000 AXNT20 KNHC 212341 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST FRI JAN 21 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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2300 UTC. ...THE ITCZ... THE ITCZ AXIS IS CENTERED FROM BROAD LOW PRESSURE E OF LIBERIA ALONG 7N8W 2N18W CROSSING THE EQUATOR NEAR 31W TO 4S42W. ...DISCUSSION... THE GULF OF MEXICO... A LONGWAVE UPPER TROUGH ACROSS THE ERN AND CENTRAL UNITED STATES IS MOVING INTO THE NW GULF PROVIDING MAINLY WSWLY FLOW ALOFT...AND CURRENTLY SUPPORTS A COLD FRONT THAT CONTINUES TO PUSH SE ACROSS THE BASIN. AS OF 2100 UTC...THE FRONT EXTENDS FROM S OF CAPE CANAVERAL FLORIDA AT 28N81W TO THE WRN SIDE OF THE YUCATAN PENINSULA ALONG 25N85W 20N90W 17N94W CONTINUING AS A STATIONARY FRONT INTO CENTRAL MEXICO. A THIN LINE OF SHOWERS IS ALONG THE FRONT ACROSS FLORIDA AND WITHIN 45 NM TO THE S. A PRE-FRONTAL SURFACE TROUGH IS JUST SE OF THE FLORIDA PENINSULA CONTINUING THROUGH THE FLORIDA STRAITS TO THE YUCATAN CHANNEL ALONG 25N80W 23N83W 23N86W 22N87W SUPPORTING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 60 NM N OF THE AXIS. NUMEROUS SHOWERS/THUNDERSTORMS ARE WITHIN 90 NM S OF THE AXIS IMPACTING PORTIONS OF NW CUBA. WIND OBSERVATIONS INDICATE THAT THE N-NE SURFACE FLOW BEHIND THE FRONT HAS DIMINISHED BELOW GALE FORCE AND NOW WINDS ARE MAINLY 10-15 KT WITH SOME REACHING 20 KT. BEHIND THE FRONT...WIDESPREAD STRATUS CLOUDS EXTEND TO THE W AND N GULF COASTS. EXPECT THE FRONT TO CLEAR THE BASIN BY SATURDAY AFTERNOON. UNTIL THIS OCCURS...SHOWERS/THUNDERSTORMS ARE EXPECTED AHEAD OF THE FRONTAL BOUNDARY. THE CARIBBEAN SEA... A WEAK PRESSURE GRADIENT ACROSS THE CARIBBEAN SEA IS MAINTAINING MODERATE TO FRESH TRADEWINDS ACROSS MUCH OF THE BASIN. MOSTLY FAIR WEATHER IS ACROSS THE AREA DUE TO A DRY AND STABLE AIR MASS COVERING THE BASIN WITH ZONAL WLY FLOW ALOFT AROUND A BROAD UPPER LEVEL RIDGE. HOWEVER...A SURFACE TROUGH CONTINUES TO DRIFT WNW ALONG 17N75W TO 11N73W SUPPORTING SCATTERED SHOWERS FROM 14N-18N BETWEEN 71W-76W. TOTAL PRECIPITABLE WATER IMAGERY INDICATES AN AREA OF ENHANCED MOISTURE NEAR THIS TROUGH. A SECOND AREA OF ENHANCED MOISTURE IS FARTHER E SUPPORTING SCATTERED SHOWERS FROM 14N-19N BETWEEN 66W-68W. EXPECT SHOWERS/THUNDERSTORMS TO MOVE INTO THE NW CARIBBEAN AS A FRONTAL BOUNDARY ACROSS THE ERN GULF MOVES SE. STRONG SHOWERS/THUNDERSTORMS ARE ALREADY NOTED OVER THE YUCATAN CHANNEL AND NW CUBA. THE ATLANTIC OCEAN... A COLD FRONT IS IMPACTING THE FAR W ATLC THIS EVENING ENTERING THE DISCUSSION AREA NEAR 32N72W CONTINUING ALONG 29N76W TO NEAR CAPE CANAVERAL FLORIDA AND INTO THE GULF OF MEXICO. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 120 NM AHEAD OF THE FRONT. POSSIBLE ISOLATED SHOWERS ARE WITHIN 100 NM BEHIND THE FRONT. THE SYSTEM IS SUPPORTED BY A LONGWAVE UPPER TROUGH MOVING ACROSS THE ERN HALF OF THE UNITED STATES. AN UPPER LEVEL RIDGE IS TO THE E EXTENDING FROM THE CENTRAL CARIBBEAN TO NEAR 40N53W SUPPORTING A BROAD SURFACE RIDGE ANCHORED BY A 1019 MB HIGH NEAR 27N48W WHICH IS PROVIDING GENERALLY FAIR WEATHER ACROSS MUCH OF THE CENTRAL AND ERN ATLC. A WEAKENING COLD FRONT DIPS INTO THE SURFACE RIDGE ALONG 31N44W TO 30N52W WITH ISOLATED SHOWERS WITHIN 45 NM EITHER SIDE THE AXIS. THIS BOUNDARY IS SUPPORTED BY A WEAK UPPER TROUGH EXTENDING FROM 38N35W TO 13N55W. A SECOND COLD FRONT EXTENDS ACROSS THE CANARY ISLANDS ALONG 31N13W TO 27N17W SUPPORTING ISOLATED SHOWERS ALONG THE FRONTAL BOUNDARY. THIS SYSTEM IS SUPPORTED BY AN UPPER LEVEL LOW SPINNING N OF THE MADEIRA ISLANDS NEAR 36W17W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON