958
AXNT20 KNHC 181812
TWDAT
TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1815 UTC THU DEC 18 2025
TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA, CENTRAL AMERICA
GULF OF AMERICA, 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.
..SPECIAL FEATURES
WESTERN AND CENTRAL ATLANTIC GALE WARNING:
AN INTENSIFYING 1014 MB FRONTAL LOW PRESSURE SYSTEM IS NEAR
28N56W. N TO NE NEAR-GALE TO GALE-FORCE WINDS ARE OCCURRING JUST
NORTHWEST AND JUST SOUTH OF THE CENTER. SEAS OF 12 TO 15 FT (3.5
TO 4.5 M) ARE FOUND NORTH OF 28N BETWEEN 56W AND 59W. AS THE LOW
TRACKS SLOWLY EAST-NORTHEASTWARD THROUGH THIS EVENING, NW TO NE
GALE TO STRONG- GALE WINDS WILL SHIFT AND EXPAND TO NORTH OF 28N
BETWEEN 54W AND 57W. SEAS WILL ALSO RISE TO BETWEEN 12 AND 19 FT
(3.5 TO 5.5 M) AND SHIFT TO NORTH OF 28N BETWEEN 54W AND 59W. THE
LOW IS EXPECTED TO BE NEAR 29N55.5W AND GRADUALLY WEAKEN ON FRI
MORNING. AS A RESULT, WINDS ARE FORECAST TO DECREASE BELOW GALE-
FORCE AROUND MID FRI AFTERNOON. AFTERWARD, SEAS SHOULD ALSO
SUBSIDE BELOW 12 FT LATE FRI NIGHT OR EARLY SAT MORNING.
PLEASE READ THE LATEST HIGH SEAS AND OFFSHORE WATERS FORECASTS
ISSUED BY THE NATIONAL HURRICANE CENTER AT WEBSITE:
HTTPS://WWW.NHC.NOAA.GOV/TEXT/MIAHSFAT2.SHTML AND
HTTPS://WWW.NHC.NOAA.GOV/MARINE/OFFSHORES.PHP FOR MORE INFORMATION
THIS EVENT.
..MONSOON TROUGH/ITCZ
A MONSOON TROUGH ENTERS THE ATLANTIC ALONG THE LIBERIA COAST NEAR
MONROVIA, THEN RUNS WEST-SOUTHWESTWARD TO 05N16W. AN ITCZ CONTINUES
WESTWARD FROM 05N16W TO 04N38W. SCATTERED MODERATE CONVECTION IS
OCCURRING NEAR BOTH FEATURES FROM 02N TO 06N BETWEEN 14W AND 22W.
THE EASTERN END OF THE EAST PACIFIC MONSOON TROUGH IS TRIGGERING
WIDELY SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ACROSS THE
CARIBBEAN WATERS NEAR PANAMA AND NORTHWESTERN COLOMBIA.
..GULF OF AMERICA
ENHANCED BY A PRONOUNCED MID TO UPPER-LEVEL TROUGH, A SURFACE
TROUGH IS CAUSING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
ACROSS THE EASTERN GULF. ANOTHER SURFACE TROUGH RUNS SOUTHWARD
FROM A 1011 MB LOW JUST SOUTHWEST OF NEW ORLEANS TO THE SOUTH-
CENTRAL GULF. WIDELY SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
ARE FOUND NEAR THESE FEATURES OVER THE CENTRAL GULF. FRESH TO
STRONG SE TO SW WINDS AND SEAS OF 5 TO 7 FT ARE PRESENT AT THE
NORTHEASTERN GULF. MODERATE TO LOCALLY FRESH SE TO S WINDS AND 3
TO 5 FT SEAS EXIST AT THE EAST-CENTRAL AND SOUTHEASTERN GULF,
INCLUDING THE FLORIDA STRAITS. GENTLE WITH LOCALLY MODERATE SE TO
SW WINDS AND SEAS AT 2 TO 4 FT PREVAIL FOR THE REST OF THE GULF.
FOR THE FORECAST, THE PRESSURE GRADIENT BETWEEN A RIDGE ACROSS
THE WESTERN ATLANTIC AND A SURFACE TROUGH ACROSS THE EASTERN GULF
WILL MAINTAIN FRESH TO STRONG SE TO S WINDS TODAY ACROSS THE
EASTERN GULF THAT WILL SHIFT NORTHWARD INTO THE FLORIDA BIG BEND
LATE THIS AFTERNOON AND DIMINISH. OTHERWISE, WINDS ACROSS THE REST
OF THE GULF WILL VEER TO THE S AND SW TODAY AHEAD OF THE NEXT
COLD FRONT, WHICH IS FORECAST TO MOVE INTO THE NORTHWESTERN GULF
THIS EVENING. THE FRONT WILL THEN REACH FROM THE FLORIDA BIG BEND
TO NEAR BROWNSVILLE, TEXAS BY FRI MORNING, FROM SOUTHWESTERN
FLORIDA TO NORTHEASTERN MEXICO FRI EVENING, THEN BEGIN TO STALL
AND DISSIPATE THROUGH SAT. HIGH PRESSURE WILL MOVE INTO THE
NORTHEASTERN GULF SAT AFTERNOON THROUGH SUN.
