000
AXNT20 KNHC 210550
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL  
205 AM EDT FRI OCT 21 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0515 UTC.

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

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL 
ATLC NEAR 13N16W CONTINUING ALONG 10N18W 7N23W TO 9N28W. A 
SURFACE TROUGH IS ANALYZED WITHIN THE TROPICAL ATLC EXTENDING 
FROM 16N39W THROUGH A 1010 MB LOW NEAR 16N38W AND A 1008 MB LOW 
NEAR 12N44W TO 9N47W. CLUSTERS OF SCATTERED MODERATE/ISOLATED 
STRONG CONVECTION ARE WITHIN 120 NM E OF THE TROUGH S OF 13N. A 
SECOND SURFACE TROUGH IS ANALYZED OFF THE COAST OF SOUTH AMERICA 
FROM 12N56W TO 6N55W. CLUSTERS OF SCATTERED MODERATE/ISOLATED 
STRONG CONVECTION ARE S OF 10N W OF 51W TO INLAND OVER SOUTH 
AMERICA. THE ITCZ IS DISRUPTED BY THE ABOVE SURFACE TROUGHS. 
CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE FROM 4N-11N 
BETWEEN 11W-16W INCLUDING THE COAST OF W AFRICA...FROM 6N-12N 
BETWEEN 20W-26W...AND S OF 5N ACROSS THE EQUATOR W OF 42W TO 
INLAND OVER SOUTH AMERICA.  

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER TROUGH DOMINATES THE GULF TO OVER S MEXICO ADVECTING 
A COOL/DRY AIRMASS OVER THE GULF WATERS IN WAKE OF THE RECENT 
FRONTAL PASSAGE. A SURFACE RIDGE COVERS THE GULF AND THE SE 
CONUS WITH A 1021 MB HIGH NEAR 27N91W AT 21/0300 UTC. SOME 
LINGERING COLD AIR STRATOCUMULUS CLOUDS ARE OVER THE SE GULF 
LEAVING THE REMAINDER OF THE GULF UNDER CLEAR SKIES TONIGHT. 
SURFACE RIDGE WILL CONTINUE TO BUILD ACROSS THE GULF THROUGH TUE.

CARIBBEAN SEA...
THE UPPER TROUGH OVER THE GULF OF MEXICO EXTENDS TO OVER THE 
YUCATAN CHANNEL WITH THE DRY AIR OVER THE GULF OF MEXICO 
EXTENDING TO OVER THE FAR NW CARIBBEAN W OF 85W. THE REMAINDER 
OF THE CARIBBEAN IS UNDER EASTERLY FLOW ALOFT. REMNANT MOISTURE 
OVER THE W CARIBBEAN COUPLED WITH A SURFACE TROUGH THAT EXTENDS 
ALONG 79W WITH A 1009 MB LOW ALONG THE TROUGH NEAR 14N ARE 
GENERATING CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS 
BETWEEN 75W-85W. DRY STABLE AIR ALOFT COVERS THE E CARIBBEAN E 
OF 75W WITH SOME ISOLATED SHOWERS USHERED IN ON THE NE SURFACE 
FLOW. LOW AND SURFACE TROUGH WILL REMAIN NEARLY STATIONARY 
THROUGH TUE.  

ATLANTIC OCEAN...
THE UPPER TROUGH OVER THE GULF OF MEXICO EXTENDS OVER THE W ATLC 
W OF 70W SUPPORTING A COLD FRONT THAT EXTENDS THROUGH 32N69W TO 
TO 30N71W WHERE IT CONTINUES AS A STATIONARY FRONT TO 24N74W 
WHERE TI DISSIPATES ACROSS THE BAHAMA ISLANDS TO THE N COAST OF 
CUBA NEAR 21N77W. SCATTERED SHOWERS AND POSSIBLE ISOLATED 
THUNDERSTORMS ARE WITHIN 45 NM E OF THE COLD FRONT. COLD AIR 
STRATOCUMULUS CLOUDS ARE WITHIN 180 NM W OF THE ENTIRE FRONT. A 
SURFACE RIDGE IS BUILDING FROM THE GULF OF MEXICO TO W OF THE 
FRONT. AN UPPER LOW COVERS THE REMAINDER OF THE W ATLC AND 
CENTRAL ATLC CENTERED NEAR 20N54W GENERATING SCATTERED SHOWERS/ 
THUNDERSTORMS FROM 19N-23N BETWEEN 50W-59W WITH ISOLATED 
SHOWERS/THUNDERSTORMS FROM 23N-26N BETWEEN 52W-58W. A BROAD E/W 
UPPER RIDGE COVERS THE E ATLC AND THE TROPICAL S OF 30N E OF 50W 
WITH THE AXIS ALONG 14N. A BROAD SURFACE RIDGE COVERS THE 
REMAINDER OF THE ATLC N OF 23N E OF THE FRONT TO AFRICA. THE A 
FRONT WILL REMAIN NEARLY STATIONARY INTO FRI. REMNANTS OF THE 
FRONT WILL DRIFT W FRI NIGHT THROUGH SUN. A SECOND COLD FRONT 
WILL MOVE SE ACROSS THE NW ATLC SUN NIGHT MERGING WITH THE 
FRONTAL TROUGH MON THEN THE MERGED FRONT WILL EXTEND FROM 
BERMUDA TO THE SE BAHAMAS MON NIGHT MOVING INTO THE CENTRAL ATLC 
LATE TUE.

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

$$
PAW