000 AXNT20 KNHC 201724 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST MON NOV 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...WEATHER OBSERVATIONS...RADAR... AND METEOROLOGICAL ANALYSIS. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...TROPICAL WAVES... THE TROPICAL WAVE PREVIOUSLY ALONG 85W HAS BEEN DROPPED FROM THE SFC ANALYSIS AT 12Z. THIS FEATURE IS NO LONGER DISCERNIBLE IN SATELLITE IMAGERY OR SFC OBSERVATIONS AS IT APPEARS THAT IT WAS ABSORBED BY A LARGE CONVECTIVE SFC TROUGH IN THE WRN CARIBBEAN. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 8N13W 5N30W 4N40W 2N50W. SCATTERED MODERATE CONVECTION IS WITHIN 180 NM EITHER SIDE OF THE AXIS BETWEEN 14W-20W. ISOLATED MODERATE IS WITHIN 240 NM EITHER SIDE BETWEEN 24W-30W. ...DISCUSSION... THE GULF OF MEXICO... A STRONG ELONGATED UPPER TROUGH CONTINUES TO DIG SOUTHEASTWARD NOW LOCATED ACROSS THE OHIO VALLEY INTO THE NW GULF. MID/UPPER LEVEL SWLY FLOW S AND E OF THE DIGGING TROUGH IS ADVECTING SOME MOISTURE FROM THE TROPICAL EPAC...IN WHICH T.D. SERGIO IS EMBEDDED...ACROSS THE SRN GULF SE OF A LINE ALONG 21N97W 25N87W TO NEAR ORLANDO. THIS MOISTURE IS NOT A BIG WEATHER PRODUCER AS IT IS MAINLY IN THE FORM OF MID-HIGH LEVEL CLOUDINESS AND ISOLATED SHOWERS FILTERING SUNSHINE. VERY DRY STABLE AIR ALOFT LIES N AND W OF THE LINE MENTIONED. AT THE SFC...STRONG HIGH PRES COVERS THE ENTIRE AREA ANCHORED BY A FEW 1035 MB HIGH CENTERS IN THE CENTRAL U.S. THE BIG STORY IS THE UNSEASONABLY COLD/DRY AIR AND INCREASING NLY WINDS DUE TO THE THE TIGHTENED PRES GRAD BETWEEN THIS STRONG HIGH AND A SFC LOW OFF THE GEORGIA COAST. SFC WINDS HAVE BEEN INCREASING THIS MORNING/EARLY AFTERNOON WITH MOST BUOYS REPORTING WINDS IN THE 15-25 KT RANGE. THIS FLOW CONTINUES TO ADVECT COLD/DRY AIR INTO THE REGION WITH HIGH TEMPS MAINLY IN THE 50'S AND 60'S. MODELS FORECAST THE UPPER TROUGH TO CONTINUE TO DIG SE AND BECOME CUT OFF OVER FLORIDA/GEORGIA LATE TOMORROW SIGNIFICANTLY LOWERING HEIGHTS. THIS COLD AIR ALOFT ALONG WITH NLY FLOW AT THE SFC WILL CONTINUE TO PRODUCE UNSEASONABLE COOL WEATHER ACROSS THE CENTRAL AND E GULF OVER THE NEXT FEW DAYS. THE CARIBBEAN SEA... A LARGE AREA OF SCATTERED MODERATE CONVECTION EXISTS IN THE CNTRL/WRN CARIBBEAN BETWEEN 74W-82W WHICH INCLUDES THE ISLANDS OF JAMAICA AND ERN CUBA. THIS UNSETTLED WEATHER IS ASSOCIATED WITH A SFC TROUGH WHICH EXTENDS FROM THE ATLC ACROSS THE BAHAMAS ALONG 21N73W 17N79W 11N80W. A 1048 UTC QSCAT PASS INDICATED A PRONOUNCED WIND SHIFT WHERE NLY 20-25 KT WINDS ARE COMMON W OF THE TROUGH AXIS AND LIGHTER E TO NE WINDS ARE E OF THE AXIS. IN ADDITION...VISIBLE IMAGES SHOW MID-LEVEL ROTATION IN THE CLOUDS NEAR 16N80W. IT IS POSSIBLE THAT A SFC LOW PRES SYSTEM MAY BE FORMING IN THAT VICINITY. UPPER LEVEL SWLY-WLY WINDS...NEAR AND W OF AN UPPER RIDGE AXIS ALONG 72W...ARE SPREADING MOISTURE AROUND THE RIDGE...BUT MUCH OF THIS IS QUICKLY DRYING OUT ON THE DESCENT NLY BRANCH ABOVE THE ERN CARIBBEAN. ISOLATED SHOWERS ARE N OF 15N BETWEEN 66W-74W. OTHERWISE...CONDITIONS ARE FAIRLY QUIET ACROSS THE REMAINDER OF THE E ATLC. GFS SHOWS THE DEEP MOISTURE SWATH LINGERING BUT SHRINKING IN SIZE OVER THE NEXT COUPLE DAYS IN THE CNTRL/WRN CARIBBEAN. THE ATLANTIC OCEAN... AN AMPLIFIED PATTERN LIES ACROSS THE ATLC BASIN. A REINFORCING COLD FRONT...ASSOCIATED WITH THE STRONG MID/UPPER TROUGH ACROSS THE CENTRAL/ERN U.S...STRETCHES ALONG 32N79W ACROSS THE WRN-MOST BAHAMAS TO N CUBA. NWLY WINDS ARE INCREASING BEHIND THIS BOUNDARY. SEE GULF OF MEXICO DISCUSSION FOR DETAILS ON THE AIRMASS BEHIND THIS FRONT. A LARGE TITLED RIDGE COVERS THE AREA BETWEEN 55W-75W INCLUDING MOST OF THE CARIB. AN OLD FRONTAL BOUNDARY LIES ALONG 32N63W 25N69W TO THE SE BAHAMAS. VERY ACTIVE WEATHER IS OCCURRING ALONG THE TAIL END OF THIS BOUNDARY IN THE CARIB BUT ONLY ISOLATED SHOWERS ARE WITHIN 180 NM EITHER SIDE OF THE TROUGH IN THE ATLC. ANOTHER SFC TROUGH LIES ALONG 31N49W 22N54W. A WEAK LOW PRES SYSTEM HAS FORMED ALONG THIS TROUGH NEAR 26N. THIS FEATURE IS VERY WEAK WITH ONLY ISOLATED SHOWERS NOTED WITHIN 240 NM E OF THE TROUGH AXIS N OF 25N. THIS SFC FEATURE IS ASSOCIATED WITH A SMALL UPPER LOW NEAR 26N50W. A NARROW UPPER RIDGE LIES TO THE E OF THE UPPER LOW/SFC TROUGH BETWEEN 35W-43W N OF 15N. THE REMAINDER OF THE ATLC...E OF 35W...IS DOMINATED BY A LARGE CUT OFF MID/UPPER LEVEL LOW CENTERED NEAR 26N23W. SCATTERED SHOWERS AND TSTMS ARE MAINLY CONTAINED ON THE N SIDE OF THE LOW FROM 26N-31W BETWEEN 17W-26W. A RELATED SFC TROUGH EXTENDS FROM 19N25W TO 31N18W. AT THE SFC...A 1034 MB HIGH IS CENTERED OVER THE AZORES. THIS STRONG RIDGING IS CONTAMINATED BY THE SFC TROUGHS DESCRIBED ABOVE. $$ CANGIALOSI