145
AXNT20 KNHC 180006
TWDAT
TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0015 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2345 UTC.
..TROPICAL WAVES
A CENTRAL ATLANTIC TROPICAL WAVE HAS ITS AXIS ALONG 35W FROM 03N
TO 18N, MOVING WESTWARD NEAR 15 KT. NUMEROUS MODERATE CONVECTION
IS WITHIN 240 NM WEST OF THE WAVE FROM 11N TO 16N, AND FROM
08N TO 13N BETWEEN 32W AND THE WAVE.
A CENTRAL CARIBBEAN TROPICAL WAVE HAS ITS AXIS ALONG 72W. IT
IS MOVING WESTWARD AT 10 TO 15 KT. ONLY ISOLATED SHOWERS AND
THUNDERSTORMS ARE NEAR THE WAVE NORTH OF 16N.
..MONSOON TROUGH/ITCZ
THE MONSOON TROUGH AXIS ENTERS THE ATLANTIC NEAR 17N16W AND
CONTINUES SOUTHWESTWARD TO 12N30W TO 10N40W AND TO 09N50W, WHERE
IT TRANSITIONS TO THE ITCZ TO 11N59W. ASIDE FROM CONVECTION
ASSOCIATED TO THE TROPICAL WAVES AS DESCRIBED ABOVE, SCATTERED
MODERATE TO ISOLATED STRONG CONVECTION IS EVIDENT FROM 06N TO 11N
BETWEEN 18W-21W, AND FROM 10N TO 14N EAST OF 20W TO INLAND
AFRICA. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM NORTH OF
THE TROUGH BETWEEN 47W-50W.
..GULF OF AMERICA
A TROUGH AXIS IS ANALYZED FROM JUST WEST OF THE BAHAMAS,
SOUTHWESTWARD ACROSS EXTREME SOUTH FLORIDA AND TO JUST NORTH OF
THE FLORIDA KEYS, REACHING TO NEAR 24N86W. A WESTERN GULF TROUGH
EXTENDS FROM 28N96W TO 24N97W AND TO NEAR 19N93W. AN UPPER-LEVEL
LOW IS SEEN IN WATER VAPOR IMAGERY TO BE SHIFTING WESTWARD OVER
THE NORTHERN YUCATAN PENINSULA. SATELLITE IMAGERY SHOWS SCATTERED
MODERATE CONVECTION OVER THE GULF WATERS FROM 23N TO 26N BETWEEN
84W AND 92W. ISOLATED SHOWERS AND THUNDERSTORMS ARE ELSEWHERE
SOUTH OF ABOUT 28N AND WEST OF 83W. SIMILAR ACTIVITY IS OVER SOME
SECTIONS OF THE STRAITS OF FLORIDA. ANOTHER TROUGH EXTENDS FROM
THE WESTERN ATLANTIC TO SOUTH FLORIDA TO 24N86W. THE PRESSURE
GRADIENT BETWEEN A 1025 MB HIGH CENTER CENTERED OVER EASTERN
TENNESSEE AND THE AFOREMENTIONED TROUGH THAT IS OVER THE
SOUTHEASTERN GULF CONTINUES TO SUSTAIN FRESH NORTHEAST TO EAST
WINDS OVER THE NE AND NORTH-CENTRAL GULF WATERS. MODERATE SEAS
ARE OCCURRING WITH THESE WINDS. ELSEWHERE, MODERATE OR WEAKER
WINDS, AND SLIGHT SEAS, ARE NOTED.
FOR THE FORECAST, THE AFOREMENTIONED PRESSURE GRADIENT WILL
SPREAD WESTWARD OVER THE REMAINDER OF THE NORTHERN GULF WATERS
THROUGH TONIGHT BEFORE IMPROVING FRI INTO SAT. MEANWHILE, A RATHER
BROAD UPPER-LEVEL LOW WILL MOVE TOWARD FLORIDA FROM THE WESTERN
ATLANTIC ON FRI. THIS FEATURE WILL LEAD TO INCREASING SHOWER AND
THUNDERSTORM ACTIVITY OVER FLORIDA, THEN ACROSS THE EASTERN AND
CENTRAL GULF WATERS.
