Model Runs & Discussions of GOM-Bahamas

[Stratosphere747]

0z Euro - http://www.meteo.psu.edu/~gadomski/ECMW ... ml#picture

[Nimbus]

If I had to pick a center of rotation it would be near Bimini.

That is pretty far south, if the steering winds are from the northeast that could take this SW or WSW. That would give it quite a long run across the gulf. AFM feels that any LLC will be dealing with the shear from the ULL till mid week.

Because of the southern initialization I'm leaning more towards a Texas threat at the moment. If we get a Texas trough later in the forecast that could change.

[MiamiensisWx]

Interestingly, winds are N and NW at all south FL stations. The NW winds were reported at two stations in SE Florida (West Palm Beach and Pompano Beach Airpark).

City Sky & Wx Tmp DP RH Wind Pres Remarks
NAPLES MOCLDY 79 72 78 N10 29.97R
W PALM BEACH PTSUNNY 75 72 90 NW3 29.94F
FT LAUDER-EXEC MOSUNNY 76 70 82 N5 29.95R
FT LAUDERDALE PTSUNNY 77 71 82 NE8 29.95R
POMPANO BEACH MOSUNNY 75 72 88 NW8 29.95R
PEMBROKE PINES SUNNY 75 72 90 N7 29.97R
OPA LOCKA SUNNY 76 72 87 N8 29.96R
MIAMI MOSUNNY 77 71 82 N6 29.96R
MIAMI BEACH N/A 79 74 85 N6 29.95R
WEST KENDALL SUNNY 75 71 87 N8 29.95R
HOMESTEAD SUNNY 75 72 91 N8 29.95R

http://www.srh.noaa.gov/mfl/observations.php

Additionally, I think I can see a broad low-level circulation just E of Bimini in the Bahamas. Bimini is situated ESE of Fort Lauderdale, FL. The circulation is near 25.8N and 79.1W. It is a weak circulation, but some convection is firing in the vicinity. Development would probably occur if shear was lower. There is some low-level convergence in the vicinity, too (click here).

http://www.ssd.noaa.gov/goes/east/gmex/loop-ir2.html

http://www.ssd.noaa.gov/goes/east/gmex/loop-vis.html

Additionally, I could be wrong, but it looks like the upper low is less detrimental than yesterday. Upper-level shear appears to be decreasing slightly; feel free to correct me, but I'm basing this statement on the latest visibles from GOES.

[boca]

http://www.ssd.noaa.gov/goes/east/watl/loop-avn.html

I don't see any movement what so ever.

[Stratosphere747]

The ULL is moving. Looks like right down the middle of Florida and not backing into the GOM.

http://www1.cira.colostate.edu/RAMM/Rms ... OMAIN.HTML

[cycloneye]

000
NOUS42 KNHC 181330
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
0930 AM EDT TUE 18 SEPTEMBER 2007
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 19/1100Z TO 20/1100Z SEPTEMBER 2007
TCPOD NUMBER.....07-116

I. ATLANTIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. SUCCEEDING DAY OUTLOOK: PROBABLE LOW LEVEL INVEST
NEAR 25.5N 88.0W AT 20/1800Z.


http://www.nhc.noaa.gov/text/MIAREPRPD.shtml?

The squadron is planning a mission for thursday at 2 PM,if necessary.

[Air Force Met]

Interestingly, winds are N and NW at all south FL stations. The NW winds were reported at two stations in SE Florida (West Palm Beach and Pompano Beach Airpark).

Additionally, I could be wrong, but it looks like the upper low is less detrimental than yesterday. Upper-level shear appears to be decreasing slightly; feel free to correct me, but I'm basing this statement on the latest visibles from GOES.

The winds are northerly because the massive high located over northern US is ridging down into Florida and whats left of the cold front....along with some trofing off the east coast.

As far as the shear goes...it has just begun to set up. Give it another day or so...that is when it really sets up...once the upper low cuts off and sets up over the eastern GoM.

[MWatkins]

88W? I wonder if that is a typo. Seems pretty far west for Thursday...

MW

[boca]

The ULL is moving. Looks like right down the middle of Florida and not backing into the GOM.

http://www1.cira.colostate.edu/RAMM/Rms ... OMAIN.HTML

Your right it is moving but not towards the GOM it looks like its moving west of due south.

[lrak]

I. ATLANTIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. SUCCEEDING DAY OUTLOOK: PROBABLE LOW LEVEL INVEST
NEAR 25.5N 88.0W AT 20/1800Z.


Why are those coordinates given, is this were they expect the invest to be on Thursday?

[MiamiensisWx]

http://www.ssd.noaa.gov/goes/east/watl/loop-avn.html

I don't see any movement what so ever.

Don't look at IR. Look at visibles and shortwave loops. Here's a good link. Click on "animation", select quality 100 percent, select high zoom factor, and click on the region near Bimini (off SE Florida).

http://www.ghcc.msfc.nasa.gov/GOES/goeseasthurr.html

http://www.ssd.noaa.gov/goes/east/gmex/loop-ir2.html

http://www.ssd.noaa.gov/goes/east/gmex/loop-vis.html

Additionally, you can spot some broad rotation on the NWS Miami radar.

