000 AXNT20 KNHC 301728 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST THU DEC 30 2010 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...THE ITCZ... THE ITCZ AXIS IS ANALYZED FROM THE COAST OF SIERRA LEONE NEAR 7N14W WESTWARD ALONG 5N20W 4N30W 3N40W 4N45W 3N52W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM THE EQUATOR TO 10N E OF 24W. SIMILAR CONVECTION IS WITHIN 140 NM ON EITHER SIDE OF THE AXIS BETWEEN 24W-45W. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY INDICATES SW FLOW ALOFT ACROSS THE BASIN...WITH AN UPPER LEVEL SHORTWAVE MOVING ACROSS THE N CENTRAL GULF. THIS FEATURE SUPPORTS A SURFACE TROUGH ANALYZED WITHIN 40 NM OFF THE COAST OF LOUISIANA...MISSISSIPPI...AND ALABAMA BETWEEN 87W-90W...ENHANCING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS N OF 29N BETWEEN 87W-89W. THIS ACTIVITY IS EXPECTED TO WEAKEN OVER THE NEXT 12-18 HRS AS THE UPPER LEVEL SUPPORT MOVES OUT OF THE AREA. SATELLITE DERIVED WINDS AND SFC OBS ACROSS THE GULF INDICATE 15-25 KT RETURN FLOW OVER MOST OF THE WESTERN HALF OF THE BASIN W OF 89W. SURFACE RIDGE REMAINS IN CONTROL OF THE EASTERN HALF OF THE GULF E OF 89W...INFLUENCED BY A 1024 MB HIGH OVER THE WEST ATLANTIC...PROVIDING A WARM 15-20 KT SE FLOW ACROSS THE AREA. BROKEN TO OVERCAST STRATOCUMULUS CLOUDS COVER THE SE GULF S OF 26N BETWEEN 82W AND 89W. ANOTHER ROUND OF WEATHER IS IN STORE FOR THE WEEKEND WITH THE NEXT COLD FRONT ENTERING THE NW GULF FRI AFTERNOON...ALONG WITH LOW LEVEL MOISTURE FROM THE NW CARIBBEAN ADVECTING NORTHWARD ACROSS THE CENTRAL GULF. CARIBBEAN SEA... THE SURFACE RIDGE OVER THE W ATLC COVERS THE N CENTRAL AND NW CARIBBEAN. THIS IS PROVIDING 15-20 KT TRADEWINDS ACROSS MOST OF THE CARIBBEAN...BECOMING SSE W OF 80W. THIS FLOW IS BANKING LOW LEVEL MOISTURE OVER THE FAR SW CARIBBEAN...PROVIDING FOCUS FOR SCATTERED SHOWERS WITHIN 40 NM OFF THE COAST OF PANAMA AND COSTA RICA BETWEEN 80W-83W. BROKEN TO OVERCAST COLD AIR STRATOCUMULUS CLOUDS REMAIN OVER THE NW CARIBBEAN W OF 80W. OTHERWISE... ISOLATED SHOWERS EMBEDDED IN THE TRADEWINDS DOT THE REMAINDER OF THE CARIBBEAN S OF 17N E OF 80W...MOSTLY RELATED TO THE PREVIOUS FRONTAL BOUNDARY NOW ANALYZED OUT OF THE AREA. COMPUTER MODELS SUGGEST THIS AREA OF WEAK SCATTERED CONVECTION WILL CONTINUE OVER THE NEXT 24 HOURS. THE UPPER LEVELS OF THE CARIBBEAN ARE DOMINATED BY A BROAD UPPER RIDGE ANCHORED OVER THE FAR WEST TROPICAL ATLC. ATLANTIC OCEAN... THE MAIN FEATURE OF CONCERN IN THE ATLC IS A COLD FRONT THAT ENTERS THE DISCUSSION AREA ACROSS THE CENTRAL REGION NEAR 32N31W ...EXTENDING SW ALONG 25N40W 21N48W...BECOMING STATIONARY TO 17N57W. SCATTERED SHOWERS ARE WITHIN 30 NM ON EITHER SIDE OF THE COLD FRONT N OF 22N...WHILE ISOLATED SHOWERS ARE WITHIN 50 NM EITHER SIDE OF THE STATIONARY FRONT. THIS SYSTEM IS SUPPORTED ALOFT BY A BROAD UPPER TROUGH COVERING THE N CENTRAL ATLC N OF THE DISCUSSION AREA. STRONG SUBSIDENCE ALOFT IS NOTED BEHIND THE FRONTAL BOUNDARY ON WATER VAPOR IMAGERY. THIS AREA OF SUBSIDENCE IS RELATED TO A FAIRLY STRONG AND E-W ELONGATED SUB-TROPICAL JETSTREAK MOVING ACROSS THE WESTERN AND CENTRAL BASIN. SURFACE RIDGING IS ELSEWHERE ACROSS THE WESTERN AND EASTERN REGIONS OF THE ATLC ANCHORED BY A 1024 MB HIGH EAST OF THE NORTHERN BAHAMAS NEAR 27N73W AND A 1018 MB HIGH WSW OF THE CANARY ISLANDS NEAR 26N24W. EXPECT THE CENTRAL ATLANTIC FRONT TO CONTINUE TO MOVE EASTWARD WITH CONVECTION. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA