000
AXNT20 KNHC 282335
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL  
805 PM EDT MON MAR 28 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2330 UTC.

...ITCZ...

THE ITCZ AXIS IS ANALYZED FROM THE COAST OF SIERRA LEONE NEAR 
8N13W SW ALONG 4N20W EQ40W INTO NE BRAZIL NEAR 3S48W. ISOLATED 
MODERATE CONVECTION IS WITHIN 70 NM ON EITHER SIDE OF THE AXIS 
BETWEEN 20W-28W. SCATTERED MODERATE CONVECTION IS S OF 3N W OF 
32W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL SHORTWAVE MOVES ACROSS THE FAR NW GULF WATERS 
NOTED ON WATER VAPOR IMAGERY. THIS FEATURE SUPPORTS A 1010 MB 
SURFACE LOW CENTERED OVER THE NORTHERN FLORIDA PENINSULA BETWEEN 
TALLAHASSEE AND JACKSONVILLE. A COLD FRONT EXTENDS W-SW ACROSS 
THE GULF FROM THE LOW CENTER TO SOUTHERN TEXAS ALONG 29N85W 
26N90W WHERE IT CONTINUES AS A DISSIPATING COLD FRONT TO NEAR 
26N97W. DESPITE THE EXTENSION OF THE FRONT...MOST OF THE 
INSTABILITY AND LOW-LEVEL CONVERGENCE IS FOCUSED WITHIN 140 NM 
EAST OF THE FRONT N OF 25N E OF 88W...AFFECTING THE COASTAL 
WATERS FROM TAMPA TO FORT MYERS BEACH. THIS FRONTAL SYSTEM IS 
EXPECTED TO CONTINUE TO MOVE EASTWARD THROUGH THE NEXT 24 HOURS 
WITH CONVECTION MOVING ACROSS THE FLORIDA STRAITS LATE TONIGHT.

CARIBBEAN SEA...
DRY AIR AND STRONG SUBSIDENCE ALOFT IS NOTED ACROSS THE 
CARIBBEAN SEA THIS EVENING. GIVEN THE OVERALL STABILITY OF THE 
ATMOSPHERE ALOFT...AT SURFACE...FRESH TO STRONG TRADEWINDS 
PERSIST WITH VERY FEW AREAS OF SHOWER ACTIVITY THIS AFTERNOON. 
THE FLOW TURNS SE W OF 75W IN RESPONSE OF THE WEATHER SYSTEM 
MENTIONED IN THE GULF OF MEXICO DISCUSSION. THE APPROACH OF A 
WEAK SURFACE TROUGH TO THE LESSER ANTILLES...CURRENTLY LOCATED 
IN THE TROPICAL ATLC ALONG 58W FROM 11N TO 18N...IS PROVIDING A 
FEW ISOLATED SHOWERS TO THE GROUP OF ISLANDS FROM SAINT VINCENT 
AND GRENADINES TO ANTIGUA AND BARBUDA. SIMILAR CONVECTION IS 
NOTED WITHIN 120 NM S OF PUERTO RICO AND THE MONA PASSAGE. THE 
ACTIVITY OVER THE LESSER ANTILLES IS EXPECTED TO INCREASE 
OVERNIGHT AS THE SURFACE TROUGH MOVES OVER THE AREA. 

ATLANTIC OCEAN...
A WESTERN NORTH ATLC DEEP LAYER TROUGH IS LOCATED WELL NORTH OF 
THE DISCUSSION AREA AND EXTENDS A FRONTAL SYSTEM THAT ENTERS OUR 
NORTHERN BORDER NEAR 31N74W AS A STATIONARY FRONT TO THE 
NORTHERN FLORIDA COAST NEAR 30N81W. MOSAIC DOPPLER RADAR IMAGERY 
AND LIGHTNING DATA INDICATED NUMEROUS SHOWERS AND SCATTERED 
TSTMS OCCURRING OVER THE AREA BETWEEN THE FLORIDA COAST AND THE 
NORTHERN BAHAMAS N OF 25N W OF 77W. THIS FRONTAL BOUNDARY IS 
EXPECTED TO BECOME COLD AND CONTINUE TO TRACK EASTWARD WITH 
CONVECTION MOVING ACROSS THE W ATLC OVER THE NEXT 24 HOURS. 
ALSO...COMPUTER MODELS SUGGEST MODERATE CONVECTION LINGERING 
OVER THE FAR W ATLC DURING THE TIME PERIOD. ELSEWHERE ACROSS THE 
AREA...THE REMAINDER OF THE ATLC BASIN IN UNDER THE INFLUENCE OF 
A BROAD SURFACE RIDGE ANCHORED BY A 1028 MB HIGH CENTERED NEAR 
31N29W. THIS FEATURE EXTENDS A RIDGE AXIS FROM THE HIGH CENTER 
TO THE SOUTHERN BAHAMAS BRINGING MOSTLY FAIR WEATHER CONDITIONS 
TO THE ATLC N OF 5N E OF 70W.

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

$$

GARCIA