late Wednesday,
Humberto is expected to merge with a mid-to upper-level trough, and
that should cause the system to quickly develop frontal features and
complete extratropical transition. The global models agree that
Humberto will then become extremely elongated along the front and
will likely no longer have a closed circulation by Thursday
afternoon, so the new NHC forecast has moved forward the time of
dissipation. It is important to convey that Humberto is forecast to
be a large and powerful cyclone until it dissipates on Thursday.
The large extratropical low in combination with Imelda will cause
rough marine conditions over a large portion of the western and
central Atlantic. See Key Messages below for more information.

KEY MESSAGES:

1. Humberto's outer rainbands could produce gusty winds and heavy
rainfall over Bermuda today and Wednesday. Please follow local
updates from the Bermuda Weather Service for impacts from both
Humberto and Imelda.

2. Dangerous marine conditions, including high surf and
life-threatening rip currents, will continue to affect beaches of
the northern Caribbean, Bahamas, Bermuda, and much of the east coast
of the United States through the week.


FORECAST POSITIONS AND MAX WINDS

INIT 30/0900Z 31.6N 69.4W 85 KT 100 MPH
12H 30/1800Z 33.5N 69.4W 75 KT 85 MPH
24H 01/0600Z 35.5N 67.7W 75 KT 85 MPH
36H 01/1800Z 36.5N 63.8W 70 KT 80 MPH...POST-TROP/EXTRATROP
48H 02/0600Z 37.3N 57.9W 60 KT 70 MPH...POST-TROP/EXTRATROP
60H 02/1800Z...DISSIPATED

$$
Forecaster Hagen

[cycloneye]

BULLETIN
Hurricane Humberto Advisory Number 24
NWS National Hurricane Center Miami FL AL082025
1100 AM AST Tue Sep 30 2025

...HUMBERTO GENERATING DANGEROUS SURF AND RIP CURRENTS ACROSS THE
WESTERN ATLANTIC THROUGH THE WEEK...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...33.0N 69.9W
ABOUT 300 MI...485 KM W OF BERMUDA
MAXIMUM SUSTAINED WINDS...80 MPH...130 KM/H
PRESENT MOVEMENT...NNW OR 340 DEGREES AT 18 MPH...30 KM/H
MINIMUM CENTRAL PRESSURE...979 MB...28.91 INCHES



Hurricane Humberto Discussion Number 24
NWS National Hurricane Center Miami FL AL082025
1100 AM AST Tue Sep 30 2025

Humberto is quickly decoupling. Strong westerly vertical wind shear
has exposed the low-level circulation, with a curved band of deep
convection still present in the northeastern quadrant. The Air
Force Hurricane Hunters have just completed their final mission into
Humberto, finding peak flight-level winds of 77 kt and a rising
central minimum pressure. The initial intensity has been lowered to
a possibly generous 70 kt.

The hurricane is moving at an estimated 340/16 kt. Humberto is
expect to turn northward and north-northeastward later today,
followed by a turn to the east-northeast on Wednesday with an
increase in forward motion as the hurricane merges with a large mid-
to upper-level trough over the north Atlantic. The latest
official track forecast has shifted slightly to the west, largely
due to the current north-northwest motion.

Humberto should gradually weaken while it transitions into a strong
extratropical cyclone. Global models suggest this transition will
occur sooner than previously expected, and the official forecast now
shows Humberto as an extratropical cyclone by Wednesday. By
Thursday, the cyclone is forecast to elongate along a frontal
boundary extending southwestward toward Imelda and lose its closed
circulation. The hurricane is producing a large area of hazardous
marine conditions over the western and central Atlantic, where
life-threatening rip currents are expected to affect beaches along
the eastern seaboard through the week.

KEY MESSAGES:

1. Dangerous marine conditions, including high surf and
life-threatening rip currents, will continue to affect beaches of
the northern Caribbean, Bahamas, Bermuda, and much of the east coast
of the United States through the week.


