000 AXNT20 KNHC 200544 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT FRI OCT 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0530 UTC. ...TROPICAL WAVES... A FAIRLY LARGE TROPICAL WAVE IS ALONG 38W S OF 20N MOVING W 10 TO 15 KT. A 1008 MB LOW IS ALONG THE WAVE NEAR 14N. BROAD LOW TO MID LEVEL CLOUDS ARE TURNING CYCLONICALLY ABOUT THE WAVE AXIS ESPECIALLY NEAR THE WEAK AREA OF LOW PRES. A 2024 UTC QUIKSCAT PASS INDICATED THAT THE STRONGEST UNCONTAMINATED WINDS ARE NEAR 20 KT. SWLY UPPER LEVEL WINDS ARE SHEARING MUCH OF THE CONVECTION AND STRETCHING HIGH CLOUDINESS WELL TO THE NE OF THE WAVE LEAVING THE SFC LOW EXPOSED. ISOLATED MODERATE CONVECTION IS WITHIN 240 NM E OF THE WAVE AXIS. A WEAK TROPICAL WAVE IS ALONG 50W S OF 18N MOVING W NEAR 15 KT. THIS WAVE HAS BECOME DIFFICULT TO LOCATE AS LITTLE...IF ANY...WAVE SIGNATURE IS OBVIOUS IN SATELLITE IMAGERY AND SFC OBSERVATIONS. THIS FEATURE IS MOVING INTO AN AREA OF PERSISTENT UNSETTLED WEATHER ASSOCIATED WITH A CENTRAL ATLC TROUGH AND WILL LIKELY BE CHALLENGING TO TRACK OVER THE NEXT COUPLE DAYS. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 10N15W 10N32W 13N37W 9N51W 12N70W 11N84W. SCATTERED MODERATE CONVECTION IS E OF 19W FROM 8N-11N. SIMILAR CONVECTION IS WITHIN 300 NM N OF THE AXIS BETWEEN 22W-33W...LIKELY ENHANCED OR ASSOCIATED WITH THE TROPICAL WAVE ALONG 38W. SCATTERED MODERATE IS WITHIN 300 NM S OF THE AXIS BETWEEN 58W-76W...WHICH IS MOSTLY INLAND OVER NRN S AMERICA. ...DISCUSSION... THE GULF OF MEXICO... THE LARGE MID/UPPER LEVEL ANTICYCLONE THAT HAS BEEN CENTERED OVER THE GULF OVER THE PAST FEW DAYS IS BECOMING ELONGATED AND PUSHED E...NOW CENTERED IN THE E GULF NEAR 27N85W...AS A RATHER STRONG SHORTWAVE TROUGH MOVES INTO THE NW PORTION. AN ASSOCIATED COLD FRONT STRETCHES FROM THE FLORIDA PANHANDLE SOUTHWESTWARD ALONG 28N91W 24N96W 22N98W THEN STATIONARY ALONG THE E SLOPES OF THE SIERRA MADRE MOUNTAINS IN MEXICO. ONLY ISOLATED TO SCATTERED SHOWERS ARE ALONG THE FRONT. THIS FRONTAL BOUNDARY IS EASILY NOTICEABLE WITH TEMPS AND DEWPOINTS SHARPLY FALLING BEHIND THE BOUNDARY. AHEAD OF THE FRONT TEMPS AND DEWPOINTS ARE IN THE MID TO UPPER 70'S IN N FLORIDA. THESE VALUES ARE IN THE 50'S AND 60'S BEHIND THE BOUNDARY ACROSS COASTAL MS/LA...AND EVEN COOLER/DRIER TO THE N AND W. LITTLE SHOWER ACTIVITY EXISTS ACROSS MOST OF THE AREA WITH MODERATE DRY AIR ALOFT IN PLACE. HOWEVER...CLUSTERS OF MODERATE CONVECTION ARE LOCATED JUST W OF THE