ATL : TROPICAL DEPRESSION ERIKA (06L)

[HURRICANELONNY]

The NHC is favoring the GFS & ecmf of course. Now I know were in trouble.

Concerning the broad area of low pressure some 350 miles east of the
Leeward Islands (invest al94 as designated by nhc)...the GFS still
doesn't like this feature and tracks it as an open wave reaching
the Bahamas by Tuesday. The European model (ecmwf) on the other hand does develop
this feature...on its last two runs. It takes it north of the
leeward's then turns it north as it nears 70w then NE away from
the eastern Seaboard of the United States. GFS early next week
shows a weak middle/upper trough developing off the southeast U.S. Coast
which would also favor the European model (ecmwf) scenario should this feature
develop...which NHC gives likely probabilities of doing so.
Still...it's a long ways out so will continue to monitor how this
weather pattern evolves.

[HURAKAN]

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE SEP 01 2009

...SPECIAL FEATURES...

BROAD AREA OF LOW PRESSURE ASSOCIATED WITH A 1007 MB LOW ROUGHLY
CENTERED NEAR 16N56W OR ABOUT 240 NM E OF THE LEEWARD ISLANDS
CONTINUES TO SHOW SIGNS OF ORGANIZATION BUT NOT A WELL-DEFINED
SURFACE CIRCULATION CENTER. A SURFACE TROUGH EXTENDS FROM 20N52W
THROUGH THE SURFACE LOW TO 11N63W. SCATTERED/NUMEROUS STRONG
CONVECTION IS WITHIN A 60 NM RADIUS OF 16.5N53.5W WITH SCATTERED
MODERATE/ISOLATED STRONG CONVECTION COVERING THE REMAINDER OF
THE AREA FROM 14N-20N BETWEEN 51W-55W AND CLUSTERS OF SIMILAR
CONVECTION WITHIN 45 NM OF LINE FROM 14N53W TO 12N57W. THIS
SYSTEM COULD BECOME A TROPICAL DEPRESSION OR TROPICAL STORM AT
ANY TIME OVER THE NEXT COUPLE OF DAYS AS IT MOVES WNW NEAR 8 KT.
INTERESTS IN THE LEEWARD ISLANDS...THE U.S. AND BRITISH VIRGIN
ISLANDS...AND PUERTO RICO SHOULD MONITOR THE PROGRESS OF THIS
SYSTEM.

[wxman57]

Reliable surface obs in the area (buoys) indicate that the center is well west of 56W. In fact, the latest surface analysis points to the lower pressure between closer to 57W (or a little west of there), as indicated on the chart below. If that's the case, then the blowup of convection is an illusion of strengthening. It still may lack a well-defined LLC. Of course, if that convection persists all day today, then there's a good chance a center will form underneath.

[ExBailbonds]

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

Well looking good but its becoming more clear the threat to the CONUS continues to dimish. It's nearly impossible that it will hit FL or the GOM it looks like (see models thread)

I agree with Derek, those looking for a Florida or CONUS threat should probably look elsewhere. That perma-trough is coming back to save the CONUS it looks like yet again. Have we yet to see any kind of real Bermuda High this summer? Unbelievable how strong the East coast trough is this summer.....

So let me get this right you are sounding the all clear for Florida? I think you are jumping the gun this thing it is still south of our lattatude. and the models have shown that they do not have a handle on this system or its suroundings yet. I hope your right but you could be very wrong too.

[cycloneye]

Is a go for recon this afternoon.From 8 AM Tropical Weather Outlook.

AN AIR FORCE RESERVE
RECONNAISSANCE AIRCRAFT IS SCHEDULED TO INVESTIGATE THE LOW THIS
AFTERNOON.

[Evil Jeremy]

The 06Z GFS is not up on the SFWMD chart yet, but it is more south and west than before, hugging the coasts of PR and Hispaniola before effecting Florida and the Bahamas and recurving as... something.

http://moe.met.fsu.edu/cgi-bin/gfstc2.c ... =Animation

[fci]

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

Well looking good but its becoming more clear the threat to the CONUS continues to dimish. It's nearly impossible that it will hit FL or the GOM it looks like (see models thread)

I agree with Derek, those looking for a Florida or CONUS threat should probably look elsewhere. That perma-trough is coming back to save the CONUS it looks like yet again. Have we yet to see any kind of real Bermuda High this summer? Unbelievable how strong the East coast trough is this summer.....

