ATL: ARLENE - Post-Tropical - Discussion

[TheStormExpert]

Let the 2017 Atlantic Hurricane Season begin! PLEASE BEHAVE!

...RARE APRIL TROPICAL STORM FORMS IN THE NORTH ATLANTIC... ...STILL EXPECTED TO DISSIPATE ON FRIDAY...

[gatorcane]

Interesting snippet:

Tropical storms in April are rare and Arlene is only the second
one observed in this month during the satellite era. It should be
noted, however, that this type of storm was practically impossible
to detect prior to the weather satellite era.

[weathaguyry]

The only thing I can say right now is WOW! First, we didn't even expect a STWO from the NHC, then we were sure that they wouldn't classify it, then once it became a subtropical depression we thought that would be it, then they upgraded it to a fully tropical depression this morning, and now a FULLY tropical storm and it's only April 20th

[Tampa Bay Hurricane]

TS Arlene is born! Welcome to the 2017 Hurricane Season! May we have fish spinners and no destruction!

[TheStormExpert]

Saved to look back on.

[Hypercane_Kyle]

Welcome to the 2017 Atlantic Hurricane Season.

1-0-0



First April TS since Ana in 2003, as well as the second recorded tropical cyclone to develop in the month of April.

[Hammy]

Welcome to the 2017 Atlantic Hurricane Season.

1-0-0

First April TS since Ana in 2003, as well as the second recorded tropical cyclone to develop in the month of April.

Interestingly, both were named on Apr 20 (along with the unnamed ST in 1992 on Apri 21) so while only having three storms classified, they were all in a tiny spot on the calendar.

[wxman57]

Arlene appears to be on its way out this evening. Resistance is futile, it WILL be assimilated tonight...

[tatertawt24]

So are we thinking this could tell us anything about the season or is it just a fluke? The only thing that gives me pause is the fact that we already had 90L at the end of March, and wasn't there another one recently? Or was that what became Arlene?

[KatDaddy]

In 1992 we had 7 tropical cyclones and 2003 had 16 tropical cyclones thus early tropical cyclones are no indicator that an upcoming hurricane season will be more active or inactive.

[wxman57]

So are we thinking this could tell us anything about the season or is it just a fluke? The only thing that gives me pause is the fact that we already had 90L at the end of March, and wasn't there another one recently? Or was that what became Arlene?

If Arlene had formed from a wave that moved off the coast of Africa then THAT would be significant. Forming from a non-tropical low in the subtropics over cool water means nothing as far as the tropical season.

[1900hurricane]

Arlene appears to be on its way out this evening. Resistance is futile, it WILL be assimilated tonight...

Nice Star Trek borg reference. Anyway, you are correct in saying Arlene is not long for this world. Arlene developed in the open warm sector of a nearby mid-latitude cyclone, and the fronts are rapidly closing in.

 https://twitter.com/Cyclonebiskit/status/855164349731811330

[johngaltfla]

Sigh. Anything to keep me from being competitive in the annual contest. Enjoy your fish Arlene.

[Kazmit]

45kt?

Tropical Storm ARLENE
As of 00:00 UTC Apr 21, 2017:

Location: 39.0°N 43.0°W
Maximum Winds: 45 kt Gusts: N/A
Minimum Central Pressure: 993 mb
Environmental Pressure: 1010 mb
Radius of Circulation: 400 NM
Radius of Maximum Wind: 40 NM
Eye Diameter: N/A

[Hammy]

45kt?

Tropical Storm ARLENE
As of 00:00 UTC Apr 21, 2017:

Location: 39.0°N 43.0°W
Maximum Winds: 45 kt Gusts: N/A
Minimum Central Pressure: 993 mb
Environmental Pressure: 1010 mb
Radius of Circulation: 400 NM
Radius of Maximum Wind: 40 NM
Eye Diameter: N/A

This has got to be frustrating on some level for NHC--first saying it would dissipate in a day, then saying it wouldn't strengthen to a tropical storm, then saying it would likely dissipate tonight without further strengthening. And in April no less.

[Alyono]

So are we thinking this could tell us anything about the season or is it just a fluke? The only thing that gives me pause is the fact that we already had 90L at the end of March, and wasn't there another one recently? Or was that what became Arlene?

it's a medicane that formed in the Atlantic. No impact on what happens later on

[Hammy]

So are we thinking this could tell us anything about the season or is it just a fluke? The only thing that gives me pause is the fact that we already had 90L at the end of March, and wasn't there another one recently? Or was that what became Arlene?

it's a medicane that formed in the Atlantic. No impact on what happens later on

Any chance this could indicate a more active subtropics? Both 1992 and 2003 had a fair number of storms there relative to the total season numbers.

[RL3AO]

I wouldn't try to connect this with anything later this season. This is just weather. A mid-latitude cyclone cut-off over the Atlantic. The upper-level low allowed it to slowly gain sub-tropical characteristics. It managed to find itself in a low enough shear environment. It released enough latent heat from convection to gain tropical characteristics. Has nothing to do with how favorable any part of the Atlantic will be in August.

Asking if this means an active season is ahead is a lot like trying to connect tornadoes in January to an active April/May. It's just weather.

[cycloneye]

Up to 45kts.

Tropical Storm Arlene Discussion Number 7
NWS National Hurricane Center Miami FL AL012017
1100 PM AST Thu Apr 20 2017

Despite increasing involvement with a frontal zone, Arlene
continues to produce organized convection in infrared imagery and to
show good low-level organization in microwave imagery. A partial
ASCAT overpass showed a few 40 kt vectors well to the northeast of
the center, and based on this the initial intensity is increased to
45 kt. Unfortunately, the scatterometer data did not cover the
central core and could not answer the question of whether the storm
still has a closed circulation. Based on the available data, Arlene
remains a tropical storm for this advisory. However, it could
become extratropical, lose convection and become post-tropical, or
degenerate into a trough at any time during the next 12 to 24 hours.
The official forecast has the system degenerating to a post-tropical
low in 12 hours and then dissipating as it is absorbed into a
baroclinic low.

The initial motion is 305/24. Arlene is being steered by the
aforementioned deep-layer baroclinic low centered near 36N 48W, and
the tropical cyclone, or its remnants, is expected to move in a
cyclonic loop around this low for the next few days.

Tropical storms in April are rare and Arlene is only the second
one observed in this month during the satellite era. It should be
noted, however, that this type of storm was practically impossible
to detect prior to the weather satellite era.


FORECAST POSITIONS AND MAX WINDS

INIT 21/0300Z 39.4N 44.2W 45 KT 50 MPH
12H 21/1200Z 40.0N 48.0W 40 KT 45 MPH...POST-TROPICAL
24H 22/0000Z...DISSIPATED

$$
Forecaster Beven

[Kazmit]

Somehow it's 45kt as of the 11pm update. As mentioned before, this must be frustrating for the NHC- Arlene just doesn't want to do what they predict.
Edit: I just found out Arlene became the strongest Atlantic tropical cyclone to occur in April on record!