MikeCAdministrator
(Admin)
Fri Sep 07 2007 10:52 AM
Make or Break for 99L, Worth Watching

9:00 PM EDT 7 Sep Update
99L didn't quite make it today, but if it persists overnight, maybe even just one good burst of convective activity near the center, it could get going into a storm sometime tomorrow. If dry air wins out then it may not get much activity going tomorrow either. Still about a 45% chance for development tonight.

Recon couldn't find much if any surface winds, so it has a rather uphill battle to form overnight. Hopefully it loses and this system is just a small rain maker.

4:30 PM EDT 7 Sep Update
Recon so far is finding fairly high pressures, higher than a few days ago even, so it looks like this system will not form today.

3PM EDT 7 Sep Update
Recon is in the Atlantic now, heading toward 99L, hopefully we'll have some data from then in an hour or so.

There is convection firing along the north and northwest sides of the low now, dry air is retreating to the west. The west (although starting to gain some convection now), southwest, and south sides still are void of convection, but that may change soon.


Original Update
For those watching the disturbance of our Southeastern US coastline, the low level circulation managed to survive
yesterday and the slow progression westward has started. It's currently still being sheared, but conditions may improve today. Therefore those along the southeast should be watching the progression of it.

Recon is tentatively scheduled to head out to the system this afternoon to check out the system.




Thinking hasn't changed much from yesterday, meaning that the system still has a lot to fight to keep going, and it will continue westward for a bit then back out into the Atlantic later. Odds are still that it won't make landfall or amount to much, but still there is a chance it will. Slow moving systems, sheared systems, do a lot tot complicated things. So it remains worth watching at least. Conditions for it to develop are still nowhere near ideal, and dry air and shear will remain an issue for development, but they are much better than the past two days.

Some models hook it back anywhere from out to sea to South Carolina, but most do not do well with systems of this nature, so it's difficult to take them at face value right now. The best guess right now is that the storm comes very close to the Carolinas but does not make landfall, and most of the rain would be offshore.

Have a guess or "feeling" where 99l will go or how strong it will be, let us know here



Chances for development have gone slightly up since yesterday, but today really will be a good indicator of what may happen.

Chances for Tropical Development of Disturbance off Southeast Coast (99L) In Next 2 days
Code:

(forget it) 0 1 2 3 4 5 6 7 8 9 10 (sure thing)
[--------*-----------]



Outside of 99L, not too much, a disturbance in the Gulf west of Florida may be worth watching. Look and watch if this one persists through the day.

Added: Also, a large but disorganized tropical wave moved off the coast of West Africa yesterday evening (near 13N 24W at 07/12Z). Easterly shear in that region has subsided over the last couple of days, so this one could be something to keep an eye on.
ED



Radar Loops
{{radarlink|mlb|Melbourne FL}}
{{radarlink|jax|Jacksonville FL}}
{{radarlink|clx|Charleston, SC}}
{{radarlink|ltx|Wimington, NC}}
{{StormLinks|99L|99|7|2007|3|99L (Area off Georgia/Florida)}}


MikeCAdministrator
(Admin)
Fri Sep 07 2007 12:52 PM
Re: Make or Break for 99L

99L is one of those systems you just need to watch, so much states it may not amount to much, but an equal amount of indicators have it going the other way too. It is one of those "watch and be prepared" scenarios. Close enough to home for genuine concern.

Accuweather is rather bullish on developing the system (I know Jack Boston there was even mentioning Gabrielle already), we're being pretty conservative here. The National hurricane center released a special update to bring more attention to the system as well. It deserves it, it's about a 50/50 split if it will amount to much. The Carolinas need to watch this one the most.


Ed in Va
(Weather Master)
Fri Sep 07 2007 01:25 PM
Re: Make or Break for 99L

Looks like some wrapping occurring the the more western blob of convection. If the two convection areas come together, it looks like there will be a fairly large storm in terms of area.

Lee-Delray
(Weather Master)
Fri Sep 07 2007 01:26 PM
Re: Make or Break for 99L

99L has proven very interesting. Hoewever, Accuweather would call a "sun shower" the next hurricane if it was within 1000 miles of the east coast or gulf.

jbmusic
(Weather Watcher)
Fri Sep 07 2007 01:36 PM
Re: Make or Break for 99L

Quote:

99L has proven very interesting. Hoewever, Accuweather would call a "sun shower" the next hurricane if it was within 1000 miles of the east coast or gulf.




