000 AXNT20 KNHC 171130 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST WED DEC 17 2008 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1100 UTC. ...THE ITCZ... ITCZ IS CENTERED ALONG 8N13W 5N25W 4N35W 6N40W 3N51W. NUMEROUS MODERATE TO STRONG CONVECTION IS WITHIN 150 NM EITHER SIDE OF THE AXIS BETWEEN 17W-36W. ...DISCUSSION... GULF OF MEXICO... A FRONTAL BOUNDARY IS SLOWLY LIFTING BACK N OVER THE EXTREME NW GULF FROM 30N92W TO 27N96W TO 233N98W. THE FRONT IS GRADUALLY BECOMING DIFFUSE CAUSING N TO NE WINDS TO LIGHTEN SIGNIFICANTLY W OF THE FRONT. E OF THE FRONT...E TO SE WINDS ARE LIGHT TO MODERATE EXCEPT FOR MODERATE TO FRESH WINDS OVER THE FLORIDA STRAITS. ONLY SCATTERED PATCHES OF CLOUDS AND EMBEDDED ISOLATED SHOWERS ARE BEING DRIVEN BY THE LOW-LEVEL FLOW WITH MINIMAL SHOWER ACTIVITY NOTED NEAR THE FRONT. THIS FRONT IS EXPECTED TO DRIFT BACK INLAND TODAY ALLOWING UNIFORM E TO SE FLOW TO BECOME ESTABLISHED. ALOFT...THE N PERIPHERY OF AN UPPER HIGH OVER CENTRAL AMERICA IS PRODUCING WLY FLOW...WHICH IS ONLY TRANSPORTING BROKEN HIGH LEVEL CLOUDINESS FROM THE TROPICAL PACIFIC. CARIBBEAN SEA... AN UPPER RIDGE OVER CENTRAL AMERICA AND AN UPPER LOW OVER THE SUBTROPICAL CENTRAL ATLC IS PRODUCING NW TO W FLOW ALOFT AND ENHANCING WIDESPREAD SUBSIDENCE ACROSS THE REGION. THE AIR IS MOST STABLE IN A CONFLUENT ZONE OVER THE E CARIBBEAN. IN THE LOWER LEVELS...THE TIGHT PRES GRADIENT N OF THE AREA IS PRODUCING STRONG N TO NE WINDS...WHICH ARE STEERING SCATTERED SHOWERS AND LOW TOPPED TSTMS SOUTHWARD OVER THE NE CARIBBEAN ISLANDS...BENEATH THE MID-LEVEL CAP. THESE SHALLOW SHOWERS/TSTMS BECOME MORE ISOLATED IN NATURE AS THEY SPREAD S/SW STEERED BY NE TRADES. AS IS TYPICAL IN THESE WEATHER PATTERNS...SFC WINDS ARE STRONGEST IN THE ATLC PASSAGES WHERE ENHANCED FUNNELING EXISTS. THE LOW N OF THE AREA IS EXPECTED TO TRACK SW TOWARD THE GREATER ANTILLES AND WEAKEN OVER THE NEXT DAY OR SO. THIS WILL MAINTAIN STRONG N/NE WINDS AND SCATTERED SHOWERS ACROSS MUCH OF THE AREA. ATLANTIC OCEAN... DEEP LAYER LOW PRESSURE OVER THE CENTRAL ATLC IS CAUSING AN AREA OF ACTIVE WEATHER THIS MORNING. THE SFC CENTER IS ANALYZED 1008 MB NEAR 26N58W WITH ITS ASSOCIATED TROUGH EXTENDING BOTH N AND S ALONG 57W/58W N OF 19N. SCATTEROMETER AND TO SOME DEGREE SFC OBS SHOW A WELL DEFINED SFC CIRCULATION AND N WINDS TO GALE FORCE BETWEEN THE TROUGH AND 67W N OF 25N. LOW-LEVEL CONVERGENCE AND INSTABILITY NEAR THE LOW IS PRODUCING SCATTERED SHOWERS AND TSTMS WITHIN 300 NM OF THE CENTER. A LARGER AND MORE INTENSE AREA OF TSTMS EXIST FARTHER NE N OF 24N BETWEEN 44W-54W IN AN UPPER DIFFLUENT ZONE. THIS LOW IS EXPECTED TO TRACK SW FOR ANOTHER DAY OR TWO BEFORE BECOMING GREATLY SHEARED AND SPLIT APART BY A SHORTWAVE TROUGH. THE W ATLC IS RELATIVELY TRANQUIL BENEATH ABUNDANT DRY AIR ALOFT ON THE W SIDE OF THE UPPER LOW. HOWEVER...AS MENTIONED ABOVE... STRONG N/NE LOW-LEVEL WINDS AND INSTABILITY ARE STIRRING UP SHOWERS AND LOW-TOPPED TSTMS MAINLY E OF 75W. OVER THE TROPICAL E ATLC...STRONG WLY FLOW ALOFT IS TRANSPORTING WIDESPREAD MID-HIGH LEVEL CLOUDINESS AND ENHANCING ITCZ CONVECTION. $$ CANGIALOSI