000 AXNT20 KNHC 101723 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST SUN DEC 10 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 1700 UTC. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 5N9W 3N27W 2N46W 2N53W. THE ITCZ IS QUIET TODAY WITH ONLY ISOLATED MODERATE CONVECTION WITHIN 120 NM S OF THE AXIS E OF 20W. SCATTERED SHOWER ACTIVITY LIES N OF THE AXIS ASSOCIATED WITH STRONG SWLY UPPER LEVEL WINDS OUTLINED IN THE ATLC SECTION. ...DISCUSSION... THE GULF OF MEXICO... A MID/UPPER LEVEL SHORTWAVE TROUGH EXTENDING FROM MS/AL ACROSS THE CENTRAL PORTION OF THE GULF IS SLOWLY WEAKENING AND LIFTING N. THE SUBTROPICAL JET HAS NOW SHIFTED S AND E OF THE AREA AND MOST OF THE WIDESPREAD MID AND HIGH LEVEL CLOUDINESS AND SHOWER ACTIVITY HAS DONE THE SAME. THIS IS DUE TO DRY STABLE AIR ALOFT BEING ADVECTED ACROSS MEXICO AND INTO THE WRN GULF AS AN UPPER RIDGE BUILDS E...NOW CENTERED ABOVE MEXICO AND TEXAS ALONG 99W. AT THE SFC...STRONG 1035 MB HIGH NEAR THE COASTLINE OF THE CAROLINAS CONTINUES TO KEEP RATHER WINDY CONDITIONS IN THE ERN AND MIDDLE GULF WHERE SEVERAL BUOY AND SHIP OBS ARE REPORTING E TO NE WINDS IN THE 20-25 KT RANGE. THERE ARE A COUPLE WEAK SFC TROUGH OR PERTURBATIONS IN THE LOW-LEVEL FLOW ACROSS THE AREA. THE MORE NOTABLE IS IN THE CENTRAL GULF EXTENDING ALONG 87W/88W S OF 28N STRETCHING FAR S INTO THE WRN CARIB. THE OTHER IS IN THE NW GULF ALONG 96W FROM 24N-29N. THE ERN-MIDDLE GULF TROUGH IS PRODUCING BROKEN TO OVERCAST SKIES AND LIKELY ISOLATED TO SCATTERED SHOWERS WITHIN 200 NM OF THE TROF AXIS. THE NWRN GULF FEATURE IS MUCH WEAKER ONLY PRODUCING A NARROW LINE OF SCATTERED SHOWERS ALONG THE TROF AXIS AS DEPICTED ON DOPPLER RADAR FROM CORPUS CHRISTI OR HOUSTON/GALVESTON. THE STRONG HIGH WILL CONTINUE TO RETREAT N AND E AS A WEAK COLD FRONT PUSHES OFF THE TEXAS COAST ON TUE. THIS PATTERN WILL ALLOW WINDS TO SLACKEN SLIGHTLY IN THE E AND CENTRAL GULF LATE MON AND TUE. THE CARIBBEAN SEA... WIDESPREAD CLOUDINESS AND SCATTERED SHOWERS ARE THE RULE ACROSS A GOOD PORTION OF THE NRN AND WRN CARIBBEAN NW OF A LINE FROM ERN HONDURAS TO HAITI. THIS WEATHER IS BEING PRODUCED BY SWIFT SWLY UPPER LEVEL FLOW ASSOCIATED WITH A PORTION OF THE SUBTROPICAL JET AND LOW-LEVEL LIFT NEAR A SFC TROUGH EXTENDING FROM 15N82W TO THE YUCATAN CHANNEL CONTINUING NWD INTO THE GULF OF MEXICO. ANOTHER CONTRIBUTING FEATURE IS THE TAIL END OF A SLOWLY WEAKENING STATIONARY FRONT WHICH LIES FROM HAITI NE INTO THE WRN/CENTRAL ATLC. SCATTERED MODERATE CONVECTION EXISTS IN THE SW CARIB FROM 