Accuweather was saying last night we will have something develop in the next couple of days in the gulf. That shocked me I had not heard anyone make any kind of mention to that. Sometimes I feel like they go to the opposite extreme from the NHC


Ed in Va
(Weather Master)
Fri Sep 07 2007 01:51 PM
Re: Make or Break for 99L, Worth Watching

I'm reposting this link from the other day. It gives a great view of the developing storm:

http://www.ssd.noaa.gov/goes/flt/t3/loop-rgb.html


cieldumort
(Moderator)
Fri Sep 07 2007 02:36 PM
Re: Make or Break for 99L, Worth Watching

It's just about a done deal, imho. 99L has freed itself from the clutches of dry air as the shear began to relax. In the hours and probably days ahead, shear will likely only continue to relax more, overall.. especially as, if as now seemingly much more probable, 99 starts to build high pressure aloft.

With the environment surrounding 99 starting to moisten up in response to the diminished shear making for better internals, and a fairly tight little vortex already in place within a reasonably large broader cyclonic envelope, it seems highly probable to me that recon will find a storm there by later today. Recall that sustained winds are already running, perhaps conservatively running, 30 knots.

Whether this is yet a fully tropical entity, or becomes a fully tropical entity in the short-run is somewhat inconsequential at the moment. In fact, if 99s subtropical characteristics should win out, and as models are trending to forecast more of a sideswipe than a direct hit to the Carolinas/Mid-Atlantic, the cyclone will tend to work in tandem with the building ridge to its north to result in some of the strongest winds funneling down from the northeast well away from the center of circulation - such as might be far more typical of a subtropical storm or extratropical gale. Nonetheless, a core of strong winds already exists in the center, and as time begins working for rather than against 99, this thing may become fully tropical - with the kicker of a nor'easter-like element along its northern and western extent.

Accuweather might not be that far off the rocker with regard to something developing in the GOM. There does appear to be a general surface weakness there, and in the western Caribbean, left by the remnants of former Category 5 Felix. Just last night an impressive mesolow formed in the Bay of Campeche and quickly ramped up quite an impressive cluster of deep thunderstorms about and near its center. Upper level winds being rather favorable as well, water temps still very conducive, etc. .. imho, they are not at all out to lunch. Area is ripe.


WeatherNut
(Weather Master)
Fri Sep 07 2007 03:23 PM
Re: Make or Break for 99L, Worth Watching

Looking at the latest visible satellite images, it looks as if the LLC has tucked itself under the main blob of convection. They have been holding on to this being a 970mb hurricane during landfall at accuweather and I think the reasoning is quite sound. There is dramatic improvement over yesterday. The LLC survived conditions that could not have been harsher (minus low water temps). Ship reports have also seen substantial winds with this system today. It will be interesting to see what recon finds there

Beaumont, TX
(Storm Tracker)
Fri Sep 07 2007 03:28 PM
Re: Make or Break for 99L, Worth Watching

When is recon heading out to 99L? Also, the system in the Gulf west of Florida. Will it continue to move slowly west? Also, aren't upper
level winds not favorable at this time for development?


punkyg
(Weather Watcher)
Fri Sep 07 2007 03:39 PM
Re: Make or Break for 99L, Worth Watching

Quote:

When is recon heading out to 99L? Also, the system in the Gulf west of Florida. Will it continue to move slowly west? Also, aren't upper
level winds not favorable at this time for development?


I don't think the mess in the gulf will develop
and i think recon is going out this afternoon.


LoisCane
(Veteran Storm Chaser)
Fri Sep 07 2007 03:40 PM
Re: Make or Break for 99L, Worth Watching

looking better
also seems to have stopped moving east and slowed, can see where it would.. could move west

http://www.ssd.noaa.gov/goes/flt/t3/loop-rgb.html


ElizabethH
(Meteorologist)
Fri Sep 07 2007 04:04 PM
Re: Make or Break for 99L, Worth Watching

99L looks healthier as the day goes on. Convection starting to wrap on the northern sides ot the LLC. I think we could have our next TD by 4 cdt this afternoon. I do see some movement towards the west, so it'll stay tropical for a few days; I don't think we are looking at a subtropical system.

Models are persistant on developing 99L and have been for the past 3 or so days. If Recon finds decent winds speeds, looks like we'll have a Tropical system to track this weekend!


allan
(Weather Master)
Fri Sep 07 2007 04:44 PM
Re: Make or Break for 99L, Worth Watching

Looks like 99L is going to make it, although models are struggeling on intensity, I do believe it will be a another suprising storm like most of them this year thus far. The convection looks good, the outflow is great, I'd say this is close or even at TD strength, of course we got to wait for the official call on that, 99L has gotten much better in form and convection as I predicted yesterday.

MikeCAdministrator
(Admin)
Fri Sep 07 2007 05:36 PM
Re: Make or Break for 99L, Worth Watching

I've left the steering current graphic animation recording run since Felix, it may give some insight to where 99l may go. Here it is

danielwAdministrator
(Moderator)
Fri Sep 07 2007 05:50 PM
Recon

Recon is airborne and enroute at this time.
Tasking is for a 2100Z center fix or 5PM EDT/ 4PM CDT.

edit: At 24000ft recon encountered a wind shift.
From SW at 12 mph to E at 10 mph. 133 degree shift.

