ATL: TROPICAL STORM BILL (03L)

[KWT]

I'm talking about the 06z GFS wxman57 not the Bams!

[srainhoutx]

989
WHXX01 KWBC 131247
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1247 UTC THU AUG 13 2009

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

DISTURBANCE INVEST (AL902009) 20090813 1200 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
090813 1200 090814 0000 090814 1200 090815 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 11.6N 22.5W 12.5N 25.1W 13.0N 28.5W 13.5N 32.3W
BAMD 11.6N 22.5W 12.0N 25.1W 12.3N 27.9W 12.4N 30.8W
BAMM 11.6N 22.5W 12.2N 25.0W 12.5N 27.9W 12.7N 31.2W
LBAR 11.6N 22.5W 12.0N 24.6W 12.2N 27.3W 12.4N 30.3W
SHIP 25KTS 28KTS 35KTS 42KTS
DSHP 25KTS 28KTS 35KTS 42KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
090815 1200 090816 1200 090817 1200 090818 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 13.8N 36.6W 15.5N 47.2W 19.0N 59.9W 22.9N 69.5W
BAMD 12.5N 34.0W 12.9N 41.1W 13.5N 48.5W 13.8N 55.1W
BAMM 12.9N 34.7W 13.6N 42.6W 14.6N 51.5W 15.7N 60.7W
LBAR 12.6N 33.8W 13.4N 42.3W .0N .0W .0N .0W
SHIP 50KTS 65KTS 66KTS 71KTS
DSHP 50KTS 65KTS 66KTS 71KTS

...INITIAL CONDITIONS...
LATCUR = 11.6N LONCUR = 22.5W DIRCUR = 280DEG SPDCUR = 7KT
LATM12 = 11.4N LONM12 = 21.1W DIRM12 = 281DEG SPDM12 = 8KT
LATM24 = 11.0N LONM24 = 19.4W
WNDCUR = 25KT RMAXWD = 60NM WNDM12 = 25KT
CENPRS = 1009MB OUTPRS = 1012MB OUTRAD = 120NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

$$
NNNN

[cycloneye]

Its only one run of one model.Lets wait for GFS and the other models at the 12z run to see how they do and then we can discuss from there.

[wxman57]

Anyone got a historical map for 90L?

You can easily make your own right here. Just choose Latitude/Longitude from the left navigation menu, put in 90L's position and select the other criteria (distance from that location, type of storm, years, months.

http://csc-s-maps-q.csc.noaa.gov/hurricanes/viewer.html

[wxman57]

the latest models do give me some pause about this developing now (what was that about nothing really until the end of August...)

Still... we need more model runs to be sure

I'm quite impressed by the spin-up overnight. It has as good a circulation as TD 2 now, though a bit broad. More convection than TD 2. With convergence increasing near the center, I think it could be upgraded within 24 hours, possibly this afternoon. Probably only 1 storm. Don't by the twins predictions.

[KWT]

Agreed on that Wxman57, what do you think of the feeder arms that have developed on the outer edge of the circulation?

Also has that twins situation the GFS forecasted actually ever happened before like that?

[Thunder44]

the latest models do give me some pause about this developing now (what was that about nothing really until the end of August...)

Still... we need more model runs to be sure

I'm quite impressed by the spin-up overnight. It has as good a circulation as TD 2 now, though a bit broad. More convection than TD 2. With convergence increasing near the center, I think it could be upgraded within 24 hours, possibly this afternoon. Probably only 1 storm. Don't by the twins predictions.

I agree. It looks like it's slowly organizing. I'm not concerned with what the models are showing now.

[Derek Ortt]

21KT of shear is unfavorable for any tropical cyclone

[Dean4Storms]

Agree, the 06z run of GFS was garbage in regards to 90L.

It looked like it parks 90L right where it is sitting and another Tropical Wave rotates around the northern periphery of it forming into another TC once it passes 90L. Crazy

[Frank2]

El Nino = shear = ongoing unfavorable conditions for cyclone development, no matter what comes off Africa...

That's not to say that it won't lessen from time to time (per the Andrew lesson), but we have all learned that El Nino periods (similar to 2006) usually will mean at least some shear most of the time, especially west of 50W, since the southwesterly shear originates over the eastern Pacific and flows over Central America and northeastward...

Frank

P.S. Derek, do the older models now have a built-in "El Nino" bias of some sort, or do they just interpret current upper air sounding data and nothing more?

[wxman57]

Agreed on that Wxman57, what do you think of the feeder arms that have developed on the outer edge of the circulation?

Also has that twins situation the GFS forecasted actually ever happened before like that?

Just a model irregularity. 00Z GFS has no such twin. There is another vorticity center over Africa approaching from the east. GFS does spin that one up a little.

[KWT]

Yeah that makes sense I suppose.

So it indeed does mean we can probably chuck out the 06z GFS though we should be aware the synoptics it shows aren't that removed from the 0z ECM or in fact other GFS runs, its just the run does odd things with 90L itself.

[Sanibel]

There's an equally impressive wave approaching from Africa. Nothing is really firing convection. You can't make a strong cyclone from no convection.

The switch is flickering on because we got over 2 inches this dawn from convection that was only over the Gulf with none over land.

[cycloneye]

Continues to organize.

[KWT]

It reminds me of one of those big WPAC systems you get that have big lumbering circulations but not as much convection. Those tend to take a little while to take off depsite the good circulation.

Still no denying thats a decent circulation there, a little more convection and we will be in red alert I suspect.

[Sanibel]

Indeed Cycloneye, that is tightening up. Perhaps a d-max is right around the corner with an MJO uptick in a few days?

GFS loses this system by the islands and sends a deeper following system towards the Bahamas in a recurve under an east-centered Bermuda High.

[Thunder44]

SSD has positioned a floater for it, on the NHC site. But it's not in full view yet:

http://www.ssd.noaa.gov/goes/flt/t2/vis-l.jpg

[cycloneye]

Here is Dr Jeff Masters take on 90L.

A strong tropical wave with a large circulation and plenty of heavy thunderstorm activity is a few hundred miles south of the Cape Verdes Islands, off the coast of Africa. NHC dubbed this disturbance 90L this morning. This morning's QuikSCAT pass shows that 90L has a very large circulation, and top winds of about 30 mph. Satellite imagery from the European METEOSAT satellite show that the heavy thunderstorms associated with 90L are in two major bands, to the north and to the south of the center. There is no heavy thunderstorm activity near the center yet, and this would have to happen before 90L can be named Tropical Depression Three. Water vapor imagery shows that since 90L is forming several hundred miles south of the dry air of the Saharan Air Layer (SAL), the storm should not affected by dry air and dust as much as Tropical Depression Two has been. Wind shear is about 20 knots over 90L, and is forecast to remain in the moderate range, 10 - 20 knots, over the next five days. Sea Surface Temperatures are about 28°C, and will remain in the 27 - 28°C range the next five days, which are high enough above the 26°C threshold for tropical cyclone formation to allow some slow development to occur. The GFS and ECMWF models continue to predict the development of this wave, though they are now less aggressive about intensifying it than they were in earlier runs. The consensus among the reliable HWRF, GFDL, GFS, and ECMWF models is to bring 90L to point near or just north of the northernmost Lesser Antilles Islands 6 - 8 days from now. The storm could be at hurricane strength by then, as forecast by the SHIPS intensity model.

[MGC]

Does look to have a large circulation envelope which will require time to tighten up. I don't see development for a couple of days....MGC

[KWT]

Quite comical that they've put a floater on a system that isn't even within range yet, quite eager aren't they!

Also wil be interesting to see if the 12z GFS decides to change away from the 06z run.