000
AXNT20 KNHC 210545
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL  
105 AM EST SUN NOV 21 2010

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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND 
RADAR.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0515 UTC.

...THE ITCZ...
 
ITCZ AXIS IS ANALYZED ALONG 11N16W 7N23W 9N42W 7N57W. A SURFACE 
TROUGH IS EMBEDDED WITHIN THE ITCZ FROM 16N43W TO 9N46W. 
CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE FROM 9N TO 
JUST S OF THE EQUATOR BETWEEN 20W-27W. CLUSTERS OF SCATTERED 
MODERATE/ISOLATED STRONG CONVECTION ARE FROM THE ITCZ TO 2N 
BETWEEN 9W-20W.

...DISCUSSION...

GULF OF MEXICO...
A SHALLOW SHORTWAVE UPPER TROUGH EXTENDS FROM THE FLORIDA 
PANHANDLE NEAR PANAMA CITY TO OFF THE COAST OF MEXICO NEAR 
TAMPICO WHILE THE BROAD UPPER RIDGE ANCHORED IN THE CARIBBEAN 
COVERS THE SE GULF. MODERATE/STRONG SUBSIDENCE AND DRY STABLE 
AIR ALOFT ARE NOTED ON SATELLITE WATER VAPOR IMAGERY ACROSS THE 
ENTIRE GULF BASIN. A BROAD SURFACE RIDGE DOMINATES THE GULF 
ANCHORED IN THE W ATLC. ISOLATED LOW LEVEL SHOWERS ARE OBSERVED 
IN THE STRAITS OF FLORIDA S OF 25N E OF 86W AND ALONG THE COAST 
OF MEXICO IN THE BAY OF CAMPECHE FROM CAMPECHE TO TUXPAN LEAVING 
THE REMAINDER OF THE GULF WITH FAIR CONDITIONS AGAIN TONIGHT. 

CARIBBEAN SEA...
BROAD UPPER RIDGE COVERS THE ENTIRE CARIBBEAN AND EXTENDING OVER 
THE SE GULF OF MEXICO AND W ATLC ANCHORED S OF HAITI NEAR 
16N73W. THIS UPPER RIDGE IS PROVIDING DIFFLUENCE ALOFT TO ENHANCE
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ACROSS THE S CARIBBEAN 
S OF 15N FROM THE WINDWARD ISLANDS TO 73W AND FROM 77W-83W. 
MODERATE/STRONG SUBSIDENCE AND DRY STABLE AIR ALOFT ARE NOTED ON 
SATELLITE WATER VAPOR IMAGERY N OF 16N E OF 84W ALTHOUGH THERE 
IS SOME RESIDUAL MOISTURE FROM A RECENT FRONTAL PASSAGE OVER THE 
FAR NW CARIBBEAN. THIS MOISTURE IS GENERATING ISOLATED LOW LEVEL 
SHOWERS NW OF A LINE FROM SANTA CRUZ DEL SUR CUBA TO THE GULF OF 
HONDURAS AND THE COAST OF GUATEMALA LEAVING THE REMAINDER OF THE 
N CARIBBEAN WITH MOSTLY FAIR WEATHER TONIGHT. 

ATLANTIC OCEAN...
THE BROAD UPPER RIDGE ANCHORED IN THE CARIBBEAN EXTENDS OVER THE 
FAR W ATLC W OF 65W. BROAD UPPER LEVEL TROUGH COVERS THE 
REMAINDER OF THE W ATLC AND CENTRAL ATLC N OF 20N BETWEEN 
35W-65W SUPPORTING A COLD FRONT THAT ENTERS THE REGION NEAR 
32N40W EXTENDING SW ALONG 25N50W 23N58W TO 21N66W DISSIPATING AS 
A STATIONARY FRONT ALONG 21N69W THROUGH THE TURKS AND CAICOS TO 
22N74W AND ENDING OVER CUBA NEAR CAMAGUEY. ISOLATED SHOWERS ARE 
WITHIN 60 NM EITHER SIDE OF THE FRONTAL BOUNDARY. A SURFACE 
TROUGH IS TO THE E OF THE FRONT EXTENDING FROM 30N37W TO 23N43W. 
A HIGH AMPLITUDE UPPER RIDGE IS JUST TO THE E EXTENDING FROM THE 
TROPICS NEAR 7N25W ALONG 25N20W TO BEYOND 32N22W PROVIDING 
DIFFLUENCE ALOFT TO ENHANCE SCATTERED SHOWERS WITHIN 120/150 NM 
OF LINE FROM 24N39W TO BEYOND 32N34W. A WEAKENING SURFACE RIDGE 
COVERS THE REMAINDER OF THE E ATLC N OF 23N E OF 30W ANCHORED BY 
A 1021 MB HIGH JUST W OF THE MADEIRA ISLANDS NEAR 32N20W. 

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

$$
PAW