996
AXNT20 KNHC 181640
TWDAT
TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1815 UTC FRI SEP 18 2026
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
1600 UTC.
..TROPICAL WAVES
A CENTRAL ATLANTIC TROPICAL WAVE HAS ITS AXIS ALONG 40W, S OF 21N,
MOVING WESTWARD 10 TO 15 KT. SCATTERED MODERATE ISOLATED STRONG
CONVECTION IS FROM 08N TO 16N BETWEEN 35W AND 44W. A CLUSTER OF
STRONG CONVECTION IS OCCURRING ALONG THE N END OF THE WAVE, FROM
21N TO 23.5N BETWEEN 41W AND 44W.
A CENTRAL CARIBBEAN TROPICAL WAVE HAS ITS AXIS ALONG 77W-78W, S OF
19N TO EASTERN PANAMA, MOVING WESTWARD AT AROUND 15 KT. ISOLATED
MODERATE CONVECTION IS NOTED S AND W OF JAMAICA, WHILE NUMEROUS
STRONG CONVECTION IS NOTED ALONG THE INTERSECTION OF THE WAVE AND
THE EASTERN PACIFIC MONSOON TROUGH, ACROSS THE COASTAL WATERS OF
PANAMA AND COLOMBIA.
..MONSOON TROUGH/ITCZ
THE MONSOON TROUGH ENTERS THE ATLANTIC ALONG THE COAST OF SENEGAL
NEAR 14N17W AND CONTINUES SOUTHWESTWARD TO 09N22W TO 13N34W TO
13N44W. THE ITCZ EXTENDS FROM 11N44W TO 12.5N50W, THEN RESUMES
FROM 11N53W TO 10.5N61W. ASIDE FROM CONVECTION ASSOCIATED TO THE
TROPICAL WAVES AS DESCRIBED ABOVE, SCATTERED MODERATE ISOLATED
STRONG CONVECTION IS NOTED FROM 06N TO 12.5N BETWEEN THE COAST OF
AFRICA AND 34W. A SMALL 1014 MB LOW ABOUT THE ITCZ NEAR 12N50.5W
IS PRODUCING SCATTERED MODERATE CONVECTION WITHIN 120 NM ACROSS
THE N SEMICIRCLE OF THE LOW.
..GULF OF AMERICA
THE OLD FRONTAL TROUGH EXTENDING FROM THE ATLANTIC NEAR THE NW
BAHAMAS AND ACROSS PORTIONS OF S FLORIDA AND INTO THE SE GULF IS
NO LONGER CLEARLY IDENTIFIABLE. HOWEVER, ASSOCIATED LOW LEVEL
MOISTURE PERSISTS ACROSS THE SOUTHERN GULF S OF 26N BETWEEN
FLORIDA AND MEXICO. SCATTERED MODERATE ISOLATED STRONG CONVECTION
IS OCCURRING WITHIN THIS BAND OF MOISTURE FROM 22N TO 26N BETWEEN
THE STRAITS OF FLORIDA AND 94.5W. AT THE SURFACE, A BROAD HIGH
PRESSURE RIDGE EXTENDS ACROSS THE SOUTHEASTERN U.S. ALONG ABOUT
34N, AND IS PROMOTING GENTLE TO MODERATE EASTERLY WINDS ACROSS THE
BASIN N OF 25N, WHERE SEAS ARE 4 TO 7 FT. A SURFACE TROUGH IS
ALONG 89-90W FROM 23N TO 26.5N AND IS AIDING IN FOCUSING
CONVECTION TO ITS EAST, AND PROMOTING THE STRONGEST WINDS AND SEAS
ACROSS THE BASIN ACROSS THE NORTHERN END OF THE TROUGH. LIGHT TO
GENTLE MOSTLY EASTERLY WINDS PREVAIL S OF 25N, WHERE SEAS ARE 2-4
FT. A WEAK THERMAL SURFACE TROUGH IS OVER THE EASTERN BAY OF
CAMPECHE, WITH ANOTHER WEAK TROUGH EXTENDING FROM THE NEARSHORE
WATERS OF SE TEXAS TO NEAR VERACRUZ, MEXICO. SCATTERED SHOWERS ARE
WITHIN 90 NM OF VERACRUZ AND WITHIN 45 NM OF THE NE MEXICO COAST.
