000 AXNT20 KNHC 211723 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST TUE NOV 21 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. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 9N13W 6N26W 4N37W 3N46W 3N54W. THE ITCZ IS FAIRLY QUIET WITH ONLY ISOLATED MODERATE FROM 4N-9N BETWEEN 26W-30W. ELSEWHERE SCATTERED SHOWERS ARE WITHIN 300 NM EITHER SIDE OF THE AXIS. ...DISCUSSION... THE GULF OF MEXICO... THE STRONG TROUGH THAT WAS DIGGING ACROSS THE SRN U.S. YESTERDAY HAS CUT OFF OVER N FLORIDA/S GEORGIA. THIS WAS WELL FORECAST BY MANY OF THE MODELS. THE GULF LIES TO THE W...DRY SIDE...OF THIS SYSTEM WITH STRONG NLY MID-UPPER LEVEL FLOW AND MODERATE TO STRONG SUBSIDENCE NOTED ACROSS NEARLY THE ENTIRE AREA. THERE IS SOME BROKEN MOISTURE ACROSS THE SRN BAY OF CAMPECHE S OF 20N...BUT THIS IS LIKELY ONLY PRODUCING ISOLATED SHOWERS. AT THE SFC...STRONG HIGH PRES COVERS THE ENTIRE AREA ANCHORED BY A 1033 MB HIGH IN NRN LOUISIANA. THE BIG STORY CONTINUES TO BE THE UNSEASONABLY COLD AIR AND STRONG NLY WINDS DUE TO THE TIGHT PRES GRAD BETWEEN THIS STRONG HIGH AND A SFC LOW OFF THE FLORIDA/GEORGIA COAST. NLY WINDS ARE STRONGEST IN THE E AND CENTRAL GULF WHERE SEVERAL BUOYS ARE REPORTING WINDS BETWEEN 20-30 KT. CONDITIONS ARE SUBSIDING AND DEVELOPING AN EASTERLY COMPONENT IN THE NW GULF...CLOSE TO THE SFC HIGH CENTER. BROKEN STRATO-CU CLOUDS ARE WIDESPREAD ACROSS THE E GULF...THESE CLOUDS ARE THICKEST IN THE EXTREME ERN GULF WHERE DOPPLER RADAR IS INDICATING SCATTERED SHOWERS OFF THE W COAST FROM TAMPA BAY SWD. THE STACKED LOW OFF THE FL/GA COAST WILL BEGIN TO PULL NE AS AN UPPER RIDGE BUILDS OVERHEAD LATER THIS WEEK. THIS WILL ALLOW THE AIRMASS TO MODIFY...HOWEVER A COUPLE MORE DAYS OF BELOW NORMAL TEMPS IN THE CNTRL AND ERN GULF ARE STILL EXPECTED BEFORE IT DOES SO. THE CARIBBEAN SEA... A FAIRLY SHARP AIRMASS DIFFERENCE EXISTS IN THE CARIB. THE DIVIDER IS A STRONG COLD FRONT WHICH EXTENDS FROM THE ATLC ACROSS THE BAHAMAS/ERN CUBA EXTENDING SWD TOWARDS THE COAST OF PANAMA NEAR 10N82W. BEHIND THE FRONT...COOLER AND NOTABLE DRIER AIR IS ADVECTED INTO THE REGION ON STRONG NLY WINDS. THESE WINDS HAVE REACHED GALE FORCE S OF 18N BETWEEN 80W-85W. STRONG WINDS AND HIGH SEAS ARE ALSO REPORTED FROM SHIPS IN THE YUCATAN CHANNEL. FOR MORE DISCUSSION ON THIS UNSEASONABLE AIRMASS REFER TO THE GULF OF MEXICO SECTION AND FOR WINDS AND SEAS REFER TO MIAOFFNT3 AND MIAOFFNT4. ACTIVE WEATHER...IN TERMS OF SHOWERS AND TSTMS...LIES TO THE E OF THE FRONT. A PRE-FRONTAL TROUGH IS ANALYZED ABOUT 120-150 NM AHEAD OF THE FRONT FROM THE SE BAHAMAS SWD ALONG 17N76W 13N79W TO PANAMA. SFC OBSERVATIONS AND VIS