Miami radar loop

Here's the area where I see the rotation. It's probably nothing significant, but I decided to mention the feature.

http://img232.imageshack.us/img232/1363/bahamassep18071rv5.png

Additionally, there is an upper low off central FL, where a possible sfc low may be forming:

GULF OF MEXICO...
AN UPPER LOW IS INLAND OVER MEXICO NEAR TAMPICO AND COVERS THE
THE FAR WEST GULF. AN UPPER RIDGE EXTENDS FROM THE YUCATAN
PENINSULA NW TO THE LOUISIANA/TEXAS BORDER. A DEEP LAYERED UPPER
TROUGH IS OVER THE EASTERN SEABOARD DIGGING INTO THE E GULF AND
THE STATE OF FLORIDA WITH A POSSIBLE LOW CLOSING OFF THE COAST
OF FLORIDA PENINSULA. LATEST WV IMAGERY IS ALREADY SHOWING THE
UPPER LOW FORMING OFF THE CENTRAL FLA COAST. THERE IS SOME
SHOWERS NEAR THE BASE OF THE TROUGH OVER THE SE GULF. WIDELY
SCATTERED SHOWERS ARE ALSO SEEN OVER THE WESTERN GULF. AT THE
SURFACE...HIGH PRES DOMINATES THE EASTERN US AND THE GULF
PRODUCING LIGHT TO MODERATE NELY WINDS N OF 25N. SOME OF THE
COMPUTER MODELS ARE SUGGESTING A SFC LOW WILL DEVELOP IN THE ERN
GULF WED NIGHT AND THU. THE PRECURSOR OF THIS LOW COULD BE THE
SFC TROUGH THAT IS CURRENTLY E OF FLORIDA. THE GFS MODEL MOVES
THIS TROUGH WWD INTO THE GULF DURING THIS TIME FRAME.

8:05 a.m. TWD

[Air Force Met]

88W? I wonder if that is a typo. Seems pretty far west for Thursday...

MW

Yeah. The GFS has it near 85W (on the 850 vort) at 18Z on Thursday. 88W seems a little too far west...but then again...any further east is almost under the ULL.

[tailgater]

If I had to pick a center of rotation it would be near Bimini.

That is pretty far south, if the steering winds are from the northeast that could take this SW or WSW. That would give it quite a long run across the gulf. AFM feels that any LLC will be dealing with the shear from the ULL till mid week.

Because of the southern initialization I'm leaning more towards a Texas threat at the moment. If we get a Texas trough later in the forecast that could change.

I'm not sure how this sytem is supposed to come together yet but I do see your rotation on radar, click off the Topo and it's faily easy to see.

http://radar.weather.gov/radar.php?prod ... X&loop=yes

[lrak]

Thanks AFM,

I thought so myself. Pretty far that is.

[Air Force Met]

Thanks for the response. Currently, it looks like the upper low is temporarily ventilating the system before it cuts off and enhances stronger UL divergence (shear). Do you think I'm correct?

Yes...and that is what we were talking about last night. The ULL would baroclinically spark it at the sfc...get it going...then the shear would kick up and a sheared low would track into the GoM and wait for better conditions later in the period.

[rockyman]

Abrams and Bettes are advertising tonight's TWC program...with the headline (paraphrased) "monitoring possible tropical system developing off Florida east coast"

[wxman57]

88W? I wonder if that is a typo. Seems pretty far west for Thursday...

MW

Yeah. The GFS has it near 85W (on the 850 vort) at 18Z on Thursday. 88W seems a little too far west...but then again...any further east is almost under the ULL.

I'm plotting the GFS/ECMWF at 0.5mb increments in GARP. Here's what I have:

GFS
18Z Thu: 25N/86.5W
21Z Thu: 25N/87.0W
00Z Fri: 25N/87.4W

EC:
00Z Fri: 22.8N/87.8W

European is a good bit farther south, but both models aren't too far from 88W by Thursday afternoon.

[gatorcane]

Is it me or is yet another King TUTT going to kill this thing in the GOM.

These upper-level lows have single-handedly protected the U.S the past couple of years (except for Humberto)

You can see our Hurricane-killing friend on WV loop heading south from north Florida into the GOM right where we would expect some development.

[Ivanhater]

Well I just got done with PT with the air force this morning so Im awake! It seems if this develops, it will be a slow mover in the gulf..interesting week for sure

[Stormcenter]

Jeff Masters is discussing the possibility of a hurricane in the GOM for this weekend.
I personally think that is a big time stretch here but hey look at what Humberto did.
We shall see.

The four reliable computer models for forecasting tropical cyclone genesis all predict that once this area of disturbed weather crosses Florida and emerges into the eastern Gulf of Mexico on Thursday, wind shear will drop enough to allow a tropical depression to form. The path such a storm might take is highly uncertain, and the models have diverged significantly since yesterday's runs. A strong ridge of high pressure is setting up over the eastern half of the U.S., and is expected to remain anchored in place for at least ten days. This is the type of steering pattern we experienced during the Hurricane Season of 2005, and favors westward-moving storms. This ridge will act to steer any developing storm in the Gulf of Mexico towards the west, to the Texas coast, or even west-southwest, to the northeastern mainland Mexico. However, this steering pattern will be complicated by the presence of an upper-level low pressure system over the Gulf of Mexico. This upper-level low is currently forming over northern Florida, and is expected to drift southwestward or westward over the Gulf later this week, and gradually weaken. Depending on the strength and movement of this low, a storm that forms in the eastern Gulf could be steered anywhere from the Florida Panhandle to northeastern Mexico. One model, the NOGAPS, predicts that the storm will move west-southwest into the Bay of Campeche (southwestern Gulf of Mexico), and stall out for many days. The UKMET, GFS, and ECMFW models foresee that the storm will make landfall in Texas or Louisiana Sunday or Monday. All residents along the Gulf of Mexico coast need to consider what actions they might need to take if a hurricane develops in the Gulf this weekend. The highest danger region is from New Orleans westward to Brownsville, Texas. A hurricane hunter airplane is on call for Thursday afternoon.