[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 242347
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE APR 24 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
2315 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 9N10W 2N20W EQ30W INTO NE BRAZIL
NEAR 4S44W. SCATTERED MODERATE/ ISOLATED STRONG CONVECTION FROM
1N-6N BETWEEN 12W-20W. SIMILAR CONVECTION IS WITHIN 60 NM EITHER
SIDE OF THE AXIS BETWEEN 32W-38W...AND OVER NE BRAZIL.

...DISCUSSION...

GULF OF MEXICO...
THE LEADING EDGE OF CLOUDS ASSOCIATED WITH A FRONTAL BOUNDARY
OVER TEXAS AND NORTHERN COAHUILA IN MEXICO IS BEGINNING TO
AFFECT THE NW CORNER OF THE GULF WHERE DOPPLER RADAR IS SHOWING
SOME SHOWER ACTIVITY. A CUT-OFF LOW OVER THE SW US AND ITS
ASSOCIATED UPPER LEVEL TROUGH SUPPORTS THIS FRONTAL SYSTEM. THIS
UPPER TROUGH WILL MOVE EWD ENTERING THE W GULF TOMORROW.  AN
UPPER RIDGE DOMINATES THE GULF WITH THE AXIS EXTENDING FROM THE
YUCATAN PENINSULA TO THE SE U.S..THE E HALF OF THE GULF AND THE
FLORIDA PENINSULA IS DOMINATED BY MODERATE/STRONG SUBSIDENCE
WHILE UPPER LEVEL MOISTURE IS ON INCREASE OVER THE W PART OF THE
GULF STREAMING ACROSS NE MEXICO BY SWLY UPPER LEVEL WINDS. THE
COLD FRONT IS EXPECTED TO MOVE OFF THE TEXAS COAST EARLY THU.
THIS SCENARIO WOULD THEN ONLY SUPPORT SCATTERED SHOWERS/TSTMS
OVER THE FAR NRN GULF WED THROUGH FRI AS THE MAIN ENERGY
ASSOCIATED WITH THE FRONT SKIRTS BY TO THE N. SE RETURN FLOW OF
20 TO 25 KT WILL CONTINUE TO BLOW ACROSS THE WESTERN GULF
TONIGHT AND WEDNESDAY.

CARIBBEAN...
AN UPPER LEVEL TROUGH LOCATED OVER THE W/CENTRAL ATLC DRAPES SW
INTO THE W CARIBBEAN FROM THE WINDWARD PASSAGE SW TO NICARAGUA
AND HONDURAS. STRONG CONFLUENCE INTO THE TROUGH AXIS IS
PRODUCING VERY STRONG SUBSIDENCE FROM THE CAYMAN ISLANDS TO
BEYOND THE SOUTHERN BAHAMAS. TO THE E...BROAD SW FLOW ALOFT LIES
AHEAD OF THE TROUGH AND IS TRANSPORTING SLIGHTLY MORE MOIST AIR
UP FROM SOUTH AMERICA TO THE NE CARIBBEAN. A WEAKENING SURFACE
TROUGH REMAINS OVER THE AREA EXTENDING FROM THE VIRGIN ISLANDS
SW TO 15N74W. SCATTERED SHOWERS AND ISOLATED TSTMS LIE TO THE N
OF THE TROUGH...SOME OF WHICH ARE AFFECTING PUERTO RICO AND THE
VIRGIN ISLANDS...HISPANIOLA...AND JAMAICA. SIMILAR CONVECTION IS
OBSERVED OVER NORTHERN COLOMBIA AND E PANAMA...PARTLY AIDED BY A
DIFFLUENT PATTERN ALOFT. SE OF THE TROUGH...DRIER LOW-LEVEL AIR
AND SUBSIDENCE IN THE MID/UPPER LEVELS IS PRODUCING MAINLY FAIR
WEATHER CONDITIONS ACROSS THE SRN LEEWARD AND WINDWARD ISLANDS
AS WELL AS ACROSS THE VENEZUELA COAST...WITH THE EXCEPTION OF
SOME SHOWERS NEAR LAKE MARACAIBO. WEATHER CONDITIONS ARE
EXPECTED TO IMPROVE OVER THE NE CARIBBEAN AS THE SFC TROUGH
CONTINUES TO WEAKEN AND THE UPPER TROUGH MOVES EWD AND AWAY FROM
THE REGION.

ATLANTIC...
A 1026 MB HIGH IS CENTERED OVER THE W ATLC JUST SE OF BERMUDAS
WITH A RIDGE ALIGNED FROM BERMUDA TO N FLORIDA. AN UPPER LEVEL
TROUGH IS LOCATED OVER THE SAME AREA WITH THE AXIS FROM 31N60W
TO THE WINDWARD PASSAGE...AND THIS IS PRODUCING MAINLY DRY
CONDITIONS AT ALL LEVELS OF THE ATMOSPHERE. THIS UPPER TROUGH
HAVE SUPPORTED THE DEVELOPMENT OF A WEAK SFC LOW ALONG THE
STATIONARY FRONTAL BOUNDARY WHICH HAS BEEN OVER THE CENTRAL ATLC
AND THE NE CARIBBEAN FOR A FEW DAYS. THIS FRONT EXTENDS SW FROM
A 1018 MB SFC LOW NEAR 31N50W TO THE VIRGIN ISLANDS. A WIDE BAND
OF MULTILAYERED CLOUDS WITH EMBEDDED SHOWERS IS ASSOCIATED WITH
THE FRONT. TO THE E OF THE LOW...THE FRONT HAS MOVED N AS A WARM
FRONT. OVER THE E ATLC...A STRONG MID-LEVEL HIGH IS CENTERED
NEAR 20N40W WHICH IS KEEPING MOST OF THE HIGH CLOUDINESS
SPREADING N OF THE AREA TOWARDS THE AZORES...AND MODERATE/STRONG
SUBSIDENCE SWD TO 6N. AT THE SURFACE...A RIDGE DOMINATES THE
REGION GENERATING MODERATE TRADE WINDS. ONLY FRAGMENTS OF LOW
LEVEL MOISTURE ARE FOUND UNDER THE INFLUENCE OF THIS RIDGE.

$$
GR





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