[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 120530
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST MON JAN 12 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0445 UTC.

...THE ITCZ...

ITCZ IS CENTERED ALONG 6N10W 3N21W 2N31W 1N42W AND INTO NE
BRAZIL NEAR 1S48W. SCATTERED MODERATE CONVECTION IS S OF 5N
BETWEEN 20W-34W. SCATTERED MODERATE CONVECTION IS ALSO S OF 6N
BETWEEN 36W-41W.

...DISCUSSION...

GULF OF MEXICO...
SOUTHWESTERLY FLOW ALOFT CONTINUES TO INCREASE ACROSS THE GULF
REGION AS A DEEP TROUGH OVER THE E CONUS MOVES EASTWARD. A
SURFACE COLD FRONT ASSOCIATED WITH THIS DEEP TROUGH EXTENDS FROM
THE N FLORIDA PENINSULA NEAR 30N82W TO 24N91W ACROSS THE BAY OF
CAMPECHE TO S MEXICO NEAR 19N95W. LOW LEVEL CONVERGENCE IS
SUPPORTING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ALONG
AND WITHIN 90 NM E OF THE COLD FRONT. THIS ACTIVITY IS BEING
ENHANCED IN THE SW QUADRANT OF AN UPPER LEVEL JET MAXIMUM
LOCATED OVER THE SE CONUS. THE COLD FRONT IS FORECAST TO BECOME
STATIONARY AND THEN BECOME REINFORCED MONDAY NIGHT. THIS FRONT
IS THEN FORECAST TO MOVE SOUTHWARD ACROSS THE REMAINDER OF THE
GULF ON TUESDAY. INCREASED NORTHERLY WINDS...AS WELL AS COOLER
AND DRIER CONDITIONS...ARE PRESENT IN THE WAKE OF THE COLD
FRONT. ALSO...A GALE WARNING IS IN EFFECT FOR PORTIONS OF THE SW
GULF. AHEAD OF THE FRONT...INCLUDING PORTIONS OF THE SE
GULF...THE RETURN FLOW AROUND A 1028 MB SURFACE HIGH OVER THE
CENTRAL ATLC NEAR 34N46W IS RESULTING IN E TO SE SURFACE WINDS
OF 10 KT OR LESS. ADDITIONALLY...STRONG N TO NE SURFACE WINDS
ARE FORECAST TO BLOW THROUGH THE ISTHMUS OF TEHUANTEPEC
RESULTING IN GALE FORCE WINDS IN THE E PACIFIC REGION BEGINNING
AT 12/0600 UTC.

CARIBBEAN SEA...
AN UPPER RIDGE IS PRESENT ACROSS THE CARIBBEAN SEA...WITH THE
UPPER RIDGE AXIS EXTENDING FROM N VENEZUELA NEAR 11N70W TO
17N80W TO 21N85W. SUBSIDENCE AND STABLE ATMOSPHERIC CONDITIONS
ASSOCIATED WITH THIS UPPER RIDGE ARE RESULTING IN GENERALLY FAIR
WEATHER ACROSS MUCH OF THE CARIBBEAN SEA. HOWEVER...ACROSS THE W
CARIBBEAN...DEEP MOISTURE IS BEING TRANSPORTED NORTHWARD TO THE
W OF THE UPPER RIDGE AXIS...WHICH IS RESULTING IN ISOLATED
SHOWERS S OF 20N W OF 81W. MODERATE TO STRONG EASTERLY TRADE
WINDS ARE PRESENT ACROSS MUCH OF THE CARIBBEAN SEA. THESE TRADE
WINDS ARE FORECAST TO CONTINUE THROUGH LATE TUESDAY AS THE 1028
MB SURFACE HIGH IN THE CENTRAL ATLC NEAR 34N46W MOVES
EAST-NORTHEASTWARD. A COLD FRONT IS FORECAST TO ENTER THE NW
CARIBBEAN SEA LATE TUESDAY AND REACH A LINE FROM CENTRAL CUBA TO
HONDURAS ON WEDNESDAY BEFORE IT STALLS THROUGH FRIDAY.

ATLANTIC OCEAN...
SOUTHWESTERLY FLOW ALOFT CONTINUES TO INCREASE ACROSS THE W ATLC
AS A DEEP TROUGH OVER THE E CONUS MOVES EASTWARD. A SURFACE COLD
FRONT IN THE W ATLC ASSOCIATED WITH THIS DEEP TROUGH EXTENDS
FROM SE OF SOUTH CAROLINA NEAR 32N80W TO THE N FLORIDA PENINSULA
NEAR 30N82W. LOW LEVEL CONVERGENCE IS SUPPORTING SCATTERED
SHOWERS ALONG AND WITHIN 60 NM E OF THE COLD FRONT. TO THE E OF
THIS FRONT...DEEP LAYER DRY AIR AND SUBSIDENCE ARE RESULTING IN
GENERALLY FAIR WEATHER ACROSS MUCH OF THE SW AND CENTRAL ATLC.
THIS SUBSIDENCE IS BEING ENHANCED AROUND THE 1028 MB SURFACE
HIGH NEAR 34N46W. THE W ATLC COLD FRONT IS FORECAST TO MERGE
WITH A REINFORCING SURFACE COLD FRONT ON TUESDAY. SW WINDS TO
GALE FORCE ARE FORECAST FOR LOCATIONS N OF 29N WITHIN 360 NM E
OF THE COLD FRONT FOR TUESDAY THROUGH EARLY WEDNESDAY. ALSO...AN
UPPER TROUGH IS N OF 17N BETWEEN 25W-48W. THIS UPPER TROUGH IS
ASSOCIATED WITH A SURFACE TROUGH THAT EXTENDS FROM 27N49W TO
29N44W TO 31N39W AND A SURFACE COLD FRONT THAT EXTENDS FROM
31N39W TO 32N35W TO NE OF THE DISCUSSION AREA. LOW LEVEL
CONVERGENCE IS SUPPORTING SCATTERED SHOWERS WITHIN 60 NM EITHER
SIDE OF THE SURFACE COLD FRONT AND ISOLATED SHOWERS WITHIN 30 NM
EITHER SIDE OF THE SURFACE TROUGH. ALSO...ATMOSPHERIC
INSTABILITY AND UPPER LEVEL DIFFLUENCE ASSOCIATED WITH THE
UPPER TROUGH ARE SUPPORTING SCATTERED SHOWERS FROM 26N-31N
BETWEEN 17W-28W AND FROM 17N-22N BETWEEN 28W-37W. ACROSS THE
TROPICAL ATLC...AN UPPER RIDGE IS PRESENT WITH AN AXIS EXTENDING
FROM 5N8W TO 2N24W TO 1N31W. UPPER LEVEL DIVERGENCE NEAR THIS
UPPER RIDGE IS ENHANCING THE CONVECTION ASSOCIATED WITH THE ITCZ.

$$
COHEN




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