000 AXNT20 KNHC 121741 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST SAT JAN 12 2013 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 1715 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE COAST OF LIBERIA EWD ACROSS AFRICA. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 6N11W TO 3N20W TO 3N40W TO THE COAST OF BRAZIL NEAR 0N48W. SCATTERED MODERATE CONVECTION IS WITHIN 150 NM N OF AXIS FROM 33W-42W. ...DISCUSSION... GULF OF MEXICO... A 1025 MB HIGH CENTERED OVER THE W ATLANTIC NEAR 31N72W EXTENDS A RIDGE SW ACROSS THE STATE OF FLORIDA AND THE GULF OF MEXICO PRODUCING A WARM AND MOSTLY DRY WEATHER PATTERN AND MAINLY MODERATE TO FRESH WINDS. DOPPLER RADAR SHOWS SCATTERED SHOWERS SHOWERS ACROSS THE STRAITS OF FLORIDA AND OVER THE SE GULF FROM 24N TO 26N BETWEEN 81W AND 83W. THE HIGH IS FORECAST TO SHIFT WWD TO A POSITION NEAR 30N75W BY SUN MORNING. SOUTHERLY RETURN FLOW HAS ESTABLISHED ACROSS THE WESTERN GULF AHEAD OF THE NEXT COLD FRONT FORECAST TO MOVE ACROSS THE GULF WATERS ON SUNDAY. THE FRONT WILL REACH FROM SE LOUISIANA TO THE WESTERN BAY OF CAMPECHE SUN EVENING. FRESH TO STRONG NLY WINDS WILL FOLLOW THE FRONT. EXPECT ALSO SHOWERS AND TSTMS ALONG THE FRONTAL BOUNDARY. IN THE UPPER LEVELS...A RIDGE EXTENDS FROM THE BAY OF CAMPECHE ALL THE WAY NE TO BEYOND THE CAROLINAS. A TROUGH CROSSES THE SE GULF AND THE YUCATAN PENINSULA AND EXTENDS FROM A SMALL UPPER LEVEL LOW CENTERED NEAR NE FLORIDA. HIGH CLOUDS ARE NOTED OVER THE WESTERN GULF AND ALONG THE COAST OF TEXAS WHILE MODERATE TO STRONG UPPER LEVEL SUBSIDENCE AND IMPLIED DRY AIR MASS IS OBSERVED WITHIN THE TROUGH AXIS AND OVER SE MEXICO. CARIBBEAN SEA... HIGH PRESSURE N OF AREA IS PRODUCING FRESH TO STRONG TRADE WINDS ACROSS THE SOUTH-CENTRAL CARIBBEAN WITH THE STRONGEST WINDS AS USUAL NEAR THE COAST OF COLOMBIA. LATEST SCATTEROMETER DATA PROVIDED OBSERVATIONS OF 20-30 KT NE-E WINDS ACROSS THIS AREA. MODERATE TO FRESH WINDS ARE BLOWING ACROSS THE REMINDER OF THE BASIN. EXPECT THIS WEATHER PATTER TO PERSIST DURING THE NEXT 24 HOURS. HOWEVER...WINDS ARE FORECAST TO DIMINISH TO 20-25 KT AS HIGH PRES TO THE N SLIGHTLY WEAKENS ON SUN. SHALLOW MOISTURE EMBEDDED IN THE TRADE WIND FLOW WILL MOVE ACROSS THE REGION PRODUCING ISOLATED TO SCATTERED PASSING SHOWERS. LOW LEVEL CONVERGENCE IS ALSO GENERATING SOME SHOWER ACTIVITY OVER PARTS OF HONDURAS AND NICARAGUA. A WEAKENING COLD FRONT EXTENDING ACROSS THE NORTHERN REGIONAL WATERS OF PUERTO RICO AND HISPANIOLA IS PRODUCING SCATTERED SHOWERS. THE SAN JUAN DOPPLER RADAR CLEARLY DEPICTS THIS SHOWER ACTIVITY...MORE CONCENTRATED ON THE ATLC SIDE. ISOLATED TO SCATTERED SHOWERS ARE ALSO NOTED OVER PUERTO RICO. MOISTURE ASSOCIATED WITH THIS WEAKENING FRONTAL BOUNDARY WILL REACH PUERTO RICO AND DOMINICAN REPUBLIC LATER TODAY AND TONIGHT RESULTING IN AN INCREASE OF CLOUDINESS AND SHOWER ACTIVITY FOLLOWED BY A DRIER AIR MASS AS THE THE WEAKENING FRONTAL BOUNDARY OR SHEAR LINE MOVES SOUTH INTO THE NE CARIBBEAN BY SUN. ALOFT...A RIDGE DOMINATES THE MAJORITY OF THE AREA WHILE A TROUGH IS NEARING THE YUCATAN CHANNEL. ATLANTIC OCEAN... A 1025 MB HIGH PRESSURE CENTERED NEAR 31N72W COVERS THE WESTERN ATLC...FLORIDA AND CUBA PRODUCING A WARM AND MOSTLY FAIR WEATHER. TEMPERATURES ARE RUNNING ABOVE AVERAGE ACROSS SOUTH FLORIDA AND CUBA...AND THESE CONDITIONS ARE FORECAST TO PERSIST THROUGH NEXT WEEK. A COLD FRONT ENTERS THE FORECAST REGION NEAR 31N36W THEN CONTINUES SW TO NEAR 21N48W WHERE IT BEGINS TO WEAKEN ALONG 20N60W TO 20N70W. AS PREVIOUSLY MENTIONED...THIS WEAKENING COLD FRONT OR SHEAR LINE WILL REACH PUERTO RICO AND DOMINICAN REPUBLIC LATER TODAY AND TONIGHT. GALE FORCE WINDS ARE BLOWING ACROSS THE CENTRAL ATLC...PARTICULARLY N OF 28N AND W OF THE AFOREMENTIONED FRONT TO 55W IN ASSOCIATION WITH A 985 MB WINTER STORM LOCATED N OF AREA. SEVERAL SCATTEROMETER PASSES INDICATED 30-40 KT W TO NW WINDS. EXPECT WINDS TO BE BELOW GALE FORCE ACROSS THE FORECAST REGION IN ABOUT 24 HOURS. THE EASTERN ATLC IS UNDER THE INFLUENCE OF A RIDGE ANCHORED BY A HIGH PRES LOCATED NE OF THE MADEIRA ISLANDS. ALOFT...A RIDGE/TROUGH/RIDGE PATTER DOMINATES THE DISCUSSION AREA. A VERY LARGE UPPER LEVEL LOW IS SPINNING OVER THE CENTRAL ATLANTIC NEAR 38N47W SUPPORTING THE CENTRAL ATLANTIC COLD FRONT. A SMALL UPPER LEVEL LOW IS JUST OFF OF NE FLORIDA NEAR 30N80W WITH A TROUGH EXTENDING SW ACROSS FLORIDA AND THE SE GULF OF MEXICO. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GR