..CARIBBEAN SEA
A SURFACE TROUGH AT THE GULF OF HONDURAS IF TRIGGERING WIDELY
SCATTERED MODERATE CONVECTION NEAR THE YUCATAN CHANNEL AND WESTERN
CUBA. ANOTHER SURFACE TROUGH IS CAUSING WIDELY SCATTERED SHOWERS
AT THE EASTERN BASIN AND NEAR THE LESSER ANTILLES. REFER TO THE
MONSOON TROUGH/ITCZ SECTION FOR ADDITIONAL CONVECTION IN THE
CARIBBEAN SEA. OTHERWISE, A TRADE-WIND PATTERN CONTINUES WITH
FRESH TO STRONG EASTERLY TRADES AND SEAS OF 6 TO 8 FT AT THE
SOUTH-CENTRAL AND PART OF THE SOUTHWESTERN BASIN. MODERATE TO
FRESH ENE WINDS AND 4 TO 6 FT SEAS ARE NOTED AT THE NORTH-CENTRAL
AND EASTERN BASIN. GENTLE TO MODERATE NE TO E WINDS AND SEAS AT 3
TO 5 FT PREVAIL ELSEWHERE IN THE CARIBBEAN SEA.
FOR THE FORECAST, FRESH TO LOCALLY STRONG TRADE WINDS AND
MODERATE TO LOCALLY ROUGH SEAS WILL PREVAIL OVER THE SOUTH-CENTRAL
BASIN THROUGH TONIGHT AS HIGH PRESSURE SHIFTS EASTWARD ACROSS THE
WESTERN ATLANTIC. ELSEWHERE, MODERATE TO FRESH WINDS ARE EXPECTED,
WITH THE EXCEPTION OF GENTLE TO MODERATE WINDS OVER THE
NORTHWESTERN BASIN. LARGE E SWELL WILL PERSIST OVER THE TROPICAL
ATLANTIC WATERS, THROUGH THE ATLANTIC PASSAGES AND INTO THE
EASTERN PART OF THE BASIN THROUGH FRI. HIGH PRESSURE WILL
STRENGTHEN NORTH OF THE BASIN THU INTO THE WEEKEND TO BRING A
RETURN TO FRESH TO STRONG TRADES ACROSS THE CENTRAL AND SOUTHWEST
BASIN.
..ATLANTIC OCEAN
PLEASE SEE THE SPECIAL FEATURES SECTION ABOUT A GALE WARNING IN
THE WESTERN AND CENTRAL ATLANTIC.
A STATIONARY FRONT STRETCHES WEST-SOUTHWESTWARD FROM THE NORTH-
CENTRAL ATLANTIC ACROSS 31N43W TO 30N55W, THEN CONTINUES A WARM
FRONT TO A 1014 MB LOW NEAR 28N58W. A WEAK COLD FRONT EXTENDS
SOUTHWESTWARD FROM THIS LOW TO NEAR 25N61W, THEN CONTINUES A
SURFACE TROUGH TO 22N67W. SCATTERED MODERATE CONVECTION IS FLARING
UP NEAR THESE FEATURES, NORTH OF 25N BETWEEN 51W AND 57W. FARTHER
SOUTH, A SURFACE TROUGH IS PRODUCING SCATTERED SHOWERS EAST OF
NORTHERN BRAZIL FROM 03N TO 06N BETWEEN 40W AND 48W. REFER TO THE
MONSOON TROUGH/ITCZ SECTION FOR ADDITIONAL CONVECTION IN THE
ATLANTIC BASIN.
OUTSIDE THE GALE WARNING AREA AND VERY ROUGH SEAS MENTIONED IN THE
SPECIAL FEATURES SECTION, FRESH TO STRONG NE TO SE WINDS AND SEAS
AT 6 TO 10 FT ARE EVIDENT NEAR AND NORTH OF THE FRONTS AND
SURFACE TROUGH, INCLUDING THE NORTHEASTERN FLORIDA OFFSHORE
WATERS. TO THE EAST, A 1026 MB HIGH NEAR 29N30W IS SUPPORTING
GENTLE TO MODERATE SE TO S WINDS AND 8 TO 10 FT IN LARGE NW SWELL
NORTH OF 24N BETWEEN 35W AND 55W/COLD FRONT. FOR THE TROPICAL
ATLANTIC FROM 06N TO 23N/24N BETWEEN 35W AND THE LESSER ANTILLES,
FRESH TO STRONG ENE TO E WINDS AND SEAS OF 8 TO 11 FT IN LARGE NE
SWELL DOMINATE. FOR THE REMAINDER OF THE ATLANTIC BASIN WEST OF
35W, GENTLE TO MODERATE E TO SE WINDS AND 5 TO 7 FT SEAS IN MIXED
MODERATE SWELLS PREVAIL.
FOR THE FORECAST W OF 55W, THE LOW PRESSURE IS EXPECTED TO BECOME
BETTER ORGANIZED AND DEEPEN TODAY AS IT MOVES SLOWLY EAST-
NORTHEASTWARD ACROSS THE FAR NORTHEASTERN ZONES. GALE-FORCE WINDS
ARE ALREADY OCCURRING WITHIN ABOUT 60 NM OF THE LOW CENTER. VERY
ROUGH SEAS ARE EXPECTED ACROSS THE WEST SEMICIRCLE OF THE LOW
CENTER LATER THIS MORNING THROUGH FRI MORNING, WITH WINDS
INCREASING TO STRONG GALES THIS EVENING, BEFORE THE LOW BEGINS TO
SLOWLY WEAKEN AND GRADUALLY EXITS THE FORECAST AREA SAT MORNING.
THE NEXT COLD FRONT WILL MOVE INTO THE OFFSHORE WATERS OF
NORTHEASTERN FLORIDA FRI AFTERNOON, REACH FROM NEAR BERMUDA TO
THE STRAITS OF FLORIDA SAT MORNING, THEN STALL AND WEAKEN FROM
31N60W TO THE NORTHWEST BAHAMAS SAT EVENING. ANOTHER COLD FRONT
MAY MOVE INTO THE SAME OFFSHORE WATERS AGAIN SUN NIGHT.
CHAN
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