EPAC: FRANK - Post-Tropical

[cycloneye]

Tropical Storm Frank Discussion Number 27
NWS National Hurricane Center Miami FL EP072022
200 PM PDT Mon Aug 01 2022

Frank's convection continues to fade as it maintains its trek over
cooler waters. In response, both subjective and objective Dvorak
numbers are decreasing. In addition, we received a direct overhead
ASCAT-B pass at 1820 UTC, which showed a peak wind retrieval of
43-kt in the northern semicircle of the storm. Assuming a little
undersampling from this instrument, the intensity was reduced to 45
kt this advisory, favoring the lower end of Dvorak estimates.

Frank is still moving northwestward at 310/10 kt. There is little
change in the track reasoning this cycle. Frank's track should
gradually bend more poleward as it becomes a shallow vortex and is
steered by the southerly flow ahead of a deep-layer trough. The
latest NHC track forecast remains near the consensus aids, and is
just a touch left of the previous forecast.

Sea surface temperatures under the storm are already down to 22 C
and only cool further along the forecast track. The latest model
output from the GFS, ECMWF, CMC, and HWRF all suggest the remaining
convection will fizzle out over the next 24 hours. The latest
forecast now shows Frank becoming a post-tropical cyclone by that
time-frame. It will take another few days for the large wind
field of Frank to spin down enough for it to open up into a
trough. This is expected to occur by Friday, well offshore
southeastward of coastal California.


FORECAST POSITIONS AND MAX WINDS

INIT 01/2100Z 22.8N 123.4W 45 KT 50 MPH
12H 02/0600Z 24.0N 124.5W 40 KT 45 MPH
24H 02/1800Z 25.5N 125.8W 35 KT 40 MPH...POST-TROPICAL
36H 03/0600Z 27.4N 126.8W 30 KT 35 MPH...POST-TROP/REMNT LOW
48H 03/1800Z 29.4N 127.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
60H 04/0600Z 31.4N 127.3W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 04/1800Z 33.0N 127.1W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 05/1800Z...DISSIPATED

$$
Forecaster Papin

[cycloneye]

Tropical Storm Frank Discussion Number 28
NWS National Hurricane Center Miami FL EP072022
800 PM PDT Mon Aug 01 2022

Frank continues to produce a small patch of moderate convection near
its center, but cloud tops of -50 degrees Celsius appear more
related to remnant cirrus rather than the convection itself.
Assuming continued weakening of the circulation since the afternoon
ASCAT passes, Frank's initial intensity is lowered to 40 kt, which
is also a blend of the latest Dvorak CI numbers from TAFB and SAB.
Frank's large circulation will continue to spin down over waters of
20-22 degrees Celsius over the next couple of days, but the NHC
intensity forecast is near the higher end of the guidance through
that period, favoring the slower decay shown by the GFS global model
fields. Frank should lose its remaining convection soon and become
post-tropical by 24 hours, and all global models indicate the
remnant low should open up into a trough in 3 or 4 days about
300 n mi west of the California coast.

Frank slowed down a little bit today, and is moving toward the
northwest (310/8 kt). Although it's decaying, Frank is essentially
expected to recurve around strong mid-level ridging over the
southwestern United States and ahead of a deep-layer trough well
west of California. There is good model consensus on this
scenario, and only a slight westward adjustment was required on the
new forecast after 24 hours based on the lastest track guidance.


FORECAST POSITIONS AND MAX WINDS

INIT 02/0300Z 23.4N 124.0W 40 KT 45 MPH
12H 02/1200Z 24.5N 125.1W 35 KT 40 MPH
24H 03/0000Z 26.2N 126.3W 35 KT 40 MPH...POST-TROPICAL
36H 03/1200Z 28.1N 127.3W 30 KT 35 MPH...POST-TROP/REMNT LOW
48H 04/0000Z 30.2N 127.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
60H 04/1200Z 32.0N 127.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 05/0000Z 33.8N 126.6W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 06/0000Z...DISSIPATED

$$
Forecaster Berg

[cycloneye]

Tropical Storm Frank Discussion Number 29
NWS National Hurricane Center Miami FL EP072022
200 AM PDT Tue Aug 02 2022

Only a tiny region of -45 to -50 degree Celsius cloud top
temperatures remain with Frank southeast of its center this morning.
In fact, the tropical cyclone appears well on its way to becoming a
low-level cloud swirl devoid of any remaining deep convection.
Subjective and objective Dvorak classifications range from 30-kt to
45-kt this morning. Absent of any recent scatterometer data, but
noting that the passes yesterday afternoon had a large region of
greater than 40 kt winds, the initial intensity was held at 40-kt
this advisory. Frank should continue to gradually spin down over
20-22 C ocean waters as it moves further into a more stable
environment. The meager amount of cold cloud tops near Frank now
already do not meet the necessary criteria of a tropical cyclone,
and it is likely the storm will become post-tropical later today.
Most of the guidance now suggests Frank will open up into a trough
by 72 hours, and that is reflected in the latest forecast, showing
the remnant low dissipating about 300 n mi west of the California
coast.

