[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 291714
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI MAY 29 2009

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1645 UTC.

...SPECIAL FEATURE...
TROPICAL DEPRESSION ONE IS CENTERED NEAR 39.6N 64.0W AT 29/1500
UTC OR ABOUT 300 NM SOUTH OF HALIFAX NOVA SCOTIA MOVING
EAST-NORTHEAST AT 16 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS
1006 MB. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40
KT. SCATTERED MODERATE CONVECTION IS FROM 38N-40N BETWEEN
61W-63W. PLEASE SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. THE DEPRESSION
IS EXPECTED TO BECOME EXTRATROPICAL OR DISSIPATE IN THE NEXT 12
TO 24 HOURS AS IT MOVES OVER COLDER WATERS.

...TROPICAL WAVES...
A TROPICAL WAVE IS ALONG 47W S OF 8N MOVING W 15-20 KT. TOTAL
PRECIPITABLE WATER PRODUCT FROM CIMSS INDICATES THAT THIS WAVE
COINCIDES WITH A MAXIMUM IN DEEP LAYER MOISTURE. ALSO...CIMSS
WAVETRAK PRODUCT INDICATES A MAXIMUM IN LOW LEVEL CYCLONIC
CIRCULATION AROUND THE WAVE. SCATTERED MODERATE CONVECTION IS S
OF 5N BETWEEN 44W-49W.

ADDITIONALLY...TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS
INDICATES THAT A NORTH-SOUTH ELONGATED DEEP LAYER MOISTURE
MAXIMUM IS ALONG 18W S OF 9N MOVING W NEAR 15 KT. THIS FEATURE
IS ASSOCIATED WITH NUMEROUS MODERATE/SCATTERED STRONG CONVECTION
FROM 1N-8N BETWEEN 11W-20W. HOWEVER...RECENT SURFACE
OBSERVATIONS AND SCATTEROMETER DATA DO NOT YET CONFIRM THE
PRESENCE OF A TROPICAL WAVE AT THE SURFACE NEAR THIS FEATURE.
HOWEVER...A TROPICAL WAVE IS SUSPECTED TO BE PRESENT
HERE...WHICH WILL CONTINUE TO BE MONITORED.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 7N11W 4N20W 2N31W CROSSING THE
EQUATOR NEAR 41W EXTENDING INTO NE BRAZIL NEAR 2S47W. NUMEROUS
MODERATE/SCATTERED STRONG CONVECTION IS FROM 1N-8N BETWEEN
11W-20W. SCATTERED MODERATE CONVECTION IS FROM 1N-5N BETWEEN
28W-32W. SCATTERED MODERATE CONVECTION IS ALSO S OF 2N BETWEEN
40W-43W.

...DISCUSSION...

GULF OF MEXICO...
A COLD FRONT IS PRESENT ACROSS THE N GULF AND EXTENDS FROM THE
FLORIDA PANHANDLE NEAR 30N85W TO 28N90W CONTINUING WESTWARD AS A
DEVELOPING COLD FRONT TO 28N96W. ALSO...A SURFACE TROUGH EXTENDS
FROM 28N85W TO 23N91W ACROSS THE SW GULF TO THE COAST OF MEXICO
NEAR 18N93W. LOW LEVEL CONVERGENCE NEAR THE COLD FRONT AND
SURFACE TROUGH IS RESULTING IN SCATTERED SHOWERS AND
THUNDERSTORMS FROM 25N-28N BETWEEN 83W-88W...AS WELL AS
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS S OF 21N W OF 95W.
ALL OF THIS ACTIVITY IS BEING SUPPORTED BY UPPER LEVEL
DIFFLUENCE IN MOIST AND WESTERLY UPPER LEVEL FLOW. ACROSS THE N
GULF TO THE N OF THE COLD FRONT...GENERALLY FAIR WEATHER IS
OCCURRING WHERE STABLE ATMOSPHERIC CONDITIONS ARE PRESENT. NE
WINDS OF 10 TO 15 KT ARE PRESENT ACROSS PORTIONS OF THE W
GULF...WITH SW WINDS OF 10 TO 15 KT PRESENT ACROSS PORTIONS OF
THE MIDDLE AND E GULF.

