000 AXNT20 KNHC 272339 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT FRI OCT 27 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 40W S OF 13N MOVING W 10 TO 15 KT. THIS WAVE REMAINS RATHER LOW AMPLITUDE AND HAS BECOME LESS DEFINED THAN IT WAS YESTERDAY WITH LITTLE CURVATURE NOTED IN SAT IMAGES AND AVAILABLE SFC DATA. FOR THESE REASONS...THE AXIS IS CHALLENGING TO LOCATE AND BASED MOSTLY ON CONTINUITY. ASSOCIATED ISOLATED MODERATE CONVECTION IS WITHIN 300 NM EITHER SIDE OF THE AXIS. A TROPICAL WAVE IS ALONG 57W/58W S OF 21N MOVING W 10 TO 15 KT. A 1009 MB LOW IS ALONG THE WAVE NEAR 14N. THIS LOW PRES SYSTEM REMAINS FAIRLY WELL DEFINED. IN ADDITION...SHOWERS AND TSTMS HAVE INCREASED IN INTENSITY AND BECOME MORE ORGANIZED OVER THE PAST SEVERAL HOURS. SCATTERED MODERATE CONVECTION EXISTS FROM 11N-16N BETWEEN 53W-61W. THE WRN EDGE OF THIS CONVECTION IS MOVING ACROSS THE ERN CARIB ISLANDS...POSSIBLY PRODUCING SOME GUSTY WINDS. THE UPPER LEVEL ENVIRONMENT IS FORECAST TO BECOME SOMEWHAT MORE FAVORABLE NEAR THE SYSTEM FOR SOME ADDITIONAL DEVELOPMENT DURING THE NEXT DAY OR TWO. A WEAK TROPICAL WAVE IS ALONG 72W S OF 18N MOVING W 10 TO 15 KT. CYCLONIC WIND SHIFTS ARE NO LONGER EVIDENT IN THE LOW-LEVELS BASED UPON THE AVAILABLE DATA. THE WAVE IS EMBEDDED IN A SLIGHT MOISTENING ENVIRONMENT JUST S OF THE ATLC FRONTAL BOUNDARY/TROUGH...PRODUCING ONLY ISOLATED SHOWERS. ...THE ITCZ... ITCZ AXIS IS ALONG 10N14W 7N29W 6N47W 10N55W. BESIDES FOR THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED MODERATE IS WITHIN 180 NM N AND 90 NM S OF THE AXIS BETWEEN 23W-35W. SIMILAR ACTIVITY IS WITHIN 120 NM EITHER SIDE BETWEEN 48W-53W. ...DISCUSSION... THE GULF OF MEXICO... A STRONG COLD FRONT...ASSOCIATED WITH A SHARP UPPER TROUGH CENTERED OVER THE CENTRAL US...CONTINUES TO MOVE QUICKLY SOUTHEASTWARD IN THE GULF. AS OF 2100 UTC...THE FRONT WAS ANALYZED FROM SRN ALABAMA TO 25N91W SURGING SWD TO MEXICO NEAR 20N97W THEN NWD ALONG THE E SLOPES OF THE SIERRA MADRE MOUNTAINS NEAR 22N99W. SCATTERED SHOWERS AND TSTMS ARE WITHIN 120 NM AHEAD OF THE COLD FRONT...BUT MORE CONVECTIVE WEATHER LIES FURTHER E IN THE WARM SECTOR ACROSS THE ERN FL PANHANDLE AND SWWARD INTO THE GULF FOR 200 NM. THIS SQUALL LINE IS QUICKLY MOVING EWARD. CLUSTERS OF MODERATE CONVECTION HAS ALSO BLOSSOMED NEAR THE BASE OF THE FRONT OVER MEXICO AND THE SW GULF FROM 18N-21N BETWEEN 96-100W. THIS FRONTAL BOUNDARY MARKS A CLEAR AIRMASS CHANGE FROM WARM AND HUMID TEMPS IN THE 80'S AND DEWPOINTS IN THE 70'S S E OF THE FRONT TO TEMPS FALLING THRU THE 60'S AND DEWPOINTS PLUMMETING INTO THE 40'S BEHIND THE BOUNDARY. STRONG NLY WINDS BETWEEN 20 AND 30 KT ARE COMMON BEHIND THE FRONT AND SIMILAR MAGNITUDE SWLY