000 AXNT20 KNHC 312348 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU AUG 31 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. ...SPECIAL FEATURE... TROPICAL STORM ERNESTO IS APPROACHING THE CAROLINA COASTLINE. AT 0000 UTC...ERNESTO WAS LOCATED AT 33.2N 78.3W OR ABOUT 75 MILES...125 KM...SOUTH-SOUTHWEST OF WILMINGTON NORTH CAROLINA. MOVING TOWARDS THE N-NE NEAR 16 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE HAS DROPPED TO 988 MB. MAXIMUM SUSTAINED WIND SPEEDS ARE 60 KT WITH GUSTS TO 75 KT. THIS IS JUST BELOW HURRICANE STRENGTH...WHILE LITTLE CHANGE IN INTENSITY IS EXPECTED BEFORE LANDFALL...ANY STRENGTHENING DURING THE NEXT FEW HOURS WOULD BRING ERNESTO TO THE COAST AS A CATEGORY ONE HURRICANE. TROPICAL STORM FORCE WINDS SPREAD OUTWARD WITHIN 115 MILES. ERNESTO HAS STRENGTHENED TO A STRONG TROPICAL STORM THROUGHOUT THE DAY AS IT HAS BEEN TRACKING IN A RATHER LOW SHEAR ENVIRONMENT AND OVER WARM WATERS. THE TROPICAL STORM HAS A WELL-DEFINED CIRCULATION AND RAINBANDS BASED UPON DOPPLER RADAR. MANY OF THESE RAINBANDS HAVE ALREADY SPREAD ACROSS THE COASTAL AREAS OF THE CAROLINAS. RAINFALL TOTALS OF 4 TO 8 INCHES ARE POSSIBLE FROM NORTHEASTERN SOUTH CAROLINA INTO THE MID-ATLANTIC STATES...AND THE SOUTHERN AND CENTRAL APPALACHIANS...WITH ISOLATED MAXIMUM AMOUNTS OF 12 INCHES...THROUGH SATURDAY. THESE AMOUNTS COULD CAUSE LIFE-THREATENING FLASH FLOODS. WEAKENING IS EXPECTED ONCE ERNESTO MAKES LANDFALL LATER TONIGHT. EXTRA-TROPICAL TRANSITION WILL LIKELY OCCUR BEYOND 36 HOURS AS THE TROPICAL CYCLONE INTERACTS WITH A FRONTAL BOUNDARY. PLEASE REFER TO THE LATEST NHC FORECAST ADVISORY UNDER HEADERS MIATCMAT5/WTNT25 KNHC AND THE PUBLIC ADVISORY MIATCPAT5/WTNT35 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 45W S OF 16N MOVING W NEAR 10 KT. THE WAVE IS NEAR THE WESTERN EDGE OF A MONSOON TROUGH THAT EXTENDS OFF AFRICA. A 1011 MB LOW HAS BEEN PLACED ON THE WAVE NEAR 11N. THE LOW IS CURRENTLY BROAD AND ELONGATED BUT LOW CLOUD MOTIONS AND A FEW SFC OBS HELP LOCATE IT. THE OVERALL STRUCTURE OF THE WAVE APPEARS TO HAVE IMPROVED OVER THE LAST 24 HOURS OR SO WITH AN INVERTED V-PATTERN OBSERVED ON INFRARED IMAGES. SCATTERED MODERATE CONVECTION IS STILL DISORGANIZED BUT IS INCREASING SLIGHTLY IN COVERAGE AND INTENSITY TO THE NW OF THE SFC LOW FROM 11N-14N BETWEEN 33W-38W. SLOW DEVELOPMENT IS POSSIBLE AS THIS SYSTEM TRACKS WESTWARD. A TROPICAL WAVE IS IN THE CENTRAL ATLC ALONG 51W S OF 21N MOVING W NEAR 10 KT. A 1012 MB LOW IS ALONG THE WAVE NEAR 16N. THE SFC LOW REMAINS WEAK AND EASY TO LOCATE AS IT MAINLY A LOW-LEVEL SWIRL DEVOID OF ANY SIGNIFICANT CONVECTION. BECAUSE OF THE LACK OF ORGANIZATION....SIGNIFICANT DEVELOPMENT IS NOT EXPECTED AT THIS TIME. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 13N16W 11N25W 12N32W 9N36W 8N50W 8N60W. BESIDES FOR THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED MODERATE CONVECTION IS WITHIN 180 NM EITHER SIDE OF THE AXIS E OF 28W. SOME OF THIS ACTIVITY IS LIKELY ASSOCIATED WITH ANOTHER TROPICAL WAVE THAT MAY BE INTRODUCED IN THE 00 UTC ANALYSIS. SCATTERED SHOWERS ARE WITHIN 240 NM EITHER SIDE BETWEEN 38W-47W. TYPICAL SCATTERED SHOWERS AND TSTMS ARE OVER N PORTIONS OF S AMERICA ENHANCED BY THE ITCZ. ...DISCUSSION... THE GULF OF MEXICO... TROPICAL STORM ERNESTO HAS PULLED NE OF FLORIDA AND IS NEARING THE CAROLINA COASTLINE. A TAIL TROUGH LEFT FROM THE