EPAC: HENRIETTE - Post-Tropical - Discussion

[cycloneye]

EP, 90, 2025080218, , BEST, 0, 120N, 1098W, 25, 1008, DB, 34, NEQ, 0, 0, 0, 0, 1010, 120, 90, 0, 0, E, 0, , 0, 0, INVEST, S, 0, , 0, 0, 0, 0, genesis-num, 016, SPAWNINVEST, ep772025 to ep902025,

https://ftp.nhc.noaa.gov/atcf/btk/bep902025.dat

Central East Pacific:
An area of low pressure is expected to form well southwest of
southwestern Mexico within the next day or so. Environmental
conditions appear conducive for some gradual development of this
system, and a tropical depression is likely to form late this
weekend or early next week as the system moves west-northwestward
at 10 to 15 mph.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 7 days...high...80 percent.

The big question is what will be the ceiling for this one.

[cycloneye]

If you look at the first models run for this one, the ceiling looks to be fairly high.

[cycloneye]

Central East Pacific (EP90):
Disorganized showers and thunderstorms located well southwest of the
southwestern coast of Mexico are associated with a broad area of
low pressure. Environmental conditions are conducive for
development of this system, and a tropical depression is expected
to form late this weekend or early next week while the system moves
west-northwestward at 10 to 15 mph.
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 7 days...high...90 percent.

[cycloneye]

This latitude is good in terms of the ceiling for this system.

EP, 90, 2025080300, , BEST, 0, 110N, 1128W, 25, 1009, DB

[cycloneye]

[cycloneye]

Central East Pacific (EP90):
Disorganized showers and thunderstorms located well west-southwest
of the southwestern coast of Mexico are associated with a broad area
of low pressure. Environmental conditions are conducive for
development of this system, and a tropical depression is likely to
form during the next day or two while the system moves
west-northwestward at 10 to 15 mph. For additional information,
including gale warnings, please see High Seas Forecasts issued by
the National Weather Service.
* Formation chance through 48 hours...high...90 percent.
* Formation chance through 7 days...high...90 percent.

[Kingarabian]

Models have this moving more NW vs a WNW heading. With a sharp SST gradient this is likely to have the same fate as the others.

[cycloneye]

Central East Pacific (EP90):
Disorganized showers and thunderstorms located well south-southwest
of the southern tip of the Baja California Peninsula are associated
with a broad area of low pressure. Environmental conditions are
conducive for development of this system, and a tropical depression
is very likely to form during the next day or two while the system
moves west-northwestward at 10 to 15 mph. For additional
information, including gale warnings, please see High Seas
Forecasts issued by the National Weather Service.
* Formation chance through 48 hours...high...90 percent.
* Formation chance through 7 days...high...90 percent.

[AJC3]

Central East Pacific (EP90):
Disorganized showers and thunderstorms located well south-southwest
of the southern tip of the Baja California Peninsula are associated
with a broad area of low pressure. Environmental conditions are
conducive for development of this system, and a tropical depression
is very likely to form during the next day or two while the system
moves west-northwestward at 10 to 15 mph. For additional
information, including gale warnings, please see High Seas Forecasts
issued by the National Weather Service.
* Formation chance through 48 hours...high...90 percent.
* Formation chance through 7 days...high...90 percent.

[ElectricStorm]

Models backing off on intensity, was hoping this could stay further south and have a chance to become a stronger storm than Gil but now seems like that probably won't be the case. 0z GFS has it passing north of Hawaii and becoming a significant typhoon in the WPAC but that's pretty far north so I'm not really buying that solution yet.

[cycloneye]

Tropical Depression Eight-E Discussion Number 1
NWS National Hurricane Center Miami FL EP082025
1100 PM HST Sun Aug 03 2025

Showers and thunderstorms associated with an area of low pressure
well southwest of the Baja California Peninsula have become better
organized during the past 12 hours. Additionally, an overnight ASCAT
pass showed a well-defined circulation with peak winds near 30 kt.
Given the improved convective organization and well-defined
circulation, advisories are being initiated on Tropical Depression
Eight-E. The initial intensity is set at 30 kt, based on a blend of
the ASCAT pass and Dvorak current intensity estimates from both
TAFB and SAB.

The initial motion is estimated at 300/13 kt, along the southern
side of a strong subtropical ridge. This ridge is forecast to remain
in place through the 5-day period, steering the system generally
west-northwestward for the entire forecast. A slightly more westward
motion is possible by day 4 as the cyclone becomes more shallow and
is steered within the low- to mid-level flow. The updated track
forecast is close to the consensus aids.

