Tropical Weather Discussion
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000
AXNT20 KNHC 241117
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST WED DEC 24 2014

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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1045 UTC.

...SPECIAL FEATURES...

A STRONG COLD FRONT IS MOVING ACROSS THE GULF WATERS FOLLOWED BY
GALE FORCE WINDS. AS OF 0900 UTC...THE FRONT EXTENDS FROM MOBILE
ALABAMA TO VERACRUZ MEXICO. A RECENT ASCAT PASS SHOWED NORTHERLY
WINDS OF 30-35 KT W OF THE FRONT ALONG THE COAST OF MEXICO FROM
MATAMOROS TO TAMPICO...WITH FRESH TO NEAR GALE FORCE WINDS
ELSEWHERE W OF THE FRONT. SCATTEROMETER DATA ALSO PROVIDED
OBSERVATIONS OF FRESH TO STRONG SOUTHERLY WINDS AHEAD OF THE
FRONT DUE TO THE TIGHT PRES GRADIENT BETWEEN THE ATLANTIC RIDGE
AND LOWER PRES ACROSS THE EAST AND CENTRAL GULF. THE FRONT WILL
CONTINUE EAST AND REACH FROM THE WESTERN FLORIDA PANHANDLE TO
THE CENTRAL BAY OF CAMPECHE THIS MORNING...FROM NEAR TAMPA BAY
TO THE YUCATAN CHANNEL THIS EVENING...THEN SHIFT SE OF THE GULF
BY THU MORNING WHEN IT IS EXPECTED TO MOVE ACROSS SOUTH FLORIDA.
GALE FORCE NORTHERLY WINDS BEHIND THE FRONT IN THE WESTERN GULF
WILL DIMINISH BY THIS EVENING. HIGH PRES WILL BUILD IN THE WAKE
OF THE FRONT.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH CROSSES THE COAST OF AFRICA NEAR 09N13W AND
CONTINUES OVER THE E ATLC WATERS TO NEAR 06N20W. THE ITCZ BEGINS
NEAR 06N20W AND CONTINUES ALONG 04N30W TO 05N40W TO THE COAST OF
SOUTH AMERICA AT 04N51W. ISOLATED MODERATE CONVECTION IS WITHIN
60 NM N OF THE ITCZ AXIS BETWEEN 21W AND 24W.

...DISCUSSION...

GULF OF MEXICO...

A STRONG COLD FRONT IS MOVING ACROSS THE GULF REGION PRODUCING
GALE FORCE WINDS  AND ROUGH SEAS. SEE SPECIAL FEATURES FOR
DETAILS. MOSAIC DOPPLER RADAR FROM THE SE U.S. SHOWS BANDS OF
SHOWERS AND STRONG TSTMS AHEAD OF THE FRONT AFFECTING THE
FLORIDA PANHANDLE AND NORTHERN FLORIDA. SEVERE WEATHER
CONDITIONS AS DAMAGING WINDS AND FLASH FLOODING ARE POSSIBLE IN
ASSOCIATION WITH THIS BANDS OF STRONG TSTMS OVER THE FLORIDA
PANHANDLE...NORTHERN FLORIDA AND SOUTHERN GEORGIA. IN THE UPPER
LEVELS...WATER VAPOR IMAGERY SHOWED PLENTY OF MOISTURE STREAMING
NORTHEAST ACROSS THE GULF REGION FROM SE MEXICO TO THE SE CONUS.
THIS MID TO UPPER LEVEL MOISTURE IS ASSOCIATED WITH A
SOUTHWESTERLY FLOW AHEAD OF A LONG-WAVE TROUGH THAT CROSSES
CENTRAL TEXAS AND NORTHERN MEXICO. THIS TROUGH SUPPORTS THE COLD
FRONT THAT IS CURRENTLY MOVING ACROSS THE GULF. BY FRI...EXPECT
INCREASING SOUTHERLY WINDS ACROSS THE WESTERN GULF AHEAD OF THE
NEXT COLD FRONT FORECAST TO ENTER THE NW GULF BY SAT NIGHT.

CARIBBEAN SEA...

