465  
AXNT20 KNHC 221643  
TWDAT  
 
TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL  
1805 UTC FRI OCT 22 2021  
 
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 31N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE  
IMAGERY, WEATHER OBSERVATIONS, RADAR AND METEOROLOGICAL ANALYSIS.  
 
BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH  
1635 UTC.  
   
..TROPICAL WAVES
 
 
THE AXIS OF A TROPICAL WAVE IS ALONG 44W, SOUTH OF 17N AND IT IS  
MOVING W AT 10-15 KT. SCATTERED MODERATE CONVECTION IS OBSERVED  
FROM 05N TO 10N AND BETWEEN 39W AND 50W.  
 
THE AXIS OF A TROPICAL WAVE IS ALONG 59W, SOUTH OF 17N AND IT IS  
MOVING W AT 10-15 KT. A BROAD SURFACE CURVATURE IS EVIDENT ON  
VISIBLE SATELLITE IMAGERY. SCATTERED SHOWERS ARE NOTED FROM THE  
COASTS OF NE VENEZUELA AND GUYANA TO 12N AND BETWEEN 55W AND 63W.  
 
THE AXIS OF A TROPICAL WAVE IS ALONG 70W, SOUTH OF 21N, EXTENDING  
FROM THE DOMINICAN REPUBLIC TO W VENEZUELA, AND IT IS MOVING W AT  
10-15 KT. NO DEEP CONVECTION IS ASSOCIATED WITH THIS WAVE.  
 
THE AXIS OF A TROPICAL WAVE IS ALONG 78W, SOUTH OF 21N, EXTENDING  
FROM THE E CUBA TO PANAMA, AND IT IS MOVING W AT 10-15 KT.  
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FOUND WHERE  
THE WAVE INTERACTS WITH THE E PACIFIC MONSOON TROUGH, MAINLY FROM  
THE COAST OF PANAMA TO 13N AND BETWEEN 75W TO 83W.  
   
..MONSOON TROUGH/ITCZ
 
 
THE MONSOON TROUGH PASSES THROUGH THE COAST OF THE GAMBIA NEAR  
13N17W TO 07N22W. THE ITCZ CONTINUES FROM 07N22W TO 07N33W AND  
07N44W. ANOTHER SEGMENT OF THE ITCZ CONTINUES FROM 07N46W TO  
04N51W. SCATTERED MODERATE CONVECTION IS NOTED WITHIN 60 NM OF THE  
ITCZ FROM 32W TO 39W.  
 
GULF OF MEXICO...  
 
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS OBSERVED  
ACROSS THE SOUTHERN PORTION OF THE GULF OF MEXICO, EXTENDING FROM  
SW FLORIDA TO THE W BAY OF CAMPECHE, MAINLY AS A RESULT OF  
DIVERGENCE ALOFT AND A SURFACE TROUGH PRESENT ALONG 94W, FROM 17N  
TO 23N. THE REST OF THE GULF, ESPECIALLY N OF 25N, IS UNDER A DRY  
AIRMASS THAT IS SUPPRESSING THE DEVELOPMENT OF SHOWERS AND  
THUNDERSTORMS. A COLD FRONT DRAPES ACROSS THE N GULF, FROM THE  
FLORIDA PANHANDLE TO SE TEXAS, BUT IT IS NOT PRODUCING ANY  
SIGNIFICANT CONVECTION. A WEAK PRESSURE GRADIENT RESULTS IN  
MODERATE OR WEAKER WINDS ACROSS THE BASIN. SEAS S OF 25N ARE 3-4  
FT, WITH THE HIGHEST SEAS OCCURRING IN THE FLORIDA STRAITS, AND  
1-3 FT ELSEWHERE.  
 
FOR THE FORECAST, A COLD FRONT ENTERING THE NORTHERN GULF OF  
MEXICO WILL CONTINUE TO PRESS SOUTHWARD ACROSS THE EASTERN GULF  
THROUGH SAT. THE FRONT IS EXPECTED TO STALL LATER ON SAT AND WILL  
LINGER THROUGH EARLY NEXT WEEK. MODERATE TO FRESH WINDS ARE  
EXPECTED ACROSS THE NW GULF ON SAT INTO SUN. GENTLE TO MODERATE  
WINDS WILL PREVAIL IN THE WESTERN THROUGH EARLY NEXT WEEK.  
 
CARIBBEAN SEA...  
 
DIVERGENCE ALOFT AND A SURFACE TROUGH ALONG THE COAST OF THE  
YUCATAN PENINSULA RESULT IN SCATTERED MODERATE CONVECTION IN THE  
GULF OF HONDURAS. THE REST OF THE CARIBBEAN SEA ENJOYS FAIRLY  
TRANQUIL WEATHER CONDITIONS DUE IN PART TO THE DRY SAHARAN AIRMASS  
MOVING THROUGH THE REGION. THE MODEST PRESSURE GRADIENT BETWEEN  
THE 1028 MB RIDGE OVER THE NW ATLANTIC AND LOWER PRESSURES IN  
SOUTH AMERICA ALLOW FOR FRESH TO LOCALLY STRONG TRADES E OF 76W  
ACCORDING TO THE LATEST SCATTEROMETER SATELLITE DATA AND SYNOPTIC  
OBSERVATIONS. THE STRONGEST WINDS ARE FOUND NEAR THE LESSER  
ANTILLES. MODERATE OR WEAKER TRADES ARE PREVALENT IN THE REMAINDER  
OF THE CARIBBEAN. SEAS OF 5-8 FT ARE OCCURRING E OF 75W AND 2-5  
FT ELSEWHERE. A RECENT ALTIMETER WAVE DATA SHOW SEAS OF 8 FT IN  
THE SE CARIBBEAN.  
 
