Invest Thread

[Iceberg]

98L is still there and going, looks a bit better lately and is moving slowly into a more favourable environment.

[tcc]

I'm really going at the wrong time aren't I!

So now I don't have to worry about Felix, is this one starting to look like it could develop? It is further north which means it could head more NW, it all depends I guess on the high pressure over SE USA and whether it's going to weaken. I think there's a trough over the SW States headin east which could weaken the high pressure, which in turn could cause this invest to swing NW and head towards Florida northwards.

[Iceberg]

Latest ships for 98L. Still suffering shear but looks OK considering.

Track veraies but a General NW movement looks likely.

DISTURBANCE INVEST (AL982007) 20070903 0600 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...

070903 0600 070903 1800 070904 0600 070904 1800

LAT LON LAT LON LAT LON LAT LON

BAMS 10.7N 39.7W 10.3N 40.8W 9.7N 41.8W 9.3N 42.8W

BAMD 10.7N 39.7W 10.1N 41.8W 9.9N 44.0W 9.7N 45.9W

BAMM 10.7N 39.7W 10.1N 41.3W 9.7N 42.7W 9.5N 43.9W

LBAR 10.7N 39.7W 10.3N 40.9W 10.5N 42.3W 11.0N 43.9W

SHIP 25KTS 24KTS 24KTS 26KTS

DSHP 25KTS 24KTS 24KTS 26KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...

070905 0600 070906 0600 070907 0600 070908 0600

LAT LON LAT LON LAT LON LAT LON

BAMS 9.1N 43.7W 9.9N 44.8W 10.6N 45.2W 10.9N 47.5W

BAMD 9.5N 48.0W 9.3N 51.8W 9.5N 54.7W 10.2N 56.8W

BAMM 9.5N 44.9W 10.1N 46.9W 10.8N 48.9W 11.2N 51.1W

LBAR 11.6N 45.6W 13.3N 49.2W 14.4N 53.5W 15.2N 57.6W

SHIP 30KTS 39KTS 46KTS 49KTS

DSHP 30KTS 39KTS 46KTS 49KTS

[kold weather]

Still looks a mess with convection unorganised thanks to shear but as long as it can keep the LLC with it then it will probably eventually find itself out of the higher shear set-up. 98L is only crawling westwards at 4kts. The SHIPS show some slow strengthening occuring once it gets into a slightly lower shear set-up and given how long lasting the LLC has been i can only assume it probably will develop down the road.

Its eventual track still uncertain but an average motion of a little north of west occurs throughout the 120hr period and it does pick up a little foward speed. Very early days but I feel this may be more of a risk to the US then the last two long trackers Felix and Dean.

[tinybill]

all eyes should be on the next big storm leaving africa on the time scale on 114 hr at the moment its heading for the east coast

http://www.stormsurfing.com/cgi/display.cgi?a=natla_height13

[Iceberg]

I've just menioned this one in the wave thread, very much worth watching.

98L has lost it's central convection again, to be expected but as KW says worth looking at in the medium timeframe

[kold weather]

By the way we have a new invest. (well its actually been up for about 18hrs...) Invest 99L currently sitting about 300 miles offshore from Florida heading slowly ESE under quite a complicated upper atmospheric pattern with a slightly decaying ridge just about holding off a trough to the NE and 99L is trying to be picked up by the trough heading eastwards but the lattiude is being surpressed as the upper high starts to re-strengthen again.

Long track is complicated and the models are honestly all over the place. Given how strong the high has been so far this summer its quitepossible the system wil leventually get dragged back westwards. The new global model runs show 99L eventually heading back west/WNW the SE states of the USa.

right now the system is suffering a little from shear though convection is still strong as you'd expect given its over the gulf stream. The SHIPS do strength 99L into a mid-level tropical storm but its early days to tell. systems like this have gone on to become hurricanes in the past, two suchsystem from 2004 were Alex and Gaston and the eCM does take it upto that sort of range by 120hrs.

[kold weather]

While invest 99L is still being sheared its starting to really look a tropical depression and maybe even a tropical storm. it has a good ciruclation present though due to shear the western part of the circulation is exposed right now somewhat the low level circulation is on the NW side of the convection and will probably tuck into the convection quite reaidly.

Despite the slightly exposed LLC it has some really impressive convection on that eastern side and clearly has a strong cyclonic circulation to it, maybe even first signs of banding. I should think this won't take long to be TD7 and probably Gabrielle in the next 24hrs based on the current development even if the shear doesn't ease down.

Long term model show it heading Eastwards for a little while longer before a strong ridge forms to the north of the system and send sit back westwards probably aiming at the US east coast as a hurricane and if the ECM and CMC are to be believed, a major hurricane at that...

(ps, Dvorak estimates at 2.0---looks like we already have a TD, may be upgraded soon.)

Edited September 4, 2007 by kold weather

[Somerset Squall]

Blimey, another one to watch! The NHC said there might be tropical or sub-tropical development, is this purely tropical or not?

