2 p.m. NHC Disc: GOM "Very favorable" for developm

[dixiebreeze]

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON JUL 04 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE
AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING
INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER
OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...

TROPICAL DEPRESSION THREE WAS NEAR 20.7N 89.2W AT 1500 UTC ABOUT
55 MILES SE OF PROGRESO MEXICO MOVING NW 11 KT. THE ESTIMATED
MINIMUM CENTRAL PRESSURE IS 1010 MB AND THE MAXIMUM SUSTAINED
WIND SPEED IS 25 KT GUSTING TO 35 KT. SEE THE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC
AND/OR MIATCPAT3/WTNT33 KNHC FOR MORE DETAILS. SURFACE
OBSERVATIONS INDICATE THAT THE CENTER MAY BE EMERGING OR
REFORMING OFFSHORE OF THE N COAST OF YUCATAN WITH SLY WINDS
OBSERVED THROUGHOUT THE PENINSULA. THE UPPER ENVIRONMENT IS
VERY FAVORABLE FOR FURTHER DEVELOPMENT WITH AN ANTICYCLONE
ALMOST SITTING RIGHT ON TOP OF BROAD LOW-LEVEL CIRCULATION.
SCATTERED SHOWERS AND TSTMS ARE OVER THE SOUTHERN GULF AND
YUCATAN FROM 20N-25N BETWEEN 84.5W-89.5W

A STRONG TROPICAL WAVE LIES ACROSS THE LESSER ANTILLES WITH A
WEAK 1012 MB LOW PRESSURE CENTER IN THE SOUTHERN WINDWARD
ISLANDS W 15-20 KT. PRESSURES CONTINUE TO FALL IN THE AREA WITH
SLY WINDS NOTED IN THE WINDWARDS S OF GRENADA AND ELY WINDS AT
BARBADOS. THERE ARE BANDING FEATURES ESPECIALLY IN THE E
SEMICIRCLE WITH ANTICYCLONIC FLOW ALOFT PROVIDING AN ENVIRONMENT
CONDUCIVE TO FURTHER DEVELOPMENT. SCATTERED SHOWERS AND A FEW
TSTMS ARE S OF 15N BETWEEN 56W-65W WITH WIDELY SCATTERED
MODERATE CONVECTION FROM 15N-19N BETWEEN 54W-60W APPROACHING
THE LEEWARD ISLAND. COMPUTER MODELS SUGGEST THIS WAVE HAS THE
POTENTIAL TO EVENTUALLY DEVELOP INTO A TROPICAL CYCLONE AS WIND
SHEAR IS FORECAST TO REMAIN WEAK DURING ITS TREKS WESTWARD THRU
THE CARIBBEAN. REGARDLESS OF DEVELOPMENT... HEAVY RAIN IS
LIKELY ACROSS THE LESSER ANTILLES ESPECIALLY IN THE WINDWARD
ISLANDS FOR THE NEXT COUPLE DAYS WITH INCREASED MOISTURE NOTED S
OF 15N W OF 50W.

[dixiebreeze]

Like Arlene, I believe 03 will bloom larger than expected in the next day or so.

[Agua]

20.7N ? They've still got this thing inland. Maybe I've been looking at the wrong swirl.

[Ixolib]

THE UPPER ENVIRONMENT IS
VERY FAVORABLE FOR FURTHER DEVELOPMENT WITH AN ANTICYCLONE
ALMOST SITTING RIGHT ON TOP OF BROAD LOW-LEVEL CIRCULATION.

So... What conditions may exist that are "unfavorable" and counteract the "favorable" conditions? Shear? Dry air?

[tailgater]

20.7N ? They've still got this thing inland. Maybe I've been looking at the wrong swirl.

Yes just now emerging NE of Merida into the coolest waters in the GOM should strengthen tonight and tomorrow

[CYCLONE MIKE]

Sure looks like things are becoming more favorable. Look at the outflow that is developing and how more symetrical the TD looks. Even on the infrared loops you can clearly see a much better counter-clockwise rotation pattern with the system.

[Derek Ortt]

In contrast to what the models are saying, conditions are not that favorable for pure tropical development and this is starting to look like Arlene when it formed as a subtrop, more of a frontal type comma shape with convection in a band well away from the center.

Things could change, but I tend to doubt global model upper wind forecasts. Ms Cleo could do about as well as GFS does with shear forecasts on some days

[iceangel]

The Mobile NWS

...DISCUSSION...

GULF OF MEXICO...
ATTENTION IS FOCUSED TO T.D. THREE WHICH APPEARS TO BE MOVING
INTO THE SOUTHERN GULF THIS AFTERNOON. THE PLAYERS IN THE
STEERING OF THE CYCLONE ARE A MID/UPPER TROUGH ALIGNED FROM SW
LOUISIANA TO NE MEXICO AND A BUILDING MID/UPPER HIGH WITH ONE
CENTER OVER THE NW BAHAMAS AND ANOTHER CENTER NEAR 24N86W CLOSER
TO THE DEPRESSION. MOST MODEL GUIDANCE SUGGEST THE TRACK WILL
BE BETWEEN THE TROUGH AND THE HIGH WITH THE CYCLONE GENERALLY
STAYING UNDER LIGHT SHEAR FOR A DAY OR TWO UNDER THE SW FLANK OF
AN UPPER RIDGE. MOISTURE FROM THE SYSTEM IS JUST A COUPLE
HUNDRED MILES SE OF LOUISIANA AND SHOULD BEGIN TO AFFECT THE
CENTRAL GULF COAST OVERNIGHT WITH WIDELY SCATTERED
SHOWERS/TSTMS. THE NW GULF HAS MODERATE/STRONG SUBSIDENCE ALOFT
WHICH IS SUPPRESSING MOST CONVECTION WHILE TYPICAL SEA-BREEZE
CONVECTION HAS BEGUN IN EARNEST OVER LOUISIANA EASTWARD THRU THE
FLORIDA PANHANDLE. CONDITIONS LOOK MUCH DRIER THAN AVERAGE IN S
FLORIDA FOR THE NEXT FEW DAYS AS SUBSIDENCE/RIDGING BUILDS IN
THE WAKE OF THE DEPRESSION.