[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 270516
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0445 UTC.

...THE ITCZ...
ITCZ IS ANALYZED ALONG 8N12W 4N24W 3N45W 1N51W. CLUSTERS OF
SCATTERED MODERATE/STRONG CONVECTION ARE WITHIN 150 NM S OF THE
ITCZ FROM 13W-26W AND WITHIN 225 NM N OF THE ITCZ FROM 26W-40W.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE
WITHIN 90/120 NM N OF THE ITCZ FROM 16W-20W AND WITHIN 120/150
NM S OF THE ITCZ FROM 27W-39W.

...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 E US WITH
MODERATE/STRONG SUBSIDENCE AND DRY STABLE AIR NOTED ACROSS THE
ENTIRE BASIN. SURFACE RIDGE ANCHORED IN THE W ATLC COVERS THE
GULF GIVING THE ENTIRE GULF RETURN FLOW WITH ISOLATED PATCHES OF
LOW CLOUDS AND ISOLATED SHOWERS. PATCHES OF FOG ARE INLAND AND
WITHIN 60/75 NM ALONG THE N GULF COAST FROM MISSISSIPPI/ALABAMA
BORDER TO CORPUS CHRISTI TEXAS. NEXT MAJOR FRONT TO ENTER THE
GULF IS EXPECTED LATE SAT/EARLY SUN.

CARIBBEAN SEA...
BROAD UPPER RIDGE DOMINATES THE CARIBBEAN ANCHORED OVER SOUTH
AMERICA AND A RIDGE AXIS EXTENDING NW ACROSS W CUBA AND THE E
GULF OF MEXICO INCLUDING PORTIONS OF THE W ATLC COVERING THE
CARIBBEAN WITH STRONG SUBSIDENCE AND DRY AIR. SURFACE RIDGE
REMAINS OVER THE ATLC AND WITH THE LOWER PRESSURE OVER SOUTH
AMERICA IS PRODUCING MODERATE/STRONG ELY TRADE WINDS. THESE
TRADE WINDS COUPLED WITH LOW LEVEL CONVERGENCE IS BANKING CLOUDS
WITH SCATTERED SHOWERS AND OVER CENTRAL AMERICA. ISOLATED FAST
MOVING SHOWERS DOT MUCH OF THE CARIBBEAN WITH THE EXCEPTION OF
THE FAR NW WHERE MOSTLY CLEAR SKIES PREVAIL. THE MODERATE/STRONG
TRADE WINDS WILL CONTINUE THROUGH THE MON THEN DIMINISHING AS
THE HIGH PRESSURE OVER THE ATLC WEAKENS.

ATLANTIC OCEAN...
THE UPPER RIDGE THAT DOMINATES THE CARIBBEAN EXTENDS OVER THE
FAR W ATLC TO 70W WITH A DEEP LAYERED TROUGH DIPPING S OVER THE
REMAINDER OF THE W ATLC AND CENTRAL ATLC TO 20N AND THE
ACCOMPANYING COLD FRONT ENTERING THE REGION NEAR 32N50W
EXTENDING W ALONG 30N60W TO 30N72W. BROKEN/OVERCAST LOW CLOUDS
WITH ISOLATED SHOWERS ARE WITHIN 60 NM NW OF THE FRONT. THE HIGH
PRESSURE CONTINUES TO DOMINATE MOST OF THE W AND CENTRAL ATLC
BRIDGING THE ABOVE FRONTAL BOUNDARY. A SECOND COLD FRONT ENTERS
THE E ATLC NEAR 32N17W JUST TO THE W CANARY ISLANDS TO 23N23W
WITH ANY SHOWER ACTIVITY N OF AREA. THE ASSOCIATED UPPER TROUGH
IS IS N OF 29N E OF 35W TO THE NW COAST OF AFRICA. UPPER
DIFFLUENCE AND SW UPPER FLOW ARE ACROSS THE TROPICAL ATLC FROM E
OF THE WINDWARD ISLANDS NEAR 11N55W ALONG 23N33W TO OVER AFRICA
S OF THE CANARY ISLANDS NEAR 27N13W WITH DENSE CLOUD COVER WITH
ISOLATED SHOWERS WITHIN 500 NM S OF THIS LINE.

$$
WALLACE



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