[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 041743
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED MAY 04 2011

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTION 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
1715 UTC.

...ITCZ...

ITCZ AXIS IS ANALYZED ALONG 5N8W 5N16W 2N26W CROSSING THE
EQUATOR NEAR 34W CONTINUING S OF THE EQUATOR TO INLAND OVER
SOUTH AMERICA. SCATTERED/NUMEROUS STRONG CONVECTION IS WITHIN 90
NM OF LINE FROM 1N2W TO INLAND OVER THE IVORY COAST NEAR 5N5W.
CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE WITHIN 90
NM N OF THE ITCZ AND WITHIN 150 NM S OF THE ITCZ BETWEEN 17W-34W
AND FROM 3N TO S OF THE EQUATOR BETWEEN 36W-43W.

...DISCUSSION...

GULF OF MEXICO...
A DEEP LAYERED TROUGH CONTINUES TO MOVE E EXTENDING FROM THE
EASTERN GREAT LAKES AND INTO THE NW ATLC COVERING THE N GULF N
OF 27N SUPPORTING A COLD FRONT THAT AT 04/1500 UTC EXTENDS INTO
THE GULF ACROSS FLORIDA BETWEEN DAYTONA BEACH AND TAMPA TO
24N90W BECOMING STATIONARY ALONG 21N94W THEN S TO THE COAST OF S
MEXICO JUST E OF THE ISTHMUS OF TEHUANTEPEC WITH SCATTERED
SHOWERS WITHIN 90 NM W OF THE FRONT S OF 22N AND ISOLATED
SHOWERS WITHIN 45 NM W OF THE ENTIRE COLD FRONT. SKIES CONTINUE
TO CLEAR OVER THE N GULF N OF 28N FROM FLORIDA TO TEXAS. A
SURFACE RIDGE CONTINUES TO BUILD W OF THE FRONT ANCHORED BY A
1029 MB HIGH OVER E TEXAS. BROAD UPPER RIDGE ANCHORED IN THE E
PACIFIC REGION COVERS THE REMAINDER OF THE GULF. COLD FRONT WILL
DISSIPATE TONIGHT OVER THE SE GULF. THE SURFACE RIDGE WILL THEN
DOMINATE AREA THROUGH THE WEEKEND.

CARIBBEAN SEA...
THE UPPER RIDGE OVER THE GULF OF MEXICO COVERS THE FAR NW
CARIBBEAN W OF 82W. A SHORTWAVE UPPER TROUGH EXTENDS FROM THE
WINDWARD PASSAGE SW TO THE SE COAST OF NICARAGUA COVERING THE
ARE WITHIN 250 NM OF THE TROUGH AXIS. WATER VAPOR SATELLITE
IMAGERY SHOWS DRY STABLE AIR ALOFT W OF A LINE FROM HAITI TO THE
COSTA RICA/NICARAGUA BORDER. THE E/W UPPER RIDGE THAT CONTINUES
TO DOMINATE THE TROPICAL ATLC EXTENDS OVER THE REMAINDER OF THE
CARIBBEAN E OF UPPER TROUGH DRAWING TROPICAL MOISTURE ALOFT
ACROSS THE E CARIBBEAN. THE SURFACE RIDGE OVER THE W ATLC IS
WEAKENING RELAXING THE PRESSURE GRADIENT TO GENERATE MODERATE TO
FRESH EASTERLY TRADE WINDS ACROSS THE BASIN. REMNANT LOW LEVEL
MOISTURE REMAINS OVER THE CARIBBEAN E OF 78W AND COUPLED WITH
THE CONVERGENCE OF THE WINDS AT THE SURFACE AND ALOFT ARE
GENERATING PATCHES OF SCATTERED SHOWERS TO OVER THE LESSER
ANTILLES TO 58W INCLUDING BARBADOS. THE EASTERLY TRADE WINDS ARE
BANKING LOW LEVEL CLOUDS WITH SCATTERED SHOWERS ALONG THE
MOUNTAINS OF W PANAMA AND COSTA RICA AND INTO THE SW CARIBBEAN
WITHIN 60 NM OF THE COAST S OF 11N W OF 80W. THIS IS LEAVING THE
REMAINDER OF THE CARIBBEAN UNDER FAIR WEATHER CONDITIONS THIS
AFTERNOON. SURFACE RIDGE OVER THE W ATLC WILL CONTINUE TO WEAKEN
AND DRIFT S THROUGH TONIGHT ALLOWING TRADEWINDS TO GRADUALLY
DECREASE ACROSS THE CARIBBEAN. TRADES WILL INCREASE ACROSS THE
CENTRAL CARIBBEAN FRI THROUGH THE WEEKEND AS A SURFACE RIDGE
MOVE BACK OVER THE W ATLC AFTER THE FRONTAL PASSAGE.

ATLANTIC OCEAN...
AN UPPER RIDGE REMAINS OFF THE EASTERN SEABOARD AHEAD OF AN
UPPER TROUGH THAT IS BEGINNING TO MOVE OFF THE COAST SUPPORTING
A COLD FRONT THAT AT 04/1500 UTC ENTERS THE DISCUSSION AREA NEAR
32N78W EXTENDING INTO THE GULF OF MEXICO ACROSS FLORIDA NEAR
DAYTONA BEACH. A SURFACE TROUGH IS JUST TO THE E EXTENDING FROM
31N78W TO THE COAST OF FLORIDA NEAR WEST PALM BEACH WITH
SCATTERED SHOWERS WITHIN 30 NM E OF THE SURFACE TROUGH AND
CLEARING SKIES W OF THE FRONT. A WEAK SURFACE RIDGE COVERS THE W
ATLC W OF 60W TO THE FLORIDA PENINSULA ANCHORED BY A 1021 MB
HIGH NEAR 31N72W. A DEEP LAYERED LOW COVERS THE REMAINDER OF THE
W ATLC AND CENTRAL ATLC N OF 24N BETWEEN 40W-65W WITH THE UPPER
LOW CENTERED NEAR 33N52W SUPPORTING A A 1007 MB SURFACE LOW NEAR
31N51W AND AN OCCLUDED FRONT EXTENDING NE TO A COLD FRONT THAT
EXTENDS INTO THE DISCUSSION AREA NEAR 33N46W ALONG 26N47W 22N53W
TO 19N66W WITH SCATTERED SHOWERS AND POSSIBLE ISOLATED
THUNDERSTORMS N OF 30N BETWEEN 41W-47W AND ISOLATED SHOWERS
WITHIN 60 NM E AND 75 NM W OF THE FRONT. A BROAD SURFACE RIDGE
DOMINATES THE E ATLC N OF 15N E OF THE ABOVE FRONT ANCHORED BY A
1022 MB HIGH NEAR 32N26W LEAVING THE E ATLC WITH FAIR WEATHER
THIS AFTERNOON. AN E/W UPPER RIDGE CONTINUES TO DOMINATE THE
TROPICAL ATLC INTO THE E CARIBBEAN WITH UPPER LEVEL MOISTURE
PRODUCING POSSIBLE ISOLATED SHOWERS WITHIN 120 NM OF A LINE FROM
23N37W TO OVER THE NE CARIBBEAN NEAR THE VIRGIN ISLANDS/PUERTO
RICO. W ATLC SURFACE RIDGE WILL WEAKEN THROUGH TONIGHT. W ATLC
COLD FRONT WILL EXTEND MOVE E THROUGH THU MORNING AND DISSIPATE
FROM NEAR BERMUDA TO THE NEAR THE N BAHAMA ISLANDS FRI MORNING.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
PAW





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