WINDS AHEAD OF THE FRONT AS STRONG SFC HIGH PRES BUILD IN. FOR MORE DETAILS IN WINDS AND WAVES REFER TO MIAOFFNT4 AND MIAHSFAT2. THIS FAST MOVING FRONT WILL LIKELY CLEAR THE ENTIRE AREA LATE TOMORROW. THE CARIBBEAN SEA... THE TAIL END OF AN ATLC FRONTAL BOUNDARY/TROUGH IS GRADUALLY FALLING APART IN THE NRN CARIBBEAN. THIS FEATURE IS ANALYZED AS A SFC TROUGH FROM HISPANIOLA TO THE YUCATAN CHANNEL. THERE IS ONLY SLIGHT WIND SHIFT AND SPEED GRADIENT ALONG THE BOUNDARY. A BROKEN LINE OF SCATTERED SHOWERS AND TSTMS ARE WITHIN 90 NM EITHER SIDE OF THE TROUGH. THIS ACTIVITY IS BEING ENHANCED BY UPPER DIFFLUENT FLOW BETWEEN A SPRAWLING UPPER HIGH CENTERED OVER CENTRAL CUBA AND A SMALL UPPER LOW NEAR 16N80W. THE SRN CARIB IS FAIRLY QUIET WITH MODERATE DRY AIR ALOFT IN PLACE ...HOWEVER DEBRIS MOISTURE...DRIVEN BY NLY UPPER LEVEL FLOW ACROSS THE OLD FRONTAL BOUNDARY...IS SPILLING INTO THE AREA SPARKING ISOLATED SHOWERS. THE MOST ACTIVE WEATHER IS IN THE ERN CARIB WHERE THE WRN EDGE OF MODERATE CONVECTION ASSOCIATED WITH A TROPICAL WAVE AND 1009 MB LOW IS NOW MOVING ACROSS THE WINDWARD ISLANDS. LOCALLY HEAVY RAINS AND GUSTY WINDS ARE POSSIBLE AS THE SYSTEM CONTINUES TO MOVE W ACROSS THE LESSER ANTILLES TONIGHT AND TOMORROW. FOR MORE INFORMATION ON THIS SYSTEM REFER TO THE TROPICAL WAVES SECTION. THE ATLANTIC OCEAN... A HIGHLY AMPLIFIED PATTERN REMAINS ESTABLISHED ACROSS THE ATLC. HIGH PRES RIDGING EXISTS ACROSS MUCH OF THE CARIBBEAN AND WRN ATLC W OF 62W. A LARGE SLOWLY WEAKENING TROUGH LIES TO THE E OF THE RIDGE AND COVERS MUCH OF THE CENTRAL ATLC BETWEEN 40W AND 62W N OF 20N. AN ASSOCIATED COLD FRONT CONTINUES TO SLOWLY BECOME LESS DEFINED ALONG 32N42W 24N56W THEN ANALYZED A TROUGH/SHEAR AXIS TO THE DOMINICAN REPUBLIC AND ACROSS THE NRN CARIBBEAN. SCATTERED SHOWERS AND TSTMS ARE WITHIN 180 NM E OF THE FRONT. BEHIND THE FRONT...A MODIFIED DRIER AND COOLER AIRMASS EXISTS. A LARGE STRONG MID/UPPER LEVEL RIDGE IS LOCATED E OF THE TROUGH CENTERED IN THE SUBTROPICS NEAR 29N29W. THIS RIDGE COVERS THE REMAINDER OF THE ATLC E OF 40W N OF 20N WITH DRY STABLE AIR ALOFT WIDESPREAD IN THE REGION. SFC HIGH PRES IS ALSO ANALYZED UNDERNEATH THE MID/UPPER RIDGE WITH A 1023 MB HIGH NEAR 32N27W. IN THE DEEP TROPICS...AN UPPER HIGH IS CENTERED NEAR 13N53W. THE TROPICAL WAVE AND AREA OF LOW PRES APPROACHING THE ERN CARIBBEAN LIES ON THE WRN EDGE OF THIS ANTICYCLONE. AN UPPER LOW LIES TO THE E OF TH ANTICYCLONE CENTERED NEAR 17N38W... ERODING THE SWRN EDGE OF THE AMPLIFIED RIDGE IN THE SUBTROPICS. THIS LOW IS PROVIDING AN UNFAVORABLE ENVIRONMENT FOR THE TROPICAL WAVE NEAR 40W. UPPER DIFFLUENCE ON THE SE SIDE OF THE LOW IS ENHANCING CONVECTION IN THE ITCZ BETWEEN 25W-40W. $$ CANGIALOSI