000
AXNT20 KNHC 042354
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL  
805 PM EDT THU AUG 04 2011

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL 
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST
FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED
ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2345 UTC.
 
...TROPICAL WAVES...

A TROPICAL WAVE IS MOVING ACROSS THE CENTRAL TROPICAL ATLC WITH 
AXIS ANALYZED FROM 15N35W TO 10N43W...MOVING WNW AT 10-15 KT. A 
SLIGHT CURVATURE OBSERVED IN THE LOW/MID LEVEL CLOUDS. NO 
ASSOCIATED DEEP CONVECTION IS OBSERVED.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS WEST FROM THE AFRICAN COAST OF 
GUINEA-BISSAU NEAR 12N16W ALONG 11N20W TO 13N30W. THE ITCZ IS 
ANALYZED WEST OF THE CENTRAL ATLC TROPICAL WAVE NEAR 11N45W 
ALONG 9N53W TO THE ISLAND OF TRINIDAD AND TOBAGO NEAR 11N61W. 
ISOLATED MODERATE TO HEAVY SHOWERS AND THUNDERSTORMS ARE WITHIN 
50 NM ON EITHER SIDE OF THE ITCZ. SCATTERED HEAVY SHOWERS AND 
THUNDERSTORMS ARE IN THE VICINITY OF THE MONSOON TROUGH FROM 5N 
TO 14N BETWEEN THE COAST OF AFRICA AND 27W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER RIDGE CENTERED OVER THE SE CONUS BRINGS ANTICYCLONIC 
FLOW ACROSS THE GULF THIS EVENING ON WATER VAPOR IMAGERY. 
THEREFORE...A DRY SUBSIDENT AIRMASS ALOFT IS SUPPRESSING DEEP 
CONVECTION ACROSS THE DISCUSSION AREA...AND LEAVING ONLY A FEW 
ISOLATED SHOWERS DOTTING BASIN. AT SURFACE...FAIR WEATHER 
CONDITIONS ARE PRESENT THIS AFTERNOON...WITH LIGHT TO MODERATE 
ANTICYCLONIC WINDS ANCHORED BY A 1015 MB HIGH NEAR 25N92W. THE 
SURFACE RIDGE IS FORECAST TO REMAIN ACROSS THE GULF THROUGH THE 
WEEKEND.

CARIBBEAN SEA...
THE CONVECTION ASSOCIATED TO TROPICAL STORM EMILY CLASHED WITH 
THE MOUNTAINS OF HISPANIOLA THIS AFTERNOON...AND THE SYSTEM 
BECAME A REMNANT TROUGH OF LOW PRESSURE. HOWEVER...A BROAD AREA 
OF SCATTERED HEAVY SHOWERS AND THUNDERSTORMS REMAINS OVER THE N 
CENTRAL CARIBBEAN N OF 15N BETWEEN 67W-75W INCLUDING INLAND 
PORTIONS OF HISPANIOLA. THE NATIONAL METEOROLOGICAL OFFICE IN 
DOMINICAN REPUBLIC REPORTED 12-24 HR RAINFALL TOTALS RANGING 
FROM LESS THAN ONE INCH TO OVER 7 INCHES ACROSS DIFFERENT 
LOCATIONS THROUGHOUT THE COUNTRY. ALTHOUGH THIS SYSTEM IS NO 
LONGER A SPECIAL FEATURE...IT CONTINUES TO BE THE PRIMARY FOCUS 
ACROSS THE DISCUSSION AREA OVER THE NEXT FEW DAYS. THIS AREA OF 
CONVECTION WILL CONTINUE TO MOVE NW ACROSS HISPANIOLA TONIGHT. 
ELSEWHERE ACROSS THE CARIBBEAN...SCATTERED SHOWERS AND ISOLATED 
THUNDERSTORMS ARE OVER THE FAR SW BASIN WITHIN 50 NM OFF THE 
ACROSS THE COAST OF COSTA RICA...PANAMA...AND COLOMBIA...DUE TO 
CLOSE PROXIMITY TO THE MONSOON TROUGH. OTHERWISE...MOSTLY FAIR 
WEATHER WITH LIGHT TO MODERATE TRADE WINDS IS OBSERVED ELSEWHERE 
ACROSS THE DISCUSSION AREA THIS EVENING.

ATLANTIC OCEAN...
THE CONVECTION ASSOCIATED TO THE REMNANT TROUGH OF LOW PRESSURE 
FROM EMILY IS AFFECTING THE ATLC WATERS N OF HISPANIOLA AND E OF 
THE BAHAMAS S OF 24N BETWEEN 66W-71W. SCATTERED HEAVY SHOWERS 
AND THUNDERSTORMS ROAM THIS AREA. COMPUTER MODELS SUGGEST THIS 
AREA OF CONVECTION WILL CONTINUE TO MOVE NE ACROSS THE BAHAMAS 
OVER THE NEXT FEW DAYS. A LARGE SURFACE RIDGE DOMINATES THE 
REMAINDER OF THE ATLC BASIN...ANCHORED BY A 1029 MB HIGH SW OF 
THE AZORES NEAR 33N32W. THIS FEATURE EXTENDS A RIDGE AXIS WSW TO 
THE FAR WEST ATLC NEAR THE FLORIDA PENINSULA. THE CIMSS SAHARAN 
AIR LAYER TRACKING PRODUCT AND LAST VISIBLE METEOSAT-9 SATELLITE 
IMAGERY OF THE DAY SHOWED A LARGE AREA OF AFRICAN DUST FROM 
10N-30N BETWEEN 30W-63W. WITHIN THIS AREA OF DRY DUSTY AIR...AN 
UPPER LEVEL CYCLONIC CIRCULATION WAS FOUND ON WATER VAPOR NEAR 
27N47W WITHOUT ANY CONVECTION. 

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

$$

GARCIA