128  
AXNT20 KNHC 291714  
TWDAT  
 
TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL  
1805 UTC THU JUL 29 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  
1730 UTC.  
   
..TROPICAL WAVES
 
 
AN ATLANTIC TROPICAL WAVE IS NEAR 29W FROM 18N SOUTHWARD AND  
MOVING WEST AROUND 10 KT. SCATTERED MODERATE CONVECTION IS  
EVIDENT FROM 05N-09N BETWEEN 26W-33W. THIS WEAK WAVE IS MAINLY  
IDENTIFIABLE VIA 700 MB TROUGH DIAGNOSTICS.  
 
ANOTHER ATLANTIC TROPICAL WAVE IS NEAR 49W FROM 18N SOUTHWARD AND  
MOVING WEST AROUND 15 TO 20 KT. NO SIGNIFICANT CONVECTION IS  
NOTED CURRENTLY IN ASSOCIATION WITH THE WAVE. HOWEVER, THE WAVE IS  
APPARENT AS A TROUGH IN THE SURFACE WINDS.  
 
A CARIBBEAN TROPICAL WAVE IS NEAR 66W FROM 17N SOUTHWARD ACROSS  
CENTRAL VENEZUELA, AND MOVING WEST AT 5 TO 10 KT. DIVERGENT FLOW  
ASSOCIATED WITH AN UPPER-LEVEL LOW THAT IS LOCATED JUST NORTHWEST  
OF PUERTO RICO IS SUPPORTING SCATTERED MODERATE CONVECTION IS  
SEEN FROM 11N- 17N BETWEEN 62W-66W. THE WAVE IS MAINLY DIAGNOSED  
FROM 850 AND 700 MB RAWINDSONDES IN THE CARIBBEAN.  
 
ANOTHER CARIBBEAN TROPICAL WAVE IS NEAR 81W FROM 13N SOUTHWARD  
THROUGH W PANAMA INTO THE EASTERN PACIFIC OCEAN, AND MOVING WEST  
AROUND 10 TO 15 KT. SCATTERED MODERATE TO ISOLATED STRONG  
CONVECTION IS OCCURRING FROM 6N-9N BETWEEN 78W-82W, INCLUDING  
EASTERN PANAMA. THIS WEAK WAVE IS MAINLY IDENTIFIABLE VIA 700 MB  
TROUGH DIAGNOSTICS.  
   
..MONSOON TROUGH/ITCZ
 
 
A MONSOON TROUGH EXTENDS ACROSS THE COAST OF SENEGAL AT 14N17W TO  
07N38W. AT THIS TIME, THERE IS NO COHERENT ITCZ WEST OF THE  
MONSOON TROUGH. IN ADDITION TO THE CONVECTION ASSOCIATED WITH THE  
TROPICAL WAVE NEAR 29W, SCATTERED MODERATE CONVECTION EXISTS FROM  
05N-14N EAST OF 26W.  
   
..GULF OF MEXICO
 
 
A SURFACE TROUGH IS NOTED OVER THE NORTHWESTERN GULF OF MEXICO,  
NEAR THE SOUTHEAST TEXAS COAST. SCATTERED MODERATE CONVECTION IS  
ASSOCIATED WITH THIS TROUGH FROM 23N TO 29N BETWEEN 94W TO 98W.  
ANOTHER TROUGH EXTENDS FROM THE BIG BEND OF FLORIDA INTO THE  
NORTHEASTERN GULF OF MEXICO TO 30N88W. SCATTERED MODERATE  
CONVECTION EXISTS WITH THIS SECOND TROUGH FROM THE FLORIDA COAST  
TO 87W FROM 26N TO 30N. ANOTHER DIURNAL TROUGH IS SEEN IN THE SW  
GULF FROM 21N93W TO 19N94W. ISOLATED MODERATE CONVECTION EXISTS  
SOUTH OF 21N WEST OF 92W. ELSEWHERE, SURFACE RIDGING EXTENDS  
WESTWARD INTO THE EASTERN GULF OF MEXICO. FRESH SE WINDS ARE  
OCCURRING OVER THE SW GULF, WHILE TRANQUIL CONDITIONS PREVAIL  
ELSEWHERE. SEAS ARE 2-4 FT ACROSS THE GULF.  
 
