[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 272350
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI APR 27 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND THE 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
2345 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 5N9W 3N20W 1N40W TO THE EQUATOR NEAR
50W INLAND OVER SOUTH AMERICA TO 1S52W. SCATTERED MODERATE AND
ISOLATED STRONG CONVECTION IS N OF 4N INLAND OVER LIBERIA AND
COTE D'IVOIRE AND EXTENDING WESTWARD TO 17W. CLUSTERS OF SIMILAR
CONVECTION ARE S OF 5N W OF 48W TO INLAND OVER SOUTH AMERICA OVER
FRENCH GUIANA.

...DISCUSSION...

GULF OF MEXICO...
SLOW MOVING AND WEAKENING COLD FRONT EXTENDS ACROSS SOUTHEAST
GEORGIA AND THE FLORIDA BIG BEND AND INTO THE GULF NEAR CEDAR
KEY THEN SOUTHWEST TO 26N86W WHERE IT BECAME STATIONARY TO
25.5N91W. THE FRONT WILL WEAKEN FURTHER...POSSIBLY DISSIPATE
ALTOGETHER AS IT MOVES ACROSS THE FLORIDA PENINSULA AND E OF THE
GULF SAT. WIDELY SCATTERED SHOWERS ARE ALONG THE FRONT NEAR
ORLANDO. LIGHTNING DATA INDICATED STRONGER THUNDERSTORM ACTIVITY
SE OF THE FRONT WITHIN 30-45 NM OF 24.5N86.5W. SUPPORT FOR THIS
FRONT IS WANING AS THE ASSOCIATED SHORTWAVE UPPER LEVEL TROUGH
MOVING ACROSS THE FAR SE/OFF THE FLORIDA NE COAST IS SHEARING
OUT TO THE NORTHEAST AND IS GRADUALLY BEING OVERRUN BY
ANTICYCLONIC FLOW ASSOCIATED WITH A BUILDING UPPER LEVEL RIDGE
THAT EXTENDS FROM AN ANTICYCLONE OVER THE GULF OF TEHUANTEPEC
ACROSS MEXICO THROUGH THE BAY OF CAMPECHE TO THE LOWER
MISSISSIPPI VALLEY. AXIS OF SUBTROPICAL JET STREAM AROUND THE
PERIPHERY OF THE RIDGE AND JUST TO THE E OF ANOTHER SHORTWAVE
TROUGH OVER NORTHERN MEXICO IS ADVECTING MAINLY MID AND UPPER
LEVEL TROPICAL MOISTURE ACROSS MEXICO...TEXAS AND THE NORTHWEST
THIRD OF THE GULF OF MEXICO.

CARIBBEAN SEA...
THE SOUTHERN END OF THE SHORTWAVE UPPER TROUGH ALONG THE E COAST
OF FLORIDA DIPS INTO THE FAR NW CARIBBEAN N OF 18N ALONG 80W
WITH MODERATE TO STRONG SUBSIDENCE/DRY AIR ALOFT OVER THE AREA.
THE REMAINDER OF THE CARIBBEAN IS UNDER THE INFLUENCE OF A FLAT
BROAD UPPER RIDGE ANCHORED OVER SOUTH AMERICA WITH THE AXIS
EXTENDING ACROSS THE ABC ISLANDS NORTHWARD OVER HISPANIOLA. AN
UPPER LEVEL WIND MAX IS ADVECTING TROPICAL MOISTURE ACROSS
PANAMA...COSTA RICA AND THE SW CARIBBEAN. DAYTIME HEATING
COUPLED WITH SEABREEZE CONVERGENCE IS RESULTING IN SCATTERED
SHOWERS/THUNDERSTORMS ACROSS NORTHWEST COLOMBIA...PANAMA AND
COSTA RICA WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
INDICATED ELSEWHERE OVER THE SW CARIBBEAN S OF 13N BETWEEN 79W
AND 84W. THE LEADING EDGE OF A MODERATE/STRONG EASTERLY TRADE
WIND SURGE ARE RESULTING IN AN AREA OF BROKEN TO OVERCAST LOW
AND MID CLOUDS WITH WIDELY SCATTERED SHOWERS ACROSS THE E
CARIBBEAN E OF 67W BETWEEN THE ABC ISLANDS AND PUERTO RICO.
THE BULK OF THE ACTIVITY HAS MOVED WEST OF THE CENTRAL LESSER
ANTILLES. THE REMAINDER OF THE AREA IS UNDER FAIR SKIES.

ATLANTIC...
BROAD HIGH PRESSURE IS IN CONTROL OVER VIRTUALLY THE ENTIRE
ATLANTIC OCEAN WITH A 1026 MB HIGH LOCATED NEAR 31N63W.
AT THE UPPER LEVELS THE SHEARING SHORTWAVE TROUGH ALONG THE E
COAST OF FLORIDA EXTENDS NORTHEASTWARD OVER THE ATLC TO JUST OFF
THE NORTH CAROLINA COAST AND WAS SHEARING WITH TIME. ASSOCIATED
SHOWER ACTIVITY CURRENTLY NEAR ORLANDO TO TITUSVILLE WILL MOVE
OFF THE FLORIDA COAST INTO THE COASTAL WATERS OVER THE NEXT FEW
HOURS. NARROW EXTENSION OF CARIBBEAN UPPER RIDGE CUTS ACROSS
HISPANIOLA INTO THE W ATLC TO BEYOND 32N66W. SLIGHTLY DIFFLUENT
FLOW OVER THE SE BAHAMAS AND ADJACENT ATLANTIC WATERS IS
GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER THE
REGION. OVER THE CENTRAL ATLC...A SHEARED MID TO UPPER TROUGH
EXTENDS THROUGH 31N38W SOUTHWESTWARD TO SMALL CYCLONIC
CIRCULATIONS NEAR 23N57W AND 24N61W. THESE FEATURES ARE
PRODUCING ONLY ISOLATED SHOWERS WITHIN 60-90 NM OF THEIR
RESPECTIVE LOCATIONS. THIS TROUGH HAS FRACTURED OFF OF A DEEP
LAYERED TROUGH OVER THE NE ATLC THAT HAS MOVED EASTWARD NOW
COVERING THE AREA N OF 23N E OF 25W. OVER THE DEEP TROPICS A
RATHER LARGE CYCLONIC CIRCULATION NEAR 13N42W WAS MOVING
WESTWARD AT 10-15 KT WITH AN ASSOCIATED AREA OF MODERATE TO
STRONG SUBSIDENCE/DRY AIR ALOFT FROM 6N TO 20N WEST OF 35W.
A BUILDING RIDGE WAS IN PLACE TO THE EAST OF THE CYCLONIC
CIRCULATION AND EXTENDED ACROSS THE CAPE VERDE ISLANDS TO THE
WEST COAST OF AFRICA. THE SURFACE RIDGE OVER THE ATLC WILL
REMAIN ACROSS THE AREA WITH SOME WEAKNESS IN THE RIDGE
EXPECTED WITH THE APPROACHING FRONT OFF THE FLORIDA EAST
COAST.

$$
COBB




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