[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 151749
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SAT NOV 15 2008

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 32N. THE FOLLOWING INFORMATION IS BASED
ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...THE ITCZ...
THE ITCZ AXIS IS ANALYZED ALONG 6N10W 5N30W 7N40W 9N50W 10N57W.
A SURFACE TROUGH...WHICH EXTENDS FROM 14N57W TO 6N58W...IS
EMBEDDED WITHIN THE ITCZ. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS NEAR THE INTERSECTION OF THE TROUGH WITH THE ITCZ
COVERING THE AREA FROM 6N-11N BETWEEN 56W-62W. A DIFFLUENT
PATTERN ALOFT IS ENHANCING THIS ACTIVITY. ELSEWHERE...SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 4N-10N BETWEEN
21W-33W. SIMILAR CONVECTION IS WITHIN 80 NM SOUTH OF AXIS
BETWEEN 13W-20W.

...DISCUSSION...

GULF OF MEXICO...
A DEEP LAYERED TROUGH OVER THE EAST-CENTRAL CONUS AND THE
NORTHERN GULF WATERS SUPPORTS A STRONG COLD FRONT WHICH IS
MOVING SE ACROSS THE GULF REGION. AS OF 15/1500 UTC...THE
FRONTAL SYSTEM EXTENDS FROM THE FLORIDA BIG BEND ALONG THE
CENTRAL GULF NEAR 25N90W INTO NE MEXICO NEAR 23N98W. A PRE-
FRONTAL TROUGH LIES WITHIN 100-120 NM SE OF FRONT. A WIDE BAND
OF LOW/MID CLOUDS WITH EMBEDDED SHOWERS IS ASSOCIATED WITH THE
FRONT/TROUGH. SHOWERS ARE CONCENTRATED NEAR THE LEADING EDGE OF
THE BAND. STRONG NLY WIND...ALREADY REACHING GALE FORCE PER A
RECENT QSCAT PASS...ARE FOUND BEHIND THE FRONT WHILE SLY WINDS
OF 10 TO 15 KT ARE AHEAD OF THE FRONTAL BOUNDARY. A GALE WARNING
IS ALREADY IN EFFECT WEST OF THE COLD FRONT WHICH IS EXPECTED TO
MOVE RAPIDLY SE AND LIE FROM CEDAR KEY FLORIDA TO THE EASTERN
BAY OF CAMPECHE THIS AFTERNOON AND SE OF THE AREA EARLY TONIGHT.
THE FRONT IS ALSO FORECAST TO MOVE ACROSS SOUTH FLORIDA EARLY
THIS EVENING BRINGING A COOLER AIR MASS WITH TEMPERATURES
DROPPING FROM THE UPPER 80S SATURDAY AFTERNOON TO THE LOWER 70S
SUNDAY AFTERNOON. AS HIGH PRESSURE RAPIDLY BUILDS IN THE WAKE OF
THE FRONT...THE STRONG WINDS SHOULD BEGIN TO SURGE FROM THE NW
TO THE SW PORTION OF THE GULF...INCLUDING THE BAY OF CAMPECHE
THIS AFTERNOON. DENSE FOG DEVELOPED AHEAD OF THE FRONT OVER
SOUTH FLORIDA AND THE YUCATAN PENINSULA THIS MORNING. MERIDA IN
THE STATE OF YUCATAN MEXICO REPORTED VISIBILITIES IN THE FOG
NEAR ZERO EARLY THIS MORNING.

CARIBBEAN SEA...
AN UPPER-LEVEL RIDGE ANCHORED ON A HIGH NEAR THE CAYMAN ISLANDS
IS AFFECTING THE WESTERN CARIBBEAN...WITH THE UPPER RIDGE AXIS
EXTENDING FROM HONDURAS/NICARAGUA THROUGH E-CENTRAL CUBA INTO
THE BAHAMAS. SUBSIDENCE IN THE VICINITY OF THIS UPPER RIDGE IS
BRINGING MOSTLY FAIR WEATHER TO MUCH OF THE W CARIBBEAN AND CUBA
AS WELL AS OVER NORTHERN CENTRAL AMERICA. AN UPPER-LEVEL LOW
LOCATED NEAR 15N70W DOMINATES THE REMAINDER OF THE BASIN. SWLY
FLOW AHEAD OF THIS LOW IS ENHANCING CONVECTION ASSOCIATED WITH
THE TROUGH OVER THE TROPICAL N ATLC ALONG 57W/58W. PART OF THIS
ACTIVITY IS AFFECTING THE WINDWARD ISLANDS. TRINIDAD REPORTED
1.16 INCHES OF RAIN THIS MORNING. THE UPPER LOW IS ALSO HELPING
TO INDUCE SCATTERED SHOWERS AND ISOLATED TSTMS OVER THE EAST AND
CENTRAL CARIBBEAN...INCLUDING PUERTO RICO AND DOMINICAN
REPUBLIC. MODERATE TRADE WINDS ARE BLOWING ACROSS THE AREA. THE
COLD FRONT CURRENTLY MOVING ACROSS THE GULF OF MEXICO WILL REACH
THE YUCATAN CHANNEL AND WESTERN CUBA TONIGHT. INCREASING WINDS
IN THE 20 TO 25 KT RANGE WILL FOLLOW THE PASSAGE OF THE FRONT.

ATLANTIC OCEAN...
AN UPPER-LEVEL RIDGE EXTENDS FROM EAST-CENTRAL CUBA AND THE
BAHAMAS BEYOND THE BERMUDAS. SUBSIDENCE RELATED TO THE UPPER
FEATURE IS INHIBITING DEEP CONVECTION ACROSS MUCH OF THE W ATLC.
FARTHER TO THE E...THE AXIS OF A DEEP LAYERED TROUGH ENTERS THE
FORECAST DISCUSSION NEAR 31N42W THEN CONTINUES SW ENTERING THE
CARIBBEAN SEA THROUGH THE VIRGIN ISLANDS TO THE ABOVE MENTIONED
UPPER-LEVEL LOW. THE ATTENDANT COLD FRONT IS NORTH OF THE AREA
BUT A SFC TROUGH EXTENDS FROM THE TAIL END OF THE FRONT NEAR
31N36W ALONG 27N37W TO 23N40W. SCATTERED MODERATE CONVECTION IS
WITHIN 200 NM E OF THE TROUGH AND N OF 28N. STRONG WESTERLY FLOW
ASSOCIATED WITH A JET STREAM BRANCH WITH CORE WINDS OF 70-90 KT
DOMINATES MUCH OF THE TROPICAL ATLC. THE STRONGEST WINDS ARE
NOTED JUST N OF THE CAPE VERDE ISLANDS. A WIDE BAND OF
TRANSVERSE HIGH CLOUDS IS ASSOCIATED WITH THE JET STREAM AND
GOES FROM 14N55W ALL THE WAY E AND THE SE TO THE WEST AFRICAN
COAST. AT THE SURFACE...A 1026 MB HIGH CENTERED NEAR 34N57W
ENVELOPS THE WEST AND CENTRAL ATLC WITH ANOTHER RIDGE COVERING
THE EAST ATLANTIC OCEAN E OF 30W. BETWEEN RIDGES...THE
AFOREMENTIONED SFC TROUGH LIES. ANOTHER SFC TROUGH IS ALONG
57W/58W ACCOMPANIED BY A WIND SURGE. MOISTURE FROM THIS TROUGH
IS AFFECTING THE WINDWARD ISLANDS.

$$
GR





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