[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 290607
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST MON DEC 29 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
0545 UTC.

...THE ITCZ...

ITCZ IS CENTERED ALONG 07N12W 05N23W 08N43W 04N51W. SCATTERED
MODERATE CONVECTION WITHIN 60 NM S OF AXIS BETWEEN 26W AND 32W.

...DISCUSSION...

GULF OF MEXICO...
A WEAK STATIONARY FRONT EXTENDS FROM THE WESTERN FLORIDA
PANHANDLE TO ROUGHLY VERACRUZ MEXICO THIS MORNING. UPPER SUPPORT
FOR THE FRONT HAS BEEN WEAKENING AS A VERY BROAD MID TO UPPER
LEVEL TROUGH DIGS THROUGH THE CENTRAL PLAINS INTO THE MID
MISSISSIPPI VALLEY. SATELLITE IMAGERY AND LIGHTNING DATA SHOW A
WEAK ENHANCED V SIGNATURE ALONG THE FRONT NEAR 25N94W. OTHERWISE
NO SIGNIFICANT WEATHER IS ASSOCIATED WITH THE FRONT. WINDS N OF
THE FRONT ARE GENERALLY 10 TO 15 KT...AND 10 OR LESS ELSEWHERE
WITH THE EXCEPT OF 15 KT EAST FLOW THROUGH THE STRAITS OF
FLORIDA. LOOKING AHEAD...THE FRONT WEAKENS FURTHER THEN
DISSIPATES ON TUE AS THE MID/UPPER TROUGH WILL SHIFT EAST
THROUGH TUE...ALLOWING GENERALLY ZONAL FLOW ALOFT. A LOW
AMPLITUDE RIDGE BUILDS OVER THE WESTERN U.S. IN THE WAKE OF THE
TROUGH. THIS WILL PUSH A SECOND FRONT INTO THE NORTHERN GULF
WATERS BY EARLY WED...BEFORE STALLING OVER THE CENTRAL GULF BY
THU.

CARIBBEAN SEA...
MAIN ISSUE IS PERSISTENT STRONG TRADE WIND FLOW SOUTH OF HIGH
PRES NE OF THE BAHAMAS. AN ASCAT PASS FROM 0300Z SHOWED WINDS TO
25 KT OFF THE COLOMBIAN COAST. GENERALLY 15 TO 20 KT FLOW
CONTINUES ACROSS ALL BUT THE FAR NW CARIBBEAN WATERS. THESE
WINDS ARE EXPECTED TO DIMINISH THROUGH THROUGH MIDWEEK AS THE
HIGH PRES WEAKENS AND SHIFTS EAST AHEAD OF A TROUGH DIGGING OFF
THE EAST COAST. DEEP LAYER MOISTURE IS LACKING ACROSS THE
BASIN...NO SIGNIFICANT WEATHER IS NOTED.

ATLANTIC OCEAN...
THE MID/UPPER LEVEL PATTERN HERE IS VERY PROGRESSIVE WITH LARGE
AMPLITUDE FEATURES TRANSLATING EWD AS THEY PUSH OFF THE SE
CONUS. THE FIRST FEATURE IS A CONTINUATION OF THE ERN CARIBBEAN
MID/UPPER LEVEL TROUGH WHICH EXTENDS NE THROUGH 20N50W TO BEYOND
32N38W. A CONFLUENT FLOW PATTERN INTO THE BACK SIDE OF THE
TROUGH IS RESULTING IN STABLE ATMOSPHERIC CONDITIONS OVER THE
WRN PORTION OF THE ATLC. THE SURFACE COLD FRONT ASSOCIATED WITH
THE MID/UPPER LEVEL TROUGH ENTERS THE REGION AT 32N22W AND
EXTENDS ALONG 27N30W SW TO 23N45W WHERE IT BECOMES A DIFFUSE
SURFACE TROUGH TO 23N59W. THE FRONT IS CHARACTERIZED BY MAINLY
BROKEN/OVERCAST LOW AND MID CLOUDS WITH ISOLATED SHOWERS ALONG
THE FRONT. TO THE SE OF THE FRONTAL BOUNDARY OVER THE FAR E
ATLC...VERY STRONG SW UPPER LEVEL FLOW RESIDES E OF THE UPPER
TROUGH AXIS AND EXTENSIVE BROKEN TO OVERCAST CLOUDINESS IS
ACROSS THE ERN TROPICAL ATLC SE OF A LINE FROM TRINIDAD TO
WESTERN SAHARA OVER WRN AFRICA. SCATTERED SHOWERS AND TSTMS ARE
IN AN AREA OF UPPER DIFFLUENCE FROM 6N-15N BETWEEN 34W-46W.

$$
CHRISTENSEN





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