000 AXNT20 KNHC 201043 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1030 UTC. ...TROPICAL WAVES... A FAIRLY LARGE TROPICAL WAVE IS ALONG 39W/40W S OF 20N MOVING W 10 TO 15 KT OVER THE PAST 24 HOURS. A 1009 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. S TO SWLY UPPER LEVEL WINDS...ON THE SW PERIPHERY OF AN UPPER RIDGE CENTERED NEAR THE CAPE VERDE ISLANDS...ARE SHEARING MUCH OF THE CONVECTION AND STRETCHING HIGH CLOUDINESS WELL TO THE N/NE OF THE WAVE LEAVING THE SFC LOW EXPOSED. ISOLATED MODERATE CONVECTION IS WITHIN 240 NM E OF THE WAVE AXIS. MORE ORGANIZED MODERATE CONVECTION IS FURTHER E FROM 12N-16N BETWEEN 30W-34W. A WEAK TROPICAL WAVE IS ALONG 51W S OF 16N 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 10N14W 10N32W 12N37W 9N52W 11N63W. BESIDES FOR THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...CLUSTERS OF MODERATE CONVECTION IS WITHIN 360 NM S OF THE AXIS BETWEEN 58W-63W...WHICH IS MAINLY INLAND OVER 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 OVER SW FLORIDA...AS A RATHER STRONG SHORTWAVE TROUGH MOVES INTO THE NW PORTION. AN ASSOCIATED COLD FRONT STRETCHES FROM THE FLORIDA PANHANDLE SOUTHWESTWARD ALONG 28N88W 23N96W 21N98W 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 LOW 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...SMALL CLUSTERS OF MODERATE CONVECTION ARE LOCATED JUST W OF THE AREA OVER A PORTION OF ERN MEXICO ASSOCIATED WITH TROPICAL MOISTURE DRAWN NWD FROM 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 ANALYZED JUST N OF HISPANIOLA AND A SFC TROUGH THAT EXTENDS FROM THIS LOW TO THE NRN COAST OF COLOMBIA. WHILE PRESSURES ARE LOW IN THE AREA...THE LOW ITSELF IS POORLY ORGANIZED WITH LITTLE CONVECTION NEAR ITS BROAD ILL-DEFINED CENTER. SCATTERED SHOWERS AND TSTMS ARE WITHIN 240 NM OF THE SFC BOUNDARY...ESPECIALLY S OF 16N. SIMILAR ACTIVITY IS ALSO OCCURRING FARTHER E ACROSS THE VIRGIN ISLANDS EXTENDING NE FOR 200 NM. THIS ACTIVITY IS MAINLY PRODUCED BY UPPER DIFFLUENT AIR AND MOIST SWLY FLOW ON THE E SIDE OF THE LARGE CUT OFF LOW OVER HISPANIOLA. FAIR WEATHER DOMINATES MUCH 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'S 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 AS THE SFC TROUGH REMAINS NEARLY STATIONARY. THEREAFTER MORE TYPICAL EASTERLY TRADES WILL RESUME. 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. THE DRIEST AIR NOTED ON WATER VAPOR IMAGES IS LOCATED BETWEEN 63W AND 80W. A COMPLEX TROUGH PATTERN LIES E OF THE RIDGE COVERING THE CENTRAL ATLC BETWEEN 40W AND 65W-70W. TWO SFC LOWS ARE EMBEDDED IN THIS TROUGHING. A 1010 MB FRONTAL LOW IS LOCATED NEAR 31N51W WITH A COLD FRONT EXTENDING SWD TO 27N54W. A 1005 MB LOW IS LOCATED NEAR HISPANIOLA WITH A SFC TROUGH EXTENDING WELL S TOWARDS S AMERICA AND N TO 26N67W. 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 19N BETWEEN 55W AND 57W AND ANOTHER CLUSTER NEAR THE VIRGIN ISLANDS. 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 25W 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 40W. THE SFC PATTERN IS DOMINATED BY A E-W RIDGE AXIS FROM A 1019 MB HIGH NEAR 27N33W AND A 1017 MB HIGH NEAR 28N14W. $$ CANGIALOSI