000
AXNT20 KNHC 211117
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL  
805 AM EDT THU APR 21 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1015 UTC. 

...THE ITCZ...

FROM LIBERIA NEAR 6N10W...CROSSING THE EQUATOR ALONG 19W...TO
4S28W AND INTO THE NORTHEASTERN BRAZIL COAST NEAR 5S37W. STRONG 
RAINSHOWERS AND THUNDERSTORMS ARE FROM THE EQUATOR TO 5N BETWEEN 
5W AND 20W...AND FROM THE EQUATOR TO 4N BETWEEN 22W AND 28W.
STRONG RAINSHOWERS AND THUNDERSTORMS ALSO ARE TO THE SOUTH OF 
THE EQUATOR FROM 5S TO 7S BETWEEN 24W AND 27W...AND FROM 7S TO 
THE EQUATOR BETWEEN 30W AND 37W. ISOLATED MODERATE RAINSHOWERS 
AND POSSIBLE THUNDERSTORMS ARE ELSEWHERE WITHIN 280 NM OF THE 
COAST BETWEEN BRAZIL AT 38W AND SURINAME AT 57W.

...DISCUSSION...

THE GULF OF MEXICO...
MIDDLE LEVEL TO UPPER LEVEL WESTERLY WIND FLOW SPANS THE AREA.
A COLD FRONT CUTS THROUGH TEXAS...FROM NORTHWESTERN LOUISIANA 
INTO CENTRAL TEXAS...CURVING TOWARD THE FAR WEST OF TEXAS...AND 
THEN NORTHWARD INTO CENTRAL NEW MEXICO. THE SURFACE PRESSURE 
GRADIENT BETWEEN THE HIGH PRESSURE THAT IS IN THE EASTERN GULF 
OF MEXICO...AND THE BROAD LOW PRESSURE WITH THE FRONTAL BOUNDARY 
WILL RESULT IN MODERATE TO FRESH SOUTHEASTERLY RETURN FLOW IN 
THE GULF OF MEXICO UNTIL AT LEAST MONDAY OF THE NEXT WEEK.
OVERCAST LOW CLOUDS AND AREAS OF FOG AND HAZE COVER THE GULF 
COASTAL PLAINS FROM SOUTH TEXAS TO TALLAHASSEE FLORIDA.

THE CARIBBEAN SEA...
BROAD UPPER LEVEL SOUTHWESTERLY WIND FLOW COVERS THE AREA.
RAINSHOWERS ARE POSSIBLE IN SMALL CLUSTERS OF LOW CLOUDS...
MOSTLY FROM 16N TO 19N BETWEEN 60W AND 75W...AND STILL
POSSIBLE ELSEWHERE TO THE WEST OF 75W.

THE ATLANTIC OCEAN...
BROAD UPPER LEVEL CYCLONIC FLOW COVERS THE ATLANTIC OCEAN TO THE 
NORTH OF 20N BETWEEN 50W AND 80W. A 1010 MB LOW PRESSURE CENTER 
IS NEAR 23N62W. ONE SHEAR AXIS IS ALONG 22N67W 23N72W 27N73W.
A SECOND SHEAR AXIS IS ALONG 20N54W 23N57W 23N61W. EACH SHEAR 
AXIS IS A BOUNDARY THAT SEPARATES WIND SPEEDS THAT RANGE FROM
20 TO 25 KT ON THE EASTERN/NORTHEASTERN SIDE OF IT FROM WIND
SPEEDS THAT ARE IN THE 10 TO 15 KT RANGE ON THE OTHER SIDE OF
THE AXIS. SCATTERED MODERATE RAINSHOWERS TO ISOLATED STRONG 
THUNDERSTORMS ARE FROM 24N TO 28N BETWEEN 56W AND 63W. ISOLATED 
MODERATE RAINSHOWERS ARE ELSEWHERE TO THE NORTH OF 14N BETWEEN 
48W AND THE EASTERN SHORES OF THE BAHAMAS. AN UPPER LEVEL TROUGH 
PASSES THROUGH 33N13W...ACROSS THE CANARY ISLANDS...TO 22N26W. 
THIS TROUGH SUPPORTS A SURFACE TROUGH THAT PASSES THROUGH 
32N11W...TO JUST TO THE NORTH OF THE CANARY  ISLANDS...BEYOND 
32N23W. RAINSHOWERS ARE POSSIBLE TO THE NORTH OF 27N BETWEEN 
AFRICA AND 22W. ONE SURFACE RIDGE EXTENDS FROM A 1030 MB HIGH 
PRESSURE CENTER THAT IS NEAR 34N46W TO 24N29W AND 10N27W.
A SECOND SURFACE RIDGE EXTENDS FROM THE SAME 1030 MB HIGH 
PRESSURE CENTER TO A 1022 MB HIGH PRESSURE CENTER THAT
IS NEAR 33N68W...TO 29N77W.

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

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MT