000 AXNT20 KNHC 122331 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT AUG 12 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 HAS PULLED OFF THE W COAST OF AFRICA ALONG 18W S OF 19N MOVING W 5-10 KT OVER THE PAST 24 HOURS. DAKAR SOUNDINGS SUGGESTS THAT THE WAVE HAS MOVED THRU THE STATION NEAR 06Z. GFS HAS THIS WAVE INITIALIZED FAIRLY WELL AND INDICATES THAT IT WILL PICK UP SPEED AS IT TRACKS UNDER A LOW-MID LEVEL RIDGE. THE OVERALL STRUCTURE OF THE WAVE IS FAIR AT BEST AT THE MOMENT...AS IT IS EMBEDDED IN A QUASI-STATIONARY MONSOON TROUGH. PATCHES OF MODERATE CONVECTION LIES FROM 14N-17N BETWEEN 15W-19W. TROPICAL WAVE IS ALONG 53W S OF 19N...ABOUT 450 NM E OF THE LESSER ANTILLES...MOVING W 10-15 KT. THIS WAVE CONTINUES TO BE WELL-DEFINED WITH A CLASSIC INVERTED V-SHAPE EVIDENT ON SATELLITE IMAGERY. A 1011 MB LOW IS LOCATED ON THE WAVE NEAR 13N...MARKED ONLY BY A LOW CLOUD SWIRL. DESPITE THE VERY NICE SIGNATURE OF THE WAVE...IT CONTINUES TO BE EMBEDDED IN A DRY ENVIRONMENT LIMITING ANY ORGANIZED CONVECTION. THERE IS A PATCH OF MODERATE CONVECTION AHEAD OF THE WAVE AXIS FROM 11N-13N BETWEEN 56W-60W...LIKELY AIDED BY THE FLOW AROUND THE MID TO UPPER HIGH JUST TO THE NW OF THE WAVE. FURTHER DEVELOPMENT IS NOT EXPECTED. TROPICAL WAVE IN THE WRN CARIBBEAN IS ALONG 78W/79W S OF 21N MOVING W NEAR 15 KT. THIS WAVE REMAINS RATHER DISORGANIZED AND IS SHOWING NO SIGNS OF ORGANIZING. SATELLITE IMAGERY AND SURFACE WINDS IN THE VICINITY DO SHOW SOME CYCLONIC TURNING ABOUT THE AXIS...BUT DEEP CONVECTION NEAR THE WAVE N OF 12N REMAINS AT A MINIMUM. THIS PORTION OF THE WAVE LIES UNDERNEATH A FAIRLY DRY UPPER LEVEL LOW WHICH IS LIKELY HELPING TO SUPPRESS/DECOUPLE ANY LOW LEVEL INSTABILITY. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 14N16W 9N31W 12N50W TO INLAND OVER SOUTH AMERICA NEAR 10N62W. BESIDES FOR THE TROPICAL WAVES...SCATTERED SHOWERS AND TSTMS ARE WITHIN 120 NM EITHER SIDE OF THE AXIS BETWEEN 30W-36W. ELSEWHERE...ONLY ISOLATED SHOWERS DOT THE AXIS. ...DISCUSSION... GULF OF MEXICO... QUIET WEATHER CONTINUES ACROSS THE GULF OF MEXICO THIS EVENING WITH A SFC RIDGE STRETCHING FROM THE ATLC OCEAN ACROSS SOUTH FLORIDA TO A 1016 MB HIGH IN THE CENTRAL GULF NEAR 26N89W. THIS PATTERN IS KEEPING WINDS LIGHT AND ANTICYCLONIC AROUND THE SFC HIGH. THE BREEZIEST CONDITIONS ARE IN THE THE WRN GULF WHERE WINDS ARE FROM THE S-SE NEAR 15-20 KT. IN THE UPPER LEVELS...AN UPPER HIGH IS CENTERED ABOUT 150 NM E OF DAYTONA BEACH NEAR 29N78W. THE UPPER LEVEL LOW THAT HAS TRACKED ACROSS THE ENTIRE GULF OVER THE PAST FEW DAYS HAS SLOWED AND BECOME LESS ACTIVE JUST INLAND OVER NRN MEXICO/SRN TEXAS NEAR 26N98W. THIS UPPER LEVEL PATTERN IS PRODUCING PLENTY OF DRY STABLE AIR ACROSS THE E AND CNTRL GULF. HIGH CLOUDINESS AND POSSIBLY SOME ISOLATED SHOWERS ARE IN THE WRN GULF...BUT OVERALL A WARM DRY DAY IS THE THEME ACROSS THE ENTIRE AREA. RAIN CHANCES ARE