000
AXNT20 KNHC 290532
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST SAT DEC 29 2012

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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL 
ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0445 UTC.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS WEST AFRICA TO THE SOUTHERN 
COAST OF SIERRA LEONE WHERE IT TRANSITIONS INTO ITCZ ALONG 7N12W 
3N24W 2N41W 1N50W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION 
IS FROM 4N-6N BETWEEN 28W-40W. 

...DISCUSSION...

GULF OF MEXICO...
AS OF 0300 UTC...A COLD FRONT EXTENDS FROM NEAR MOBILE ALABAMA 
AT 31N88W TO THE EASTERN COAST OF MEXICO ALONG 25N92W 20N97W. 
STRONG SHOWERS/ISOLATED THUNDERSTORMS ARE UP TO 100 NM EAST OF 
THE AXIS NORTH OF 28N. SCATTERED SHOWERS ARE UP TO 60 NM EAST OF 
THE AXIS ELSEWHERE WITH ISOLATED SHOWERS ALSO SPREADING ACROSS 
THE EASTERN GULF AND FLORIDA NORTH OF 26N. STRONG 
NORTH-NORTHEAST WINDS OF 20-25 KT ARE OBSERVED BEHIND THE FRONT. 
THE FRONT IS SUPPORTED BY AN UPPER LEVEL TROUGH MOVING THROUGH 
THE MISSISSIPPI VALLEY WITH A SHORTWAVE DIPPING SOUTH OVER 
LOUISIANA. BROAD UPPER RIDGING COVERS THE SOUTHERN GULF 
ACCOMPANIED BY DRY AIR...WHICH IS HELPING PROVIDE FAIR 
CONDITIONS ACROSS THE SE GULF. THE FRONT IS EXPECTED TO CONTINUE 
TO PUSH SE ACROSS THE BASIN WITH SURFACE RIDGING BUILDING IN 
BEHIND IT. THE RIDGE WILL THEN SHIFT EAST ALLOWING THE NEXT 
FRONTAL SYSTEM TO MOVE INTO THE NW GULF BY EARLY TUESDAY. 

THE CARIBBEAN SEA...
FAIR CONDITIONS AND TRADEWIND FLOW OF 15-20 KT SPREAD ACROSS THE 
MAJORITY OF THE CARIBBEAN TONIGHT DUE TO DRY AIR ALOFT AROUND A 
BROAD UPPER LEVEL RIDGE COVERING THE BASIN. ONLY A FEW SCATTERED 
SHOWERS/POSSIBLE THUNDERSTORMS ARE IN THE FAR SW GULF ACROSS 
COSTA RICA AND PANAMA ASSOCIATED WITH THE MONSOON TROUGH JUST TO 
THE SOUTH OF BOTH COUNTRIES. LITTLE CHANGE IS EXPECTED OVER THE 
NEXT 24 HOURS. A COLD FRONT CURRENTLY IN THE GULF OF MEXICO IS 
EXPECTED TO REACH THE FAR NW CARIBBEAN EARLY SUNDAY. 

THE ATLANTIC OCEAN...
BROAD UPPER LEVEL RIDGING COVERS THE SW NORTH ATLC SUPPORTING A 
WEAK SURFACE RIDGE AROUND A 1021 MB HIGH NEAR 30N70W. ISOLATED 
SHOWERS ARE MOVING ACROSS NORTHERN FLORIDA OVER ATLC WATERS 
ASSOCIATED WITH A COLD FRONT IN THE GULF OF MEXICO. AN UPPER 
LEVEL TROUGH OVER THE NW ATLC CONTINUES TO SUPPORT A COLD FRONT 
THAT ENTERS THE DISCUSSION AREA NEAR 32N57W AND CONTINUES TO 
26N68W. POSSIBLE ISOLATED SHOWERS ARE ALONG THE AXIS. FARTHER 
EAST...A NEARLY CUT-OFF UPPER LEVEL LOW NEAR 25N40W SUPPORTS A 
1016 MB SURFACE LOW NEAR 23N43W WITH AN ASSOCIATED SURFACE 
TROUGH EXTENDING THROUGH THE CENTER ALONG 30N34W 26N41W 20N43W. 
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE MAINLY EAST OF THE 
TROUGH AXIS FROM 23N-29N BETWEEN 36W-40W. THE REMAINDER OF THE 
EASTERN ATLC IS DOMINATED BY SURFACE RIDGING AROUND A 1034 MB 
HIGH CENTERED OVER NW AFRICA. ALOFT...AN UPPER LEVEL RIDGE 
COVERS THE AREA ALONG 22W.

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

$$
WALTON