[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 152331
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 6N1W 4N10W 7N25W 6N35W 8N50W 4N60W
4N80W.  SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS OFF
THE COAST OF W AFRICA FROM 4N-7N BETWEEN 15W-20W.  SCATTERED
MODERATE CONVECTION IS FROM 3N-5N BETWEEN 20W-23W...FROM 10N-13N
BETWEEN 31W-34W...AND FROM 11N-14N BETWEEN 50W-54W.

...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 32N65W TO THE CNTRL BAHAMAS NEAR 23N75W...THEN ACROSS CNTRL
CUBA TO BELIZE AND N GUATEMALA NEAR 17N90W. COLD TEMPERATURES
BEHIND THE FRONT PRODUCED BROKEN TO OVERCAST COLD AIR
STRATOCUMULUS CLOUDS OVER THE W ATLANTIC...NW CARIBBEAN... AND
ENTIRE GULF OF MEXICO.  STRONG COLD AIR ADVECTION CONTINUES FROM
THE NORTH. THE FRONT IS PRECEDED BY A WEAK TROUGH ALONG 30N64W
20N70W 11N75W.  NEITHER FRONT OR TROUGH IS PRODUCING ANY DEEP
CONVECTION.  THE UPPER LEVEL FLOW IS FLATTENING OUT AND BECOMING
UNIFORMLY SWLY OVER THE AREA AS THE UPPER LEVEL TROUGH 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 EASTERN CARIBBEAN WITH THE AXIS
EXTENDING FROM E VENEZUELA NWD PAST PUERTO RICO...BUT VERY
LITTLE MOISTURE IS STREAMING IN ALONG THE SWLY FLOW ORIGINATING
IN THE PACIFIC. THE LACK OF AVAILABLE MOISTURE HAS KEPT THE AREA
MOSTLY DRY EXCEPT THAT NELY SURFACE 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 1032 MB HIGH N OF THE AREA NEAR 38N35W. 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 TROUGH DIPPING DOWN INTO
THE TROPICS FROM 20N40W PAST THE EQUATOR ALONG 38W AND A RIDGE
FARTHER N ALONG 28N43W 32N39W. UPPER DIFFLUENCE WHERE THE FLOW
SPLITS HAS PRODUCED A PATCH OF HIGH CLOUDINESS FROM 12N-27N
BETWEEN 50W-57W. FARTHER E...AN ELONGATED UPPER TROUGH EXTENDS
FROM THE WRN MEDITERRANEAN SEA SWWD PAST THE CANARY ISLANDS AND
IS SUPPORTED BY A 1008 MB LOW ABOUT 150 NM W OF THE COAST OF
WESTERN SAHARA NEAR 23N18W. 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.

$$
FORMOSA





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