[Gray-Wolf]

I've spent the evening watching 99L but then got drawn away by the 'plume' being sent to the N/NE of Felix. The burst of convection, heading towards the Yucatan straights and into the Gulf, looks meaty. If things are 'up to temp' in the Gulf then the introduction of this unstable mass to it's SW could throw up a 'home grown' storm. Just a thought.

Edited September 4, 2007 by Gray-Wolf

[Somerset Squall]

I've spent the evening watching 99L but then got drawn away by the 'plume' being sent to the N/NE of Felix. The burst of convection, heading towards the Yucatan straights and into the Gulf, looks meaty. If things are 'up to temp' in the Gulf then the introduction of this unstable mass to it's SW could throw up a 'home grown' storm. Just a thought.

Yes, I've seen that too, if conditions are favourable enough perhaps there could be another "Erin"?

Take a look at the Felix loop on this page, shows the plume nicely.

http://weather.unisys.com/hurricane/atlantic/2007/index.html

Edited September 4, 2007 by Somerset Squall

[Iceberg]

ALL other Invests except 99L have died.

99L has a real possibility IMO. Scat shows good ciraculation, probably closed. Precip around the LLCC. Path is the biggest headache as it could go anywhere but a US landfall as a CAT 1 or 2 is a very much a possibility.

Ships/GFDL and ECM all take her to hurricane strength.

Bit surprised she hasn't been named a TD yet but very very good chance at 10am today.

[kold weather]

It still has good convection however the new images from a few hours ago shows the LLC is still exposed, more so then about 6hrs showing the shear may have actually picked up again a touch. It did look like a tropical depression then however its starting to show more hints of being subtropical at the present moment as it heads eastwards into cooler waters. I think we are really only waiting for the shear to ease off a little and we should see some sort of development from this system, I'd be surprise dif it doesn't given its good circulation and very good model guidence.

Nearly every single model develops this into a tropical cyclone and as Iceberg has noted some take 99L upto hurricane status. The track however is a little more complicated and probably the most uncertain of any invest this season as it is totally dependant on how well an upper trough digs down over central canada/USA and how much amplication it can get as well as just how strong the high pressure ends up. Right now my call would be N.Carolina but anywhere from GA to Newfoundland may well have to watch this system because they do tend to take interesting tracks.

[kold weather]

Invest 99L looks as close to a TD as your likely to see in a sheared atmosphere, Dvarok supports it being upgraded, Quikscat also shows a 25-30kt tropical depression, Sat.images clearly shows a low level circulation to the west of the fairly deep convection. So quite why its not been upgraded yet is a touch baffling unless they still believe its extratropical in nature.

Anyway recon flying towards the system a good few hours earlier, I dare say maybe to confirm whether 99L is a tropical depression or even tropical storm, flying from Keesler base so may be a few hours before we know exactly what shape 99L is in. I honestly think they will find TD7 and maybe a small chance of finding TS Gabrielle.

most models still take 99L towards the Carolinas then start to re-curve it NNE but until it decides to pick up foward speed its very hard to know its exact track other then a strong high is forecasted to develop to the north of the system which should ease off shear and send the system westwards.

Edited September 5, 2007 by kold weather

[BrickFielder]

Invest 99L

All residents of the U.S. East Coast from the Carolinas to Maine, and the Canadian Maritimes need to closely monitor this developing system. There is the potential for a significant hurricane event along the coastline later this week and into this week-end.

CMC takes this all the way up the eastern seaboard as a hurricane but the models seem a little unsure at the moment with one model taking it north east. My feeling is a new eye will develop with it moving more east than models suggest at the moment meaning it will either hit the US coast line further north or zip north turning extra tropical.

[Iceberg]

A very good example of shearing.

Recon is currently on it's way, I've got a sneaky thought that they will upgrade as soon as they get the OK from recon regardless of shear.

Edited September 5, 2007 by Iceberg

[kold weather]

Well this must be a very hard cal lfor the NHc, all the data does seem to support this system being upgraded and winds do support a 25-30kts tropical depression right as does the other data however that frontal boundary (the tail streching SW) is still fairly close anfd that may be playing on the minds of the folks at the NHC, esp after calling this a non tropical low today.

Still expect it to be upgraded at the latest of 12hrs time and to be a real threat to the east coast. i'll make a more detailed post when/if we have the system upgraded but I'll jusy say very soon it should start to swing back to the west as the ULL that is shearing the ssytem heads SW asthe upper high builds.

Edited September 5, 2007 by kold weather

[Iceberg]

Still not named and as you say KW it must be down to the not quite tropical nature of the system atm.

An added problem they must have is that as soon as they call it, the US Media will get hold of it look and the latest GFDL and say that a 100KT storm is about to hit the states. It's got the potential but has many huddles to overcome first.

Anyway the vortex from the recon.

Connvection wrapping around the LLCC will be the tropical charecterisitic they will be watching for, if we get this for 6 hours then they might call it.

Might be my imagaination but they seem a lot more careful about calling TD's this year, almost up to a point where a TS has been reached. Maybe a bit more caution from the new boss.

