ATL: MARIA - Post-Tropical - Discussion

[MJGarrison]

An ASCAT pass over 96L is needed to see if the circulation is closed.

Visible loop suggests it might be closed.

What is the ASCAT and how does it help tell if the circulation is closed? Separate from a visual or IR satellite?

[RT23]

Isnt a Dovorak T2.5 a weak TS?

[wxman57]

An ASCAT pass over 96L is needed to see if the circulation is closed.

Visible loop suggests it might be closed.

What is the ASCAT and how does it help tell if the circulation is closed? Separate from a visual or IR satellite?

See: http://coaps.fsu.edu/scatterometry/about/overview.php

Here's the link to the data: https://manati.star.nesdis.noaa.gov/datasets/ASCATBData.php

[NotSparta]

Isnt a Dovorak T2.5 a weak TS?

Yes, it means TS winds, but a TS has to have a closed circulation, which we are not sure of yet

[NDG]

Looking at HR visible loop this morning it looks like the circulation is closed this morning. Hopefully they start advisories at 11 AM so that residents of the Lesser Antilles start getting prepared for a possible impact and hopefully this morning's ASCAT catches it.

[Sanibel]

Double trouble once again...They are forming in pairs and from the look of 14 they are underestimating intensity...96 bears watching for formation near the islands...

[ronjon]

Yeah 96l looks to be trouble for same islands devestated by Irma. Will that hold true for Florida? I'm not liking the long term 500mb pattern with massive midlevel high pressure sitting off the midatlantic coast in 7 days. Plenty of time to watch. Things change. I am so ready for this season to be over. Can't wait for our first strong cold front. My storm fatigue factor is near 10 now.

[GCANE]

AMSU is detecting a warm core

[CrazyC83]

Is it enough to call it a TC though? Are any Recon missions planned - those could solve the riddle.

[GCANE]

Is it enough to call it a TC though? Are any Recon missions planned - those could solve the riddle.

Tomorrow 18Z

[GCANE]

Good improvement last 3 hrs 850mb vort

[ouragans]

Looking at HR visible loop this morning it looks like the circulation is closed this morning. Hopefully they start advisories at 11 AM so that residents of the Lesser Antilles start getting prepared for a possible impact and hopefully this morning's ASCAT catches it.

When is the next pass?

[SFLcane]

Advisories for potential TC at 11am from NHC

[OuterBanker]

NC will be breathing a sigh of relief with Jose. Now I'm afraid we'll have to deal with Maria. Thought this was going to be a carib runner into the GOM.
Now most models have it off Fl coast. Season over really needs to happen.
I'm afraid for the crow population. Lots of crow will be consumed this year.

[cycloneye]

@NHC_Atlantic

NHC will initiate advisories at 11 AM AST on Potential Tropical Cyclone Fifteen, currently located east of the Lesser Antilles.

[Gustywind]

@NHC_Atlantic

NHC will initiate advisories at 11 AM AST on Potential Tropical Cyclone Fifteen, currently located east of the Lesser Antilles.

[GCANE]

Warm core definitely got mid-levels turning better.

[CrazyC83]

Warm core definitely got mid-levels turning better.

That looks like a closed system to me on satellite there.

[cycloneye]

BULLETIN
Potential Tropical Cyclone Fifteen Advisory Number 1
NWS National Hurricane Center Miami FL AL152017
1100 AM AST Sat Sep 16 2017

...TROPICAL STORM WATCHES ISSUED FOR A PORTION OF THE LESSER
ANTILLES...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...12.2N 50.5W
ABOUT 755 MI...1220 KM ESE OF THE LESSER ANTILLES
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...W OR 280 DEGREES AT 22 MPH...35 KM/H
MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

The government of St. Lucia has issued a Tropical Storm Watch for
St. Lucia.

The government of France has issued a Tropical Storm Watch for
Martinique and Guadeloupe.

The government of Barbados has issued a Tropical Storm Watch for
Dominica.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Watch is in effect for...
* St. Lucia
* Martinique
* Guadeloupe
* Dominica
----------------------------------------------------------------------------------------


Potential Tropical Cyclone Fifteen Discussion Number 1
NWS National Hurricane Center Miami FL AL152017
1100 AM AST Sat Sep 16 2017

Satellite images indicate that the area of low pressure located
several hundred miles east of the Lesser Antilles has become better
organized with curved banding features now better established.
Since there is still no indication of a well-defined center and
because tropical storm watches have been issued for portions of
the Leeward Islands, NHC has initiated advisories on this system as
a potential tropical cyclone. The initial wind speed is estimated
to be 30 kt based on a blend of the Dvorak classifications from TAFB
and SAB.

The initial motion estimate is 280/19, but this is uncertain due to
the lack of a clear center. A slower west-northwestward motion is
expected during the next several days as a mid-level ridge to the
north of the system weakens but remains nearly stationary. The NHC
track forecast takes the system across the Leeward Islands in a few
days and then near the Virgin Islands and Puerto Rico by the end of
the forecast period. It should be noted that confidence in the
track and forward speed of this system is low due to the spread in
the models and the current lack of a well-defined center.

The disturbance is expected to be in environmental conditions
conducive for strengthening during the next several days as the
shear is expected to be 10 kt or less while the cyclone moves over
warm 29 deg C SSTs. These conditions should allow for at least
steady strengthening, and the models unanimously show that trend.
The NHC intensity forecast is conservative for now, but does show
the system becoming a tropical storm later today and a hurricane by
the time it reaches the Leeward Islands.

KEY MESSAGES:

1. The disturbance is expected to intensify and will likely bring
tropical storm and hurricane conditions as well as flooding
rainfall to portions of the Lesser Antilles early next week. These
conditions could also spread into the Virgin Islands and Puerto Rico
by mid week. Interests in these areas should monitor the progress
of this system and follow any advice given by local officials.

FORECAST POSITIONS AND MAX WINDS

INIT 16/1500Z 12.2N 50.5W 30 KT 35 MPH...POTENTIAL TROP CYCLONE
12H 17/0000Z 12.8N 52.8W 35 KT 40 MPH...TROPICAL STORM
24H 17/1200Z 13.6N 55.1W 40 KT 45 MPH
36H 18/0000Z 14.3N 56.9W 50 KT 60 MPH
48H 18/1200Z 15.0N 58.6W 60 KT 70 MPH
72H 19/1200Z 16.3N 61.3W 75 KT 85 MPH
96H 20/1200Z 17.6N 64.0W 80 KT 90 MPH
120H 21/1200Z 18.7N 67.3W 80 KT 90 MPH

$$
Forecaster Cangialosi

[TheStormExpert]

Looks like this will be Maria as TD#14 suddenly took the name Lee.