Low Pressure near Northern Leewards

[ronjon]

From NWS Tallahassee AFD:

LATE IN THE PERIOD...THINGS COULD GET EVEN MORE INTERESTING AS SOME OF THE GLOBAL MODELS (25/00Z EURO INCLUDED) ARE BRINGING A TROPICAL SYSTEM INTO THE YUCATAN CHANNEL. SINCE THIS IS PROGGED TO OCCUR AROUND WEDNESDAY EVENING...THERE IS MUCH UNCERTAINTY IN THIS SYSTEM. NEVERTHELESS...IF SOMETHING DEVELOPS IT WILL SERVE TO KEEP THE
PRESSURE GRADIENT TIGHT ACROSS OUR REGION AND WINDS ELEVATED THROUGH THE REMAINDER OF THE WEEK.

[TampaFl]

Morning Florida NWS AFD Thoughts:


000
FXUS62 KKEY 251002
AFDKEY

AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
600 AM EDT THU OCT 25 2007

.DISCUSSION...

THERE IS A LARGE AREA OF BROAD LOW PRESSURE OVER THE CARIBBEAN
SEA...AS IS NORMAL FOR THIS TIME OF YEAR WHEN A COLD FRONT HAS NOT
SCOURED THE AREA...AND THERE IS A GOOD AMOUNT OF DISAGREEMENT AMONG
THE FORECAST MODELS IN THE EXTENDED PERIOD BECAUSE OF THEIR ATTEMPTS
TO DEVELOP LOW PRESSURE SYSTEMS IN THIS AREA. AS THERE IS LITTLE
SKILL IN MODEL FORECASTS OF SUCH A SCENARIO AT EXTENDED RANGE...WILL
CARRY INHERITED FORECASTS OF TEMPS/POPS SLIGHTLY ABOVE CLIMO.
HOWEVER...GIVEN THE RELATIVELY HIGH PWAT VALUES THAT PERSIST WELL
INTO NEXT WEEK...AND ESPECIALLY IF INDEED ANY WAVES OR OTHER LOW
PRESSURE SYSTEMS DEVELOP AROUND THE CARIBBEAN...POPS WILL NEED TO BE
RAISED FROM THE CURRENT LEVEL OF 20 IN THE EXTENDED FORECAST. I HAVE
BUMPED UP WINDS AND SEAS JUST A BIT IN THE MARINE FORECAST FOR EARLY
NEXT WEEK...AS A MASSIVE HIGH PRESSURE AREA OVER THE CONTINENTAL
U.S. WILL COMBINE WITH THE LOW PRESSURE IN THE CARIBBEAN TO PRODUCE
A DECENT PRESSURE GRADIENT NEAR OUR AREA.

&&



FXUS62 KMLB 250852
AFDMLB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MELBOURNE FL
450 AM EDT THU OCT 25 2007

.DISCUSSION...

MON-WED...BRISK EASTERLY FLOW PERSISTS AS GRADIENT BETWEEN HIGH
PRESSURE TO THE NORTH AND LOWER PRESSURES OVER THE CARIBBEAN...CUBA
AND THE KEYS REMAINS TIGHT. REPEATING THE DAY SHIFT...HEMISPHERIC
MODELS CONSISTENT WITH SCENARIO OF SLOWLY LOWERING PRESSURES AND
CONSOLIDATION OF SURFACE LOW OVER NW CARIBBEAN/YUCATAN REGION
THROUGH THE EXTENDED PERIOD...FAVORING EVENTUAL N/NW MOVEMENT. MUCH
TOO EARLY TO DETERMINE ANY POSSIBLE IMPACT TO CWA...HOWEVER PROSPECT
FOR PROLONGED MOISTURE FEED FROM THE TROPICS LOOKS REASONABLE.

&&


000
FXUS62 KTBW 250710
AFDTBW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
310 AM EDT THU OCT 25 2007

.LONG TERM (SATURDAY NIGHT - THURSDAY)...MODEL CONSENSUS INDICATES THE
CUTOFF LOW OVER THE MISSISSIPPI VALLEY DRIFTS NORTH AND IS ABSORBED
INTO A BROAD ZONAL FLOW ACROSS THE NORTHERN THREE QUARTERS OF THE
U.S. ON THE SURFACE... A LARGE HIGH PRESSURE SYSTEM DROPS OUT OF
NORTHWESTERN CANADA OVER THE CENTRAL U.S. BY SUNDAY AS A WEAK AREA
OF LOW PRESSURE DEVELOPS OVER THE CARIBBEAN. THIS SUBSTAINS THE WEAK
BOUNDARY WITH CLOUDS AND SHOWERS OVER THE FLORIDA PENINSULA WITH A
SHARPENING MID LEVEL TROUGH PUSHING TOWARD FL THEN BECOMING
STATIONARY MONDAY. THIS PATTERN DOESN`T CHANGE MUCH THROUGH
THURSDAY WITH EASTERLY FLOW. SOUTH OF THE FRONTAL BOUNDARY CLOUDS
AND SHOWERS ARE EXPECTED WITH TEMPERATURES SLIGHTLY ABOVE NORMAL AND
DRIER CONDITIONS NORTH OF THE BOUNDARY.

