164
AXNT20 KNHC 181717
TWDAT
TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1815 UTC WED DEC 18 2024
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
1700 UTC.
.MONSOON TROUGH/ITCZ
A MONSOON TROUGH ENTERS THE ATLANTIC NEAR THE SIERRA LEONE/LIBERIA
BORDER AND EXTENDS TO 05N18W. THE ITCZ CONTINUES FROM 05N18W TO
03N35W TO 03N51W. SCATTERED MODERATE CONVECTION IS OCCURRING N OF
THE ITCZ TO ABOUT 06N BETWEEN 44W AND 51W.
..GULF OF MEXICO
A SURFACE TROUGH EXTENDS FROM 27N89W SOUTHWARD THROUGH THE NE
YUCATAN PENINSULA INTO THE NORTHWESTERN CARIBBEAN, AND SCATTERED
SHOWERS AND THUNDERSTORMS ARE OCCURRING NEAR THE TROUGH AXIS.
MODERATE E WINDS ARE NOTED TO THE EAST OF THIS TROUGH. ELSEWHERE,
GENTLE TO MODERATE E TO SE WINDS PREVAIL. SEAS ARE GENERALLY IN
THE 2 TO 4 FT RANGE, EXCEPT 4 TO 5 FT E OF THE TROUGH AXIS TO
ABOUT 85W.
FOR THE FORECAST, MODERATE E WINDS WILL CONTINUE THROUGH NOON TO
THE EAST OF A TROUGH THAT EXTENDS FROM THE YUCATAN PENINSULA TO
NEAR 27N89W. WINDS THERE WILL DIMINISH THIS AFTERNOON, WHILE
GENTLE TO MODERATE WINDS PREVAIL ELSEWHERE ACROSS THE BASIN
THROUGH THIS AFTERNOON. A COLD FRONT WILL MOVE INTO THE
NORTHWESTERN GULF OF MEXICO THIS EVENING, WITH FRESH TO LOCALLY
STRONG N WINDS OCCURRING ALONG AND BEHIND THE FRONT. THE FRONT
WILL DISSIPATE THU MORNING OVER THE CENTRAL BASIN. HIGH PRESSURE
WILL BUILD OVER THE CENTRAL UNITED STATES ON FRI, LEADING TO
MODERATE N TO NE WINDS ACROSS THE GULF. LOOKING AHEAD, GENTLE TO
MODERATE E WINDS AND SLIGHT TO MODERATE SEAS ARE ANTICIPATED FOR
THIS WEEKEND.
..CARIBBEAN SEA
A SURFACE TROUGH EXTENDS FROM CENTRAL GULF OF MEXICO INTO THE
NORTHWESTERN CARIBBEAN. SCATTERED MODERATE CONVECTION IS NOTED
SURROUNDING THE SOUTHERN PORTION OF THE TROUGH, PARTICULARLY N OF
17N AND W OF 83W. ELSEWHERE, SHALLOW MOISTURE, EMBEDDED IN THE
TRADE WIND FLOW IS MOVING ACROSS THE REGION PRODUCING ISOLATED TO
SCATTERED PASSING SHOWERS. THE TIGHT PRESSURE GRADIENT BETWEEN
HIGH PRESSURE IN THE CENTRAL ATLANTIC AND THE COLOMBIAN LOW IS
LEADING TO FRESH TO STRONG TRADES OVER THE SOUTH-CENTRAL CARIBBEAN
WHERE SEAS ARE IN THE 6 TO 8 FT RANGE, WITH THE HIGHEST SEAS NEAR
THE COAST OF COLOMBIA. FRESH TO STRONG E WINDS ARE ALSO NOTED
OVER THE NE CARIBBEAN, INCLUDING THE ATLANTIC PASSAGES. SEAS THERE
ARE 6 TO 8 FT IN NE SWELL. GENTLE TO MODERATE WINDS DOMINATE THE
REMAINDER OF THE BASIN, WITH SEAS OF 3 TO 5 FT.
FOR THE FORECAST, A TIGHT PRESSURE GRADIENT BETWEEN 1034 MB HIGH
PRESSURE NE OF BERMUDA AND LOW PRESSURE OVER COLOMBIA WILL SUPPORT
MODERATE TO FRESH TRADE WINDS OVER THE CENTRAL, EASTERN AND
SOUTHWESTERN CARIBBEAN THROUGH FRI MORNING. WINDS WILL PULSE TO
STRONG SPEEDS EACH NIGHT OFF THE COAST OF COLOMBIA AND VENEZUELA.