So let me get this right you are sounding the all clear for Florida? I think you are jumping the gun this thing it is still south of our lattatude. and the models have shown that they do not have a handle on this system or its suroundings yet. I hope your right but you could be very wrong too.

Not sure that Mr. Bailbonds is now the spokesperson who has the authority to proclaim an "all clear for Florida" but the NWS discussion has this:
...the GFS still
doesn't like this feature and tracks it as an open wave reaching
the Bahamas by Tuesday. The European model (ecmwf) on the other hand does develop
this feature...on its last two runs. It takes it north of the
leeward's then turns it north as it nears 70w then NE away from
the eastern Seaboard of the United States."

Now, I am not annointed one to sound the all clear either; but I am not particularly worried about this one.
And I have yet to see a Pro Met express the opinion that this IS a threat to us in South Florida.
I will wait to see it pass before I fully trust it, as I always do; but I am not worried about 94L at this time!

[HURAKAN]

WTNT01 KNGU 011201
SUBJ/TROPICAL CYCLONE FORMATION ALERT 011201Z SEP 09//
REF/A/MSG/NAVMARFCSTCEN NORFOLK VA/311201Z AUG 09//
AMPN/REF A IS TROPICAL CYCLONE FORMATION ALERT (WTNT01 KNGU 311201)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
100 NM EITHER SIDE OF A LINE FROM 16.0N 55.9W TO 17.5N 59.7W
WITHIN THE NEXT 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF A NUMBERED TROPICAL CYCLONE WARNING AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 25 TO 30 KNOTS. METSAT IM-
AGERY AT 010600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 16.0N 55.9W. THE SYSTEM IS MOVING WEST-NORTHWESTWARD AT 8
KTS.
2. REMARKS:
AT 01/06Z INFRARED SATELLITE IMAGERY INDICATED A BROAD LOW-LEVEL
CIRCULATION LOCATED NEAR 16.0N 55.9W TRACKING WEST-NORTHWESTWARD AT 8KTS.
THIS LOW-LEVEL CIRCULATION IS LOCATED OVER WARM SEA SURFACE TEMPERATURES
OF 27 TO 29 DEGREES CELSIUS. UPPER LEVEL WINDS OVER THE SYSTEM ARE
SOUTHWESTERLY 25 TO 30 KTS AND EXPECTED TO INCREASE, INHIBITING FURTHER
DEVELOPMENT AT THIS TIME. AS THIS SYSTEM CONTINUES TO TRACK
WEST-NORTHWEST, UPPER LEVEL CONDITIONS BECOME MORE FAVORABLE FOR TROPICAL
CYCLONE DEVELOPMENT.
THIS SUPERSEDES REF A.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED
BY 021201Z.//

[HURAKAN]

Quikscat plus satellite

[xironman]

Reliable surface obs in the area (buoys) indicate that the center is well west of 56W. In fact, the latest surface analysis points to the lower pressure between closer to 57W (or a little west of there), as indicated on the chart below.

If you do a super close zoom of the RAMDIS loop it certainly does look like the spin is way out in front of the convection as well http://rammb.cira.colostate.edu/ramsdis/online/loop_640.asp?product=tropical_ge_4km_visir2_floater_2

[curtadams]

That Quickscat shows a really bizarre windfield. This is a weird one.

[cycloneye]

SSD Dvorak

01/1145 UTC 16.3N 56.8W T2.0/2.0 94L -- Atlantic

http://www.ssd.noaa.gov/PS/TROP/tdpositions.html

[Derek Ortt]

this has ran into a wall from the very large upper trough that has dug deep into South America.

Would not surprise me if we saw no development at all today

[Frank2]

The deep trough axis is currently forecast to remain over Florida for the next day or two and to only lift out into north Florida by Thursday, so that's always a sign of our not having to worry about anything tropical coming this way from the east for at least the short term...

Frank

[Gustywind]

Discussion on the weather site of crown weather
http://www.crownweather.com/?page_id=325
Invest 94L Located 350 Miles East Of The Leeward Islands:

It's been a very interesting 24 hours monitoring Invest 94L, which in my eyes, is at least a tropical depression, if not a tropical storm. Anyways, 94L has put on a impressive blowup of convection over the past 12 hours or so and it shows no signs of slowing down. I suspect when reconnaissance aircraft get in there today they will find a developing tropical depression or tropical storm. 94L is tracking west-northwest at a forward speed of 10 mph. Satellite imagery and an analysis of the wind shear around this system show some interesting things this morning.

