[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 151735
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST WED 15 DEC 2004

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...ITCZ...

ITCZ AXIS IS ALONG 6N10W 3N21W 6N31W 4N41W...THEN VERY DIFFUSE
FARTHER W INTO NORTHERN SOUTH AMERICA. SCATTERED MODERATE
CONVECTION WITHIN 160 NM S OF THE AXIS BETWEEN 12W-18W. ISOLATED
MODERATE ELSEWHERE FROM 2N-10N BETWEEN 15W-29W. WIDELY SCATTERED
MODERATE N OF THE AXIS AHEAD OF AN UPPER LEVEL TROF FROM 9N-14N
BETWEEN 29W-42W.

...DISCUSSION...

GULF OF MEXICO AND FAR WEST ATLANTIC...
A STRONG COLD FRONT WITH COLD CONTINENTAL AIR IS PUSHING ACROSS
THE W ATLC WATERS EXTENDING INTO THE NW CARIBBEAN AND SE MEXICO
FROM 32N67W TO THE CNTRL BAHAMAS...THEN ACROSS CNTRL CUBA TO
BELIZE AND GUATEMALA. LOW TEMPERATURES THIS MORNING BEHIND THE
FRONT DIPPED DOWN INTO THE 20S F ALONG THE U.S. GULF COAST AND
EVEN TO THE MID 40S F OVER S FLORIDA WITH THE CONTINUATION OF
STRONG COLD AIR ADVECTION FROM THE NORTH. THE FRONT IS PRECEDED
BY A WEAK TROF ALONG 21N73W 30N66W BUT NEITHER FEATURE IS
PRODUCING ANY DEEP CONVECTION. HOWEVER...A FAIRLY SOLID LAYER OF
STRATUS AND STRATOCUMULUS BEHIND THE FRONT MAY BE DROPPING A FEW
LIGHT SHOWERS OR DRIZZLE ESPECIALLY FROM THE BAHAMAS TO THE
YUCATAN PENINSULA AND BAY OF CAMPECHE. THE UPPER LEVEL FLOW IS
FLATTENING OUT AND BECOMING UNIFORMLY SWLY OVER THE AREA AS THE
UPPER LEVEL TROF OVER THE EAST COAST OF THE U.S. WEAKENS AND
LIFTS TO THE NE. FOR NOW...THIS PATTERN IS PULLING A FEW PATCHES
OF UPPER LEVEL CLOUDS FROM THE PACIFIC INTO THE SW GULF...WHICH
SHOULD CONTINUE FOR THE NEXT 48 HRS BEFORE THE NEXT TROF DIGS
OVER THE EASTERN U.S. AND THE FLOW COMES FROM THE WEST.

CARIBBEAN...
THE MID-LATITUDE COLD FRONT HAS MOVED INTO THE NW CARIBBEAN FROM
CNTRL CUBA TO BELIZE AND GUATEMALA WITH SOME OF THE POST-FRONTAL
STRATUS FILTERING THROUGH THE YUCATAN CHANNEL. A BROAD UPPER
LEVEL RIDGE SPANS ACROSS THE AREA WITH THE AXIS RANGING FROM W
VENEZUELA NWD PAST HISPANIOLA AND PUERTO RICO...BUT VERY LITTLE
MOISTURE IS STREAMING IN ALONG THE SWLY FLOW ORIGINATING IN THE
PACIFIC. A SFC TROF EXTENDS FROM JUST N OF HISPANIOLA NEAR
22N69W SWWD TO THE COLOMBIAN COAST NEAR 11N75W AND IT EVEN
APPEARS THAT A WEAK LOW MAY BE LOCATED ALONG THE BOUNDARY JUST
ALONG THE COAST OF THE DOMINICAN REPUBLIC NEAR 20N70W. ISOLATED
SHOWERS ARE FORMING ALONG THE BOUNDARY FROM 19N-23N BETWEEN
67W-70W. ELSEWHERE...THE LACK OF AVAILABLE MOISTURE HAS KEPT THE
AREA MOSTLY DRY EXCEPT THAT NELY FLOW IS PRODUCING SOME SHOWERS
OVER THE MOUNTAINS OF COSTA RICA...NICARAGUA...AND HONDURAS.

ATLANTIC EAST OF 65W...
EXPANSIVE SFC HIGH PRES COVERS A GOOD CHUNK OF THE E/CNTRL ATLC
ANCHORED BY A 1033 MB HIGH N OF THE AREA NEAR 37N40W. THE HIGH
IS PRODUCING A TIGHT GRADIENT OVER THE SUBTROPICS WITH EASTERLY
WINDS OF 20-30 KT SPREADING WEST FROM AFRICA. UPPER LEVEL SPLIT
FLOW IS IN CONTROL OVER THE AREA WITH A TROF DIPPING DOWN INTO
THE TROPICS FROM 20N44W PAST THE EQUATOR ALONG 38W AND A RIDGE
FARTHER N ALONG 25N42W 32N39W. UPPER DIFFLUENCE WHERE THE FLOW
SPLITS HAS PRODUCED A PATCH OF HIGH CLOUDINESS FROM 12N-27N
BETWEEN 50W-57W AND A FEW CLOUDS EMBEDDED WITHIN THE LOWER LEVEL
EASTERLY FLOW. THE TROF LOCATED OVER THE TROPICS IS ALSO
PRODUCING AN AREA OF INCREASED CLOUDINESS AND SCATTERED MODERATE
CONVECTION FROM 20N-15N BETWEEN 31W-40W...PARTIALLY FORCED BY
LOW-LEVEL SPEED CONVERGENCE ALONG THE SRN BOUNDARY OF THE STRONG
EASTERLIES. FARTHER E...AN ELONGATED UPPER TROF EXTENDS FROM THE
WRN MEDITERRANEAN SEA SWWD PAST THE CANARY ISLANDS AND HAS
SUPPORTED A 1008 MB LOW ABOUT 180 NM W OF THE COAST OF WESTERN
SAHARA NEAR 24N18W. THE LOW IS BEING SHEARED BY A 70-90 KT UPPER
LEVEL WESTERLY JET THAT RUNS INTO W AFRICA AND SCATTERED
WEAK/MODERATE CONVECTION IS FORCED EAST OF THE CENTER FROM
24N-28N BETWEEN 15W-17W.

$$
BERG




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