000 AXNT20 KNHC 181119 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST MON DEC 18 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1100 UTC. ...THE ITCZ... ITCZ AXIS IS ALONG 6N10W 4N24W 4N40W 2N51W. NO AREAS OF SIGNIFICANT CONVECTION. ONLY SCATTERED SHOWERS AND ISOLATED TSTMS WITHIN 300 NM EITHER SIDE OF THE AXIS. ...DISCUSSION... THE GULF OF MEXICO... MAINLY FAIR WEATHER EXISTS ACROSS THE GULF OF MEXICO UNDER THE INFLUENCE OF A MID TO UPPER LEVEL RIDGE ANCHORED OVER THE REGION. PLENTY OF DRY AIR ALOFT LIES ABOVE THE AREA WITH THE MOST STABLE CONDITIONS ALOFT ACROSS THE E PORTION WHERE THERE IS STRONG UPPER LEVEL CONFLUENCE BETWEEN THIS RIDGE AND AN UPPER LEVEL TROUGH IN THE W ATLC. SOME HIGH CLOUDINESS IS BEGINNING TO STREAM INTO THE W GULF. THIS CLOUDINESS MAY SPREAD NE THRU THE DAY...BUT WILL NOT BE A WEATHER CONCERN. AT THE SFC...RIDGING EXTENDS ACROSS THE GULF FROM A NEARLY STATIONARY 1026 MB HIGH IN THE W ATLC. THIS PATTERN IS PRODUCING 15-20 KT E WINDS IN THE MIDDLE AND E GULF AND LIGHTER RETURN FLOW IN THE WRN GULF. THERE ARE SOME PATCHES OF LOW/MID LEVEL CLOUDS AND SHALLOW ISOLATED SHOWERS IN THE SE GULF...S OF 26N BETWEEN 84W-88W...LEFT OVER FROM A DISSIPATED TROUGH. LOOKING AHEAD OVER THE NEXT FEW DAYS...COMPUTER MODELS SHOW THE MID-UPPER LEVEL RIDGE HOLDING IN PLACE KEEPING CONDITIONS MAINLY DRY ACROSS THE AREA. HIGH PRES AT THE SFC WILL STRENGTHEN AND SHIFT W WHICH WILL INCREASE THE WINDS AND SEAS SLIGHTLY. THE CARIBBEAN SEA... THE TAIL END OF A WEAKENING SFC TROUGH STRETCHES ACROSS THE SRN BAHAMAS. MULTILAYER CLOUDINESS AND ISOLATED SHOWERS NEAR THE TROUGH ARE BREAKING UP AS DRIER AIR PIVOTS INTO THE REGION...DUE TO THE MID/UPPER LEVEL TROUGH IN THE W ATLC SHIFTING SE. THE REMAINDER OF THE CARIBBEAN IS UNDER A WEAK MID-LEVEL RIDGE WITH PLENTY OF DRY STABLE AIR ALOFT...ESPECIALLY S OF 17N. THERE ARE PATCHES OF LOW LEVEL CLOUDS AND EMBEDDED SCATTERED SHOWERS UNDERNEATH THE STRONG MID LEVEL CAP IN THE E CARIBBEAN...MAINLY E OF THE DOMINICAN REPUBLIC AND N OF 13N. TRADE WINDS ARE MOSTLY IN THE 15-20 KT RANGE...EXCEPT FOR SLIGHTLY STRONGER WINDS IN THE SW CARIB WHERE THE PRES GRAD IS A LITTLE TIGHTER. OVER THE NEXT FEW DAYS...LITTLE CHANGE IN STRENGTH OF THE TRADES IS EXPECTED AS THE SFC PATTERN REMAINS SIMILAR. GFS SHOWS THE UPPER SHORTWAVE IN THE ATLC PULLING SE WHICH MAY DRAG A LITTLE MOISTURE INTO THE N CENTRAL AND E CARIB. THE ATLANTIC OCEAN... IN THE WRN AND CENTRAL ATLC...A MID TO UPPER LEVEL HIGHLY ELONGATED TROUGH STRETCHES FROM JUST E OF BERMUDA TO THE SE BAHAMAS. DRY STABLE AIR ALOFT COVERS THE AREA W OF THE TROUGH AXIS INCLUDING FLORIDA AND THE GULF OF MEXICO. E OF THE TROUGH AXIS...STRONG UPPER LEVEL WLY FLOW IS SPREADING THE MOISTURE PLUME WELL E COVERING A LOT OF REAL ESTATE IN AN ZONAL E-W FASHION...NAMELY FROM 20N-26N BETWEEN 30W-70W. AT THE SFC...A COLD FRONT ENTERS THE AREA NEAR 32N44W AND EXTENDS SW TO A WEAK 1016 MB LOW IS NEAR 28N51W THEN CONTINUING TO SW TO 22N61W THEN WWD AS A SFC TROUGH ACROSS THE SE BAHAMAS. THIS SFC LOW/FRONTAL BOUNDARY IS PROVIDING LIFT WHICH IS DEEPENING THE MOISTURE PLUME OUTLINED. A 1026 MB HIGH PRES SYSTEM IS CENTERED TO THE N AND W OF THE FRONTAL BOUNDARY ABOUT 200 NM W OF BERMUDA NEAR 32N69W. IN THE TROPICAL AND E ATLC...ONE OF THE MAIN FEATURES IS A STRONG UPPER LEVEL TROPICAL JETSTREAM WHICH IS LOCATED BETWEEN UPPER TROUGHING IN THE CENTRAL ATLC AND BROAD RIDGING OVER AFRICA. THIS 90-110 KT JET APPROXIMATELY RUNS ALONG 8N42W 18N27W TO THE CANARY ISLANDS. CONSIDERABLE MOISTURE LIES TO THE S AND E OF THE JET AXIS WHILE UPPER LEVEL CONFLUENCE IS PROVIDING A STABLE ENVIRONMENT WITHIN 300 NM W OF THE JET. THE OTHER MAIN FEATURE IS THE LONG LIVED SLOW MOVING LARGE 1003 MB OCCLUDED LOW PRES SYSTEM CENTERED NEAR 36N31W. THIS LOW IS SLOWLY WEAKENING WITH ITS FRONTAL BOUNDARIES BECOMING DIFFUSE AND ITS LOW-LEVEL CIRCULATION APPEARING MORE RAGGED. THE ASSOCIATED OLD FRONTAL BOUNDARY...WHICH LIES WELL E OF THE LOW CENTER...IS ALONG 32N21W 24N24W 19N32W. THE NRN BRANCH OF THE SFC TROUGH IS LOCATED IN THE MOIST REGION OF THE TROPICAL JET MENTIONED AND IS ENHANCING SHOWER ACTIVITY N OF 28N BETWEEN 18W-22W. GFS SHOWS THE OCCLUDED LOW FINALLY PULLING N AND BECOMING ABSORBED BY THE FAST MOVING COLD FRONT IN THE CENTRAL ATLC. $$ CANGIALOSI