FOR THE FORECAST, THE PRESSURE GRADIENT BETWEEN HIGH PRESSURE
OVER THE SOUTHEASTERN U.S. AND A DISSIPATING FRONTAL TROUGH OVER
THE SOUTHERN GULF SUPPORTS MODERATE TO LOCALLY FRESH E-NE TO E
WINDS AND MODERATE SEAS OVER THE NORTHERN GULF. THESE CONDITIONS
WILL GRADUALLY IMPROVE LATER TODAY INTO SAT AS THE FRONTAL TROUGH
DISSIPATES. MEANWHILE, A RATHER BROAD UPPER-LEVEL LOW WILL MOVE
TOWARDS FLORIDA FROM THE WESTERN ATLANTIC TODAY, AND INTO THE NE
GULF ON SAT. THIS FEATURE WILL LEAD TO INCREASING SHOWER AND
THUNDERSTORM ACTIVITY OVER FLORIDA, AND THEN OVER THE EASTERN AND
CENTRAL GULF WATERS. FAIRLY TRANQUIL MARINE CONDITIONS ARE
FORECAST BY THE END OF THE WEEKEND INTO EARLY NEXT WEEK.
..CARIBBEAN SEA
PLEASE REFER TO THE TROPICAL WAVE SECTION FOR DETAILS ON A WAVE IN
THE CENTRAL CARIBBEAN INCLUDING ASSOCIATED CONVECTION. WESTERLY
WINDS ALOFT ACROSS THE NORTHWEST CARIBBEAN ARE SUPPORTING
SCATTERED MODERATE CONVECTION ACROSS THE GULF OF HONDURAS AND NEAR
THE TROPICAL WAVE. ELSEWHERE, FAIR SKIES PREVAIL ACROSS THE
BASIN.
THE PRESSURE GRADIENT BETWEEN WEAKENING HIGH PRESSURE OVER THE
WESTERN ATLANTIC AND RELATIVELY LOWER PRESSURE IN NORTHERN SOUTH
AMERICA IS ALLOWING FOR FRESH TO STRONG TRADES OVER THE CENTRAL
CARIBBEAN S OF 17N BETWEEN 66W AND 77W, WHERE SEAS ARE 6-9 FT.
MODERATE TO FRESH TRADES ARE FOUND ELSEWHERE FROM 10N TO 19N TO
THE EAST OF 80W, ALONG WITH 4-7 FT SEAS. GENTLE TO MODERATE WINDS
AND 2-5 FT SEAS PREVAIL ACROSS THE REMAINDER OF THE BASIN, EXCEPT
FOR SEAS TO 6 FT ACROSS SOUTHWEST PORTIONS ACROSS THE WESTERN
COASTAL WATERS OF PANAMA.
FOR THE FORECAST, THE PRESSURE GRADIENT BETWEEN HIGH PRESSURE OVER THE
WESTERN ATLANTIC AND THE COLOMBIAN LOW WILL GENERALLY MAINTAIN
FRESH TO STRONG TRADES ALONG WITH MODERATE TO LOCALLY ROUGH SEAS
OVER MOST OF THE CENTRAL CARIBBEAN THROUGH EARLY SAT MORNING. WINDS
WILL DIMINISH TO MODERATE TO FRESH SPEEDS THEREAFTER AS THE PRESSURE
GRADIENT RELAXES ACROSS THE AREA. MODERATE OR WEAKER WINDS AND SLIGHT
TO MODERATE SEAS ARE FORECAST ELSEWHERE.
