[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 071754
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST WED JAN 07 2009

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...THE ITCZ...

ITCZ IS CENTERED ALONG 7N8W 2N18W 3N34W ALONG THE EQUATOR W OF
48W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 90
NM ALONG THE COAST OF LIBERIA OF W AFRICA BETWEEN 9W-11W.
CLUSTERS OF SCATTERED MODERATE ARE FROM THE ITCZ TO S OF THE
EQUATOR BETWEEN 18W-25W.

...DISCUSSION...

GULF OF MEXICO...
AT OF 1500 UTC...THE COLD FRONT HAS MOVED OFF THE E COAST OF THE
US CROSSING FLORIDA BETWEEN JACKSONVILLE AND ST. AUGUSTINE INTO
THE GULF NEAR S TAMPA BAY EXTENDING SW TO 21N94W THEN S INTO
MEXICO NEAR VERACRUZ. THE N PORTION OF THE FRONT IS MOVING SE
NEAR 25 KT. MOSAIC DOPPLER RADAR SHOWS A BAND OF SHOWERS AND
ISOLATED THUNDERSTORMS ALONG THE FRONT WITH SCATTERED SHOWERS
WITHIN 90/120 NM W OF THE FRONT E OF 85W AND WITHIN 75 NM W OF
THE FRONT ELSEWHERE. ISOLATED LOW LEVEL FAST MOVING SHOWERS ARE
SE OF THE FRONT. THE ASSOCIATED UPPER LEVEL TROUGH IS OVER THE E
US WITH THE UPPER LOW OVER THE UPPER MISSISSIPPI VALLEY. A JET
STREAM WITH WINDS OF 90-150 KT COVERS MUCH OF THE GULF NW OF THE
FRONT. A SURFACE RIDGE IS BUILDING BEHIND THE FRONT OVER TEXAS
AND MEXICO FORCING DRY AIR OVER THE NW GULF AND THUS CLEAR SKIES
PREVAIL FROM PANAMA CITY FLORIDA TO TAMPICO MEXICO. AN UPPER
LEVEL RIDGE COVERING THE W CARIBBEAN EXTENDS OVER THE SE GULF
AND INTO THE SW ATLC. THIS FRONT IS EXPECTED TO EXIT THE GULF
LATE TONIGHT/THU MORNING.

CARIBBEAN SEA...
A MID/UPPER LEVEL RIDGE DOMINATES THE W CARIBBEAN EXTENDING N
FROM AN UPPER LEVEL HIGH NEAR 11N76W ACROSS CUBA COVERING
PORTIONS OF THE GULF OF MEXICO AND THE SW ATLC. AN UPPER LEVEL
TROUGH FROM THE CENTRAL ATLANTIC COVERS THE REMAINDER OF THE E
CARIBBEAN NEAR E OF 67W ACROSS THE LESSER ANTILLES INTO THE
TROPICAL ATLC. A LARGE MASS OF DRY AIR COVERS THE ENTIRE
CARIBBEAN BUT DUE TO LOW LEVEL INSTABILITY PATCHES OF LOW CLOUDS
WITH EMBEDDED ISOLATED FAST MOVING SHOWERS DOT THE ENTIRE
CARIBBEAN. MODERATE TO STRONG TRADE WINDS ARE ACROSS THE BASIN
WITH LOW/MID CLOUDS BANKING ALONG THE MOUNTAINS OF W PARANA AND
COSTA RICA AND OVER THE CARIBBEAN WATERS S OF 12N W OF 81W. THE
COLD FRONT IN THE GULF OF MEXICO IS EXPECTED TO ENTER THE
CARIBBEAN LATE TONIGHT/THUS MORNING THEN DISSIPATING THROUGH
FRI.

ATLANTIC OCEAN...
AT OF 1500 UTC...THE COLD FRONT HAS MOVED OFF THE E COAST OF THE
US ENTERING THE REGION NEAR 32N80W CROSSING FLORIDA BETWEEN
JACKSONVILLE AND ST. AUGUSTINE INTO THE GULF OF MEXICO WITH GALE
FORCE SW WINDS WITHIN 180 NM E OF FRONT AND N OF 29N. AN
UPPER RIDGE ANCHORED IN THE CARIBBEAN EXTENDS ACROSS CUBA INTO
THE W ATLC BEYOND 32N76W. THE REMAINDER OF THE ATLC IS DOMINATED
BY AN UPPER LEVELS TROUGH/RIDGE/TROUGH PATTERN. HOWEVER...THE
SURFACE IS DOMINATED BY A RIDGE THAT COVERS THE AREA W OF 75W
ANCHORED BY 1026 MB HIGH NEAR 32N36W. THE UPPER RIDGE IS
PRODUCING A TROPICAL JET STREAM WITH WINDS OF 90-120 KT WITHIN
200/250 NM OF LINE FROM 15N46W 20N30W TO INLAND OVER AFRICA NEAR
20N16W. THE COLD FRONT IS EXPECTED TO MOVE ACROSS THE W ATLC AND
WEAKEN IN THE CENTRAL ATLC BY SAT.

$$
WALLACE





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