FORECAST POSITIONS AND MAX WINDS

INIT 30/1500Z 33.0N 69.9W 70 KT 80 MPH
12H 01/0000Z 34.8N 69.1W 70 KT 80 MPH
24H 01/1200Z 36.2N 66.4W 65 KT 75 MPH...POST-TROP/EXTRATROP
36H 02/0000Z 37.0N 61.5W 60 KT 70 MPH...POST-TROP/EXTRATROP
48H 02/1200Z...DISSIPATED

$$
Forecaster Bucci

[cycloneye]

BULLETIN
Hurricane Humberto Advisory Number 25
NWS National Hurricane Center Miami FL AL082025
500 PM AST Tue Sep 30 2025

...DANGEROUS SURF AND RIP CURRENTS IMPACTING THE WESTERN ATLANTIC
COASTLINE THROUGH THE WEEK...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...34.0N 69.5W
ABOUT 295 MI...475 KM WNW OF BERMUDA
MAXIMUM SUSTAINED WINDS...80 MPH...130 KM/H
PRESENT MOVEMENT...N OR 10 DEGREES AT 17 MPH...28 KM/H
MINIMUM CENTRAL PRESSURE...979 MB...28.91 INCHES




Hurricane Humberto Discussion Number 25
NWS National Hurricane Center Miami FL AL082025
500 PM AST Tue Sep 30 2025

Deep convection has persisted in the northeast quadrant through the
day and is now partially obscuring the low-level circulation. An
afternoon AMSR2 microwave satellite pass showed curved band wrapping
around eastern semicircle of the hurricane. Given the slightly
improved satellite presentation and the earlier aircraft data, the
initial intensity remains at 70 kt. The wind radii have been updated
based on a couple scatterometer passes from 1339 and 1500 UTC.

Humberto has turned northward and is moving an estimated 15 kt as
the hurricane nears the mid-latitude trough to its north. Later
today, the cyclone is expected to turn northeast and on Wednesday to
the east-northeast in the westerly flow. Only minor updates have
made to the latest NHC track forecast, which lies on the leading
edge of the track guidance envelope.

Model guidance suggests Humberto should gradually weaken while it
merges with the mid- to upper-level trough during the next day or
so. Humberto's dissipation has once again been moved up based on
recent model trends, now at 36 h. While the official intensity
forecast shows Humberto becoming an extratropical cyclone on
Wednesday, the European model is showing the potential that it could
retain deep organized convection up until the cyclone becomes
elongated and loses its closed surface circulation. The hurricane
is producing a large area of hazardous marine conditions over the
western and central Atlantic, where life-threatening rip currents
are expected to affect beaches throughout the region through the
week.

KEY MESSAGES:

1. Dangerous marine conditions, including high surf and
life-threatening rip currents, will continue to affect beaches of
the northern Caribbean, Bahamas, Bermuda, and much of the east coast
of the United States through the week.


FORECAST POSITIONS AND MAX WINDS

INIT 30/2100Z 34.0N 69.5W 70 KT 80 MPH
12H 01/0600Z 35.3N 68.3W 65 KT 75 MPH
24H 01/1800Z 36.1N 65.0W 60 KT 70 MPH...POST-TROP/EXTRATROP
36H 02/0600Z...DISSIPATED

$$
Forecaster Bucci

[cycloneye]

BULLETIN
Hurricane Humberto Advisory Number 26
NWS National Hurricane Center Miami FL AL082025
1100 PM AST Tue Sep 30 2025

...HUMBERTO LIKELY TO MERGE WITH A FRONTAL BOUNDARY ON WEDNESDAY...
...DANGEROUS SURF AND RIP CURRENTS TO CONTINUE ACROSS THE WESTERN
ATLANTIC COASTLINE THROUGH THE WEEK...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...34.8N 68.5W
ABOUT 275 MI...440 KM NW OF BERMUDA
MAXIMUM SUSTAINED WINDS...80 MPH...130 KM/H
PRESENT MOVEMENT...ENE OR 65 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...979 MB...28.91 INCHES




Hurricane Humberto Discussion Number 26
NWS National Hurricane Center Miami FL AL082025
1100 PM AST Tue Sep 30 2025

Humberto continues to produce a very large area of deep convection,
primarily to the northeast of its circulation center. However, a
2106 UTC GPM microwave pass received after the prior advisory still
showed the low-level center was mostly exposed on the southwest edge
of the cirrus canopy. Satellite estimates have only been in the
45-55 kt range for the last 6-12 hours. However, a recently received
ASCAT pass showed a peak wind retrieval of 61 kt, and assuming the
significant low bias of this instrument at hurricane intensity, the
initial intensity is being held at 70 kt for this advisory. Wind
radii were also adjusted based on the scatterometer data.

The hurricane appears to have made an east-northeastward turn, but
has not accelerated, with the motion estimated at 065/9 kt. A
longwave mid-latitude trough located to the north of Humberto is
quickly dropping southward and will soon start to impinge upon the
hurricane's circulation. The resulting interaction should cause a
strengthening frontal boundary to form to the northeast of
Humberto's center. In fact, the scatterometer data already shows
this boundary beginning to develop in the convection. The global and
hurricane-regional model fields now show Humberto's circulation
quickly becoming indistinguishable from the intensifying baroclinic
zone in 18-24 h. The latest NHC track and intensity forecast will
now show Humberto merging with this boundary by that time. The
remnant vorticity of the storm may ultimately be advected
towards Imelda's circulation beyond that time frame, as it also
interacts with the same boundary.

