ATL: ARLENE - Post-Tropical - Discussion

[Kazmit]

No upgrade.

[weathaguyry]

Oh well, I guess a more worthy system down the road will get to be named Arlene.

[weathaguyry]

000
WTNT41 KNHC 200836
TCDAT1

Subtropical Depression One Discussion Number 4
NWS National Hurricane Center Miami FL AL012017
500 AM AST Thu Apr 20 2017

Data from nearby drifting buoys indicate that the subtropical
depression is now moving over sea-surface temperatures of 19C or
less. These cooler waters have resulted in a significant weakening
and erosion of the inner core convection during the past few hours.
In contrast, curved outer band convection has been increasing in the
eastern semicircle. Intensity estimates at 0600Z were ST1.5/25 kt
from TAFB and ADT T3.1/47 kt from UW-CIMSS. Although it is possible
that the system could have reached subtropical storm intensity
around 0300-0500Z when a donut-ring of moderate convection
completely encircled the low-level circulation center, the recent
rapid erosion of the central convection argues for maintaining an
intensity of 30 kt for this advisory.

The cyclone is now moving a little west of due north at 12 kt. As a
large extratropical cyclone located to the west of the depression
continues to amplify and dig southeastward over the next 24-48
hours, the subtropical cyclone should turn toward the northwest
later today, and move west-northwestward to westward tonight and on
Friday as a shallow remnant low. A 24-h position has been added
based on the 00Z ECMWF and GFS models now showing the depression
persisting as a well-defined, shallow low pressure system into
Friday before it is absorbed by the aforementioned larger
extratropical low.

The combination of decreasing sea-surface temperatures and
increasing southwesterly vertical wind shear ahead of the large
extratropical low should act to steadily erode the associated
convection, resulting in the depression weakening to a remnant low
pressure system by tonight...if not sooner.

FORECAST POSITIONS AND MAX WINDS

INIT 20/0900Z 34.4N 39.3W 30 KT 35 MPH
12H 20/1800Z 36.7N 41.6W 30 KT 35 MPH
24H 21/0600Z 38.0N 46.5W 30 KT 35 MPH...POST-TROP/REMNT LOW
36H 21/1800Z...DISSIPATED

$$
Forecaster Stewart

[Hypercane_Kyle]

Looking the very definition of "meh" today. But it's cool to see the first subtropical cyclone in April since 2003.

http://www.ssd.noaa.gov/PS/TROP/floater ... imated.gif

[Kazmit]

It may have been a subtropical storm briefly overnight per the NHC's latest discussion.

[TheStormExpert]

Stop! We get your point now.

 https://twitter.com/bigjoebastardi/status/855059263554813952

[CrazyC83]

It's now fully tropical. Not expected to strengthen though.

I do think that the TCR will find that it was a storm and not a depression - not just this morning, but also earlier this week (since I believe the genesis time will move up quite significantly).

[wxman57]

It's now fully tropical. Not expected to strengthen though.

I do think that the TCR will find that it was a storm and not a depression - not just this morning, but also earlier this week (since I believe the genesis time will move up quite significantly).

Was there any ASCAT pass that indicated 34kt winds while it was classified as an STD? If not, then I would not expect any upgrade post-season.

[Florida1118]

It's now fully tropical. Not expected to strengthen though.

I do think that the TCR will find that it was a storm and not a depression - not just this morning, but also earlier this week (since I believe the genesis time will move up quite significantly).

Was there any ASCAT pass that indicated 34kt winds while it was classified as an STD? If not, then I would not expect any upgrade post-season.

"Although it is possible that the system could have reached subtropical storm intensity around 0300-0500Z when a donut-ring of moderate convection completely encircled the low-level circulation center"

I wouldn't say anyone should "expect" an upgrade per say, but it certainly is on the table. I don't think not having an ASCAT confirmation automatically disqualifies it.

[cycloneye]

JB continues with his rant about having a Td/Named system over 19C waters but I wont post the many tweets.If anyone wants to post the long list of tweets since Wednesaday about this go ahead.

[Florida1118]

It looks pretty impressive for a TD, particularly in April.

[Alyono]

this thing may get named yet. Definitely becoming better organized

[Alyono]

JB continues with his rant about having a Td/Named system over 19C waters but I wont post the many tweets.If anyone wants to post the long list of tweets since Wednesaday about this go ahead.

JB should not be used as an expert source any longer. These types of mistakes make me wonder if he even got a degree. Hard to get through thermo and dynamics making mistakes like this

[cycloneye]

 https://twitter.com/TropicalTidbits/status/855104484984401920

[TropicalAnalystwx13]

Tropical Storm Arlene

AL, 01, 2017042018, , BEST, 0, 373N, 407W, 40, 993, TS, 34, NEQ, 90, 90, 0, 0, 1010, 400, 40, 0, 0, L, 0, , 0, 0, ARLENE, M,

[wxman57]

I'm at the National Hurricane Conference in a room with James Franklin, Daniel Brown & Mike Brennan. Waiting for the 1:30pm session to start. I showed them the latest visible and James said "yeah, we see it", sort of in a tone that it's a pain in the butt since it's not behaving and just going away as forecast.

They'd like to see an ASCAT pass before deciding to call it a TS. If it doesn't go away soon, then they may have to upgrade it without confirmation by ASCAT.

[Hypercane_Kyle]

Stunned that we're already looking at Tropical Storm Arlene. What's this, the 3rd season in a row we've seen a pre-season tropical storm and the 2nd we've seen it before May?

[TropicalAnalystwx13]

Stunned that we're already looking at Tropical Storm Arlene. What's this, the 3rd season in a row we've seen a pre-season tropical storm and the 2nd we've seen it before May?

8 out of the past 17 hurricane seasons have seen a tropical storm before June 1. Yes, this is the 3rd consecutive season in a row though.

[Hurricaneman]

Looks like the first April tropical storm since 2003

[HurricaneRyan]

Is there not an advisory on Arlene yet?