CARIBBEAN SEA...
DEEP LAYER DRY AIR AND SUBSIDENCE IN NORTHWESTERLY FLOW
ALOFT...ALONG WITH MID-LEVEL DRY SAHARAN AIR...ARE RESULTING IN
GENERALLY FAIR WEATHER CONDITIONS ACROSS MUCH OF THE CARIBBEAN.
HOWEVER...ATMOSPHERIC INSTABILITY OVER HIGHER TERRAIN IS
RESULTING IN SCATTERED SHOWERS AND THUNDERSTORMS AFFECTING COSTA
RICA AND NEARBY COASTAL WATERS. FRESH TO STRONG TRADE WINDS ARE
OCCURRING ACROSS THE CARIBBEAN. THE STRONGEST OF THESE WINDS ARE
FOUND NEAR THE COAST OF COLOMBIA...WHERE E WINDS OF 25 TO 30 KT
ARE OCCURRING. THE TRADE WINDS ARE ADVECTING POCKETS OF LOW
LEVEL MOISTURE AND ISOLATED SHOWERS WESTWARD ACROSS THE
CARIBBEAN. THE GREATEST CONCENTRATION OF THESE SHOWERS IS FROM
15N-17N BETWEEN 70W-74W. ALSO...ATMOSPHERIC INSTABILITY
ASSOCIATED WITH AN UPPER LEVEL LOW CENTERED NEAR 18N68W IS
SUPPORTING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS OVER THE
NE CARIBBEAN N OF 16N E OF 64W...INCLUDING PORTIONS OF THE
LEEWARD ISLANDS.

ATLANTIC OCEAN...
UPPER LEVEL DIVERGENCE AND DEEP LAYER MOISTURE W OF AN UPPER
LEVEL HIGH CENTERED NEAR 25N56W ARE RESULTING IN SCATTERED
SHOWERS AND THUNDERSTORMS FROM 23N-29N BETWEEN 64W-69W. THIS
ACTIVITY IS ALSO BEING SUPPORTED BY LOW LEVEL CONVERGENCE NEAR A
SURFACE TROUGH EXTENDING FROM 28N67W TO 26N68W TO 24N70W.
ALSO...UPPER LEVEL DIVERGENCE ASSOCIATED WITH AN UPPER LEVEL
RIDGE WITH AN AXIS EXTENDING FROM 30N72W TO 24N78W IS SUPPORTING
SCATTERED SHOWERS AND THUNDERSTORMS N OF 24N W OF 75W INCLUDING
THE NW BAHAMAS...THE FLORIDA KEYS...AND ADJACENT INLAND
LOCATIONS OF FLORIDA. THIS ACTIVITY IS ALSO BEING SUPPORTED BY
LOW LEVEL CONVERGENCE NEAR A SURFACE TROUGH EXTENDING FROM
31N77W TO 32N76W TO N OF THE DISCUSSION AREA. FARTHER TO THE
E...AN UPPER LEVEL TROUGH N OF THE DISCUSSION AREA IS ASSOCIATED
WITH A COLD FRONT EXTENDING FROM NE OF THE DISCUSSION AREA TO
32N30W TO 31N32W CONTINUING SOUTHWESTWARD AS A STATIONARY FRONT
TO 28N39W TO 28N45W. ALSO...A SURFACE TROUGH EXTENDS FROM 27N53W
TO 24N56W TO 21N57W. LOW LEVEL CONVERGENCE IS SUPPORTING
SCATTERED SHOWERS WITHIN 60 NM EITHER SIDE OF THE COLD AND
STATIONARY FRONTS AND SURFACE TROUGH. BEHIND THE FRONTS...A 1025
MB SURFACE HIGH IS LOCATED NEAR 32N47W AND IS FORECAST TO MOVE
SOUTHWARD DURING THE NEXT DAY AND BE LOCATED NEAR 30N46W AS A
1024 MB SURFACE HIGH AT 30/1200 UTC. SUBSIDENCE ASSOCIATED WITH
THIS SURFACE HIGH IS RESULTING IN GENERALLY FAIR WEATHER BEHIND
THE COLD AND STATIONARY FRONTS. ACROSS THE E ATLC...A SURFACE
RIDGE IS PRESENT WHERE MAINLY ZONAL FLOW ALOFT IS OCCURRING AND
FAIR WEATHER CONDITIONS PERSIST. ACROSS THE TROPICAL ATLC...AN
UPPER LEVEL RIDGE IS PRESENT S OF 12N E OF 54W WITH AN UPPER
LEVEL HIGH NEAR 9N19W. UPPER LEVEL DIVERGENCE ASSOCIATED WITH
THE UPPER LEVEL HIGH AND RIDGE IS ENHANCING THE CONVECTION
ASSOCIATED WITH THE ITCZ AND THE TROPICAL WAVE ALONG 47W S OF
8N...AS WELL AS NUMEROUS SHOWERS AND THUNDERSTORMS FROM 1N-5N
BETWEEN 1W-10W.

$$
COHEN




This weather bulletin was brought to you by:
www.nashvilleweather.net