000 AXNT20 KNHC 242350 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE OCT 24 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 2330 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 38W S OF 17N MOVING W NEAR 15 KT. LOW TO MID LEVEL CYCLONIC TURNING IS NOTED ABOUT THE WAVE AXIS ON VIS AND SHORTWAVE IR IMAGES. A FEW SFC OBS ALSO SHOWED GOOD TURNING IN THE WINDS FROM S-SE E OF THE WAVE TO ENE W OF THE WAVE...MAKING IT RELATIVELY EASY TO LOCATE. THIS WAVE IS CURRENTLY UNDERNEATH A SMALL UPPER HIGH WHICH IS SPREADING UPPER LEVEL MOISTURE ANTICYCLONICALLY AROUND THE FEATURE. STRONG WLY WINDS ON THE N SIDE OF THE UPPER HIGH IS PROVIDING AN UNFAVORABLE ENVIRONMENT ACROSS THE NRN EXTENSION OF THE WAVE. SCATTERED MODERATE CONVECTION IS WITHIN 300 NM EITHER SIDE OF THE AXIS S OF 14N. A FAIRLY LARGE TROPICAL WAVE IS NEARING THE LESSER ANTILLES ALONG 60W S OF 20N MOVING W NEAR 15 KT. THE WAVE AXIS IS ANALYZED NEAR THE WRN EDGE OF A WIDE AREA OF ISOLATED TO SCATTERED MODERATE CONVECTION BETWEEN 50W-59W FROM 12N-18N. SFC OBSERVATIONS HELPED LOCATE THE AXIS. NWLY UPPER LEVEL FLOW...BETWEEN AN UPPER HIGH IN THE ERN CARIBBEAN AND AN UPPER LOW NE OF THE WAVE...IS SHEARING MUCH OF THE CONVECTION E OF THE WAVE AXIS. TROPICAL WAVE IS ALONG 76W S OF 19N DRIFTING SLOWLY TO THE W. IT APPEARS THIS WAVE IS SLOWING AND BECOMING TILTED FROM SE TO NW...AND MAY BECOME EVEN MORE DIFFICULT TO TRACK AS IT INTERACTS WITH THE APPROACHING FRONTAL SYSTEM FROM THE NW. DEEP CONVECTION IS MINIMAL WITH A FEW ISOLATED SHOWERS/TSTMS NOTED WITHIN 100NM OF THE AXIS...WHICH IS LIKELY ENHANCED OR ASSOCIATED WITH MOIST SSW UPPER LEVEL FLOW ON THE E SIDE OF AN UPPER LOW IN THE WRN CARIBBEAN. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 9N13W 9N30W 11N40W 14N57W 11N64W. BESIDES FOR THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED MODERATE CONVECTION IS WITHIN 180 NM N OF THE AXIS BETWEEN 42W-50W. SCATTERED MODERATE IS ALSO WITHIN 180 NM S OF THE AXIS BETWEEN 61W-71W...THIS IS MOSTLY INLAND OVER NRN S AMERICA. ...DISCUSSION... GULF OF MEXICO... A STRONG COLD FRONT CLEARED THE ENTIRE AREA LATE YESTERDAY ALLOWING MUCH COOLER AND DRIER AIR TO BUILD INTO THE ERN PORTION OF THE AREA. TEMPS AND DEWPOINTS ARE UNSEASONABLY LOW ACROSS THE STATE OF FLORIDA. NLY SFC WINDS WHICH WERE IN THE 15-25 KT RANGE EARLIER TODAY IN THE ERN GULF ARE SUBSIDING. MILDER CONDITIONS EXIST ACROSS THE CENTRAL AND WRN GULF UNDER MAINLY ELY WINDS S OF THE SFC HIGH PRES SYSTEM OVER THE CENTRAL U.S. THE ONLY AREA OF SHOWER ACTIVITY IS IN THE SW GULF FROM 18N-22N BETWEEN 94W-97W. THESE SCATTERED SHOWERS ARE ASSOCIATED WITH A SFC TROUGH...WHICH BROKE OFF FROM THE MAIN FRONTAL SYSTEM IN THE WRN ATLC/CARIBBEAN...AND SOME ENHANCEMENT FROM SLY UPPER LEVEL FLOW ON THE W SIDE OF AN UPPER HIGH CENTERED NEAR 21N93W. SFC HIGH PRES WILL CONTINUE TO MOVE EWARD ALLOWING WARMER RETURN FLOW TO DEVELOP BEFORE THE NEXT COLD FRONT ENTERS THE NW PART OF THE