000
AXNT20 KNHC 221744
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST THU DEC 22 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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL 
ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1700 UTC.

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

THE ITCZ BEGINS INLAND OVER WRN AFRICA REACHING THE COAST OF 
LIBERIA NEAR 5N9W CONTINUING ALONG 6N15W 4N22W 5N34W 4N40W. 
SCATTERED MODERATE CONVECTION IS WITHIN 75 NM EITHER SIDE OF THE 
AXIS BETWEEN 24W-39W. 

...DISCUSSION...

GULF OF MEXICO...
THE FRONTAL BOUNDARY THAT HAS BEEN SITTING ACROSS THE NW GULF OF 
MEXICO HAS NOW RECEIVED THE UPPER LEVEL PUSH FROM A SHORTWAVE 
UPPER TROUGH OVER ERN TEXAS TO BEGIN MOVING EWD AGAIN AS A COLD 
FRONT. THE FRONT EXTENDS FROM S CENTRAL LOUISIANA NEAR 30N91W 
CONTINUING SW ALONG 27N94W 22N98W...AS OF 1500 UTC. WIDESPREAD 
SHOWERS/SCATTERED THUNDERSTORMS ARE WITHIN 150 NM EITHER SIDE OF 
THE FRONT. N-NE WINDS UP TO 20 KTS ARE BEHIND THE FRONT. THE ERN 
GULF REMAINS UNDER SURFACE RIDGING EXTENDING FROM A HIGH 
PRESSURE SYSTEM IN THE W ATLC. THIS PATTERN IS PROVIDING MAINLY 
SE-S FLOW AHEAD OF THE FRONT. DUE TO THE STRONG PRESSURE 
GRADIENT BETWEEN THE FRONT AND THE HIGH...WIND SPEEDS ARE 
BETWEEN 15-20 KTS WITH HIGHER GUSTS. ALOFT...MAINLY SWLY FLOW 
DOMINATES BETWEEN THE UPPER TROUGH OVER THE WRN CONUS AND AN 
UPPER LEVEL RIDGE ACROSS THE ERN CONUS AND W ATLC. BESIDES THE 
MOISTURE PRESENT NEAR THE FRONT...THE 
REMAINDER OF THE BASIN IS COVERED BY DRY AIR ALOFT WHICH IS 
HELPING PROVIDE FAIR CONDITIONS ACROSS MUCH OF THE SRN AND ERN 
GULF. EXPECT THE FRONT TO CONTINUE MOVING SE OVER THE NEXT 24 
HOURS WITH LIKELY SHOWER/THUNDERSTORM ACTIVITY ALONG IT. 

CARIBBEAN SEA...
WINDY CONDITIONS REMAIN ACROSS THE CARIBBEAN TODAY WITH MAINLY 
NE-E TRADEWIND FLOW OF 20-25 KTS REACHING 30 KTS IN THE CENTRAL 
CARIBBEAN AND GALE FORCE NEAR THE COAST OF COLOMBIA FROM 11N TO 
16N BETWEEN 73W AND 78W. ISOLATED SHOWERS ARE EMBEDDED WITHIN 
THE TRADEWIND FLOW WITH SOME STRONGER ACTIVITY ALONG THE COAST 
OF VENEZUELA. TRINIDAD HAS REPORTED A TOTAL OF 1.34 INCHES OF 
RAIN OVER THE PAST 24 HOURS...AND CURACAO WITH .77 INCHES. THESE 
AREAS COULD GET MORE RAINFALL TODAY. SCATTERED SHOWERS/ISOLATED 
THUNDERSTORMS ARE ALSO ALONG THE SRN CENTRAL AMERICA COAST 
INCLUDING NICARAGUA AND COSTA RICA LIKELY DUE TO WIND 
CONVERGENCE ALONG THE COASTLINE. ALOFT...MOSTLY DRY AIR IS 
PRESENT AROUND AN UPPER LEVEL RIDGE WITH AXIS FROM THE BAHAMAS 
TO THE WINDWARD ISLANDS. SURFACE HIGH PRESSURE OVER THE W ATLC 
IS EXPECTED TO REMAIN STATIONARY FOR THE NEXT 24 HOURS WHICH 
WILL CAUSE THE STRONG PRESSURE GRADIENT...AND THUS HIGH 
WINDS...TO PERSIST OVER THE CARIBBEAN THROUGH TOMORROW BEFORE 
BEGINNING TO DIMINISH OVER THE WEEKEND.  

ATLANTIC OCEAN...
SURFACE RIDGING AROUND A 1030 MB HIGH NEAR 31N60W IS PROVIDING 
MOSTLY FAIR WEATHER ACROSS THE WRN ATLC. THE RIDGE IS SUPPORTED 
BY AN UPPER LEVEL RIDGE WITH AXIS ALONG 72W. AN UPPER LEVEL 
TROUGH TO THE E ALONG 42W CONTINUES TO SUPPORT A STATIONARY 
FRONTAL BOUNDARY IN THE CENTRAL ATLC WITH AXIS ALONG 32N35W 
27N40W 22N43W. SCATTERED SHOWERS ARE MAINLY E OF THE FRONT N OF 
22N BETWEEN 34W-40W. THE REMAINDER OF THE BASIN IS INFLUENCED BY 
SURFACE RIDGING AROUND A 1034 MB HIGH E OF THE AZORES ISLANDS 
NEAR 38N17W PROVIDING GENERALLY FAIR WEATHER ACROSS THE ERN 
ATLC. ALOFT...AN UPPER LEVEL RIDGE CENTERED NEAR 44N5W IS 
SUPPORTING THE SURFACE RIDGE.

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

$$
WALTON