&&

[cycloneye]

[wxman57]

It's a good thing we have computer models. Without them, if we just looked at what was happening - at the surface obs, satellite loops, long-term water vapor loops, etc., then we'd say "What? You've got to be kidding! TC development in the Caribbean??" Just keep in mind that in most cases, the models are wrong in predicting cyclogenesis. In such a hostile environment, I have to think the odds are against development. But I'll keep an eye on the area - just in case.

[HURAKAN]

[Fego]

An Invest?????
http://www.ssd.noaa.gov/PS/TROP/float1.html

[cycloneye]

It looks that NRL will tag a invest for this later today.

[Fego]

G. Morning. Cycloneye is there another way to confirm that this low will be tag as an invest other than the navy page?

[ronjon]

From HPC Preliminary Discussion:

COASTAL SE INTO FL...

THE BEST CHANCE FOR WET WEATHER DURG THE MED RANGE PERIOD WILL BE ACRS THE COASTAL SE AND INTO FL. THE TRAILING COLD FRONT FROM THE DEPARTING LOW ACRS ERN CAN AT THE BEGINNING OF THE MED RANGE WL BECOME STNRY FROM OFF THE SERN COAST AND ACRS NRN TO CNTRL FL THRU THE MED RANGE PERIOD. LOW LEVEL ELY FLOW ALONG AND TO THE NORTH OF THIS BNDRY WL KEEP PCPN CHANCES HIGH ALONG THE SERN COAST AND INTO FL. IN ADDITION...MODELS ARE SUGGESTING SOME POTENTIAL FOR
LOW PRESSURE TO ORGANIZE OVR THE WRN CARIBBEAN...POSSIBLY PUSHING NEWD TOWARD THE GULF OF MEXICO. CONFIDENCE IS LOW ON DETAILS...BUT ALL MODELS DO SHOW LOW PRESSURE DEVELOPING HERE.

[cycloneye]

G. Morning. Cycloneye is there another way to confirm that this low will be tag as an invest other than the navy page?

If you see that the Tropical Model suite comes out at this site:

http://twister.sbs.ohio-state.edu/text/ ... ic/models/

then,it means invest is up.

The models are:BAMM,BAM,LBAR and the intensity SHIP and DSHP.

[wxman57]

I'm unimpressed. Development chances 20% tops. Probably less. Tremendous shear. Models aren't very good at predicting TC genesis, and they're probably going to be even worse at such predictions when shear is high. Could be all that will develop is a weak wave/low along the strong cold front in the southern/southeastern Gulf next week.

By the way, the weak low moved 214nm in 24 hours toward 292 degrees (8.9kts). It's about 80 miles north of the BVI now near 19.5N/63.9W. It was near 18.5N/61W this time yesterday.

[cycloneye]

SSD is starting to assign T Numbers for this:

25/1145 UTC 19.4N 63.2W T1.0/1.0 INVEST -- Atlantic Ocean

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

[msbee]

TEMP DEW POINT PRESSURE WINDS
Latest 8 AM (12) Oct 25 78 (26) 71 (22) 29.80 (1009) WSW 10

7 AM (11) Oct 25 78 (26) 71 (22) 29.80 (1009) WSW 12
6 AM (10) Oct 25 78 (26) 71 (22) 29.77 (1008) W 9
5 AM (9) Oct 25 78 (26) 69 (21) 29.74 (1007) WSW 9
4 AM (8) Oct 25 77 (25) 69 (21) 29.77 (1008) WSW 8
3 AM (7) Oct 25 78 (26) 69 (21) 29.77 (1008) W 6
2 AM (6) Oct 25 78 (26) 71 (22) 29.77 (1008) W 5
1 AM (5) Oct 25 77 (25) 69 (21) 29.80 (1009) Variable 3

Above is our current weather on St. Maarten. I notice our pressure dropped a little overnight, but now is going up a little. The winds have changed direction and picked up a little.
Currently at my location it is cloudy..very overcast..very little wind.. and we have been having intermittent showers..nothing really heavy
and nothing really significant

[cycloneye]

Is now invest 90L.Go to Active Storms forum to continue the discussions about this system.