SYSTEM REMAINS ACROSS THE SUNSHINE STATE AND THE E GULF WITH CONSIDERABLE MOISTURE. SCATTERED SHOWERS AND TSTMS EXIST OVER CENTRAL FLORIDA FROM 26N-29N E OF 83W. IN THE UPPER LEVELS...THE MID-UPPER LEVEL HIGH THAT WAS CENTERED OVER THE SE U.S. EARLIER THIS WEEK HAS PUSHED E INTO THE ATLC AS AN UPPER TROUGH BECAME ESTABLISHED ACROSS THE CENTRAL-EASTERN U.S INTO THE N GULF WITH THE BASE OF THE TROUGH NEAR 23N87W. AN ASSOCIATED SFC COLD FRONT EXTENDS FROM THE FL PANHANDLE SW ALONG 27N86W 25N94W TO THE TEXAS/MEXICO BORDER. THE FRONT IS EASY TO LOCATE WITH ONLY A THIN BAND OF LOW-MID LEVEL CLOUDS AND ISOLATED SHOWERS WITHIN 60 NM AHEAD OF THE BOUNDARY. VERY DRY STABLE AIR ACCOMPANIES THE UPPER TROUGH WITH STRONG SUBSIDENCE NOTED N OF 23N W OF 89W...PRESSING ESE. SOME MOISTURE IS LIKELY TO PERSIST OVER FLORIDA TOMORROW ASSOCIATED WITH ERNESTO'S TRAILING TROF....OTHERWISE MAINLY DRY CONDITIONS ARE EXPECTED. THE CARIBBEAN SEA... PATCHES OF SHOWERS AND TSTMS HAVE FIRED UP THIS AFTERNOON AND EVENING STRONGEST OVER THE LAND AREAS OF HISPANIOLA...JAMAICA AND CUBA. THIS ACTIVITY IS LIKELY TRIGGERED BY UPPER DIFFLUENCE ON THE W SIDE OF A LARGE UPPER LOW...DEBRIS MOISTURE FROM ERNESTO AND LOCAL UPSLOPE FLOW OVER MOUNTAINOUS TERRAIN. SCATTERED SHOWERS AND TSTMS HAVE ALSO DEVELOPED ACROSS THE SEA W OF 78W. THE REMAINDER OF THE CARIBBEAN IS FAIRLY QUIET WITH ONLY BROKEN CLOUDINESS AND ISOLATED SHOWERS. NORTHERLY UPPER LEVEL FLOW LIES ABOVE THE REGION BETWEEN AN UPPER HIGH OVER S MEXICO AND AN UPPER LOW N OF THE LEEWARD ISLANDS. DRY STABLE UPPER LEVEL AIR COVERS THE MAJORITY OF THE REGION NOT OUTLINED. TRADE WINDS ARE MAINLY IN THE 15-20 KT RANGE E OF 80W...LIGHTER WINDS W OF THERE. MODELS SHOW LITTLE CHANGE OVER THE NEXT DAY OR TWO IN THE CNTRL AND E CARIBBEAN KEEPING DRY AIR INTACT. SOME INCREASE IN TROPICAL MOISTURE IS SUGGESTED BY THE GFS IN THE SW CARIBBEAN. THE ATLANTIC OCEAN... TROPICAL STORM ERNESTO IS APPROACHING THE CAROLINA COASTLINE. BANDS OF MODERATE TO HEAVY RAINFALL AND GUSTY WINDS EXIST W OF 75W. FOR MORE DETAILS REFER TO THE SPECIAL FEATURE SECTION ABOVE. A MID-UPPER LEVEL RIDGE CENTERED OFF THE SE U.S. COASTLINE NEAR 32N74W HAS RIDGING THAT STRETCHES ENE TO 45W ALONG 35N. ERNESTO IS MOVING AROUND THE W PERIPHERY OF THIS ERODING MID-LEVEL RIDGE. THE S PORTION OF THE RIDGE HAS BECOME SQUASHED BY A CUT OFF LARGE UPPER LOW CENTERED 450 NM NNE OF PUERTO RICO NEAR 22N65W. AN ASSOCIATED SFC TROF EXTENDS FROM 29N59W 25N65W 22N71W. THE UPPER LOW MAY BE TRYING TO BUILD DOWN TO THE SFC ALONG THIS TROF. ISOLATED TO SCATTERED SHOWERS EXIST MAINLY FROM 22N-27N BETWEEN 60W-70W. AREAS OF MID-HIGH LEVEL CLOUDINESS AND ISOLATED SHOWERS ARE N OF 17N BETWEEN 64W-74W. MUCH OF THE CENTRAL AND E ATLC IS DOMINATED BY A BROAD UPPER RIDGE EXTENDING FROM AFRICA TO NEAR 55W WITH A HIGH CENTER NEAR 17N25W AND ANOTHER NEAR 17N48W. AN UPPER LEVEL TROUGH CLIPS THE NE PORTION OF THE AREA EXTENDING FROM AN UPPER LOW NEAR 33N17W TO ANOTHER UPPER LOW NEAR 29N40W TO 28N53W. MOSTLY FAIR WEATHER COVERS THE AREA UNDER THE LARGE RIDGE. A PLUME OF SAHARAN DUST HAS SPREAD TO NEAR 45W BASED ON THE MILKY LOOK IN EARLIER VIS IMAGES AND THE CIMSS SAL TRACKING PRODUCT. AT THE SURFACE...A WEAK PRES GRAD EXISTS W OF 60W DUE TO THE SFC TROF DRAPED ACROSS THE AREA. STRONGER GRAD IN THE E ATLC AS A 1025 MB AZORES HIGH INTERACTS WITH THE TROPICAL WAVES. $$ CANGIALOSI