10N-13N BETWEEN 81W-84W ASSOCIATED WITH UPPER DIFFLUENCE AND THE ITCZ. ELSEWHERE THE WEATHER IS FAIRLY QUIET IN THE CENTRAL AND EASTERN CARIBBEAN UNDER THE INFLUENCE OF A FLAT UPPER RIDGE. VERY DRY AIR ALOFT IS BEING ADVECTED FROM THE TROPICAL ATLC....WHERE UPPER LEVEL CONFLUENCE IS PRONOUNCED ...INTO THE ERN CARIBBEAN PROVIDING A STRONG MID LEVEL CAP PREVENTING THE TYPICAL TRADE WIND CLOUD STREAKS ACQUIRE MUCH DEPTH. HIGH PRES TO THE N OF THE REGION WILL GRADUALLY PULL FURTHER N AND THE SFC TROUGH IN THE W CARIB WILL WEAKEN WHICH WILL HELP WINDS TO RELAX IN THE NW CARIB EARLY THIS WEEK. THE ATLANTIC OCEAN... A MID TO UPPER LEVEL TROUGH/RIDGE/TROUGH PATTERN DOMINATES THE SUBTROPICAL AND TROPICAL ATLANTIC. STARTING FROM W TO E...AN UPPER TROUGH EXTENDS FROM 32N70W TOWARD THE BAHAMAS. STRONG MID-UPPER LEVEL SWLY FLOW OR JET LIES ON THE E SIDE OF THE TROUGH EXTENDING FROM THE SW BAHAMAS NE ALONG 29N68W 3260W. THE ATTENDANT SFC FRONTAL SYSTEM IS STATIONARY FROM 32N48W STRETCHING SWWARD ALONG 27N60W 23N67W TO WRN HAITI. WIDESPREAD BROKEN TO OVERCAST MULTILAYERED CLOUDS AND EMBEDDED SCATTERED SHOWERS/TSTMS ARE WITHIN 300 NM W OF THE STATIONARY BOUNDARY. STRONG SFC HIGH PRESSURE...ANCHORED BY A 1035 MB HIGH NEAR THE CAROLINA COASTLINE IS BEHIND THE FRONT GENERATING NE WINDS OF 20-30 KT ACROSS THE SW NORTH ATLC AND THE BAHAMAS. THESE STRONG WINDS ACROSS A LONG FETCH IS CREATING HIGH SEAS WITH NE SWELL W OF THE FRONT. THE UPPER LEVEL PATTERN IS MORE AMPLIFIED IN THE CENTRAL AND ERN ATLC AS A STRONGLY TITLED RIDGE EXTENDS NEWARD FROM THE CARIBBEAN ALONG 23N58W 32N45W. THE FLOW THEN FOLDS INTO A VERY LARGE TROUGH WHICH EXTENDS FROM AN UPPER LOW OVER MOROCCO TO ANOTHER LARGER UPPER LOW NEAR 22N33W CONTINUING SW TO 12N55W. THE LATTER UPPER LOW HAS AN ASSOCIATED ILL-DEFINED SFC TROUGH FROM 17N36W TO 25N34W. SCATTERED SHOWERS ARE WITHIN 300 NM EITHER SIDE OF THE TROUGH AXIS. THESE UPPER LOWS ARE JUST ABOUT BECOMING CUT OFF AS AN UPPER RIDGE IS BUILDING BETWEEN THEM. VERY DRY STABLE AIR ALOFT...DUE TO UPPER LEVEL CONFLUENCE...IS WIDESPREAD BETWEEN 40W AND THE FRONTAL BOUNDARY. THIS DRY AIR IS ALSO SPREADING INTO THE ERN CARIB. ABUNDANT UPPER LEVEL MOISTURE ADVECTED FROM THE ITCZ AND ENHANCED BY STRONG SWLY UPPER LEVEL WINDS ON THE E SIDE OF THE LARGE TROUGH EXISTS SE OF A LINE ALONG 12N38W 23N21W 26N14W. THE SFC PATTERN IS DOMINATED BY A STRONG 1039 MB HIGH JUST S OF THE AZORES NEAR 37N25W. THE TIGHT PRES GRAD IS PRODUCING A LARGE AREA OF STRONG WINDS MOSTLY N OF 12N E OF 45W. $$ CANGIALOSI