000
AXNT20 KNHC 261115
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST MON DEC 26 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1100 UTC.

...ITCZ/MONSOON TROUGH...

MOST OF THE MONSOON TROUGH REMAINS INLAND OVER AFRICA. A SMALL 
SECTION OF IT ENTERS THE ATLC THROUGH THE COAST OF SIERRA LEONE 
ALONG 8N13W AND QUICKLY ENDS AT 7N17W. THE ITCZ AXIS EXTENDS WSW 
FROM THIS POINT ALONG 3N30W TO 2N43W. SCATTERED WEAK TO MODERATE 
CONVECTION IS WITHIN 70-100 NM ON EITHER SIDE OF THE ITCZ AXIS 
BETWEEN 25W-37W.

...DISCUSSION...

GULF OF MEXICO...
SW FLOW ALOFT COVERS THE ENTIRE GULF THIS MORNING. THIS UPPER 
LEVEL FLOW PATTERN IS MOVING MIDDLE TO UPPER LEVEL MOISTURE 
NORTHEASTWARD ACROSS THE NRN AND ERN HALF OF THE GULF. WITHIN 
THIS REGION OF MOISTURE ALOFT...A NEARLY STATIONARY SURFACE 
TROUGH IS ANALYZED FROM 29N91W TO 24N93W THEN SOUTH TO THE COAST 
OF MEXICO NEAR 18N93W. VISIBLE NIGHT CHANNEL AND IR WINDOW SHOW 
A BROAD LAYER OF LOW LEVEL STRATOCUMULUS CLOUDS W OF THE TROUGH 
TO THE MEXICO AND TEXAS COAST W OF 92W...WITH A FEW ISOLATED 
SHOWERS OCCURRING WITHIN 90 NM EITHER SIDE OF THE TROUGH AXIS S 
OF 26N92W. MOSAIC DOPPLER RADAR INDICATES SCATTERED SHOWERS AND 
ISOLATED THUNDERSTORMS NE OF THE TROUGH N OF 28N BETWEEN 84W-90W 
AFFECTING THE COASTAL WATERS OF LOUISIANA...MISSISSIPPI... 
ALABAMA...AND THE FLORIDA PANHANDLE. AN EARLIER ASCAT PASS 
REVEALED GUSTY N WINDS UP TO 20 KT W OF THE TROUGH AXIS. SURFACE 
RIDGING WILL RETURN TO THE WRN GULF OVER THE NEXT FEW DAYS.

CARIBBEAN SEA...
VERY DRY AIR ALOFT AND STRONG SUBSIDENCE COVERS MOST OF THE 
CARIBBEAN WATERS THIS MORNING. THIS AIRMASS IS SUPPRESSING DEEP 
CONVECTION ACROSS THE DISCUSSION AREA. FRESH TO STRONG TRADE 
WIND FLOW CONTINUES ACROSS MUCH OF THE BASIN...ESPECIALLY 
BETWEEN 68W-80W...WITH A FEW SMALL CLUSTERS OF LOW-TOP WEAK 
SHOWERS EMBEDDED IN THE FLOW. THESE CONDITIONS ARE EXPECTED TO 
PERSIST THROUGH TUESDAY MORNING.

ATLANTIC OCEAN...
THE TAIL END OF A COLD FRONT IS ENTERING THE FAR WRN ATLC WITH 
LIMITED CONVECTION AT THE MOMENT. HOWEVER...THIS FRONT WILL 
CONTINUE TO TRACK EASTWARD WITH INCREASING CONVECTION AS THE DAY 
PROGRESSES. IN THE MEAN TIME...AN UPPER LEVEL RIDGE IS ACROSS 
MUCH OF THE WESTERN ATLC W OF 45W WITH VERY DRY AIR ALOFT AND 
STRONG SUBSIDENCE NOTICED ON WATER VAPOR IMAGERY. THIS FEATURE 
SUPPORTS A 1023 MB HIGH CENTERED NEAR 28N65W. SLICING THROUGH 
THE SURFACE RIDGE IS A WEAK COLD FRONT ANALYZED FROM 32N48W TO 
27N56W TO 26N64W WHERE LOW-LEVEL MOISTURE BECOMES MORE DIFFUSE 
AND A DISSIPATING COLD FRONT EXTENDS TO 27N70W. THIS FRONT IS 
GENERATING POSSIBLE ISOLATED SHOWERS WITHIN 30 NM EITHER SIDE OF 
IT. TO THE EAST OF THE FRONT...AN EARLIER ASCAT PASS REVEALED AN 
AREA OF LOW LEVEL CONFLUENCE OF LIGHT WINDS ANALYZED AS A WEAK 
SURFACE TROUGH FROM 29N45W TO 23N48W WITHOUT ANY RAINSHOWER 
ACTIVITY ASSOCIATED. A SIMILAR SURFACE TROUGH IS ALSO ANALYZED 
FROM 17N46W TO 10N50W. FARTHER EAST...AN UPPER LEVEL LOW IS 
CENTERED NEAR 21N38W. THIS UPPER LEVEL CIRCULATION IS GENERATING 
A BROAD AREA OF DIFFLUENCE FLOW ALOFT THAT COVERS THE ERN ATLC S 
OF 25N E OF 38W. SCATTERED SHOWERS AND POSSIBLE ISOLATED 
THUNDERSTORMS ARE IN THIS REGION...WITH NE WINDS UP TO 25 KT.

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

$$

GARCIA