CPAC: GREG - Remnants - Discussion

[cycloneye]

Western East Pacific (EP99):
Satellite-derived winds indicate that the area of low pressure
located about 1300 miles east-southeast of the Hawaiian Islands has
a well-defined circulation. Showers and thunderstorms continue to
show signs of organization and any increase in this activity is
likely to lead to the formation of a tropical depression either
tonight or on Monday. The system is expected to move westward to
west-northwestward, crossing into the Central Pacific basin late
tonight.
* Formation chance through 48 hours...high...90 percent.
* Formation chance through 7 days...high...90 percent.

[cycloneye]

Moves to CPAC and up to 30kt.

EP, 99, 2023081400, , BEST, 0, 114N, 1381W, 30, 1007, LO

[Yellow Evan]

1381W is not the CPAC.

[Yellow Evan]

EP, 08, 2023081400, , BEST, 0, 114N, 1381W, 30, 1007, TD

[Yellow Evan]

TXPZ24 KNES 140025
TCSENP

A. TROPICAL DISTURBANCE (99E)

B. 14/0000Z

C. 11.2N

D. 138.2W

E. THREE/GOES-W

F. T2.0/2.0

G. IR/EIR/VIS

H. REMARKS...CONVECTION WRAPS JUST OVER .3 ON LOG10 SPIRAL YIELDING A
DT OF 2.0. MET = 1.5 AND PT = 2.0. THE FT IS BASED ON THE DT.

I. ADDL POSITIONS

NIL


...KIBLER

[Sciencerocks]

[cycloneye]

Tropical Depression Eight-E Discussion Number 1
NWS National Hurricane Center Miami FL EP082023
500 PM HST Sun Aug 13 2023

The low pressure system that NHC has been monitoring over the far
western portion of the east Pacific basin has become a tropical
depression. An ASCAT pass from several hours ago revealed that
the system has a well-defined circulation and recent infrared
satellite images indicate that deep convection has been persisting
near and to the west of the center. Based on the ASCAT data and
Dvorak estimates of T1.5 and T2.0 from TAFB and SAB, respectively,
the initial intensity is set at 30 kt.

The depression is moving west-northward at 12 kt. A westward to
west-northwestward motion is expected during the next few days as
the system remains steered by a mid-level ridge to its northeast
and moves toward a weakness in that ridge. Beyond a few days, a
turn to the west is forecast as the weakening system moves in the
low- to mid-level flow. The models are in good agreement and show
this system moving well to the south of the Hawaiian Islands. This
forecast lies near the middle of the guidance envelope.

The depression is in generally conducive conditions to strengthen
during the next couple of days while it remains over warm waters
and in a relatively moist and low wind shear environment. Beyond
that time, however, increasing shear, drier air, and slightly
cooler waters should cause a slow weakening trend. There is not a
significant spread in the intensity models and none of them show
this system reaching hurricane strength. The NHC intensity
forecast is in good agreement with the HCCA and IVCN models.

The depression should cross into the central Pacific basin by 1200
UTC.

FORECAST POSITIONS AND MAX WINDS

INIT 14/0300Z 11.4N 138.6W 30 KT 35 MPH
12H 14/1200Z 11.5N 140.3W 35 KT 40 MPH
24H 15/0000Z 11.6N 142.8W 40 KT 45 MPH
36H 15/1200Z 11.9N 145.2W 45 KT 50 MPH
48H 16/0000Z 12.4N 147.8W 50 KT 60 MPH
60H 16/1200Z 13.0N 150.0W 50 KT 60 MPH
72H 17/0000Z 13.6N 152.6W 45 KT 50 MPH
96H 18/0000Z 13.6N 157.7W 40 KT 45 MPH
120H 19/0000Z 12.9N 162.6W 35 KT 40 MPH

$$
Forecaster Cangialosi

[ElectricStorm]

Now the question is will it be Greg or Hone... I'm kinda hoping for Hone, would be neat to finally break the CPAC name drought dating back to 2019

[Extratropical94]

EP, 08, 2023081406, , BEST, 0, 113N, 1392W, 30, 1007, TD

Looks like Hone, unless the NHC decides to upgrade at 9Z for whatever reason. 08E will most likely be in the CPAC by 12Z.

[Subtrop]

EP, 08, 2023081406, , BEST, 0, 113N, 1392W, 35, 1005, TS, 34, NEQ, 30, 0, 0, 30, 1011, 150, 30, 45, 0, E, 0, , 0, 0, GREG, M, 0, , 0, 0, 0, 0, genesis-num, 013,

[Hurricane2022]

EP, 08, 2023081406, , BEST, 0, 113N, 1392W, 30, 1007, TD

Looks like Hone, unless the NHC decides to upgrade at 9Z for whatever reason. 08E will most likely be in the CPAC by 12Z.