Satellite imagery showed two things: One is that there is some decent inflow developing and Two is that the tops of the thunderstorms around the system are fanning out which means that shear is decreasing around 94L. Also, there appears to be a rather quick weakening of the trough of low pressure located near 25 North Latitude, 70 West Longitude, which looks like caused the shear axis to pull back to the northwest, therefore, this put 94L in a divergent (ie. favorable) environment. So, if this trend continues, we may see fairly rapid intensification from 94L; although a quick analysis showed that shear may be increasing on the western side of the system and this could ultimately put a damper on the deep convection we are currently seeing.

Now, what does the future hold for Invest 94L? Well, I think it will be upgraded to depression or perhaps even tropical storm status today, especially when recon aircraft get in there. I would be surprised if Hurricane Hunter aircraft cannot close off a center. Looking at the model guidance for the next several days, it appears that the more simple models like the BAMS and LBAR models are doing a better job than the dynamical consensus models. The model performance statistics can be viewed HERE. So, I think 94L will track on a general west-northwest track over the next several days and pass about 75 to 80 miles north of the Virgin Islands on Thursday morning. After that, a continued course to the west-northwest seems likely and I think that in 5 days (Sunday morning), Invest 94L/Erika will be located near 20.8 North Latitude, 70.0 West Longitude. All of the available hurricane intensity models forecast gradual strengthening over the next few days, however, if 94L tracks quicker than what the shear zone is backing to the west and northwest, it would find itself in a very hostile environment. The global models like the European and NOGAPS models forecast intensification over the next several days and it appears they forecast that 94L will move in tandem with the shear zone and remain in a favorable environment. So, I am going with the consensus and am going to forecast steady strengthening over the next several days and this system could be a hurricane by the end of the week.

The long range future, beyond Sunday, for 94L/Erika is a tough call and there are a lot of unknowns, so I don't want to make a hedge beyond Sunday. I will note though that the European model has forecasted a turn northward around 70 West Longitude and an eventual turn out to sea for the second run in a row. It is interesting to note that much like with Bill that the UKMET model does not agree with the European model and forecasts that it will be in the southeast Bahamas in 6 days. So, I wonder if the European model will trend westward with time or will the UKMET model trend towards the European model. Now, since I am forecasting a position that is south and west of the European model, I will be bold and forecast that the European model will trend westward with time and potentially curve to the north along the 75 West Longitude line early next week.

In the more immediate term, all interests in the Leeward Islands, the U.S. and British Virgin Islands and Puerto Rico should closely monitor the progress of this system. Do not be surprised to see Watches and maybe even Warnings be issued for parts of these areas later today or tonight.

The effects from this storm will be felt in the Leeward Islands on Wednesday into Wednesday night, the Virgin Islands from late Wednesday through Wednesday night and into Thursday morning and possibly Puerto Rico from Thursday afternoon through Thursday night and into early Friday morning. So, if you are in the Leeward Islands, Virgin Islands and Puerto Rico, please be aware that at the very least tropical storm force winds will be affecting you within the next 30 to 60 hours from east to west. Whether this system affects the Bahamas, the southeastern United States or even areas further up the US East Coast is still a huge unknown, however, there is plenty of time to watch this system and see what it does or even does not do.

The next tropical weather discussion will be issued by 6 am EDT Wednesday.

[cycloneye]

[jasons2k]

That Quickscat shows a really bizarre windfield. This is a weird one.

Looks like a classic open wave, which it probably is based on that center fix provided by WxMan57.

[Gustywind]

SSD Dvorak

01/1145 UTC 16.3N 56.8W T2.0/2.0 94L -- Atlantic

http://www.ssd.noaa.gov/PS/TROP/tdpositions.html

DATE/TIME LAT LON CLASSIFICATION STORM
01/0615 UTC 16.4N 55.9W T2.0/2.0 94L
31/2345 UTC 16.7N 54.5W T2.0/2.0 94L

3 latest positions are a bit slighty south...and more west

[Gustywind]

[size=200]94L...[/size]

[Ivanhater]

Quick recap of the models...I don't see this "perma-trough" Gator. In fact it looks like this will get trapped under the ridge over the East coast.

CMC



GFDL



GFS



HWRF



NOGAPS