[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 252359
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON MAY 25 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2245 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE IS ALONG 30W/31W S OF 10N MOVING W NEAR 15 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. SUBSIDENCE ASSOCIATED WITH A
SURFACE RIDGE ACROSS THE E ATLC IS SUPPRESSING DEEP CONVECTION
NEAR THIS WAVE. HOWEVER...SCATTERED SHOWERS ARE OCCURRING FROM
3N-7N BETWEEN 25W-30W.

A TROPICAL WAVE IS ALONG 62W/63W S OF 14N MOVING W 15-20 KT.
RECENT SURFACE OBSERVATIONS SHOW CYCLONIC CURVATURE IN THE LOW
LEVEL WINDS AROUND THIS WAVE. THIS WAVE IS ASSOCIATED WITH A
MAXIMUM IN DEEP LAYER MOISTURE BASED ON TOTAL PRECIPITABLE WATER
PRODUCT FROM CIMSS. SCATTERED MODERATE CONVECTION IS OCCURRING
FROM 3N-10N BETWEEN 61W-64W...INCLUDING PORTIONS OF E VENEZUELA
AND NW GUYANA. FARTHER TO THE NORTH...DEEP CONVECTION IN THE
VICINITY OF THIS WAVE IS BEING SUPPRESSED BY SUBSIDENCE IN
NORTHWESTERLY FLOW ALOFT. HOWEVER...SCATTERED SHOWERS ARE
OCCURRING WITHIN 90 NM EITHER SIDE OF THE WAVE AXIS FROM 10N-13N
INCLUDING PORTIONS OF THE WINDWARD ISLANDS.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 8N12W 4N19W 2N26W CROSSING THE
EQUATOR NEAR 32W EXTENDING TO 2S39W AND INTO NE BRAZIL NEAR
3S46W. SCATTERED MODERATE CONVECTION IS FROM 1N-3N BETWEEN
19W-22W...S OF 1N BETWEEN 23W-29W...AND S OF 2N BETWEEN 35W-44W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL TROUGH IS PRESENT ACROSS THE N GULF...WITH AN
ASSOCIATED SURFACE TROUGH ACROSS THE NW GULF EXTENDING FROM
26N96W TO 30N93W TO 32N92W TO N OF THE DISCUSSION AREA. LOW
LEVEL CONVERGENCE NEAR THE SURFACE TROUGH...AS WELL AS
ATMOSPHERIC INSTABILITY ASSOCIATED WITH THE UPPER LEVEL
TROUGH...ARE SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS
ACROSS THE GULF N OF 25N AS WELL AS ADJACENT INLAND LOCATIONS
ALONG THE GULF COAST. ACROSS THE S GULF...DEEP LAYER DRY AIR IN
WESTERLY FLOW ALOFT IS SUPPORTING GENERALLY FAIR WEATHER.
SOUTHERLY RETURN FLOW IS FORECAST TO INCREASE ACROSS THE FAR W
GULF ON TUESDAY BETWEEN A TROUGH OVER TEXAS AND HIGH PRES
BUILDING OVER THE E GULF.

CARIBBEAN SEA...
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE OCCURRING
ACROSS THE CARIBBEAN FROM 11N-15N BETWEEN 78W-82W. THIS ACTIVITY
IS BEING SUPPORTED BY UPPER LEVEL DIVERGENCE AND DEEP LAYER
MOISTURE AROUND AN UPPER LEVEL RIDGE ACROSS THE SW CARIBBEAN.
ADDITIONALLY...ATMOSPHERIC INSTABILITY OVER HIGHER TERRAIN IS
RESULTING IN SCATTERED SHOWERS AND THUNDERSTORMS AFFECTING
CUBA...HISPANIOLA...PUERTO RICO...NICARAGUA...HONDURAS...COSTA
RICA...AND PANAMA...AND NEARBY COASTAL WATERS. UPPER LEVEL
MOISTURE AND HIGH LEVEL CLOUDS ARE STREAMING GENERALLY
EAST-SOUTHEASTWARD ACROSS THE CARIBBEAN. MEANWHILE...THE
PRESSURE GRADIENT S OF SURFACE HIGH PRESSURE E OF BERMUDA IS
MAINTAINING E WINDS OF 20 TO 25 KT ACROSS PORTIONS OF THE E
CARIBBEAN. ADDITIONALLY...A TROPICAL WAVE IS OVER THE SE
CARIBBEAN. PLEASE SEE ABOVE FOR FURTHER INFORMATION ON THIS
TROPICAL WAVE.