This was from 25 SSW of Valdosta,Ga to 50 ESE of Valdosta,GA.


NewWatcher
(Storm Tracker)
Fri Sep 07 2007 05:53 PM
Re: Make or Break for 99L, Worth Watching

Been watching those steering currents all day along with model runs, water vapor images and some more info. I have been thinking this isnt going as far north as the models were predicting. Modeling with a weak system is very tricky. I see more of a western movement then slightly more wnw and then after landfall more nw, n and then ne. I dont think it is gonna landfall much north of the GA- SC border. IMHO

Unregistered User
(Unregistered)
Fri Sep 07 2007 06:54 PM
Re: Recon

What due you make of the East wind at that flight level so close to the coast?

MikeCAdministrator
(Admin)
Fri Sep 07 2007 06:54 PM
Re: Make or Break for 99L, Worth Watching

Recon is in the Atlantic now, heading toward 99L, hopefully we'll have some data from then in an hour or so.


There is convection firing along the north and northwest sides of the low now, dry air is retreating to the west. The west (although starting to gain some convection now), southwest, and south sides still are void of convection, but that may change soon.


troy2
(Storm Tracker)
Fri Sep 07 2007 07:00 PM
Re: Make or Break for 99L, Worth Watching

Quote:

I've left the steering current graphic animation recording run since Felix, it may give some insight to where 99l may go. Here it is




Comparing where Felix went and what I am seeing on teh current steering map. I would say that this 'feature' has a very good chance of heaidng a bit more west than what models are predicting


TampaBayHurricaneChaser
(Registered User)
Fri Sep 07 2007 07:24 PM
Re: Make or Break for 99L, Worth Watching

99L is looking a lot better today, and I think that recon
may find a tropical depression. This is based on the system
being nonfrontal as the front has dissapated, so we should
see a warmer core. This system may threaten north carolina.

A greater concern for Florida and the Gulf of Mexico
might be the area of convection currently off florida's west
coast and in the eastern gulf of mexico. This area is associated
with a vigorous tropical wave that is migrating across
the gulf. I am not familiar with the current shear profiles
over the southern gulf, but I would expect perhaps
a niche to form between a sheared trough to the north and
shear to the west. Now if shear does lessen, I would expect
the potential for rapid development and intensification.
Convection is already concentrated and the system
looks fairly organized. Though a tropical wave, it bears
very close watching by all interests in Florida and along the
Gulf Coast. If shear lessens a tropical storm is possible

What opinions do others have regarding the status of the gulf of
mexico tropical wave?.


WeatherNut
(Weather Master)
Fri Sep 07 2007 07:33 PM
Re: Make or Break for 99L, Worth Watching

Looks like something is trying to consolidate around 25n 87w. I'm also starting to see a slight spin to the convection

cieldumort
(Moderator)
Fri Sep 07 2007 08:56 PM
Re: Make or Break for 99L, Worth Watching

The obs coming in thus far sure aren't anything to write home about. Would seem that a second center has attempted to form to the wsw of the original coc, under the fresh deep convection that has blown up on the west. May be a bit too unorganized this afternoon, just yet. A lot of the stronger winds found with scatterometer and ship reports look to have laxed from two days ago, less those which persist in response to the pressure gradient tightening from the high building in to 99s north.

Just a wee little bit longer tho, and we'll see what NHC wants to do with this one, at this time.


Ed in Va
(Weather Master)
Fri Sep 07 2007 09:08 PM
Re: Make or Break for 99L, Worth Watching

New NHC statement as of 5:05. Still not trop or subtrop, but could at any time.

Hugh
(Senior Storm Chaser)
Fri Sep 07 2007 09:10 PM
Re: Make or Break for 99L, Worth Watching

Quote:

Just a wee little bit longer tho, and we'll see what NHC wants to do with this one, at this time.




Per the STDS issued just a few minutes ago, the plane will continue to investigate the system for awhile longer, and a subtropical or tropical cyclone could form *at any time*. The statement also says that tropical storm watches could be issued this evening.

I read this to mean that winds are sufficient for the system to be named Gabrielle, but that the aircraft has not been able to close off the low - yet, at least.


ltpat228
(Storm Tracker)
Fri Sep 07 2007 09:18 PM
Re: Make or Break for 99L, Worth Watching

Quote:

New NHC statement as of 5:05. Still not trop or subtrop, but could at any time.