The system is forecast to steadily strengthen during the next couple
of days as it moves over warm waters and through a moist, low-shear
environment. It is expected to become a tropical storm on Monday
and could approach hurricane strength between 36 and 60 hours. After
that time, a gradual weakening trend is anticipated as the cyclone
moves over sea surface temperatures below 26 degrees C and begins to
entrain drier mid-level air within a more stable environment.
Simulated satellite imagery from the global models supports this
scenario, showing a reduction in deep convection as the system
continues west-northwestward into the central Pacific basin. The
forecast is slightly above the intensity guidance through 60 hours,
then is in good agreement with the consensus aids thereafter.


FORECAST POSITIONS AND MAX WINDS

INIT 04/0900Z 13.7N 118.2W 30 KT 35 MPH
12H 04/1800Z 14.4N 119.7W 35 KT 40 MPH
24H 05/0600Z 15.4N 122.1W 40 KT 45 MPH
36H 05/1800Z 16.4N 124.6W 50 KT 60 MPH
48H 06/0600Z 17.4N 127.2W 60 KT 70 MPH
60H 06/1800Z 18.2N 129.9W 55 KT 65 MPH
72H 07/0600Z 18.8N 132.6W 50 KT 60 MPH
96H 08/0600Z 19.8N 138.8W 45 KT 50 MPH
120H 09/0600Z 21.2N 145.0W 40 KT 45 MPH

$$
Forecaster Gibbs (CPHC)

[cycloneye]

Tropical Depression Eight-E Discussion Number 2
NWS National Hurricane Center Miami FL EP082025
500 AM HST Mon Aug 04 2025

Satellite imagery since the previous advisory shows little overall
structural change in Tropical Depression Eight-E. The system
continues to produce mainly fragmented convective bands, with a few
intermittent bursts of deeper convection over the low-level
circulation center. The overall organization has not appreciably
improved, and the most recent subjective Dvorak current intensity
estimates from TAFB and SAB remain at 2.0/30 kt. Given these
data and the satellite presentation, the initial intensity is held
at 30 kt.

The depression is moving toward the west-northwest, or 295/13 kt,
along the southern side of a strong subtropical ridge. This ridge is
expected to persist through much of the forecast period, steering
the system generally west-northwestward for the next several days. A
slightly more northwestward motion is possible by day 5 as it moves
into the Central Pacific basin and responds to a weakness in the
ridge far north of Hawaii. The latest NHC track forecast is very
close to the previous one and remains close to the consensus aids.

The system is forecast to steadily strengthen during the next couple
of days as it moves over warm waters and through a moist, low-shear
environment. It is expected to become a tropical storm by tonight
and could approach hurricane strength between 36 and 60 hours. After
that time, a gradual weakening trend is anticipated as the cyclone
moves over sea surface temperatures below 26 degrees C and begins to
entrain drier mid-level air within a more stable environment.
Despite these less favorable conditions, much of the guidance
maintains a well-defined cyclone with deep convection through the
120-hour forecast period, with only gradual weakening. The official
forecast remains slightly above the intensity guidance through
midweek, then more gradually trends back toward the consensus aids
thereafter.


FORECAST POSITIONS AND MAX WINDS

INIT 04/1500Z 14.2N 119.9W 30 KT 35 MPH
12H 05/0000Z 14.9N 121.7W 40 KT 45 MPH
24H 05/1200Z 15.9N 124.1W 45 KT 50 MPH
36H 06/0000Z 16.8N 126.6W 50 KT 60 MPH
48H 06/1200Z 17.7N 129.1W 60 KT 70 MPH
60H 07/0000Z 18.4N 132.0W 55 KT 65 MPH
72H 07/1200Z 18.9N 135.1W 50 KT 60 MPH
96H 08/1200Z 20.0N 141.5W 45 KT 50 MPH
120H 09/1200Z 21.7N 147.2W 45 KT 50 MPH

$$
Forecaster Gibbs (CPHC)

[TallyTracker]

If TD Eight-E stays on the southern end of the forecast track, the possibility starts to open up to either a weak storm or remnants impacting Hawaii some. Not expecting it, but just an observation at this time.

[StormWeather]

ATCF updated and it now calls this Henriette

https://www.tropicaltidbits.com/storminfo/#08E

[cycloneye]

EP, 08, 2025080418, , BEST, 0, 145N, 1200W, 40, 1004, TS, 34, NEQ, 40, 30, 30, 40, 1010, 170, 40, 0, 0, E, 0, , 0, 0, HENRIETTE,

[cycloneye]

Tropical Storm Henriette Discussion Number 3
NWS National Hurricane Center Miami FL EP082025
1100 AM HST Mon Aug 04 2025

Conventional satellite imagery shows that the cyclone has become
better organized, during the past several hours. A curved band has
developed over the west side of the cyclone, and deep convection is
developing over the surface center. A 1336 UTC ESA Soil Moisture
Ocean Salinity (SMOS) overpass indicated 34-40 kt winds in the
north quadrant of the cyclone, and a 1746 UTC ASCAT-B pass
revealed 38 kt winds in the same region. ADT/AiDT and ATMS
sounder objective satellite intensity estimates yield 34 kts, while
the subjective Dvorak estimates from TAFB and SAB support 35 kt.
Based on these data, the depression has been upgraded to Tropical
Storm Henriette with the initial intensity set at 40 kt.

