[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 152310
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON JUN 15 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 77W S OF 17N MOVING W AROUND 15 KT. THIS
WAVE COINCIDES WITH A MAXIMUM IN DEEP LAYER MOISTURE BASED ON THE
TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. THIS WAVE IS ALSO
ASSOCIATED WITH A MAXIMUM IN LOW LEVEL CYCLONIC CIRCULATION BASED ON
COMPUTER MODEL GUIDANCE. SUBSIDENCE IN NORTHERLY FLOW ALOFT IS
LIMITING THE COVERAGE OF DEEP CONVECTION NEAR THIS WAVE. HOWEVER...
SCATTERED MODERATE CONVECTION IS OCCURRING WITHIN 240 NM E OF THE
WAVE AXIS FROM 8N-12N INCLUDING PORTIONS OF N COLOMBIA. THIS
CONVECTION IS BEING ENHANCED BY LOW LEVEL CONVERGENCE NEAR A 1012 MB
SURFACE LOW OVER N COLOMBIA NEAR 9N74W.

...THE ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 11N15W 8N22W 6N30W 3N40W 1N51W.
SCATTERED MODERATE CONVECTION IS FROM 11N-13N BETWEEN 18W-20W.
SCATTERED MODERATE CONVECTION IS ALSO FROM 3N-8N BETWEEN 25W-32W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 3N-6N BETWEEN
34W-39W. SCATTERED MODERATE CONVECTION IS FROM 1N-5N BETWEEN 40W-54W.

...DISCUSSION...

GULF OF MEXICO...
A SURFACE TROUGH EXTENDS FROM THE S FLORIDA PENINSULA NEAR 26N81W TO
W CUBA NEAR 23N83W. LOW LEVEL CONVERGENCE NEAR THIS TROUGH IS
SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS OVER W CUBA AND THE
NEARBY COASTAL WATERS OF THE FAR SE GULF. ALSO...AN UPPER LEVEL
TROUGH EXTENDS FROM THE BAY OF CAMPECHE SOUTHWESTWARD INTO THE E
PACIFIC REGION. THIS UPPER LEVEL TROUGH IS ASSOCIATED WITH A SURFACE
TROUGH EXTENDING FROM N OF THE YUCATAN PENINSULA NEAR 22N89W ACROSS
THE BAY OF CAMPECHE TO 19N93W. LOW LEVEL CONVERGENCE AND ATMOSPHERIC
INSTABILITY NEAR THESE FEATURES ARE SUPPORTING SCATTERED SHOWERS AND
THUNDERSTORMS OVER THE YUCATAN PENINSULA AND THE NEARBY COASTAL
WATERS OF THE FAR S GULF. A SURFACE TROUGH CURRENTLY OVER THE W
CARIBBEAN IS FORECAST TO MOVE INTO THE YUCATAN PENINSULA OVERNIGHT
TONIGHT AND ACROSS THE SOUTHERN GULF TUESDAY AND WEDNESDAY...
ACCOMPANIED BY SCATTERED THUNDERSTORMS. ELSEWHERE ACROSS THE GULF
REGION...DEEP LAYER DRY AIR AND SUBSIDENCE IN CONFLUENT NORTHERLY
FLOW ALOFT ARE RESULTING IN GENERALLY FAIR WEATHER. THE SUBSIDENCE
IS SUPPORTING A 1017 MB SURFACE HIGH OVER THE CENTRAL GULF NEAR
27N89W. ANTICYCLONIC FLOW AROUND THE SURFACE HIGH IS AFFECTING MUCH
OF THE GULF...WITH SE WINDS OF 15 TO 20 KT OCCURRING ACROSS PORTIONS
OF THE W GULF IN RESPONSE TO A BROAD SURFACE TROUGH OVER MEXICO AND
THE SOUTHERN PLAINS OF THE UNITED STATES.

