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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