000

URNT12 KNHC 052059

VORTEX DATA MESSAGE AL992007

A. 05/20:25:40Z

B. 29 deg 28 min N

070 deg 14 min W

C. NA mb 3139 m

D. 33 kt

E. 092 deg 066 nm

F. 232 deg 033 kt

G. 092 deg 071 nm

H. 1006 mb

I. 9 C/ 3050 m

J. 10 C/ 3046 m

K. 4 C/ NA

L. NA

M. NA

N. 134 / 0

O. 0.02 / 9 nm

P. AF302 01GGA INVST OB 13

MAX FL WIND 33 KT SE QUAD 20:02:20 Z

MAX FL TEMP 11 C, 91 / 15NM

[Nick F]

I think we need to lose the dry air entrainment being drawn South on the Western side (looking at recent WV imagery) of the system and also lose that shear until we see a better chance of it moving into TD or TS category.

[kold weather]

Well it won't be a tropical depression this morning, it looks far worse then it did last night with shear really powering up and the deep convection that was just west last night has been blown away from the center to the east. It is going to have a lot more re-organising to do to get to the same stage it was at last night. I still think this is a big threat in the next few days but this system is going to have to lose the shear and pretty quickly otherwise it'll lose the good LLC it had last night and be back to square one. The dry air you mention Nick may also be a problem and will help to keep this system pretty lop-sided I reckon even if it reaches hurricane force.

EDIT 2---Actually scrap that last edit , just found the LLC again but the convevction is being completely stripped away from the LLC, it has also stalled from the looks of things.

Edited September 6, 2007 by kold weather

[Iceberg]

This is being officially classified as extra tropical now, from a T2 rating.

06/1145 UTC 28.7N 69.3W EXTRATROPICAL 99L

06/0645 UTC 29.2N 69.4W EXTRATROPICAL 99L

05/2345 UTC 29.5N 69.7W T2.0/2.0 99L

[kold weather]

99L is still being pretty badly sheared this morning but convection is still firing now close to the center but alas the shear is still blowing the convection away. However saying that its situation maybe isn't quite as severe as yesterday. The air is slightly moister then yesterday around the LLC which is allowing convection to blow up around the still pretty strong LLC...its certainly a fighter.

Models have backed off development this morning however I really don't like the model forecasts on strength as they were amazingly bad with Felix and Dean. Its hard to know exactly what is going to happen next with this system. The ULL that is shearing the system pretty badly is heading westwards at the moment and until it can get further away from the system then 99L will not develop. The only good thing that 99L has is the fact it hasn't really moved much at all over the last few hours, probably a slight drift the to the SW. All the models are forevcasting the system to get whisked away westwards under a developing high pressure cell to the north of the system and that should bolt it westwards, though the models may have overdone the intial foward speed of this system as its barely drifting.

Given the strong LLC this system has if it can ever get its act on no reason why it can't become a strong tropical storm pretty rapidly but will it get the better set-up that it requires??

[kold weather]

Well last few hours has seen the shear ease off quite neatly and the system is now developing quite a decent area of convection on its eastern quadrants though dry air is still limiting the western quadrant it looks far better then yesterday. The LLC is still a touch exposed on the west side but its very close tothe large mass of convection. Shear is easing as the ULL is finally sinking SW, 99L looks to be on a track a little south of NW right now.

Recon is going into the system later today to see just how well organised it is, honestly it could be anything from a subtropical depression to a full blown tropical storm by the time recon reaches the system in question. IF it does get its act on no reason why this system can't get close to hurricane status given the gulf stream waters are pretty warm, however the air is still fairly dry on the western side and i don't think this system will completely shake of the shear which may limit the systems strength IF it gets going, which looks more and more possible right now however that may for a little while closer to landfall help the outflow of any system.

Anyway here is a special tropical disturbance statement:

SATELLITE IMAGES INDICATE THAT THE AREA OF LOW PRESSURE LOCATED

BETWEEN BERMUDA AND THE SOUTHEAST U.S. COAST HAS BECOME BETTER

ORGANIZED OVERNIGHT. UPPER-LEVEL WINDS ARE BECOMING MORE FAVORABLE

FOR ADDITIONAL DEVELOPMENT...AND A TROPICAL DEPRESSION COULD FORM

LATER TODAY. AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT IS

SCHEDULED TO INVESTIGATE THIS SYSTEM THIS AFTERNOON. THE LOW IS

FORECAST TO MOVE GENERALLY WESTWARD OR NORTHWESTWARD DURING THE

NEXT COUPLE OF DAYS...AND INTERESTS ALONG THE EAST COAST OF THE

UNITED STATES SHOULD CLOSELY MONITOR THE PROGRESS OF THIS SYSTEM.

Edited September 7, 2007 by kold weather

[Cumulonimbus Tower]

Hello Weather-watchers

Is 99L the same storm they are talking about here?

http://wcbstv.com/topstories/local_story_248185549.html

Cheers

Ned

[karyo]

Hello Weather-watchers

Is 99L the same storm they are talking about here?

http://wcbstv.com/topstories/local_story_248185549.html

Cheers

Ned

Yeap, that's the one!

Karyo