CARIBBEAN SEA...
ACROSS THE W CARIBBEAN...A SURFACE TROUGH EXTENDS FROM 21N85W TO N
HONDURAS NEAR 16N85W. THE ASCAT PASS AROUND 15/1600 UTC CONFIRMS
CYCLONIC CURVATURE IN THE LOW LEVEL FLOW ACROSS THIS TROUGH. LOW
LEVEL CONVERGENCE NEAR THIS TROUGH IS SUPPORTING SCATTERED SHOWERS
AND THUNDERSTORMS FROM 12N-21N BETWEEN 80W AND 88W...INCLUDING
PORTIONS OF HONDURAS AND NICARAGUA. THIS ACTIVITY IS BEING SUPPORTED
BY DEEP LAYER MOISTURE AND UPPER LEVEL DIVERGENCE ASSOCIATED WITH AN
UPPER LEVEL RIDGE OVER THE W CARIBBEAN. ADDITIONALLY...ATMOSPHERIC
INSTABILITY IS RESULTING IN SCATTERED SHOWERS AND THUNDERSTORMS
ACROSS CUBA...HISPANIOLA...AND THE NEARBY COASTAL WATERS. THE SHOWER
AND THUNDERSTORM ACTIVITY OVER W CUBA IS ALSO BEING SUPPORTED BY A
SURFACE TROUGH THAT EXTENDS FROM W CUBA NEAR 23N83W NORTHEASTWARD
INTO THE FAR SE GULF OF MEXICO. FARTHER TO THE E...SUBSIDENCE IN
NORTHERLY FLOW ALOFT IS INHIBITING DEEP CONVECTION ACROSS MUCH OF
THE E CARIBBEAN. HOWEVER...ATMOSPHERIC INSTABILITY NEAR AN UPPER
LEVEL TROUGH OVER THE FAR E CARIBBEAN IS SUPPORTING SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS N OF 14N E OF 67W INCLUDING
PORTIONS OF PUERTO RICO AND THE LEEWARD ISLANDS.

ATLANTIC OCEAN...
ACROSS THE SW NORTH ATLC...A SURFACE TROUGH EXTENDS FROM 31N79W TO
THE E FLORIDA PENINSULA NEAR 28N80W. LOW LEVEL CONVERGENCE NEAR THIS
TROUGH IS INTERACTING WITH MOISTURE IN NORTHWESTERLY FLOW ALOFT TO
RESULT IN SCATTERED SHOWERS AND THUNDERSTORMS FROM 23N-29N W OF 75W
INCLUDING PORTIONS OF THE NW BAHAMAS AND THE E FLORIDA PENINSULA.
ALSO...UPPER LEVEL DIFFLUENCE IS SUPPORTING SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS N OF 21N BETWEEN 63W-68W. ACROSS MUCH OF THE
CENTRAL AND E ATLC...GENERALLY FAIR WEATHER IS PRESENT WHERE
SUBSIDENCE IS OCCURRING NEAR A BROAD SURFACE RIDGE. HOWEVER...AN
UPPER LEVEL TROUGH AXIS EXTENDS FROM 31N51W TO AN UPPER LEVEL LOW
NEAR 27N50W TO 16N57W TO 11N57W. THE UPPER LEVEL LOW IS ASSOCIATED
WITH A SURFACE TROUGH EXTENDING FROM 31N50W TO 29N51W TO 28N52W.
THESE FEATURES ARE SUPPORTING SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS FROM 14N-18N W OF 57W INCLUDING PORTIONS OF THE
LEEWARD ISLANDS...AS WELL AS SCATTERED SHOWERS N OF 27N BETWEEN
44W-52W. ACROSS THE TROPICAL ATLC...A BROAD UPPER LEVEL RIDGE IS
PRESENT WITH AN AXIS EXTENDING FROM 14N17W TO AN UPPER LEVEL HIGH
NEAR 14N29W TO 9N47W. UPPER LEVEL DIVERGENCE ASSOCIATED WITH THESE
FEATURES IS SUPPORTING THE CONVECTION ASSOCIATED WITH THE ITCZ.

$$
COHEN


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