AREA LATE THU/EARLY FRI. CARIBBEAN SEA... AN UPPER LEVEL TROUGH/RIDGE PATTERN IS ESTABLISHED ACROSS THE CARIBBEAN. AN UPPER LOW REMAINS NEARLY STATIONARY OVER THE WRN CARIBBEAN NEAR 17N82W. THE WEAK SFC TROUGH ASSOCIATED WITH THIS UPPER LOW...THAT ALSO HAS BEEN STATIONARY OVER THE PAST COUPLE OF DAYS...APPEARS TO HAVE DISSIPATED. THE TAIL END OF AN ATLC FRONTAL BOUNDARY CUTS ACROSS THE NW CARIBBEAN FROM CENTRAL CUBA TO THE YUCATAN PENINSULA NEAR 19N88W. ISOLATED SHOWERS AND TSTMS ARE WITHIN 90 NM S OF THE BOUNDARY. SIMILAR ISOLATED ACTIVITY EXISTS ACROSS THE SW CARIBBEAN ASSOCIATED WITH A WEAK TROPICAL WAVE ALONG 76W AND MOIST SLY FLOW...ON THE E SIDE OF THE UPPER LOW MENTIONED...ADVECTING SOME TROPICAL MOISTURE FROM THE ITCZ NWD. THE ERN CARIBBEAN IS DOMINATED BY AN UPPER RIDGE WHICH IS CENTERED NEAR 16N64W. MODERATELY DRY AIR ALOFT IS ASSOCIATED WITH THE RIDGE. SCATTERED MODERATE TO STRONG CONVECTION HAS BLOSSOMED OVER THE PAST FEW HOURS OVER THE ISLANDS OF PUERTO RICO AND HISPANIOLA...WHICH IS LIKELY ASSOCIATED WITH LOCAL TOPOGRAPHIC LIFT...LOW LEVEL CONVERGENCE NEAR A PRE-FRONTAL TROUGH AND SLY UPPER FLOW. SOME MOISTURE...ASSOCIATED WITH A LARGE TROPICAL WAVE E OF THE AREA...WILL BEGIN TO SPREAD ACROSS THE LESSER ANTILLES LATER TOMORROW AND THU. ATLANTIC OCEAN... THE WRN ATLC IS DOMINATED BY A LARGE DEEP LAYER TROUGH WITH PLENTY OF VERY DRY AIR ALOFT N OF 25N W OF 62W. AN ASSOCIATED STRONG SURFACE COLD FRONT IS PUSHING THROUGH THE AREA ANALYZED ALONG 32N62W 26N70W TO CENTRAL CUBA. THIS HAS USHERED IN SOME OF THE COOLEST AIR OF THE SEASON THUS FAR WITH WIDESPREAD COLD AIR STRATOCUMULUS CLOUDS BEHIND THE BOUNDARY...ALONG WITH INCREASING N/NW FLOW AND RISING SHORT TO MEDIUM PERIOD SWELL. ASSOCIATED SWELL WILL SPREAD E THROUGH THE CARIBBEAN THROUGH THE END OF THE WORK WEEK BRINGING THE FIRST APPRECIABLE WINTER-LIKE SWELL EVENT OF THE SEASON...SEE STATEMENTS FROM LOCAL WEATHER SERVICE OFFICES AND MIAOFFNT3 FOR MORE DETAILS. A PREFRONTAL TROUGH ANALYZED ALONG 21N68W 29N63W MAY BE EXTENDED SLIGHTLY FURTHER S TO ACCOUNT FOR THE CONVECTIVE BLOW-UP OVER HISPANIOLA. SCATTERED MODERATE CONVECTION IS WITHIN 180 NM E OF THE SFC TROUGH...MOVING QUICKLY EWARD. IN THE CENTRAL ATLC...A WELL DEFINED UPPER LOW IS CENTERED NEAR 22N50W. NW-W UPPER LEVEL FLOW ON THE SW PERIPHERY OF THIS FEATURE IS PROVIDING MODERATE TO STRONG SHEAR ACROSS THE TROPICAL WAVE NEAR THE LESSER ANTILLES. AN AMPLIFIED MID-LEVEL SUBTROPICAL RIDGE CENTERED NEAR 27N42W IS SURROUNDED BY VERY DRY AIR BETWEEN 30W AND 55W. A 1019 MB SFC HIGH IS BENEATH IT NEAR 29N44W WITH ANOTHER WEAKENING 1017 MB HIGH NEAR 22N34W. A WEAK SFC TROUGH LIES BETWEEN THE HIGHS ALONG 22N51 26N37W. ONLY A LINE OF LOW CLOUDS AND WEAK ISOLATED SHOWERS ARE NEAR THE BOUNDARY. LARGE UPPER TROUGHING DOMINATES THE ERN ATLC FROM THE CANARY ISLANDS TO A CUT OFF LOW CENTERED NEAR 18N27W. ASSOCIATED MOISTURE IS CONFINED TO WITHIN 360 NM E OF THE THE UPPER LOW. $$ CANGIALOSI