..ATLANTIC OCEAN
A WEAKENING STATIONARY FRONT EXTENDS FROM NEAR 31N70W SOUTHWESTWARD
TO NEAR THE COAST OF VERO BEACH, FLORIDA, WHERE IT BECOMES ILL
DEFINED ACROSS THE PENINSULA. ACROSS THE NW BAHAMAS AND TO THE
FLORIDA KEYS. BROAD UPPER LEVEL LOW PRESSURE OVER NORTHERN FLORIDA
IS PROMOTING UNSTABLE CONDITIONS ACROSS MUCH OF THE AREA W OF
68W. CONVERGING LOW LEVEL MOISTURE ASSOCIATED WITH THE FRONT IS
PRODUCING SCATTERED MODERATE ISOLATED STRONG CONVECTION FROM 23N
TO 28.5N BETWEEN THE STRAITS OF FLORIDA AND 68W. RECENT SATELLITE
SCATTEROMETER DATA SHOWS GENTLE TO MODERATE NE WINDS TO THE N OF
THE FRONT, WHERE SEAS ARE 4 TO 6 FT. S OF THE FRONT, WINDS ARE
LIGHT TO GENTLE BETWEEN 60W AND S FLORIDA, EXCEPT FOR FRESH SE
WINDS ALONG THE N COASTAL WATERS OF HISPANIOLA TO 22N. WEAK HIGH
PRESSURE AND LIGHT WINDS PREVAIL E OF THE FRONT TO ABOUT 46W,
WHERE A LOW LEVEL TROUGH IS INTERACTING WITH AN UPPER- LEVEL
TROUGH TO PRODUCE SCATTERED TO LOCALLY NUMEROUS MODERATE
CONVECTION FROM 24.5N TO 31N BETWEEN 40W AND 55W. FARTHER NE, A
1023 MB IS CENTERED NEAR 35N45W AND EXTENDS A BROAD RIDGE SOUTH
AND SOUTHWESTWARD ACROSS THE EASTERN AND CENTRAL ATLANTIC.
MODERATE NE TO E TRADES PREVAIL S OF 25N BETWEEN THE CABO VERDES
AND THE TROPICAL WAVE ALONG 40W, WHERE SEAS ARE 5 TO 7 FT. WELL TO
THE EAST, FRESH TO STRONG N-NE WINDS AND 6-9 FT SEAS ARE FOUND
FROM 16N TO 22N BETWEEN AFRICA AND 22W DUE TO A TIGHT PRESSURE
GRADIENT BETWEEN LOW PRESSURE ACROSS NW AFRICA AND THE ATLANTIC
RIDGE. MODERATE TO FRESH N-NE WINDS AND 6-9 FT SEAS ELSEWHERE FROM
16N TO 31N TO THE EAST OF 28W. MODERATE OR WEAKER WINDS AND
MODERATE SEAS DOMINATE THE REMAINDER OF THE TROPICAL ATLANTIC
WATERS.
FOR THE FORECAST WEST OF 55W, A WEAKENING STATIONARY FRONT THAT
EXTENDS FROM NEAR BERMUDA TO THE CENTRAL FLORIDA COAST WILL
GRADUALLY WASH OUT TODAY. CONDITIONS WILL IMPROVE EARLY ON FRI AS
HIGH PRESSURE BECOMES THE DOMINANT FEATURE ACROSS THE BASIN DURING
THE WEEKEND INTO EARLY NEXT WEEK. MEANWHILE, ABUNDANT TROPICAL
MOISTURE, COMBINED WITH AN UPPER- LEVEL LOW LOCATED EAST OF
FLORIDA, WILL CONTINUE TO SUPPORT SCATTERED TO NUMEROUS SHOWERS
AND THUNDERSTORMS, MAINLY W OF 70W, THROUGH AT LEAST SUN.
STRIPLING
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