Regardless of Humberto's evolution, the hurricane, in combination
with Imelda is producing a large area of hazardous marine conditions
over the western and central Atlantic, where life-threatening rip
currents are expected to affect beaches throughout the region
through the week.

KEY MESSAGES:

1. Dangerous marine conditions, including high surf and
life-threatening rip currents, will continue to affect beaches of
the northern Caribbean, Bahamas, Bermuda, and much of the east coast
of the United States through the week.


FORECAST POSITIONS AND MAX WINDS

INIT 01/0300Z 34.8N 68.5W 70 KT 80 MPH
12H 01/1200Z 35.3N 67.4W 65 KT 75 MPH
24H 02/0000Z...MERGED WITH A FRONTAL BOUNDARY

$$
Forecaster Papin

[cycloneye]

BULLETIN
Hurricane Humberto Advisory Number 27
NWS National Hurricane Center Miami FL AL082025
500 AM AST Wed Oct 01 2025

...HUMBERTO LIKELY TO MERGE WITH A FRONTAL BOUNDARY TONIGHT...
...DANGEROUS SURF AND RIP CURRENTS TO CONTINUE ACROSS THE WESTERN
ATLANTIC COASTLINE THROUGH THE WEEK...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...35.8N 67.3W
ABOUT 280 MI...450 KM NNW OF BERMUDA
MAXIMUM SUSTAINED WINDS...80 MPH...130 KM/H
PRESENT MOVEMENT...NE OR 55 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...979 MB...28.91 INCHES



Hurricane Humberto Discussion Number 27
NWS National Hurricane Center Miami FL AL082025
500 AM AST Wed Oct 01 2025

GOES-19 satellite images indicate that the convective structure of
Humberto has started to deteriorate over the past few hours, with
the convection outrunning the low-level center towards the
east-northeast. If this trend continues, it won't take much longer
for Humberto's center to be exposed. Subjective Dvorak CI numbers
range from 55-77 kt, while recent UW-CIMSS objective intensity
estimates have been ranging a bit lower from 53-63 kt. Earlier
ASCAT data had 61-kt retrievals. The initial intensity is held at
70 kt for this advisory.

The initial motion is estimated towards the northeast, or 055/12 kt.
An acceleration towards the east-northeast is expected today
within the mid-latitude westerlies. A longwave mid-latitude trough
located to the north of Humberto is quickly dropping southward and
is starting to impinge upon the hurricane's circulation. The
resulting interaction is causing a strengthening frontal boundary
to extend east-northeastward from close to the cyclone center.
Given recent satellite trends as well as the solutions depicted by
the latest GFS and ECMWF models, it appears likely that Humberto
will become fully frontal, and thus extratropical, later this
morning. After that, the global and regional models agree that the
cyclone should quickly become elongated along the frontal boundary
and dissipate this evening.

Hurricanes Humberto and Imelda are producing a large area of
hazardous marine conditions over the western and central Atlantic,
where life-threatening rip currents are expected to continue
affecting beaches throughout the region through the week.

KEY MESSAGES:

1. Dangerous marine conditions, including high surf and
life-threatening rip currents, will continue to affect beaches of
the northern Caribbean, the Bahamas, Bermuda, and much of the east
coast of the United States during the next several days.


FORECAST POSITIONS AND MAX WINDS

INIT 01/0900Z 35.8N 67.3W 70 KT 80 MPH
12H 01/1800Z 36.4N 64.4W 65 KT 75 MPH...POST-TROP/EXTRATROP
24H 02/0600Z...DISSIPATED

$$
Forecaster Hagen

[cycloneye]

BULLETIN
Remnants Of Humberto Advisory Number 28
NWS National Hurricane Center Miami FL AL082025
1100 AM AST Wed Oct 01 2025

...HUMBERTO HAS MERGED WITH A FRONT...
...THIS IS THE LAST ADVISORY...
...DANGEROUS SURF AND RIP CURRENTS TO CONTINUE ACROSS THE WESTERN
ATLANTIC COASTLINE THROUGH THE WEEK...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...37.0N 63.0W
ABOUT 340 MI...550 KM NNE OF BERMUDA
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H
PRESENT MOVEMENT...ENE OR 70 DEGREES AT 23 MPH...37 KM/H
MINIMUM CENTRAL PRESSURE...980 MB...28.94 INCHES