LIKELY TO INCREASE IN THE NE GULF AND FLORIDA LATE TOMORROW AND EARLY NEXT WEEK ASSOCIATED WITH THE TAIL END OF A BACK-DOOR COLD FRONT. SOME INCREASE IN MOISTURE IS ALSO LIKELY LATE SUN/MON IN THE BAY OF CAMPECHE ASSOCIATED WITH AN APPROACHING TROPICAL WAVE. CARIBBEAN SEA... AN UPPER TROUGH DOMINATES MUCH OF THE CENTRAL AND WRN CARIBBEAN WITH TWO UPPER LOWS EMBEDDED IN THE TROUGH. THE AXIS EXTENDS FROM ONE UPPER LOW LOCATED NEAR THE SE BAHAMAS TO THE OTHER LOW ABOUT 100 NM S OF JAMAICA WITH THE BASE OF THE TROUGH DIGGING TO NEAR 13N82W. A NARROW UPPER HIGH IS CENTERED OVER GUATEMALA. UPPER DIFFLUENCE BETWEEN THESE FEATURES...AFTERNOON HEATING...LOCAL SEA-BREEZES AND UPSLOPE FLOW IS SPARKING SCATTERED SHOWERS/TSTMS OVER PORTIONS OF CENTRAL AMERICA AND DOTTED ACROSS THE NW CARIBBEAN SEA. SIMILAR ACTIVITY IS OCCURRING OVER CUBA. THE ERN CARIBBEAN IS DOMINATED BY MID-UPPER RIDGING AND DRY AIR...THOUGH A FEW SHOWERS AND TSTMS ARE MOVING E TO W ALONG THE SRN PERIPHERY OF THE UPPER HIGH ACROSS THE WINDWARD ISLANDS. AT THE SFC...RIDGING ON THE SW SIDE OF THE ATLC HIGH CONTINUES TO EXTEND INTO THE CARIBBEAN PRODUCING 15 TO 25 KT TRADE WINDS. AN INCREASE IN MOISTURE IS LIKELY ACROSS THE LESSER ANTILLES LATE SUN AS THE CENTRAL ATLC TROPICAL WAVE APPROACHES. ELSEWHERE...SIMILAR CONDITIONS ARE EXPECTED OVER THE NEXT COUPLE OF DAYS. ATLANTIC OCEAN... A SPRAWLING UPPER HIGH IS CENTERED ABOUT 150 NM E OF DAYTONA BEACH FLORIDA NEAR 29N78W WITH THE RIDGE AXIS ALONG 29N STRETCHING OUT TO 55W. A LARGE UPPER TROUGH IS LOCATED TO THE N OF THIS RIDGE. AN ASSOCIATED SFC COLD FRONT CONTINUES TO PRESS SWD AND HAS ENTERED THE NRN PORTION OF THE DISCUSSION AREA...AND AS OF 18Z EXTENDS FROM A 1005 MB LOW NEAR 35N62W TO 31N72W TO THE GEORGIA COAST. THIS IS THE FRONT THAT HAS BROUGHT VERY PLEASANT...EVEN CHILLY WEATHER FOR THIS TIME OF YEAR TO THE NE AND MID-ATLC STATES. BROKEN TO OVERCAST SKIES AND SCATTERED SHOWERS/TSTMS ARE N OF 28N W OF 51W. DOPPLER RADAR INDICATES LINES OF STRONG STORMS MOVING OFF THE SE U.S. NEAR THE BOUNDARY. ELSEWHERE...BESIDES FOR THE TROPICAL WAVES AND ITCZ RELATED CONVECTION VERY LITTLE UNSETTLED WEATHER IS OCCURRING IN THE ATLC BASIN. THERE ARE SEVERAL UPPER LEVEL FEATURES NONE OF WHICH ARE CAUSING MUCH INSTABILITY. AN UPPER LEVEL LOW CONTINUES TO TRACK WWD IN TANDEM WITH THE W CARIBBEAN TROPICAL WAVE NOW LOCATED IN THE SE BAHAMAS NEAR 22N72W. AN UPPER HIGH IS LOCATED ENE OF THE LEEWARD ISLANDS NEAR 17N56W AND ANOTHER UPPER LOW IS NEAR 27N37W. THE ERN ATLC CONTINUES TO BE DOMINATED BY AN UPPER RIDGE EXTENDING W FROM AFRICA. DRY/STABLE AIR LIES ABOVE THE MAJORITY OF THE AREA. AT THE SURFACE...HIGH PRES RIDGING CONTINUES TO BE THE THEME WITH THREE HIGH PRES CENTERS ANALYZED. THE SFC RIDGE RUNS FROM A 1020 MB HIGH IN THE ERN ATLC NEAR 28N28W TO A 1020 MB HIGH NEAR 26N44W TO A 1018 MB IN THE CNTRL ATLC NEAR 23N60W ACROSS SOUTH FLORIDA. $$ CANGIALOSI