[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 121149
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST WED JAN 12 2011

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
1115 UTC.

...ITCZ...

THE ITCZ AXIS IS ANALYZED FROM 6N8W 5N15W 4N37W CROSSING THE
EQUATOR NEAR 50W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS WITHIN 120/150 NM ON BOTH SIDES OF THE ITCZ BETWEEN 18W-27W
WITH CLUSTERS OF SIMILAR CONVECTION FROM THE EQUATOR TO 3N
BETWEEN 5W-12W AND WITHIN 90/120 NM N OF THE ITCZ BETWEEN
40W-46W. SMALL CLUSTERS OF SCATTERED MODERATE CONVECTION ARE
FROM 1N-5N BETWEEN 10N-20W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL LOW IS MOVING OVER PENNSYLVANIA EXTENDING AN
UPPER TROUGH OVER THE FAR E CONUS INTO THE W ATLC RESULTING IN W
TO WSW FLOW ALOFT OVER THE GULF. THIS UPPER TROUGH CONTINUES TO
TRAIL A COLD FRONT AT 12/0900 UTC INTO THE W ATLC THROUGH THE
STRAITS OF FLORIDA NEAR 24N80W JUST OFF THE COAST OF CUBA ACROSS
THE YUCATAN PENINSULA NEAR MERIDA TO OVER THE E BAY OF CAMPECHE
INTO S MEXICO E OF THE ISTHMUS OF TEHUANTEPEC. A SURFACE RIDGE
CONTINUES TO BUILD OVER THE CENTRAL PLAIN STATES INTO THE GULF
AND IS RESPONSIBLE FOR A RE-ENFORCING BOUNDARY THAT EXTENDS
ACROSS FLORIDA NEAR MELBOURNE TO JUST S OF FORT MYERS INTO THE
GULF ALONG 25N89W TO 23N93W. THIS BOUNDARY IS MARKED BY FALLING
DEW POINTS AND REMARKABLY CLEAR SKIES TO THE N AND OVERCAST LOW
CLOUDS WITH ISOLATED SHOWERS TO THE S. SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS ARE WITHIN 60 NM EITHER SIDE OF THE FRONT
W OF 85W TO INLAND OVER THE YUCATAN PENINSULA AND INTO THE E BAY
OF CAMPECHE. OVERCAST LOW CLOUDS WITH ISOLATED SHOWERS ARE OVER
THE W GULF W OF LINE FROM MATAGORDA BAY TEXAS TO THE COAST OF
MEXICO NEAR 18N93W. THE FRONT IS EXPECTED TO EXIT THE GULF TODAY
AS STRONG HIGH PRESSURE WILL PRODUCE STRONG N TO NE WINDS
THROUGH THU MORNING BEFORE GRADUALLY WEAKENING THROUGH FRI.

CARIBBEAN SEA...
BROAD UPPER RIDGE COVERS THE CARIBBEAN WITH THE RIDGE AXIS
ANCHORED OVER THE SE CARIBBEAN NEAR 14N65W AND EXTENDS TO OVER
PORTIONS OF THE W AND CENTRAL ATLC. FRESH/STRONG TRADE WINDS
CONTINUE ACROSS THE CENTRAL AND E CARIBBEAN DUE TO THE TIGHT
PRESSURE GRADIENT OF THE LOWER PRESSURE OVER SOUTH AMERICA AND
THE SURFACE RIDGE OVER THE W ATLC INTO THE CENTRAL ATLC. THESE
TRADE WINDS CONTINUE TO BANK LOW CLOUDS ALONG THE MOUNTAINS OF W
PANAMA AND COSTA RICA GENERATING SCATTERED SHOWERS AND POSSIBLE
ISOLATED THUNDERSTORMS INLAND AND WITHIN 60 NM ALONG THE COAST S
OF 11N W OF 81W AND CONVERGING WITH THE UPPER LEVEL WINDS TO
GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 60 NM
OF LINE FROM 18N79W TO 12N83W. THIS IS LEAVING THE REMAINDER OF
THE CARIBBEAN WITH FAIR WEATHER AGAIN THIS MORNING. A COLD FRONT
WILL MOVE INTO THE NW CARIBBEAN LATER THIS MORNING BRINGING
FRESH TO STRONG NE WINDS BEHIND IT.

ATLANTIC OCEAN...
THE UPPER TROUGH OVER THE E CONUS EXTENDS OVER THE W ATLC
SUPPORTING A COLD FRONT THAT ENTERS THE REGION AT 12/0900 UTC
NEAR 32N71W THROUGH THE STRAITS OF FLORIDA AND INTO THE GULF OF
MEXICO NEAR 24N80W. THIS UPPER TROUGH IS BEING ABSORBED INTO THE
BROAD UPPER TROUGH THAT COVERS THE N/CENTRAL ATLC SUPPORTING A
COLD FRONT THAT ENTERS THE CENTRAL ATLC NEAR 32N35W TO 28N42W
WHERE IT BECOMES A STATIONARY FRONT TO 25N50W THEN DISSIPATES TO
24N57W. ISOLATED SHOWERS ARE WITHIN 75 NM E OF THE EASTERN MOST
COLD FRONT. SURFACE HIGH PRESSURE COVERS THE REMAINDER OF THE W
ATLC ANCHORED BY A 1025 MB HIGH NEAR 29N59W. THE BROAD UPPER
RIDGE THAT COVERS THE CARIBBEAN EXTENDS OVER THE W ATLC INTO THE
CENTRAL ATLC TO 28N W OF 40W WITH STRONG SUBSIDENCE AND DRY
STABLE AIR ALOFT COVERING AREA S OF 23N AND THUS LIMITING SHOWER
ACTIVITY. A DEEP LAYERED RIDGE COVERS THE E ATLC WITH THE UPPER
LEVELS ANCHORED NEAR THE MADEIRA ISLANDS AND A SURFACE 1030 MB
HIGH OFF THE COAST OF S PORTUGAL AND THUS PRODUCING FAIR WEATHER
FOR THE ATLC E OF FRONT.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
PAW




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