..CARIBBEAN SEA
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 SOUTH-
CENTRAL CARIBBEAN. SEAS IN THE RANGE OF 6 TO 8 FT ARE OVER THESE
WATERS. MODERATE TO FRESH TRADES ALONG WITH MODERATE SEAS ARE
ELSEWHERE E OF 82W WHILE GENTLE TO MODERATE TRADES AND SEAS OF 2
TO 4 FT ARE W OF 82W, EXCEPT FOR HIGHER SEAS OF 4 TO 5 FT SOUTH
OF 17N AS NOTED IN A SATELLITE SCATTEROMETER DATA PASS.
UPPER-LEVEL DIVERGENCE EAST OF AN UPPER-LEVEL LOW THAT IS OVER
THE NORTHERN YUCATAN PENINSULA IS SUPPORTING SCATTERED SHOWERS
AND ISOLATED THUNDERSTORMS OVER THE NORTHWESTERN CARIBBEAN. AN
UPPER-LEVEL DISTURBANCE RIDING ALONG A JET STREAM BRANCH IS
KEEPING ACTIVE WEATHER IN THE FORM OF NUMEROUS MODERATE
CONVECTION OVER THE WATERS FROM 11N TO 17N WEST OF 80W TO INLAND
(NEAR 85W) OF HONDURAS AND NICARAGUA. SCATTERED MODERATE
CONVECTION IS OVER THE INTERIOR OF HONDURAS.
FOR THE FORECAST, THE AFOREMENTIONED PRESSURE GRADIENT WILL
GENERALLY MAINTAIN FRESH TO STRONG TRADES ALONG WITH MODERATE TO
LOCALLY ROUGH SEAS OVER MOST OF THE CENTRAL CARIBBEAN THROUGH
FRI NIGHT. THE TRADES WILL DIMINISH TO MODERATE TO FRESH SPEEDS
OVER THE UPCOMING WEEKEND AS THE PRESSURE GRADIENT RELAXES ACROSS
THE AREA. MODERATE OR WEAKER WINDS AND SLIGHT TO MODERATE SEAS
ARE FORECAST ELSEWHERE.
..ATLANTIC OCEAN
A STATIONARY FRONT EXTENDS FROM NEAR 31N68W SOUTHWESTWARD TO
27N75W AND TO EXTREME SOUTH FLORIDA. MODERATE TO FRESH NORTHEAST
WINDS AND SEAS 5 TO 6 FT ARE NORTH OF OF THE FRONT. SCATTERED
MODERATE CONVECTION IS SEEN NORTH OF ABOUT 23N AND WEST OF 66W
IN ASSOCIATION TO THIS FRONTAL BOUNDARY. LIGHT TO GENTLE WINDS
AND SLIGHT SEAS ARE SOUTHEAST OF THE FRONT NORTH OF 23N AND WEST
OF 55W. AN UPPER-LEVEL TROUGH THAT EXTENDS FROM NORTH OF PUERTO
RICO AND THE U.S. VIRGIN ISLANDS TO AROUND 31N IS SUPPORTING
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION BETWEEN 59W AND
62W, AND ALSO NORTH OF 26N BETWEEN 40W AND 59W. FRESH TO LOCALLY
STRONG NORTH TO NORTHEAST WINDS AND MODERATE SEAS PER LATEST
SATELLITE SCATTEROMETER DATA PASSES ARE NEAR THE CANARY ISLANDS.
THEY EXTEND WESTWARD TO NEAR 30W. ELSEWHERE, GENTLE TO MODERATE
WINDS AND MODERATE SEAS PREVAIL.
FOR THE FORECAST WEST OF 55W, THE PRESSURE GRADIENT BETWEEN HIGH
PRESSURE OVER THE SOUTHEASTERN U.S. AND A STATIONARY FRONT THAT
EXTENDS FROM NEAR BERMUDA TO THE NW BAHAMAS WILL MAINTAIN MODERATE
TO FRESH NE WINDS AND MODERATE SEAS WEST OF THE FRONT THROUGH
THIS EVENING. CONDITIONS WILL IMPROVE EARLY ON FRI AS HIGH
PRESSURE BECOMES THE DOMINANT FEATURE ACROSS THE BASIN INTO THE
WEEKEND. 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 WEST OF
70W THROUGH AT LEAST SUN.
AGUIRRE
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