[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 271110
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1045 UTC.

...THE ITCZ...
ITCZ IS ANALYZED ALONG 7N10W 4N22W 4N36W 1N51W. SCATTERED
MODERATE/STRONG CONVECTION IS WITHIN 90/120 NM N OF THE ITCZ AND
WITHIN 90 NM S OF THE ITCZ FROM 18W-24W. CLUSTERS OF SIMILAR
CONVECTION ARE WITHIN 120 NM ON BOTH SIDES OF THE ITCZ FROM
24W-36W AND WITHIN 120 NM OFF THE COAST OF THE IVORY COAST FROM
5W TO THE BORDER OF LIBERIA. CLUSTERS OF SCATTERED MODERATE/
ISOLATED STRONG CONVECTION ARE WITHIN 90 NM S OF THE ITCZ FROM
15W-18W AND WITHIN 200 NM ON BOTH SIDES OF THE ITCZ FROM
36W-40W.

...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 E OF 90W. PATCHES OF FOG ARE
INLAND AND WITHIN 60/75 NM ALONG THE N GULF COAST FROM PANAMA
CITY FLORIDA TO CORPUS CHRISTI TEXAS. UPPER LAYERED TROUGH IS
MOVING ACROSS THE CENTRAL PLAIN STATES TO OVER N MEXICO WITH THE
NEXT MAJOR FRONT ENTERING THE GULF LATE TODAY/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 LOW
CLOUDS WITH SCATTERED SHOWERS INLAND CENTRAL AMERICA. ISOLATED
FAST MOVING SHOWERS DOT MUCH OF THE CARIBBEAN FROM 11N19N WHILE
THE REMAINDER OF THE AREA 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 EXTENDING S OVER
THE REMAINDER OF THE W ATLC AND CENTRAL ATLC TO 20N AND THE
ACCOMPANYING COLD FRONT ENTERING THE REGION NEAR 32N45W
EXTENDING W TO 29N61W DISSIPATING NEAR 29N68W. BROKEN/OVERCAST
LOW CLOUDS WITH ISOLATED SHOWERS ARE WITHIN 60/75 NM NW OF THE
FRONT. THE HIGH PRESSURE CONTINUES TO DOMINATE THE W AND CENTRAL
ATLC BRIDGING THE ABOVE FRONTAL BOUNDARY. A SECOND COLD FRONT
ENTERS THE FAR E ATLC NEAR 32N15W THROUGH THE CANARY ISLANDS TO
24N20W WITH ANY SHOWER ACTIVITY WELL N OF AREA. THE ASSOCIATED
UPPER TROUGH IS N OF 29N E OF 28W TO INLAND OVER NW AFRICA.
UPPER DIFFLUENCE AND SW UPPER FLOW ARE ACROSS THE TROPICAL ATLC
FROM E OF THE WINDWARD ISLANDS NEAR 11N56W ALONG 22N34W TO OVER
AFRICA S OF THE CANARY ISLANDS NEAR 27N13W WITH DENSE CLOUD
COVER AND ISOLATED SHOWERS WITHIN 500 NM S OF THIS LINE.

$$
WALLACE



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