FOR THE FORECAST, THE SURFACE TROUGH OVER THE NE GULF WILL  
CONTINUE DRIFTING SOUTH TODAY BEFORE DISSIPATING TONIGHT. THE  
SECOND TROUGH ACROSS THE NW GULF WATERS SHOULD ALSO DISSIPATE  
TONIGHT. THE ATLANTIC HIGH PRESSURE RIDGE WILL DRIFT WESTWARD AND  
DOMINATE THE GULF REGION DURING THE UPCOMING WEEKEND THEN  
REORGANIZE OVER THE E GULF BY EARLY NEXT WEEK.  
   
..CARIBBEAN SEA
 
 
A MODERATE NORTH-SOUTH PRESSURE GRADIENT BETWEEN RIDGING NORTH  
OF THE CARIBBEAN AND LOWER PRESSURE OVER N SOUTH AMERICA IS  
CONTRIBUTING TOWARD FRESH TO STRONG NE TO E TRADES OVER THE  
SOUTH-CENTRAL CARIBBEAN AND JUST SOUTH OF HISPANIOLA. ELSEWHERE,  
THE TRADES ARE GENTLE TO FRESH. SEAS ARE 6-8 FT IN THE CENTRAL  
CARIBBEAN, 4-6 FT IN THE E CARIBBEAN, AND 3-5 FT IN THE W  
CARIBBEAN. BESIDES THE CONVECTION ASSOCIATED WITH THE TROPICAL  
WAVES NEAR 66W AND 81W, NO SIGNIFICANT DEEP CONVECTION IS  
OBSERVED.  
 
FOR THE FORECAST, FRESHENING TRADEWINDS ARE EXPECTED ACROSS E AND  
CENTRAL PORTIONS OF THE CARIBBEAN THROUGH TONIGHT AS THE ATLANTIC  
RIDGE BUILDS MODESTLY ACROSS THE W ATLANTIC. FRESH TO STRONG  
TRADES WILL PREVAIL ACROSS SOUTH CENTRAL PORTIONS AS WELL AS THE  
SOUTH CENTRAL COAST OF HISPANIOLA THROUGH SUN NIGHT BEFORE THE  
RIDGE BEGINS TO WEAKEN. STRONG WINDS TO AROUND 30 KT ARE EXPECTED  
AT NIGHT NEAR THE COAST OF COLOMBIA AND IN THE GULF OF VENEZUELA  
FRI NIGHT THROUGH MON NIGHT.  
   
..ATLANTIC OCEAN
 
 
THE ATLANTIC RIDGE EXTENDS WEST-SOUTHWEST FROM THE 1029 MB AZORES  
HIGH ACROSS CENTRAL ATLANTIC TO FLORIDA. THE RIDGE IS SUSTAINING  
LIGHT TO GENTLE TRADES ACROSS ALL OF THE WATERS, EXCEPT FOR FRESH  
SE WINDS JUST NORTH OF HISPANIOLA. SEAS ARE 6-7 FT SOUTH OF 22N  
AND 4-5 FT NORTH OF 22N. IN ADDITION TO THE CONVECTION MENTIONED  
IN THE TROPICAL WAVES AND MONSOON TROUGH/ITCZ SECTIONS, SCATTERED  
MODERATE CONVECTION IS NOTED NORTH OF 30N BETWEEN 65W-75W IN  
ASSOCIATION WITH A SHARP UPPER-LEVEL TROUGH.  
 
FOR THE FORECAST W OF 65W, THE ATLANTIC RIDGE CENTERED ON THE  
AZORES HIGH WILL DOMINATE THE FORECAST WATERS THROUGH THE PERIOD,  
WHILE A SURFACE TROUGH WILL REMAIN OVER OR JUST OFF THE COAST OF  
THE SE UNITED STATES. EXPECT FRESH TO LOCALLY STRONG EASTERLY  
WINDS LATE AFTERNOON THROUGH THE NIGHT JUST OFF THE N COAST OF  
HISPANIOLA, INCLUDING APPROACHES TO THE WINDWARD PASSAGE, MOST OF  
THE FORECAST PERIOD. MODERATE TO FRESH S TO SW WINDS ARE EXPECTED  
ACROSS THE FAR NW WATERS SUN NIGHT THROUGH MON NIGHT.  
 

 
NEPAUL/LANDSEA  
 
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