000 AXNT20 KNHC 150537 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 AM EST MON DEC 15 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0530 UTC. GOES 12 EAST SATELLITE IMAGERY HAS BEEN UNAVAILABLE SINCE 2230 UTC. NESDIS ENGINEERS WILL PLACE GOES 13 IN SERVICE AROUND 0500Z TO COMPENSATE FOR THE LACK OF GOES 12 EAST DATA... ...THE ITCZ... ITCZ IS CENTERED ALONG 7N11W 4N20W 4N34W 5N49W 5N53W. NUMEROUS MODERATE TO STRONG CONVECTION IS WITHIN 90 NM OF THE AXIS BETWEEN 23W-40W. SCATTERED MODERATE CONVECTION IS WITHIN 60 NM OF THE AXIS E OF 12W. ...DISCUSSION... GULF OF MEXICO... STRONG WLY MID TO UPPER FLOW LIES OVER THE REGION ON THE N PERIPHERY OF A HIGH CENTERED OVER THE NW CARIBBEAN. THIS FLOW IS SPREADING PACIFIC HIGH LEVEL CLOUDINESS ACROSS THE N HALF OF THE GULF WITH DRIER AIR PRESENT IN LIGHTER FLOW OVER THE S HALF... CLOSER TO THE UPPER HIGH CENTER. IN THE LOWER LEVELS...A STRONG 1039 MB HIGH OVER THE WRN ATLC IS PRODUCING SE TO S 20-25 KT OVER MUCH OF THE AREA. THIS MOIST LOW-LEVEL FLOW IS PRODUCING PATCHY LOW-LEVEL CLOUDS WITH EMBEDDED SCATTERED SHOWERS OVER THE NRN WATERS. A VERY STRONG COLD FRONT WILL APPROACH THE TEXAS COAST THIS AFTERNOON BUT IT IS NOT EXPECTED TO MAKE MUCH PROGRESS INTO THE GULF AS IT QUICKLY LOSES ITS UPPER SUPPORT. HOWEVER...AN INCREASE IN SHOWERS AND TSTMS ARE LIKELY OVER THE NW WATERS NEAR THE BOUNDARY LATER TODAY AND TUE. CARIBBEAN SEA... ABUNDANT STABLE AIR ALOFT COVERS THE ENTIRE CARIBBEAN...DRIEST OVER THE CENTRAL AND EASTERN PORTIONS WHERE THE UPPER FLOW IS MOST CONFLUENT BETWEEN AN UPPER RIDGE OVER THE NW WATERS AND AN UPPER TROUGH OVER THE W ATLC. NE TRADE WINDS HAVE INCREASED TONIGHT AS THE STRONG ATLC HIGH HAS BUILT N OF THE AREA. TYPICAL PATCHES OF LOW-LEVEL CLOUDS AND EMBEDDED QUICK MOVING SHOWERS ARE BEING DRIVEN BY THE TRADES...BUT THE LARGE SCALE SUBSIDENT ENVIRONMENT IS KEEPING THE MOISTURE SHALLOW. WINDS MAY LIGHTEN OVER THE E CARIBBEAN TUE AND WED AS A SFC TROUGH MOVES CLOSER TO THE AREA. OTHERWISE...LITTLE SIGNIFICANT CHANGES ARE EXPECTED. ATLANTIC OCEAN... A COMPLEX UPPER TROUGH OVER THE CENTRAL ATLC IS PROVIDING LIMITED SUPPORT FOR A QUASI-STATIONARY FRONT FROM 32N50W TO THE SE BAHAMAS. THE TIGHT PRESSURE GRADIENT BETWEEN THIS FRONT AND A 1039 MB HIGH NEAR 39N65W IS PRODUCING N TO NE WINDS TO GALE FORCE BETWEEN THE FRONT AND 65W N OF 25N AND 20-25 KT ELSEWHERE W OF THE FRONT. A SFC TROUGH IS BECOMING A LITTLE BETTER ORGANIZED E OF THE FRONT ALONG 52W N OF 23N. IR IMAGES REVEAL AN INCREASED AREA OF CYCLONIC TURNING IN THE MID-LEVELS WITH ASSOCIATED SCATTERED SHOWERS AND TSTMS N OF 27N BETWEEN 48W-54W. SIMILAR ACTIVITY EXISTS FROM 19N-24N BETWEEN 43W-46W IN AN UPPER DIFFLUENT ZONE. THIS SFC TROUGH WILL LIKELY GAIN VORTICITY FROM THE WEAKENING FRONT AND CLOSE INTO A LOW TUE...ACCORDING TO MANY OF THE NWP MODELS. MODELS ARE IN GOOD AGREEMENT IN SHOWING A TRACK TOWARD THE SW STEERED BY THE E PERIPHERY OF A BUILDING MID-LEVEL RIDGE. FARTHER E...A SFC TROUGH IS EVIDENT IN SCATTEROMETER DATA ALONG 50W FROM 5N-12N. HOWEVER...MUCH OF THE ASSOCIATED WEATHER IS SHEARED WELL E OF THE TROUGH BY STRONG WLY WINDS. IN FACT...THIS FLOW IS SPREADING WIDESPREAD MOISTURE ACROSS THE TROPICAL E ATLC AND ENHANCING CONVECTION IN THE ITCZ AND N OF THE AXIS FROM 7N-13N BETWEEN 40W-44W. $$ CANGIALOSI