FRESH TO STRONG TRADEWINDS PREVAIL ACROSS THE EAST AND CENTRAL
CARIBBEAN WITH THE STRONGEST WINDS OF 25-30 KT NEAR THE COAST OF
COLOMBIA...AND IN THE GULF OF VENEZUELA. SCATTEROMETER PASSES
CONFIRMED THE PRESENCE OF THESE WINDS. FRESH TO STRONG SE WINDS
ARE BLOWING ACROSS THE NW CARIBBEAN...INCLUDING THE YUCATAN
CHANNEL. SHALLOW MOISTURE EMBEDDED IN THE TRADE WIND FLOW
CONTINUES TO MOVE ACROSS THE REGION PRODUCING ISOLATED TO
SCATTERED PASSING SHOWERS. PATCHES OF LOW LEVEL MOISTURE ARE
CURRENTLY MOVING ACROSS THE LESSER ANTILLES FROM THE ATLANTIC...
MORE CONCENTRATED ACROSS THE LEEWARD ISLANDS AND THE NE
CARIBBEAN. PASSING SHOWERS ARE ALSO NOTED ACROSS EASTERN PUERTO
RICO. FRESH TO STRONG TRADE WINDS WILL PREVAIL OVER THE CENTRAL
CARIBBEAN THROUGH SUN NIGHT...AND WILL OCCASIONALLY INCREASE TO
NEAR GALE FORCE NEAR THE COAST OF COLOMBIA...MAINLY BETWEEN 0600-
1200 UTC. A COLD FRONT WILL MOVE ACROSS THE YUCATAN CHANNEL INTO
THE FAR NW CARIBBEAN THIS EVENING AND TONIGHT. THE FRONT IS
FORECAST TO STALL AND GRADUALLY DISSIPATE FROM WESTERN CUBA TO
CENTRAL HONDURAS THROUGH FRI MORNING. FRESH NORTHERLY WINDS ARE
EXPECTED IN THE WAKE OF THE FRONT. IN THE UPPER LEVELS...A RIDGE
WITH AXIS ACROSS HISPANIOLA COVERS MOST OF THE BASIN PRODUCING
STRONG SUBSIDENCE ACROSS THE CARIBBEAN SEA...MOST OF CENTRAL
AMERICA AND NORTHERN COLOMBIA AND VENEZUELA. MID TO UPPER LEVEL
MOISTURE IS ON INCREASE ACROSS GUATEMALA AND THE YUCATAN
PENINSULA AND OVER THE FAR NW CARIBBEAN AND WESTERN CUBA WHERE A
SWLY FLOW ALOFT PREVAILS.

HISPANIOLA...

A VERY STABLE ENVIRONMENT ALOFT CONTINUES TO SUPPORT MOSTLY FAIR
WEATHER ACROSS THE ISLAND. SIMILAR CONDITIONS ARE EXPECTED OVER
THE NEXT 24 HOURS WITH LOW-TOPPED TRADE WIND SHOWERS MOVING
MAINLY ACROSS THE CARIBBEAN WATERS.

ATLANTIC OCEAN...

A 1021 MB SURFACE HIGH PRESSURE LOCATED NEAR 28N64W EXTENDS A
RIDGE ACROSS THE CENTRAL AND WESTERN ATLC...MAINLY N OF 20N W OF
50W. THE PRESSURE GRADIENT WILL INCREASE BETWEEN THE HIGH PRES
AND LOWER PRESSURE OVER THE GULF OF MEXICO. AS A RESULT...EXPECT
INCREASING SOUTHERLY WINDS E OF NORTHERN FLORIDA AS A COLD FRONT
APPROACHES FROM THE W. CURRENTLY...MODERATE TO LOCALLY FRESH
EASTERLY WINDS ARE NOTED ACROSS THE SOUTHERN PERIPHERY OF THE
RIDGE...WITH MAINLY FRESH WINDS BETWEEN HISPANIOLA AND THE TURKS
AND CAICOS ISLANDS. PATCHES OF LOW LEVEL MOISTURE ARE ALSO NOTED
UNDER THE INFLUENCE OF THE RIDGE. FARTHER EAST...A COLD FRONT IS
ANALYZED AND EXTENDS FROM 31N31W TO 26N35W TO 25N41W. THIS FRONT
IS GENERATING SCATTERED MODERATE CONVECTION MAINLY N OF 25N
BETWEEN 30W AND 36W. PRES GRADIENT BETWEEN THE FRONT AND THE
RIDGE TO THE WEST IS RESULTING IN AN AREA OF FRESH NORTHERLY
WINDS OVER THE CENTRAL ATLANTIC...ESPECIALLY N OF 29N BETWEEN
44W AND 50W. A RIDGE DOMINATES THE REMAINDER OF ATLANTIC
FORECAST AREA. THE CURRENT MID TO UPPER-LEVEL MOISTURE STREAMING
NE ACROSS THE GULF OF MEXICO AND FLORIDA REACHES THE SW N
ATLC...AND IS RIDING ON THE NORTHERN PERIPHERY OF THE RIDGE THAT
DOMINATES THE CARIBBEAN SEA AND THE BAHAMAS. ALOFT...A RIDGE/
TROUGH/RIDGE PATTERN IS NOTED ACROSS THE ATLANTIC FORECAST
REGION. LOOKING AHEAD...THE STRONG COLD FRONT THAT IS MOVING
ACROSS THE GULF OF MEXICO WILL ENTER THE SW N ATLC TONIGHT. THE
FRONT WILL WEAKEN AS IT QUICKLY REACHES FROM 31N70W TO CENTRAL
CUBA BY LATE THU. FRESH TO LOCALLY STRONG NW WINDS AND BUILDING
SEAS ARE EXPECTED BEHIND THE FRONT WED NIGHT AND THU. HIGH
PRESSURE WILL BUILD IN THE WAKE OF THE FRONT.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
GR


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