TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL  
805 PM EDT THU AUG 11 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 
2315 UTC.

...SPECIAL FEATURES...

A 1010 MB LOW IS CENTERED ABOUT 740 NM W OF THE CAPE VERDE 
ISLANDS NEAR 13N35W WITH A TROPICAL WAVE EXTENDING NW FROM THE 
LOW TO 19N41W. SCATTERED MODERATE/STRONG CONVECTION IS FROM 
15N-18N BETWEEN 38W-40W. THE ASSOCIATED SHOWER/THUNDERSTORM 
ACTIVITY HAS BECOME A LITTLE LESS ORGANIZED DURING THE LAST 24 
HOURS. HOWEVER...ENVIRONMENTAL CONDITIONS APPEAR FAVORABLE FOR 
GRADUAL DEVELOPMENT OVER THE NEXT SEVERAL DAYS. THIS SYSTEM HAS 
A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 
48 HOURS AS IT MOVES TOWARD THE W-NW AT 13 KT.

A WELL-DEFINED 1011 MB LOW IS CENTERED ABOUT 195 NM S OF THE 
CAPE VERDE ISLANDS NEAR 11N24W WITH A TROPICAL WAVE EXTENDING N 
ACROSS THE CAPE VERDE ISLANDS TO 19N23W. SCATTERED MODERATE/ 
STRONG CONVECTION IS FROM 10N-13N BETWEEN 22W-25W. ENVIRONMENTAL 
CONDITIONS ARE EXPECTED TO GRADUALLY BECOME MORE CONDUCIVE FOR 
DEVELOPMENT OVER THE NEXT SEVERAL DAYS AS IT MOVES W AT 13-17 
KT. THIS SYSTEM HAS A MEDIUM CHANCE OF BECOMING A TROPICAL 
CYCLONE DURING THE NEXT 48 HOURS.

...TROPICAL WAVES...

TROPICAL WAVE IN THE CENTRAL CARIBBEAN IS ANALYZED FROM 20N75W 
TO 12N77W MOVING W 10-15 KT. WAVE IS EMBEDDED WITHIN A BROAD 
AREA OF DEEP LAYERED MOISTURE AS DEPICTED ON THE TOTAL 
PRECIPITABLE WATER IMAGERY WITH NO ASSOCIATED SHOWERS/DEEP 
CONVECTION. 

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS INTO THE E TROPICAL ATLC OFF W AFRICA 
NEAR 20N16W EXTENDING THROUGH BOTH SURFACE LOWS IN THE SPECIAL 
FEATURES...11N24W AND 13N35W THEN CONTINUING S TO 5N46W. 
SCATTERED MODERATE/STRONG CONVECTION IS MOVING OFF W AFRICA 
WITHIN 75 NM ALONG THE COAST BETWEEN 12N-15N. CLUSTERS OF 
SCATTERED MODERATE/STRONG CONVECTION ARE FROM 8N-13N BETWEEN 
26W-30W. 

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER RIDGE DOMINATES THE GULF ANCHORED NEAR 28N92W. AN 
UPPER TROUGH IS OVER SE CONUS INTO THE W ATLC N OF 30N 
SUPPORTING A SURFACE TROUGH THAT EXTENDS FROM THE W ATLC ACROSS 
S FLORIDA BETWEEN MIAMI TO THE MIDDLE KEYS TO 24N83W. SCATTERED 
SHOWERS/ISOLATED THUNDERSTORMS ARE S OF 26N TO OVER CUBA E OF 
84W THROUGH THE STRAITS OF FLORIDA. ISOLATED SHOWERS/ 
THUNDERSTORMS DOT THE REMAINDER OF THE E GULF E OF 91W. A WEAK 
SURFACE RIDGE CONTINUES TO DOMINATE THE GULF EXTENDING FROM THE 
W ATLC ACROSS FLORIDA TO THE W GULF WITH A 1015 MB HIGH NEAR 
25N88W LEAVING THE REMAINDER OF THE GULF UNDER CLEAR SKIES THIS 
EVENING. WEAK SURFACE RIDGE WILL CHANGE LITTLE THROUGH TUE. A 
WEAK COLD FRONT WILL MOVE INTO THE FAR NE GULF LATE SUN MOVING 
SLOWLY S THROUGH TUE.