IMAGES INDICATE A WIND SHIFT AND LINE OF LOW-LEVEL CONVERGENCE WHICH WAS THE REASON OF ANALYZING THIS FEATURE AHEAD OF THE MAIN BOUNDARY. SCATTERED SHOWERS AND TSTMS ARE WITHIN 150 NM AHEAD OF THE FRONT. HOWEVER MORE IMPRESSIVE ACTIVITY...NUMEROUS MODERATE CONVECTION...IS NEAR THE BASE OF THE FRONT S OF 13N BETWEEN 75W-82W. NUMEROUS MODERATE IS ALSO AHEAD OF THE TROUGH/FRONT FROM 12N-18N BETWEEN 72W-76W. SOME OF THIS STRONGER ACTIVITY IS BEING ENHANCED BY UPPER LEVEL DIFFLUENCE BETWEEN A HIGHLY AMPLIFIED STRETCHED UPPER RIDGE AND THE STRONG TROUGHING ACROSS THE SW ATLC/GULF AND NW CARIB. THE ERN ATLC IS QUIET WITH UPPER LEVEL CONFLUENCE PRODUCING PLENTY OF DRY STABLE UPPER LEVEL AIR E OF 69W. GFS SHOWS THE DEEP MOISTURE SWATH REMAINING NEARLY STATIONARY BUT SHRINKING IN SIZE AND GRADUALLY WEAKENING OVER THE NEXT COUPLE DAYS IN THE CNTRL/WRN CARIBBEAN. THE ATLANTIC OCEAN... A HIGH AMPLIFIED PATTERN LIES ACROSS THE ATLC BASIN. A LARGE STACKED LOW IS OFF THE SE COAST...THE MID-UPPER LEVEL CENTER IS ALONG THE FL/GA COAST WHILE THE 1010 MB SFC LOW IS A LITTLE FURTHER SE CENTERED NEAR 30N78W. DOPPLER RADAR SHOWS BANDS OF NUMEROUS SHOWERS AND TSTMS N OF 28N...AFFECTING MUCH OF THE CAROLINAS. THIS LOW IS BECOMING OCCLUDED WITH THE COLD FRONT EXTENDING FROM THIS LOW ALONG 32N76W ACROSS THE CENTRAL BAHAMAS AND DEEP INTO THE CARIB. A PRE-FRONTAL TROUGH STRETCHES FROM 31N75W TO THE WINDWARD PASSAGE. THESE SFC BOUNDARIES ALONG WITH UPPER DIFFLUENCE IS GENERATING A CONSIDERABLE AMOUNT OF MOISTURE BETWEEN 65W-77W. W OF THE FRONT...MUCH COLDER AND DRIER AIR ADVECTED BY STRONG NWLY WINDS EXIST WITH A GALE WARNING IN PLACE FOR THE AREA N OF 28N W OF 78W. A STRONG TITLED MID-UPPER RIDGE LIES TO THE E OF THE COMPLEX WEATHER PATTERN WITH THE AXIS EXTENDING FROM HISPANIOLA NORTHEASTWARD TO WELL BEYOND 32N57W. A NARROW TROUGH IS LOCATED TO THE E OF THE RIDGE WITH SEVERAL UPPER LEVEL LOWS EMBEDDED FROM 32N39W TO 23N45W EXTENDING DEEP INTO THE TROPICS TO AN UPPER LOW NEAR 17N53W. PLENTY OF DRY AIR LIES ACROSS MOST OF THE AREA BETWEEN 40W-67W EXCEPT FOR AN AREA OF SCATTERED SHOWERS ON THE S AND E SIDE OF THE SRN-MOST UPPER LOW FROM 6N-12N BETWEEN 43W-60W. THE REMAINDER OF THE ATLC...E OF 38W...IS DOMINATED BY A LARGE CUT OFF MID/UPPER LEVEL LOW CENTERED NEAR 28N24W. AN ASSOCIATED SFC LOW HAS DEVELOPED WITH SEVERAL MESO-SWIRLS ROTATING AROUND A MEAN CENTER NEAR 26N29W. THIS SFC SYSTEM IS VERY WEAK...ANALYZED AT 1017 MB...ONLY GENERATING ISOLATED SHOWERS TO THE NE OF THE LOW WITHIN 400 NM. AT THE SFC...A 1033 MB HIGH IS CENTERED OVER THE AZORES. THIS STRONG RIDGING DOMINATES THE CENTRAL AND ERN ATLC. $$ CANGIALOSI