The intensity forecast philosophy is unchanged from the previous one
with gradual strengthening expected during the next couple of days.
By mid-period, Henriette should slowly weaken and then level off
with little change in strength as it traverses cooler oceanic
surface temperatures and moves into a drier, more stable surrounding
environment. The NHC intensity forecast has been lowered a bit to
agree more with the Decay-SHIPS, the IVCN intensity consensus model,
and the GFS and ECMWF deterministic models.

The initial motion is estimated to be west-northwestward, or 295/13
kt. The global models indicate that a strong mid- to
upper-tropospheric ridge anchored to the north of the cyclone should
continue to steer Henriette in this general direction through 96
hours. Around day 5, a gradual turn toward the northwest is
expected in response to a mid-latitude mid-level trough moving
toward the Hawaiian Islands from the north-central Pacific.


FORECAST POSITIONS AND MAX WINDS

INIT 04/2100Z 14.8N 120.6W 40 KT 45 MPH
12H 05/0600Z 15.5N 122.4W 45 KT 50 MPH
24H 05/1800Z 16.3N 124.9W 50 KT 60 MPH
36H 06/0600Z 17.1N 127.6W 50 KT 60 MPH
48H 06/1800Z 17.6N 130.4W 50 KT 60 MPH
60H 07/0600Z 18.1N 133.4W 45 KT 50 MPH
72H 07/1800Z 18.4N 136.5W 45 KT 50 MPH
96H 08/1800Z 19.5N 142.2W 40 KT 45 MPH
120H 09/1800Z 21.5N 147.4W 40 KT 45 MPH

$$
Forecaster Roberts

[cycloneye]

Tropical Storm Henriette Discussion Number 3
NWS National Hurricane Center Miami FL EP082025
1100 AM HST Mon Aug 04 2025

Conventional satellite imagery shows that the cyclone has become
better organized, during the past several hours. A curved band has
developed over the west side of the cyclone, and deep convection is
developing over the surface center. A 1336 UTC ESA Soil Moisture
Ocean Salinity (SMOS) overpass indicated 34-40 kt winds in the
north quadrant of the cyclone, and a 1746 UTC ASCAT-B pass
revealed 38 kt winds in the same region. ADT/AiDT and ATMS
sounder objective satellite intensity estimates yield 34 kts, while
the subjective Dvorak estimates from TAFB and SAB support 35 kt.
Based on these data, the depression has been upgraded to Tropical
Storm Henriette with the initial intensity set at 40 kt.

The intensity forecast philosophy is unchanged from the previous one
with gradual strengthening expected during the next couple of days.
By mid-period, Henriette should slowly weaken and then level off
with little change in strength as it traverses cooler oceanic
surface temperatures and moves into a drier, more stable surrounding
environment. The NHC intensity forecast has been lowered a bit to
agree more with the Decay-SHIPS, the IVCN intensity consensus model,
and the GFS and ECMWF deterministic models.

The initial motion is estimated to be west-northwestward, or 295/13
kt. The global models indicate that a strong mid- to
upper-tropospheric ridge anchored to the north of the cyclone should
continue to steer Henriette in this general direction through 96
hours. Around day 5, a gradual turn toward the northwest is
expected in response to a mid-latitude mid-level trough moving
toward the Hawaiian Islands from the north-central Pacific.


FORECAST POSITIONS AND MAX WINDS

INIT 04/2100Z 14.8N 120.6W 40 KT 45 MPH
12H 05/0600Z 15.5N 122.4W 45 KT 50 MPH
24H 05/1800Z 16.3N 124.9W 50 KT 60 MPH
36H 06/0600Z 17.1N 127.6W 50 KT 60 MPH
48H 06/1800Z 17.6N 130.4W 50 KT 60 MPH
60H 07/0600Z 18.1N 133.4W 45 KT 50 MPH
72H 07/1800Z 18.4N 136.5W 45 KT 50 MPH
96H 08/1800Z 19.5N 142.2W 40 KT 45 MPH
120H 09/1800Z 21.5N 147.4W 40 KT 45 MPH

$$
Forecaster Roberts

[StormWeather]

Models backing off on intensity, was hoping this could stay further south and have a chance to become a stronger storm than Gil but now seems like that probably won't be the case. 0z GFS has it passing north of Hawaii and becoming a significant typhoon in the WPAC but that's pretty far north so I'm not really buying that solution yet.

Today’s 12Z EURO showed the same thing: going north of Hawaii and reintensifying as it moves towards the IDL and the WPAC.

[Hayabusa]

Another possible basin crossover but coming from the Epac...

[cycloneye]

Models are tight clustered on track north of Hawaii.