STRONG NE WINDS ARE ALSO EXPECTED JUST SOUTH OF HISPANIOLA AND
THROUGH THE ATLANTIC PASSAGES INTO EARLY THU. ATLANTIC NE SWELL
WILL PRODUCE ROUGH SEAS THROUGH THE ATLANTIC PASSAGES THROUGH FRI
BEFORE DIMINISHING. ELSEWHERE, GENTLE TO LOCALLY MODERATE NE WINDS
ARE EXPECTED IN THE NORTHWESTERN CARIBBEAN THROUGH FRI. LOOKING
AHEAD, BUILDING HIGH PRESSURE OVER THE GULF OF MEXICO WILL LEAD TO
GENERALLY MODERATE TO LOCALLY FRESH NE TO E WINDS ACROSS THE
BASIN THIS WEEKEND.
..ATLANTIC OCEAN
AN AREA OF SHOWERS AND THUNDERSTORMS IS AFFECTING THE WATERS E OF
NORTH-CENTRAL FLORIDA, MAINLY N OF 28N AND W OF 75W. STRONG SW TO
W WINDS ALOFT ARE HELPING TO INDUCE THIS CONVECTIVE ACTIVITY. A
SWIRL OF LOW CLOUDS IS SPINNING NEAR 29N68.5W AND SCATTEROMETER
DATA INDICATE A WEK TROUGH THERE. A COLD FRONT EXTENDS FROM
31N25W TO 28N38W THEN A WARM FRONT IS ANALYZED FROM 28N38W TO A
WEAK LOW OF 1020 MB LOCATED NEAR 27.5N45W BASED ON VISIBLE
SATELLITE IMAGERY. A COLD FRONT EXTENDS FROM THE LOW CENTER TO
ABOUT 23N60W. FRESH TO STRONG NE TO E WINDS FOLLOW THE FRONT, WITH
SEAS OF 8 TO 11 FT. A STRONG PRESSURE GRADIENT BETWEEN 1034 MB
HIGH PRESSURE SITUATED NE OF BERMUDA AND BROAD LOW PRESSURE ACROSS
THE SW CARIBBEAN ALSO SUPPORTS A LARGE AREA OF FRESH TO STRONG E
WINDS S OF 27N AND E OF THE BAHAMAS TO ABOUT 55W, INCLUDING THE
ATLANTIC EXPOSURES. SEAS ARE 8 TO 11 FT WITHIN THESE WINDS. A
RIDGE DOMINATES THE REMAINDER OF THE ATLANTIC FORECAST WATERS.
MODERATE TO LOCALLY FRESH TRADE WINDS AND SEAS OF 7 TO 9 FT ARE
OBSERVED ACROSS THE TROPICAL ATLANTIC BASED ON SCATTEROMETER AND
ALTIMETER DATA. SATELLITE DERIVED WIND DATA ALSO SHOW THE PRESENCE
OF FRESH TO LOCALLY STRONG EASTERLY WINDS BETWEEN THE CANARY AND
THE CABO VERDE ISLANDS WHERE SEAS OF 4 TO 7 FT.
FOR THE FORECAST W OF 55W, A STRONG PRESSURE GRADIENT BETWEEN
1034 MB HIGH PRESSURE NE OF BERMUDA AND BROAD LOW PRESSURE ACROSS
THE SW CARIBBEAN WILL CONTINUE TO SUPPORT FRESH E WINDS ACROSS THE
WATERS BETWEEN 25N AND THE GREATER ANTILLES TODAY, WITH STRONG
WINDS EXPECTED THROUGH THE SOUTHEASTERN BAHAMAS. FARTHER EAST, A
COLD FRONT ANALYZED FROM 28N41W TO 23N62W WILL PROGRESS SLOWLY
SOUTHWARD THROUGH THU, PRODUCING WIDESPREAD FRESH E WINDS BOTH
AHEAD AND BEHIND THE FRONT, AND STRONG WINDS OCCURRING ALONG THE
FRONT. ROUGH SEAS ASSOCIATED WITH THESE FEATURES WILL OCCUR NORTH
OF 15N THROUGH THE END OF THE WORK WEEK BEFORE SEAS BEGIN TO
SLOWLY SUBSIDE FROM NORTH TO SOUTH LATE THU THROUGH EARLY SAT.
SEAS IN EXCESS OF 12 FT WILL BE POSSIBLE ALONG AND BEHIND THE
AFOREMENTIONED COLD FRONT. ELSEWHERE, FRESH TRADE WINDS AND ROUGH
SEAS WILL PREVAIL SOUTH OF 15N THROUGH THU BEFORE WINDS DIMINISH
TO MODERATE SPEEDS ON FRI. A COLD FRONT WILL MOVE OFF THE COAST OF
THE SOUTHEASTERN UNITED STATES LATE TONIGHT INTO THU AND EXTEND
FROM NEAR 31N74W TO SE FLORIDA FRI MORNING, AND FROM 31N67W TO
EASTERN CUBA BY SAT MORNING. FRESH TO LOCALLY STRONG N TO NW WINDS
WILL OCCUR BEHIND THE FRONT.
GR
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