AREA OVER A PORTION OF ERN MEXICO ASSOCIATED WITH TROPICAL MOISTURE DRAWN NWD FROM THE ITCZ AND AN AREA OF LOW PRES IN THE EPAC. THE CARIBBEAN SEA... SOME UNSETTLED WEATHER IS STILL OCCURRING IN THE ERN CARIBBEAN ASSOCIATED WITH A 1005 MB LOW OVER HISPANIOLA AND A SFC TROUGH THAT EXTENDS FROM THIS LOW TO THE NRN COAST OF COLOMBIA. THIS SFC LOW IS POORLY ORGANIZED WITH LITTLE CONVECTION NEAR ITS BROAD CENTER. SCATTERED SHOWERS AND TSTMS ARE WITHIN 120 NM OF THE SFC BOUNDARY. MOST OF THE WEATHER IS FURTHER E ACROSS THE VIRGIN ISLANDS EXTENDING NE FOR 200 NM. MORE SHOWER ACTIVITY IS E OF THE LESSER ANTILLES WHERE UPPER DIFFLUENCE IS STRONGER. FAIR WEATHER EXISTS ACROSS MOST OF THE CENTRAL AND WRN CARIBBEAN...W OF 75W...AS VERY DRY STABLE AIR CONTINUES TO BE ADVECTED INTO THE REGION ON THE SRN PERIPHERY OF THE GULF OF MEXICO UPPER RIDGE. SFC WINDS ARE LIGHT AND VARIABLE ACROSS THE AREA WITH WLY WINDS BEING REPORTED W OF THE TROUGH TO 75W OR SO. THESE WINDS ARE EXPECTED TO REMAIN RATHER VARIABLE FRI AND SAT WITH THE SFC TROUGH DRIFTING WWD. THE ATLANTIC OCEAN... A LONGWAVE RIDGE/TROUGH/RIDGE PATTERN EXISTS ACROSS THE ATLC BASIN. STARTING FROM W TO E...A SPRAWLING ELONGATED UPPER RIDGE CENTERED OVER THE ERN GULF HAS RIDGING THAT EXTENDS WELL NE OF BERMUDA. DRY STABLE AIR ALOFT IS ASSOCIATED WITH THE RIDGE... WITH THE DRIEST AIR LOCATED BETWEEN 65W AND 80W. A COMPLEX TROUGH PATTERN LIES E OF THE RIDGE COVERING THE CENTRAL ATLC BETWEEN 40W AND 65W. TWO SFC LOWS ARE EMBEDDED IN THIS TROUGHING. A 1010 MB LOW IS POSITIONED AT THE BASE OF A FRONT NEAR 30N51W WITH A SFC TROUGH EXTENDING SWD TO 24N57W. A 1005 MB LOW IS LOCATED OVER HISPANIOLA WITH A SFC TROUGH EXTENDING WELL S TOWARDS S AMERICA. A FAIR AMOUNT OF MOISTURE EXISTS IN THIS COMPLEX TROUGH BETWEEN 40W AND 65W S OF 25W AND BETWEEN 40W AND 52W N OF 25N. HOWEVER...MOST OF THE MOISTURE IS NOT VERY DEEP IN NATURE EXCEPT FOR A CLUSTER OF MODERATE CONVECTION FROM 17N TO 20N BETWEEN 55W AND 58W. FARTHER E...AN UPPER ANTICYCLONE IS CENTERED JUST E OF THE CAPE VERDE ISLANDS WITH RIDGING EXTENDING N/NE TO THE CANARY ISLANDS. THIS PATTERN IS ENHANCING CONVECTION IN THE ITCZ BETWEEN 22W AND 35W. SWLY FLOW ON THE WRN PERIPHERY OF THE RIDGE IS SHEARING HIGH CLOUDS AND DEEP CONVECTION NE AWAY FROM THE TROPICAL WAVE AND WEAK AREA OF LOW PRES NEAR 38W. THE SFC PATTERN IS FAIRLY WEAK ACROSS THE E ATLC WITH THE DOMINANT FEATURE BEING A 1020 MB HIGH NEAR 27N36W. $$ CANGIALOSI