BULLETIN
Tropical Storm Greg Advisory Number 2
NWS National Hurricane Center Miami FL EP082023
1100 PM HST Sun Aug 13 2023

...DEPRESSION STRENGTHENS INTO TROPICAL STORM GREG...
...NEXT ADVISORY WILL BE ISSUED BY THE CENTRAL PACIFIC HURRICANE
CENTER...


SUMMARY OF 1100 PM HST...0900 UTC...INFORMATION
-----------------------------------------------
LOCATION...11.3N 139.8W
ABOUT 1170 MI...1885 KM ESE OF HILO HAWAII
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...W OR 275 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...1005 MB...29.68 INCHES

[cycloneye]

Tropical Storm Greg Discussion Number 2
NWS National Hurricane Center Miami FL EP082023
1100 PM HST Sun Aug 13 2023

After the release of the previous advisory a burst of deep
convection developed closer to the center of the cyclone. However,
easterly shear has caused the area of convection to propagate
westward away from the center, leaving it exposed. Recently
arriving ASCAT overpasses show that the depression has
strengthened into a tropical storm. Both ASCAT-B and ASCAT-C
revealed peak winds of 34-35 kt to the north-northwest of the
center.

Greg is moving westward or 275 degrees at 11 kt. A narrow
mid-level ridge to the north of the cyclone should continue to
steer it westward to west-northwestward during the next 2 to 3 days.
After that time, the tropical storm is forecast to gradually
weaken and come under the influence of the low-level trade wind
flow. That should cause the cyclone to turn westward or
west-southwestward late in the period. The track model envelope
shifted southward this cycle so the NHC forecast was adjusted
accordingly. The new forecast track is near the HFIP corrected
consensus aid, but it is not as far south as the typically reliable
GFS and ECMWF models.

The tropical storm is located over SSTs of around 28 degrees
Celsius, but within an area of light to moderate easterly shear.
These conditions are expected to allow for some modest
strengthening during the next couple of days. After that time,
slightly cool waters, the continuation of easterly shear, and a
drier mid-level air mass are likely to cause gradual weakening.
Much of the intensity guidance predict a lower peak intensity
this cycle, and the official forecast has been adjusted
slightly downward. It should be noted that the ECMWF and GFS show
the system degenerating into a trough of low pressure by day 5.
This scenario is certainly possible, but not reflected in the
latest official forecast.

The depression will cross into the central Pacific basin by 1200
UTC today. Therefore, the next advisory on this system will be
issued by the Central Pacific Hurricane Center at 1500 UTC or
500 AM HST. Information about this system will continue to be
available on the web at hurricanes.gov


FORECAST POSITIONS AND MAX WINDS

INIT 14/0900Z 11.3N 139.8W 35 KT 40 MPH
12H 14/1800Z 11.4N 141.5W 40 KT 45 MPH
24H 15/0600Z 11.5N 143.9W 45 KT 50 MPH
36H 15/1800Z 11.7N 146.2W 45 KT 50 MPH
48H 16/0600Z 12.1N 148.6W 45 KT 50 MPH
60H 16/1800Z 12.5N 151.1W 45 KT 50 MPH
72H 17/0600Z 12.8N 153.6W 40 KT 45 MPH
96H 18/0600Z 12.7N 158.7W 35 KT 40 MPH
120H 19/0600Z 12.1N 163.9W 30 KT 35 MPH

$$
Forecaster Brown

[Kingarabian]

Pretty favorable deep level environment ahead of it but it looks like mid shear will be a problem and will likely be keeping a lid on this.

[Sciencerocks]

[cycloneye]

PHFO DDHHMM

Tropical Storm Greg Discussion Number 3
NWS Central Pacific Hurricane Center Honolulu HI EP082023
500 AM HST Mon Aug 14 2023

Deep convection associated with Greg continues to develop near and
west of the low-level circulation this morning, which has become
partially exposed due to southeasterly shear estimated to be near
10 to 15 kt. An ASCAT pass from several hours ago, however,
revealed the system has a well-defined circulation, with 35 kt
winds depicted north of the center. Based on the ASCAT data and
subjective Dvorak intensity estimates ranging from T2.0 to T3.0
between PHFO, SAB, AND JTWC, the initial intensity is held at 35 kt.

