[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 170539
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN APR 17 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0530 UTC.

...THE ITCZ...

THE ITCZ AXIS IS ANALYZED FROM THE SOUTHERN COAST OF LIBERIA
NEAR 5N8W WESTWARD ALONG 1N20W 2N30W 1N40W EQ50W. SCATTERED
MODERATE TO ISOLATED STRONG CONVECTION IS WITHIN 170 NM EITHER
SIDE OF THE ITCZ. CLUSTERS OF SIMILAR CONVECTION ARE DOTTING THE
AREA S OF THE ITCZ FROM 2S-10S BETWEEN 7W-30W.

...DISCUSSION...

GULF OF MEXICO...
THE MAJORITY OF THE GULF OF MEXICO IS EXPERIENCING FAIR WEATHER
CONDITIONS UNDER THE INFLUENCE OF DRY AIR ALOFT WITH A FEW HIGH
LEVEL CLODS MOVING ACROSS THE WESTERN BASIN. A DEEP LAYER TROUGH
MOVES ACROSS THE FAR EASTERN CONUS SUPPORTING A COLD FRONT THAT
ENTERS THE AREA THROUGH THE FLORIDA PENINSULA NEAR TAMPA AND
EXTENDS SW ALONG 25N85W BECOMING NEARLY STATIONARY TO NEAR
22N94W. THIS FRONTAL SYSTEM BECOMES MOSTLY DRY AND WEAK UPON
ENTERING THE GULF REGION. ONLY A WEAK CLOUD BAND ALONG WITH A
WIND SHIFT AND LOWER DEW POINTS DEFINE THE FRONT OVER THE GULF
WATERS. MARINE OBS INDICATE 5-15 KT BEHIND THE FRONT. THE SE
PORTION OF THE COLD FRONT WILL BECOME DIFFUSE AS IT LOOSES
MOMENTUM ACROSS THE SE GULF IN THE NEXT 12 HOURS. THE N PORTION
OF THE FRONT WILL MOVE INTO THE W ATLC LATER THIS EVENING.
SURFACE RIDGE BEHIND THE FRONT WILL BUILD ACROSS THE GULF
ALLOWING FRESH SE FLOW OVER THE W GULF BY SUN. SE WINDS WILL
INCREASE ACROSS THE ENTIRE GULF EARLY NEXT WEEK AHEAD OF AN
APPROACHING TROUGH MOVING THROUGH THE SOUTHERN PLAINS.

CARIBBEAN SEA...
MAINLY DRY AIR ALOFT AND STRONG SUBSIDENCE IS ACROSS THE
CARIBBEAN SEA THIS EVENING...PROVIDING MOSTLY FAIR WEATHER
CONDITIONS ACROSS THE BASIN. AN UPPER RIDGE EXTENDS FROM THE E
PACIFIC REGION ACROSS THE W CARIBBEAN FROM NICARAGUA TO ACROSS
CENTRAL CUBA INTO THE W ATLC. STRONG SUBSIDENCE ASSOCIATED WITH
AN UPPER TROUGH DIPS S OVER THE NE CARIBBEAN ACROSS PUERTO RICO
TO THE LEEWARD ISLANDS. HIGH LEVEL CLOUDS ARE BEING DRAWN ACROSS
THE SSE CARIBBEAN DUE TO UPPER ANTICYCLONIC FLOW IN THIS REGION.
AT SURFACE...MARINE OBS INDICATE MODERATE TO FRESH ENE WIND FLOW
ACROSS THE AREA. STRONGER TRADES ARE TURNING ACROSS THE COAST OF
COLOMBIA...GENERATING SCATTERED SHOWERS OVER THE COAST OF
COLOMBIA BETWEEN 72W-77W. FAIR WEATHER IS EXPECTED TO REMAIN
ACROSS THE REST OF THE BASIN OVER THE NEXT 24 HOURS. LIGHT TO
MODERATE TRADE WINDS WILL PREVAIL ACROSS THE BASIN DUE TO THE
BROAD PRESSURE GRADIENT. THESE TRADE WINDS WILL CONTINUE OVER
MOST OF THE CARIBBEAN THROUGH NEXT WEEK.

ATLANTIC OCEAN...
A DEEP LAYER TROUGH MOVES OFF THE EASTERN CONUS SUPPORTING A
VIGOROUS COLD FRONT EXTENDING ACROSS THE COASTAL WATERS FROM
NORTH CAROLINA NEAR 35N75W...SOUTH CAROLINA NEAR 32N77W...TO THE
NORTHERN FLORIDA COAST NEAR 29N81W. WHILE SEVERE WEATHER IS
ASSOCIATED WITH THE FRONTAL BOUNDARY...IT BECOMES MOSTLY DRY
UPON ENTERING OUR AREA S OF 32N. ONLY A WEAK CLOUD BAND WITH A
FEW ISOLATED SHOWERS DEFINE THE FRONT OVER OUR AREA. THIS FRONT
WILL CONTINUE TO MOVE EASTWARD WITH LIMITED CONVECTION. FARTHER
E INTO THE CENTRAL ATLC...AN UPPER LEVEL TROUGH EXTENDS S TO
OVER THE NE CARIBBEAN SUPPORTING A BROAD AREA OF SCATTERED WEAK
TO ISOLATED MODERATE CONVECTION FROM 21N-30N BETWEEN 47W-50W.
COMPUTER MODELS SUGGEST THIS AREA OF CONVECTION WILL LINGER FOR
AT LEAST THE NEXT 24 HOURS. THE UPPER LEVEL TROUGH ALSO SUPPORTS
TWO SURFACE TROUGHS ANALYZED W AND SW FROM THE AREA OF
CONVECTION. THE FIRST ONE IS ANALYZED FROM 29N63W TO 25N61W. THE
SECOND ONE IS ANALYZED FROM 20N60W TO 15N57W. A DEEP LAYERED LOW
IS OVER THE FAR E ATLC WITH THE UPPER LOW CENTERED NEAR 30N25W
AND A 1001 MB SURFACE LOW NEAR 29N26W. A DISSIPATING COLD FRONT
IS E OF THE LOW FROM 3119 TO 20N23W. A RE-ENFORCING SURFACE
TROUGH EXTENDS ALONG 30N23W 26N22W 23N26W 22N32W. THESE TWO
BOUNDARIES ARE GENERATING ISOLATED WEAK SHOWERS WITHIN 30 NM
EITHER SIDE OF THEM. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
SURROUND THE LOW LEVEL CENTER AND EASTWARD N OF 28N BETWEEN
16W-26W. THIS LOW PRESSURE SYSTEM IS EXPECTED TO CONTINUE TO
DRIFT E AND WEAKEN OVER THE NEXT 24 HOURS.

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

$$

GARCIA




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