000
WONT41 KNHC 072106
DSAAT
SPECIAL TROPICAL DISTURBANCE STATEMENT
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
505 PM EDT FRI SEP 07 2007

THE AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT INVESTIGATING THE
LOW PRESSURE SYSTEM BETWEEN BERMUDA AND THE SOUTHEAST U.S. COAST
HAS NOT YET IDENTIFIED A WELL-DEFINED CLOSED SURFACE CIRCULATION.
THE AIRCRAFT WILL CONTINUE TO INVESTIGATE THIS SYSTEM...AND IT
COULD BECOME A TROPICAL OR SUBTROPICAL CYCLONE AT ANY TIME AS IT
MOVES WEST-NORTHWESTWARD AT ABOUT 10 MPH. INTERESTS ALONG THE
SOUTHEAST AND MID-ATLANTIC COAST OF THE U.S. SHOULD CLOSELY MONITOR
THE PROGRESS OF THIS SYSTEM...AND TROPICAL STORM WATCHES COULD BE
ISSUED THIS EVENING.

$$
FORECASTER KNABB


Storm Hunter
(Veteran Storm Chaser)
Fri Sep 07 2007 09:44 PM
Re: Make or Break for 99L, Worth Watching

just read over the recon data.... looks like we are close to having a tropical system... if the convection can wrap around more from the west side... it might help the center close off some... the low swirl can be seen moving to the west on vis shots... the tropical wave in the GOM... needs to be watched too!

cieldumort
(Moderator)
Fri Sep 07 2007 09:47 PM
Re: Make or Break for 99L, Worth Watching

Eh. Just because the winds would support classification as a tropical storm does not mean that such winds are truly representative of the incipient cyclone. Nonetheless, it is purely a judgment call from the learned folks in Miami.

Recon has now just found surface winds of 35 knots out of the ESE at 30.4 N 70.5 W. With recon not yet finding a "well-defined" center of circulation, it seems more likely to me that there are two lows competing with each other just a little bit too much just yet to close either one of them off, but, "this could happen at any time," and we would likely have ourselves Gabrielle.. but possibly a bit more subtropical, initially at least, even if NHC goes with the "tropical" moniker.


Hugh
(Senior Storm Chaser)
Sat Sep 08 2007 12:18 AM
Re: Make or Break for 99L, Worth Watching

Looking at the latest loops of both the Gulf and east coast systems... both look pretty non-tropical to me. The LLC in 99L is well south of the convection once again, it appears... so I don't think it'll form into Gabrielle "at any time"... tomorrow, possibly, but not tonight I don't believe anymore.

BillD
(User)
Sat Sep 08 2007 12:28 AM
Re: Make or Break for 99L, Worth Watching

I think this next to last obs from the recent recon says it all:

URNT11 KNHC 080014
97779 23380 60296 72400 03100 02015 22//8 /0012
RMK AF308 02GGA INVEST OB 24
SFC WINDS NOT VISIBLE

Bill


Hugh
(Senior Storm Chaser)
Sat Sep 08 2007 12:55 AM
Re: Make or Break for 99L, Worth Watching

Quote:

I think this next to last obs from the recent recon says it all:

URNT11 KNHC 080014
97779 23380 60296 72400 03100 02015 22//8 /0012
RMK AF308 02GGA INVEST OB 24
SFC WINDS NOT VISIBLE

Bill




I've never seen a recon report say that, I'll have to say.


cieldumort
(Moderator)
Sat Sep 08 2007 01:53 AM
Re: Make or Break for 99L, Worth Watching

Quote:

SFC WINDS NOT VISIBLE




Could have been anything. The sun was going down, as just one possibility.

NRL has just bumped 99 up to 40 knots, and a ship report recently came in at 00Z from a ship located at 32.40N 71.90W with a ENE wind of 45 knots.

99 is clearly a hybrid, and this should be of no surprise to anyone, given its entirely frontal beginnings. For now, the strongest winds are within a belt of tighter pressure gradients owing to the High to its north, and most likely within any thunderstorms within that belt.

With occasional flareups of deeper convection very near or just about over the primary LLC, it is most probable that when the learned folks at NHC say, "AND A TROPICAL OR
SUBTROPICAL CYCLONE COULD FORM AT ANY TIME AS THE SYSTEM MOVES
WEST-NORTHWEST AT ABOUT 10 MPH.," as they have, once again, in the 8PM TWD, they probably mean exactly that.


CarolinaGurl
(Weather Watcher)
Sat Sep 08 2007 02:34 AM
Re: Make or Break for 99L, Worth Watching

Navy site is now 07L-Gabrielle

May have Gabby at 11?


Ed in Va
(Weather Master)
Sat Sep 08 2007 02:35 AM
Re: Make or Break for 99L, Worth Watching

Subtropical Gabrielle just named:

http://www.nhc.noaa.gov/#GABRIELLE



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