atlantic hurricane season Atlantic hurricane season/invest thread

[summer blizzard]

Recon were unimpressed as suspected and i still think the circulation is quite broad (though it's probably not having a problem closing, i think the main problem is it's lack of definition) however it does look fairly stacked (so no speed/shear issues). 

If you look below then the center is more or less where the deepest blob of convection is but over a larger area, the top half of the storm is probably going to make it look like a Sonic the Hedgehog type system if it actually develops. 

Speaking of.. the Euro went nuts again..

[summer blizzard]

99L has improved somewhat overnight becoming a single blob and you can see evidence of winds from the S/E/N so we're just waiting for the circulation to close. 

Google maps suggest this will probably happen today if things hold up. 

https://earth.nullschool.net/#current/wind/surface/level/orthographic=-50.71,16.42,3000/loc=-61.497,17.006

Euro loves it again. 

[Nouska]

There's unusually good agreement from the ECM and UKMO at day 7 - @Jack Wales you still in Florida then?

  

GFS still footling with a weak TS (at best)  traversing Florida.

The ECM quite aggressive with a new pouch, exiting in seven days - this will likely be what the low- res GFS shows, as having nasty potential down the line.

[seaside 60]

As an aside the the topic.

Scroll up to the med on the above link and see the wind funneling through the med out into the Atlantic and of the NE tip of Africa a lovely small whirlpool.

[Jack Wales]

Hi Nouska, yes I'm still in Florida and eagerly watching the models.  As you say it's interesting that ECM is the most bullish with regards to development of this system. The satellite images from this morning indicate 99l has tightened up with a more defined and seemingly closed rotation in place.  I wouldn't be surprised if this is upgraded to a TD today...

[knocker]

99L Poised to Become Tropical Storm Hermine

Quote

Invest 99L is already bringing winds of tropical storm force to the northern Lesser Antilles Islands, and it could become a tropical storm at any time over the next day as it heads west-northwest at 15 mph towards Puerto Rico and the Virgin Islands. At Barbuda, sustained winds at minimal tropical storm-force—39 mph—were observed at 7:18 am AST, with a wind gust of 45 mph. At 10 am AST, Princess Juliana Airport in St. Maartin recorded sustained winds (below tropical storm-force) of 32 mph, gusting to 48 mph.

An Air Force hurricane hunter aircraft was investigating 99L late Wednesday morning, and found sustained surface winds of 45 - 50 mph, and sustained winds at their 500-foot flight level of 50 - 55 mph. At 11:35 am EDT, the National Hurricane Center issued a special Tropical Weather Outlook noting that the reconnaissance mission was still ongoing. As soon as 99L develops a well-defined surface circulation, it will be called Tropical Storm Hermine.

The storm was generating heavy rains over the northern Lesser Antilles Islands on Wednesday morning, as seen on radar out of Martinique. Satellite loops on Wednesday morning showed that heavy thunderstorm activity had increased in intensity over the previous 24 hours, and had grown more organized. A well-defined surface circulation had not yet formed, though several swirls in the cloud pattern suggested that the storm may not be far from establishing one. Moderate to high wind shear of 15 - 25 knots along the north side of the storm was keeping all of 99L’s heavy thunderstorms confined to the south. Dry air from the Saharan Air Layer (SAL) was still hindering development, as seen on water vapor satellite imagery. Sea surface temperatures (SSTs) were favorable for development: 29°C (84°F), about 0.5°C above average. A flash flood watch is posted for Puerto Rico and the U.S. Virgin Islands, where 2 - 4 inches of rain are expected.

https://www.wunderground.com/blog/JeffMasters/99l-poised-to-become-tropical-storm-hermine

[matty40s]

i wonder how many storms have hit the USA with an alphabetic name earlier than a storm that has already hit??

 

[Cookie]

Anyone know if recon has been out to it yet?

[summer blizzard]

33 minutes ago, cookie said:

Anyone know if recon has been out to it yet?

Went in and found 55mph winds however the center is somewhat exposed so the NHC won't declare.

It all comes down to the durinal minimum.  

[Nouska]

Well! That explains it all.

Can somebody put Humpty back together again.

I'll let Levi try make sense of it all.

http://www.tropicaltidbits.com/blog/2016/08/24/wednesday-evening-future-of-invest-99l-remains-uncertain-flooding-threat-to-northern-caribbean-islands-and-bahamas/

 

 

Edited August 25, 2016 by Nouska
Add Levi Cowan video.

[summer blizzard]

Looks more normal again now..

[SMU]

As the sat reps have up dates above ^^

the system is slowly getting more organised with a more symetrical shape as well as some outflow to the NE

 

[Jack Wales]

99l is a heavily sheared system at the moment. The low level centre appears to be over the turk and caicos islands with all the convection sheared well to the south over southern Hispanola.  With the shear only forecast to reduce somewhat it's less likely a TD will form in the next few days at least.

 

[Gray-Wolf]

Latest loops do show the centre but no convection around it at present? It ( central point of rotation) is also leaving the shear blighted area so keep an eye for rapid formation over the next 48hrs?

[summer blizzard]

Can't say i'm optimistic for this system, since it's peak two days ago over the Leeward Islands we've seen sustained degradation. 

Right now this wave axis (and a new center if one forms is located near the convection north of Haiti however there are only south and east winds and convection is not terribly impressive. If this does not look better in 24 hours, i'll abandon 99L. 

[summer blizzard]

Center is still being sheared with the convection being east but it's actually done okay today.

Does anybody know if recon are on route, we were due a flight i think. 

[summer blizzard]

It's dead, looks worse today than the durinal maximum. 

Next..

[Gray-Wolf]

I'm not willing to write it off just yet! It has the gulf to encounter yet and the waters over which it has to pass to get into the Gulf. One thing I've come to almost 'expect' is rapid intensification once waves/closed circulations see once conditions swing favourable?

Edited August 27, 2016 by Gray-Wolf

[summer blizzard]

Anybody have the recon schedule?

[Nouska]

47 minutes ago, summer blizzard said:

Anybody have the recon schedule?

The scheduled mission for today was cancelled but it is looking a bit more vigorous at the moment so they may change that plan.

Nice close up of new hot towers - too big to embed.

http://imgur.com/6Ap9iHv

The Global Hawk is currently out at Gaston - 80 Atlantic sampling dropsondes planned.

Edited August 27, 2016 by Nouska

[summer blizzard]

Looking at the radar image there's some amazing rainfall over Cuba right now. 

Edited August 27, 2016 by summer blizzard

[summer blizzard]

Mid level circulation is strongest around 77W, the question will be whether it can stack itself there.

[knocker]

Well the ecm isn't writing off 99L

[Nouska]

Tropical tidbits covering mission obs.

http://www.tropicaltidbits.com/recon/

[summer blizzard]

91L has become Tropical Depression 8.

Bit of a namewaster but it might bring some rain to the Carolina's.