[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 272346
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SAT DEC 27 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...THE ITCZ...
ITCZ IS ANALYZED ALONG 7N9W 1N30W CROSSING THE EQUATOR NEAR 37W
AND INTO NE BRAZIL NEAR 1S50W. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS FROM 2N-5N BETWEEN 10W-17W. CLUSTERS OF
SCATTERED MODERATE CONVECTION ARE FROM 2N-7N BETWEEN 21W-33W.

...DISCUSSION...

GULF OF MEXICO...
THE GULF IS DOMINATED BY AN UPPER RIDGE THAT EXTENDS FROM THE
CARIBBEAN ACROSS W CUBA AND THE E GULF TO OVER THE ERN U.S.
SEABOARD WITH MODERATE/STRONG SUBSIDENCE AND DRY STABLE AIR
NOTED E OF A LINE FROM LAFAYETTE LOUISIANA TO TAMPICO MEXICO. AN
UPPER LEVEL TROUGH IS MOVING ACROSS THE CENTRAL U.S. PLAIN
STATES TO OVER NW MEXICO AND SUPPORTS AN APPROACHING COLD FRONT
POSITIONED ALONG THE TEXAS COAST. SOUTHERLY RETURN FLOW IS
OBSERVED ACROSS THE ENTIRE GULF WITH PATCHES OF SCATTERED LOW
CLOUDS STREAMING NWD.

CARIBBEAN SEA...
A BROAD UPPER RIDGE DOMINATES THE CARIBBEAN W OF 65W AND IS
ANCHORED OVER SOUTH AMERICA WITH AXIS EXTENDING NW ACROSS W CUBA
AND ACROSS THE FLORIDA PENINSULA. THE BASE OF AN UPPER LEVEL
TROUGH IS E OF 65W AND EXTENDS NE INTO THE CENTRAL ATLC. STRONG
SUBSIDENCE AND DRY AIR IS NOTED ACROSS THE ENTIRE BASIN. A
SURFACE RIDGE REMAINS OVER THE W ATLC AND WITH LOWER PRESSURE
OVER SOUTH AMERICA THE PRESSURE GRADIENT ACROSS THE CARIBBEAN
IS PRODUCING MODERATE/STRONG ELY TRADE WINDS. THESE TRADE WINDS
COUPLED WITH LOW LEVEL CONVERGENCE ARE GENERATING FAST MOVING
ISOLATED SHOWERS THAT DOT MUCH OF THE CARIBBEAN. MOST NOTABLE
AREA IS N OF 15N AND E OF 71W. THE MODERATE/STRONG TRADE WINDS
WILL CONTINUE THROUGH MON THEN DIMINISH GRADUALLY AS HIGH
PRESSURE OVER THE ATLC WEAKENS.

ATLANTIC OCEAN...
THE UPPER RIDGE THAT DOMINATES THE CARIBBEAN EXTENDS OVER THE W
ATLC W OF 65W WITH A DEEP LAYERED TROUGH EXTENDING OVER THE
CENTRAL ATLC WITH AXIS ALONG 32N45W SW TO THE NRN LEEWARD
ISLANDS. THE ACCOMPANYING COLD FRONT ENTERS THE REGION NEAR
32N34W EXTENDING W-SW TO 27N50W TO 26N65W WEAKENING TO A SURFACE
TROUGH EXTENDING W TO NEAR 27N75W. BROKEN/OVERCAST LOW CLOUDS
WITH ISOLATED SHOWERS ARE WITHIN 60/75 NM OF THE FRONT. HIGH
PRESSURE CONTINUES TO IMPACT THE W AND CENTRAL ATLC BRIDGING THE
ABOVE FRONTAL BOUNDARY. A SECOND COLD FRONT ENTERS THE FAR NE
ATLC NEAR 32N13W THROUGH THE CANARY ISLANDS TO 26N17W WITH ANY
SHOWER ACTIVITY WELL N OF THE AREA. THE ASSOCIATED UPPER TROUGH
IS N OF 31N AND E OF 8W. UPPER DIFFLUENCE AND SW UPPER FLOW ARE
ACROSS THE TROPICAL ATLC E OF 55W TO OVER NW AFRICA. MULTI-
LAYERED CLOUDINESS WITH ISOLATED SHOWERS COVER MUCH OF THE
TROPICAL ATLC S OF A LINE FROM WRN SAHARA SW TO NEAR BARBADOS.

$$
HUFFMAN



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