CARIBBEAN SEA...
A SMALL UPPER LOW IS IN THE W CARIBBEAN NEAR 18N83W WHILE A  
BROAD UPPER RIDGE ANCHORED IN THE CENTRAL ATLC EXTENDS S OVER 
THE E INTO CENTRAL CARIBBEAN. THE MONSOON TROUGH EXTENDS FROM 
COLOMBIA INTO THE E PACIFIC REGION S OF PANAMA GENERATING 
SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS S OF 11N 
TO INLAND OVER COLOMBIA TO COSTA RICA. AFTERNOON THUNDERSTORMS 
HAVE AGAIN DEVELOPED OVER JAMAICA...CUBA...AND HAITI MOVING INTO 
THE ADJACENT COASTAL WATERS. FRESH TO MODERATE EASTERLY TRADE 
WINDS ARE DEVELOPING ISOLATED SHOWERS OVER THE REMAINDER OF THE 
W CARIBBEAN W OF THE TROPICAL WAVE LEAVING E CARIBBEAN UNDER 
MOSTLY CLEAR SKIES THIS EVENING. TRADE WINDS WILL WEAKEN SUN AND 
MON AS W ATLC SURFACE RIDGE WEAKENS AND SHIFTS N. THE TROPICAL 
WAVE WILL REACH THE W CARIBBEAN TONIGHT THEN DISSIPATE OVER 
CENTRAL AMERICA BY LATE SAT NIGHT. 

ATLANTIC OCEAN...
AN UPPER TROUGH IS OVER THE SE CONUS INTO THE W ATLC N OF 30N 
SUPPORTING A SURFACE TROUGH THAT EXTENDS THROUGH 32N74W ALONG 
28N78W ACROSS S FLORIDA NEAR MIAMI INTO THE STRAITS OF FLORIDA 
AND THE SE GULF OF MEXICO. SCATTERED SHOWERS/ISOLATED 
THUNDERSTORMS ARE WITHIN 150 NM E OF THE SURFACE TROUGH INTO THE 
STRAITS OF FLORIDA AND TO OVER CUBA. A WEAK SURFACE RIDGE COVERS 
THE REMAINDER OF THE W ATLC ANCHORED BY A 1018 MB HIGH NEAR 
26N64W AND EXTENDS W ACROSS FLORIDA INTO THE GULF OF MEXICO 
LEAVING THE REMAINDER OF THE W ATLC W OF 60W UNDER MOSTLY CLEAR 
SKIES THIS EVENING. AN UPPER TROUGH IS OVER THE CENTRAL ATLC 
EXTENDING AN AXIS THROUGH 32N50W TO 26N53W SUPPORTING A SURFACE 
TROUGH THAT EXTENDS THROUGH 32N48W ALONG 26N51W TO 20N54W. 
SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE FROM 
21N-26N BETWEEN 50W-57W. A BROAD SURFACE RIDGE COVERS THE E ATLC 
ANCHORED BY A 1027 MB HIGH OVER THE AZORES AND A RIDGE AXIS 
EXTENDING THROUGH 32N39W TO 25N50W LEAVING THE E ATLC UNDER 
MOSTLY FAIR CONDITIONS THIS EVENING. W ATLC SURFACE TROUGH WILL 
LINGER THROUGH SAT. THE SURFACE RIDGE WILL LIFT N BY MON. THE 
LOW PRESSURE SYSTEM IN THE SPECIAL FEATURES CURRENTLY NEAR 
13N35W...POSSIBLY BE TROPICAL CYCLONE...WILL ENTER THE CENTRAL 
ATLC LATE MON AND SHOULD MOVE INTO THE W ATLC BY TUE. THE SECOND 
LOW PRESSURE SYSTEM CURRENTLY NEAR 11N24W...POSSIBLY BE TROPICAL 
CYCLONE...WILL MOVE ACROSS THE W TROPICAL ATLC LATE SAT AND 
SHOULD MOVE NW OF THE CARIBBEAN BY MON.