FOR THE FORECAST, HIGH PRESSURE N OF THE AREA WILL SUPPORT FRESH  
TO LOCALLY STRONG TRADES E OF THE WINDWARD ISLANDS THROUGH THE  
WEEKEND. WINDS ARE EXPECTED TO BECOME MODERATE ACROSS THE CENTRAL  
CARIBBEAN EARLY NEXT WEEK. MODERATE TO FRESH WINDS ARE EXPECTED  
OVER THE SOUTH-CENTRAL CARIBBEAN WITH WINDS REACHING LOCALLY  
STRONG IN THE VENEZUELA BASIN THROUGH SUN. GENTLE TO MODERATE  
TRADEWINDS WILL PREVAIL ELSEWHERE.  
 
ATLANTIC OCEAN...  
 
A LARGE AREA OF SHOWERS AND ISOLATED THUNDERSTORMS IS PRESENT OVER  
THE WESTERN TROPICAL ATLANTIC. THE COMBINATION OF A SURFACE  
TROUGH BETWEEN FLORIDA AND THE NW BAHAMAS AND DIVERGENCE ALOFT  
RESULTS IN SCATTERED MODERATE CONVECTION FROM 22N TO 27N AND  
BETWEEN 73W AND THE COAST OF FLORIDA. THE STORM ACTIVITY IS ALSO  
AFFECTING A GOOD PORTION OF THE BAHAMAS ISLAND CHAIN. FARTHER  
EAST, TWO OTHER SURFACE TROUGHS, EXTENDING FROM 30N70W TO 24N73W,  
AND 30N45W TO 26N59W, ARE PRODUCING WIDELY SCATTERED SHOWERS AND  
ISOLATED THUNDERSTORMS FROM 22N TO 30N AND BETWEEN 47W AND 71W.  
RECENT SCATTEROMETER SATELLITE DATA SHOW FRESH WINDS IN  
ASSOCIATION WITH THE CONVECTION. THE REST OF THE TROPICAL ATLANTIC  
ENJOYS FAIRLY TRANQUIL WEATHER CONDITIONS. A WEAK SURFACE TROUGH  
ALONG 41W, FROM 20N TO 24N, IS ONLY PRODUCING A FEW SHALLOW  
SHOWERS, BUT ITS SIGNATURE WAS QUITE EVIDENT ON SCATTEROMETER  
DATA.  
 
AN EXPANSIVE 1028 MB SUBTROPICAL RIDGE DOMINATES THE NORTH  
ATLANTIC AND THE PRESSURE GRADIENT BETWEEN THIS FEATURE AND LOWER  
PRESSURES IN SOUTH AMERICA RESULT IN FRESH TO STRONG TRADES FROM  
06N TO 19N AND BETWEEN 35W AND THE LESSER ANTILLES AS OBSERVED ON  
RECENT SATELLITE-DERIVED WIND DATA. FRESH NE WINDS ARE ALSO  
OCCURRING E OF 30W AND FROM 20N TO 30N. SEAS OF 7-10 FT ARE  
FOUND E OF 60W, WITH THE HIGHEST SEAS OCCURRING E OF THE LESSER  
ANTILLES AND WELL W OF THE CANARY ISLANDS. SEAS OF 4-7 FT PREVAIL  
ELSEWHERE IN THE BASIN.  
 
THE CUMBRE VIEJA VOLCANO, ON THE ISLAND OF LA PALMA IN THE  
CANARY ISLANDS, HAS BEEN ERUPTING SINCE 19 SEPTEMBER 2021.  
MARINE AND AVIATION INTERESTS SHOULD MONITOR THIS ONGOING  
SITUATION BY READING THE VOLCANIC ASH ADVISORY ISSUED BY METEO-  
FRANCE, AT HTTP://VAAC.METEO.FR/VOLCANOES/LA-PALMA/.  
 
FOR THE FORECAST, HIGH PRESSURE WILL MOVE EAST OF THE AREA TONIGHT AS A  
WEAK COLD FRONT MOVES OFF THE SE U.S. COAST. THE FRONT WILL STALL  
NEAR THE NORTHERN BAHAMAS THROUGH EARLY NEXT WEEK. MODERATE TO  
LOCALLY FRESH WINDS WILL DEVELOP NORTH OF THE BOUNDARY SAT NIGHT  
INTO SUN OFF THE CENTRAL FLORIDA COAST. EXPECT SHOWERS AND  
THUNDERSTORMS ALONG THIS BOUNDARY.  
 

 
DELGADO  
 
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