Frank is still moving to the northwest at 310/9 kt. Even as Frank
becomes more shallow, the low-level steering flow will still enable
Frank to recurve between a narrow low-level ridge off of the Baja
California peninsula and a prominent deep-layer trough well west of
California. The track guidance remains tightly clustered, and only
slight changes were needed for the latest track forecast.


FORECAST POSITIONS AND MAX WINDS

INIT 02/0900Z 24.0N 124.7W 40 KT 45 MPH
12H 02/1800Z 25.2N 125.8W 35 KT 40 MPH...POST-TROPICAL
24H 03/0600Z 27.0N 126.9W 30 KT 35 MPH...POST-TROP/REMNT LOW
36H 03/1800Z 28.9N 127.4W 30 KT 35 MPH...POST-TROP/REMNT LOW
48H 04/0600Z 31.0N 127.4W 25 KT 30 MPH...POST-TROP/REMNT LOW
60H 04/1800Z 32.8N 126.8W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 05/0600Z...DISSIPATED

$$
Forecaster Papin

[Sciencerocks]

[cycloneye]

Tropical Storm Frank Discussion Number 30
NWS National Hurricane Center Miami FL EP072022
800 AM PDT Tue Aug 02 2022

Organized deep convection associated with Frank ceased overnight,
and the tropical storm should become post-tropical very soon. The
weakening cyclone is moving northwest near 10 kt, and should
gradually bend toward the north over the next 36 h, then
north-northeast by Thursday, steered primarily by the low-level
flow. The latest TAFB Dvorak Current Intensity estimate is 35 kt, so
the initial intensity is set at that value. Continued weakening
will occur over the next few days while Frank gradually spins down
over cold water with little or no convection to sustain it.
Dissipation is forecast by nearly all of the dynamical models near
or just after 60 h. No changes of note were made to the NHC track or
intensity forecasts, both of which are near the model consensus
aids.

FORECAST POSITIONS AND MAX WINDS

INIT 02/1500Z 24.8N 125.4W 35 KT 40 MPH
12H 03/0000Z 26.1N 126.4W 30 KT 35 MPH...POST-TROP/REMNT LOW
24H 03/1200Z 28.0N 127.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 04/0000Z 30.0N 127.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 04/1200Z 32.0N 127.2W 20 KT 25 MPH...POST-TROP/REMNT LOW
60H 05/0000Z 33.7N 126.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 05/1200Z...DISSIPATED

$$
Forecaster D. Zelinsky

[cycloneye]

Post-Tropical Cyclone Frank Discussion Number 31
NWS National Hurricane Center Miami FL EP072022
200 PM PDT Tue Aug 02 2022

Frank has failed to produce organized deep convection since last
night, and the system has been reduced to a well-defined low-level
cloud swirl over the open waters of the eastern Pacific Ocean. Since
Frank no longer satisfies the criteria of a tropical cyclone, this
will be the final NHC advisory on now post-tropical Frank.

The cyclone is expected to gradually turn northward during the next
couple of days as it moves around the western periphery of a distant
low-level ridge. Although Frank is believed to be still producing
some 34-kt winds in its northeastern quadrant, weakening is expected
through midweek as the cyclone continues to spin down over cool
SSTs. The system is forecast to open into a trough and dissipate by
early Friday. For additional information on the post-tropical
cyclone please see High Seas Forecasts issued by the National
Weather Service, under AWIPS header NFDHSFEPI, WMO header FZPN02
KWBC, and on the web at ocean.weather.gov/shtml/NFDHSFEPI.php


FORECAST POSITIONS AND MAX WINDS

INIT 02/2100Z 25.7N 125.9W 35 KT 40 MPH...POST-TROPICAL
12H 03/0600Z 27.0N 126.7W 30 KT 35 MPH...POST-TROP/REMNT LOW
24H 03/1800Z 29.0N 127.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 04/0600Z 31.1N 127.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 04/1800Z 32.9N 126.6W 20 KT 25 MPH...POST-TROP/REMNT LOW
60H 05/0600Z...DISSIPATED

$$
Forecaster Reinhart