000 AXNT20 KNHC 201751 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST WED DEC 20 2006 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA... CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA... NORTHEASTERN SECTIONS OF SOUTH AMERICA...AND THE 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 1730 UTC. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 5N10W 5N22W 4N36W 2N50W. THE ITCZ IS VERY QUIET EXCEPT FOR SCATTERED MODERATE CONVECTION WITHIN 120 NM EITHER SIDE OF THE AXIS BETWEEN 35W-50W. ...DISCUSSION... GULF OF MEXICO... ABUNDANT MOISTURE...ASSOCIATED WITH A LARGE LOW PRES SYSTEM IN THE CENTRAL U.S...COVERS MUCH OF THE CENTRAL AND WRN GULF OF MEXICO. MOSAIC DOPPLER RADAR FROM THE SE U.S. SHOWS BANDS OF SCATTERED SHOWERS AND TSTMS FEEDING NWD IN THE WARM SECTOR ACROSS E TEXAS AND LOUISIANA. THIS MOISTURE THEN ROTATES AROUND A MID-UPPER LEVEL HIGH ALIGNED FROM THE YUCATAN PENINSULA ACROSS CENTRAL FLORIDA AND INTO THE W ATLC. DRY STABLE AIR ALOFT IS HOLDING ALONG AND E OF THE RIDGE AXIS. AT THE SFC...DISTANT HIGH PRES CENTERED IN THE MID-ATLANTIC REGION IS ENHANCING RIDGING. THIS HIGH PRES ALONG WITH SLIGHTLY LOW PRES TO THE E OF THE AREA IS PRODUCING STIFF 15-20 KT E TO NE FLOW IN THE E AND MIDDLE GULF. THESE WINDS ARE VEERING MORE TO THE S-SE IN THE W GULF ON THE PERIPHERY OF THE RIDGE AND NEAR THE LOW PRES SYSTEM IN THE CENTRAL U.S. THE WEATHER WILL BECOME INTERESTING IN THE REGION LATER THIS WEEK AS A COLD FRONT MOVES TOWARD THE TEXAS COAST TOMORROW. A CONSIDERABLE AMOUNT OF MOISTURE WILL LIKELY BE ADVECTED INTO THE REGION AHEAD OF THE FRONT ON FRI AND THIS WEEKEND. GALE CONDITIONS ARE IN THE FORECAST BEHIND THE FRONT IN THE W GULF ON SUN. CARIBBEAN SEA... PLENTY OF DRY AIR ALOFT...ASSOCIATED WITH UPPER LEVEL CONFLUENCE BETWEEN AN UPPER LOW NEAR JAMAICA AND A TITLED UPPER RIDGE ACROSS THE E GULF AND WRN ATLC...IS IN PLACE ACROSS THE WRN CARIBBEAN KEEPING CONDITIONS VERY QUIET. SOME SMALL PATCHES OF CLOUDINESS AND SCATTERED SHOWERS ARE POPPING UP ON THE E SIDE OF THE UPPER SYSTEM NEAR THE CENTER ACROSS ERN JAMAICA...E CUBA AND THE SE BAHAMAS. THE REMAINDER OF THE CARIBBEAN IS DOMINATED BY UPPER LEVEL ZONAL WESTERLY FLOW. MODEST DRY AIR ALOFT COVERS THIS AREA E OF 70W. TRADE WINDS ARE GENERALLY IN THE 15-20 KT INTERVAL. THESE WINDS WILL LIKELY INCREASE SOME OVER THE NEXT COUPLE DAYS AS SFC HIGH PRES CURRENTLY IN THE MID-ATLANTIC U.S. MOVES TO THE SE TIGHTENING THE PRES GRAD. ATLANTIC OCEAN... SLIGHT UPPER LEVEL RIDGING EXTENDS FROM THE SE GULF ACROSS THE BAHAMAS AND WRN-MOST ATLC. THIS FLOW THEN FOLDS INTO AN UPPER TROUGH WHICH COVERS THE AREA BETWEEN 50W-70W N OF 23N. AN ASSOCIATED COLD FRONT JUST CLIPS THE NRN PORTION OF THE AREA ALONG 32N61W 29N75W 30N79W THEN STATIONARY TOWARD THE S GEORGIA COAST. THIS FRONT IS MOISTURE STARVED WITH ONLY A NARROW LINE OF LOW CLOUDS MARKING THE FRONT...MAKING IT EASY TO LOCATE. A SURGE IN NLY WINDS AND PATCHES OF LOW-LEVEL STRATO-CU CLOUDS ARE WIDESPREAD BEHIND THE BOUNDARY. A SFC TROUGH LIES TO THE S OF THE COLD FRONT ANALYZED FROM THE DOMINICAN REPUBLIC NEWARD ALONG 22N62W 25N58W. SCATTERED SHOWERS ARE WITHIN 120 NM OF THE BOUNDARY. A MODEST DEEP-LAYER RIDGE LIES TO THE E OF THE TROUGH COVERING THE REGION BETWEEN 28W-50W N OF 20N. THE SFC HIGH IS ANALYZED AT 1021 MB NEAR 30N41W. PLENTY OF DRY STABLE AIR AND FAIR WEATHER IS ASSOCIATED WITH THIS DEEP RIDGING. THE SUBTROPICAL E ATLC IS DOMINATED BY DEEP-LAYERED TROUGHING. THE SFC LOW IS FAIRLY WEAK ANALYZED AT 1016 MB NEAR 29N28W. MOST OF THE ASSOCIATED WEATHER...WHICH IS IN THE FORM OF WEAKENING SCATTERED SHOWERS AND ISOLATED TSTMS...LIES TO THE E OF THE LOW PRES CENTER N OF 24N BETWEEN 18W-26W. BASED UPON THE LATEST VIS IMAGES...THE SYSTEM APPEARS TO BE FRONTAL...SO THE ASSOCIATED BOUNDARIES WILL BE INTRODUCED ON THE SFC MAP AT 18Z. IN THE DEEP TROPICS...EXTENSIVE WLY UPPER LEVEL FLOW COVERS THE ENTIRE AREA ON THE N SIDE OF A VERY BROAD UPPER HIGH CENTERED NEAR 5N41W. CONVECTION IS LIMITED TO A SMALL PORTION OF THE ITCZ WHERE UPPER LEVEL DIFFLUENCE IS STRONGEST BETWEEN 35W-50W FROM 3N-6N. $$ CANGIALOSI