ATLANTIC OCEAN...
SCATTERED SHOWERS AND THUNDERSTORMS ARE OCCURRING N OF 24N W OF
70W INCLUDING THE NW BAHAMAS AND ADJACENT INLAND LOCATIONS OF
FLORIDA...AS WELL AS S OF 24N W OF 67W INCLUDING PORTIONS OF
CUBA...HISPANIOLA...PUERTO RICO...AND THE SE BAHAMAS. THIS
ACTIVITY IS BEING SUPPORTED BY LOW LEVEL CONVERGENCE NEAR A
SURFACE TROUGH NEAR THE BAHAMAS EXTENDING FROM 25N76W TO 23N75W
TO 21N74W. THE SURFACE TROUGH IS FORECAST TO MOVE TOWARD THE
NORTH TO NORTHEAST DURING THE NEXT COUPLE OF DAYS...WITH THE
POTENTIAL FOR AN INCREASING SURFACE PRESSURE GRADIENT E OF THE
TROUGH. THE SHOWER AND THUNDERSTORM ACTIVITY IS ALSO BEING
SUPPORTED BY UPPER LEVEL DIFFLUENCE IN MOIST SOUTHWESTERLY FLOW
ALOFT BETWEEN AN UPPER LEVEL TROUGH OVER THE N GULF OF MEXICO
AND AN UPPER LEVEL RIDGE ACROSS THE SW NORTH ATLC. ALSO...A
1023 MB SURFACE HIGH IS E OF BERMUDA NEAR 34N57W...WITH
SUBSIDENCE RESULTING IN GENERALLY FAIR WEATHER NEAR THIS SURFACE
HIGH. THE SURFACE HIGH IS FORECAST TO MOVE SOUTHWESTWARD DURING
THE NEXT DAY AND BE LOCATED NEAR 31N59W AS A 1023 MB SURFACE
HIGH AT 26/1800 UTC. FARTHER TO THE E...AN UPPER LEVEL TROUGH IS
PRESENT WITH AN AXIS EXTENDING FROM 25N51W TO 29N48W TO 32N45W.
THIS UPPER LEVEL TROUGH IS ASSOCIATED WITH A SURFACE TROUGH
EXTENDING FROM A 1018 MB SURFACE LOW NEAR 30N50W TO 30N47W TO
24N49W TO 20N57W. ATMOSPHERIC INSTABILITY NEAR THE UPPER LEVEL
TROUGH...UPPER LEVEL DIFFLUENCE IN MOIST SOUTHWESTERLY FLOW
ALOFT E OF THE UPPER LEVEL TROUGH...AND LOW LEVEL CONVERGENCE
NEAR THE SURFACE LOW AND TROUGH ARE SUPPORTING SCATTERED SHOWERS
AND ISOLATED THUNDERSTORMS FROM 23N-29N BETWEEN 38W-52W AND FROM
19N-23N BETWEEN 44W-64W. DURING THE NEXT DAY...THE 1018 MB
SURFACE LOW IS FORECAST TO DISSIPATE. 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 8N E OF
53W. UPPER LEVEL DIVERGENCE ASSOCIATED WITH THIS UPPER LEVEL
RIDGE IS ENHANCING THE CONVECTION ASSOCIATED WITH THE ITCZ AND
THE TROPICAL WAVE ALONG 30W/31W S OF 10N...AS WELL AS SCATTERED
SHOWERS AND THUNDERSTORMS FROM 1N-5N BETWEEN 1W-5W.

$$
COHEN


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