[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 201738
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST MON 20 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 IS CENTERED ALONG 8N10W 5N18W 5N26W 2N46W. WIDELY SCATTERED
MODERATE CONVECTION FROM EQ-7N BETWEEN 11W-20W.

...DISCUSSION...

GULF OF MEXICO AND WEST ATLANTIC...
A STRONG COLD FRONT...THE ONE RESPONSIBLE FOR THE FRIGID
TEMPERATURES OVER THE EASTERN HALF OF THE UNITED STATES...IS
SWEEPING ACROSS THE W ATLC...FLORIDA...AND THE GULF OF MEXICO.
EARLY MORNING LOW TEMPERATURES DROPPED TO THE FREEZING POINT AS
FAR S AS GAINESVILLE FLORIDA AND INTO THE 50S F OVER S FLORIDA.
THE FRONT NOW EXTENDS FROM 32N69W TO ANDROS ISLAND...THEN ACROSS
W CUBA PAST CANCUN MEXICO INTO THE BAY OF CAMPECHE. A MOSTLY
BROKEN LAYER OF STRATOCUMULUS STRETCHES BEHIND THE FRONT TO THE
SOUTHEAST U.S. COAST OVER THE W ATLC WATERS...AND FROM THE
YUCATAN CHANNEL NWD TO THE CNTRL GULF. IN ADDITION...A RIDGE OF
HIGH PRES HAS BUILT IN OVER THE GULF ALONG A LINE FROM E
ALABAMA/W GEORGIA TO A 1028 MB HIGH OVER E MEXICO. THE COLD
FRONT IS BEING SUPPORTED BY A SHARP UPPER LEVEL TROF WHICH HAS
MOVED OFF THE U.S. EAST COAST AND EXTENDS DOWN TO THE N BAHAMAS.
FARTHER E...A STATIONARY FRONT REMAINS OVER THE W ATLC WATERS
FROM 31N63W TO HAITI BUT SHOULD BEGIN TO MOVE E LATER TODAY AS
THE OTHER COLD FRONT CATCHES UP. A STRONG DIFFLUENT 150 KT JET
EXTENDS FROM S FLORIDA NEWD OVER THE W ATLC AND IS SUPPORTING
SCATTERED MODERATE CONVECTION GENERALLY 150 NM SE OF THE
STATIONARY FRONT N OF 25N.

CARIBBEAN...
A STRONG UPPER LEVEL HIGH IS CENTERED OVER N/CNTRL VENEZUELA
NEAR 9N67W WITH A RIDGE EXTENDING NEWD PAST THE NRN LEEWARD
ISLANDS INTO THE CNTRL ATLC. BROAD SW/W FLOW EXTENDS ACROSS THE
ENTIRE AREA WITH ONLY PATCHES OF MOISTURE COMING FROM CONVECTION
LOCATED S OF PANAMA. DESPITE THE MOSTLY DRY ATMOSPHERE...A SFC
TROF MOVING W TOWARDS THE ABC ISLANDS ALONG 9N67W 16N66W IS
PRODUCING SCATTERED MODERATE CONVECTION IN A SMALL AREA FROM
12N-15N BETWEEN 64W-68W. IN ADDITION...THE STATIONARY FRONT FROM
THE W ATLC EXTENDS SWD ACROSS THE WINDWARD PASSAGE ACROSS
JAMAICA TO THE COAST OF COSTA RICA WITH WIDELY SCATTERED
SHOWERS/TSTMS WITHIN 75 NM OF THE BOUNDARY.

CENTRAL AND EASTERN ATLANTIC...
MODERATE EASTERLY TRADES EXTEND ACROSS THE ENTIRE LENGTH OF THE
ATLC BASIN BETWEEN AFRICA AND 60W DUE TO AN EXPANSIVE AREA OF
HIGH PRES CENTERED N OF THE AZORES. THE FLOW IS OVERLAID BY A
DEEP MID/UPPER LEVEL TROF WHICH EXTENDS ALONG AN AXIS FROM
30N33W 20N44W 5N50W AND AN ELONGATED CYCLONIC CIRCULATION
CENTERED NEAR 25N40W. STRONG SUBSIDENCE IS OCCURRING ON THE BACK
SIDE OF THE TROF AS THE FLOW PLUNGES SWD TO THE E OF THE LESSER
ANTILLES...KEEPING THE ITCZ RATHER WEAK AND ILL-DEFINED W OF
45W. ON THE OTHER HAND...THE FLOW BECOMES SWLY AND DIVERGENT TO
THE E OF THE TROF WHICH IS SUPPORTING SCATTERED MODERATE
CONVECTION FROM 8N-14N BETWEEN 30W-44W. A BROAD SFC TROF IS
LOCATED WITHIN THIS GENERAL VICINITY ALONG 8N37W 17N38W AND
APPEARS TO BE MOVING SLOWLY TO THE W. WIDELY SCATTERED
SHOWERS/TSTMS ASSOCIATED WITH INSTABILITY IN THE UPPER TROF HAS
ALSO FORMED FROM 18N-25N BETWEEN 34W-43W. ELSEWHERE...AN UPPER
LEVEL HIGH IS CENTERED CLOSE TO THE EQUATOR OFF THE AFRICAN
COAST AND IS PUMPING LOTS OF UPPER LEVEL MOISTURE FROM THE CNTRL
ATLC CONVECTION NEWD INTO W AFRICA.

$$
BERG


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