The initial motion for this advisory is 270/11 kt, as Greg
continues to move south of the subtropical ridge. No significant
change in this steering is expected over the next couple of days.
Thereafter, a gradual turn to the west-southwest is forecast as the
weakening system becomes steered by low- to mid-level flow. Similar
to the previous advisory, the track guidance continues to shift
slowly southward, with Greg passing far south of the Hawaiian
Islands later this week. This forecast track reflects that and lies
near a combination of the previous forecast, HCCA, and TVCE.

Despite the tropical storm being located over very warm waters and
within a relatively moist environment, the aforementioned
southeasterly shear will continue to inhibit strengthening
initially. Guidance shows this shear persisting over the next 12 to
18 h before trending down. Therefore, the intensity is held steady
for the first 12 h, then followed by some modest strengthening
between 24 and 48 h. Beyond that, drier mid-level air along with
increasing shear and slightly cooler waters should result in a
gradual weakening trend, with Greg becoming post-tropical by day 5.


FORECAST POSITIONS AND MAX WINDS

INIT 14/1500Z 11.3N 140.9W 35 KT 40 MPH
12H 15/0000Z 11.4N 142.6W 35 KT 40 MPH
24H 15/1200Z 11.6N 144.9W 40 KT 45 MPH
36H 16/0000Z 11.8N 147.3W 45 KT 50 MPH
48H 16/1200Z 12.2N 149.7W 45 KT 50 MPH
60H 17/0000Z 12.6N 152.2W 45 KT 50 MPH
72H 17/1200Z 12.7N 154.7W 40 KT 45 MPH
96H 18/1200Z 12.3N 159.8W 35 KT 40 MPH
120H 19/1200Z 11.7N 164.9W 30 KT 35 MPH...POST-TROP/REMNT LOW

$$
Forecaster Gibbs/Birchard

[cycloneye]

Tropical Storm Greg Discussion Number 4
NWS Central Pacific Hurricane Center Honolulu HI EP082023
1100 AM HST Mon Aug 14 2023

Greg has demonstrated pulsing convection over the last several hours
on the western side of the low level center, due to southeasterly
shear in the vicinity. Subjective Dvorak intensities from PHFO,
JTWC and SAB ranged from 2.5 to 3.0, and objective intensities
ranged from 35 to 41 kt. Using a blend of the subjective and
objective estimates, the initial intensity has been raised to 40
kt.

The initial motion is 270/10 kt, and Greg is expected to continue
to move to the west today, along the southern edge of the
subtropical ridge to the north. Little change is expected in this
steering flow over the next couple of days, so expect Greg to
continue to move to the west in the short term, and then turn to
the west-southwest as it reaches the western edge of the ridge. As
the system weakens beyond that, the system is expected is expected
to shift slowly southward. On this path, Greg will pass far south of
the Hawaiian Islands on Thursday and Friday, with no direct impacts
in the state. The forecast track remains similar to the previous
forecast, splitting the difference between the HCCA and TVCE
particularly starting from day 3 onwards.

Although Greg will remain over very warm waters throughout the
forecast period, the southeasterly shear is expected to
prevent significant strengthening in the short term. The shear is
expected to weaken a little over the 12 to 36 hour period which
would allow Greg to strengthen some. Beyond that, guidance suggests
the shear will once again increase, with some of the models also
indicating drier air being ingested into the system. This would
contribute further to a weakening trend beyond hour 60, with Greg
weakening to a depression on day 4, and becoming post-tropical on
day 5.


FORECAST POSITIONS AND MAX WINDS

INIT 14/2100Z 11.3N 141.7W 40 KT 45 MPH
12H 15/0600Z 11.4N 143.4W 40 KT 45 MPH
24H 15/1800Z 11.7N 145.7W 40 KT 45 MPH
36H 16/0600Z 12.0N 148.3W 45 KT 50 MPH
48H 16/1800Z 12.4N 150.9W 45 KT 50 MPH
60H 17/0600Z 12.7N 153.4W 40 KT 45 MPH
72H 17/1800Z 12.6N 155.9W 40 KT 45 MPH
96H 18/1800Z 12.0N 161.0W 30 KT 35 MPH
120H 19/1800Z 11.4N 166.2W 25 KT 30 MPH...POST-TROP/REMNT LOW

$$
Forecaster M Ballard

[Sciencerocks]

[Sciencerocks]

[Kingarabian]

Looking better this afternoon.

[cycloneye]

EP, 08, 2023081500, , BEST, 0, 113N, 1426W, 40, 1002, TS