000 FXUS62 KILM 040525 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 125 AM EDT SAT JUL 4 2009 .SYNOPSIS... WEAK HIGH PRESSURE WILL PUSH ACROSS THE CAROLINAS AND OFF THEIR RESPECTIVE COASTS AND OFFSHORE SATURDAY. LOW PRESSURE SYSTEM WILL APPROACH FROM THE WEST SUNDAY...WHILE A FRONTAL BOUNDARY DROPS SOUTH ACROSS THE WATERS. THIS MAIN LOW AND SEVERAL SMALLER SURFACE IMPULSES WILL TRACK ALONG THE FRONT AND AFFECT THE AREA SUNDAY INTO EARLY MONDAY. THE FRONT WILL DROP WELL S OF THE AREA TUESDAY AND WEDNESDAY ALLOWING WEAK HIGH PRESSURE TO RIDGE ACROSS THE AREA FROM THE NORTHWEST. EXPECT NEAR TO SLIGHTLY BELOW NORMAL TEMPERATURES THROUGH THE PERIOD WITH BEST CHANCES FOR CONVECTION SUNDAY INTO MONDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 930 PM FRIDAY...WEAK IMPULSES WITHIN THAT MID LEVEL PORTION OF THE ATMOSPHERE AND JUST ENOUGH MOISTURE...WILL PUSH ACROSS THE REGION AND OFF THE COAST OVERNIGHT...RESULTING IN FEW TO POSSIBLY SCATTERED MID LEVEL CLOUDS. RELATIVELY WARM TEMPS IN THE MID LEVELS...IE ROUGHLY BETWEEN 750MB AND 600MB FROM THE 00Z JULY 4TH SOUNDINGS...WILL KEEP A PRONOUNCED CAP ON OVERNIGHT THUNDERSTORM DEVELOPMENT. THIS CAP PROGGED TO CONTINUE INTO DAYLIGHT SAT. HAVE LOWERED OVERNIGHT MINS BY 1 TO 3 DEGREES DUE TO THE EXCELLENT RAD CONDITIONS PROGGED FOR THE REMAINDER OF THE UPCOMING OVERNIGHT. A NEARLY CLOUDLESS SKY...WINDS NEARLY CALM FOR MUCH OF THE NITE...LATEST SFC DEWPOINTS ARE RUNNING SLITELY LOWER THEN LATEST GUIDANCE...AND SUBSIDENCE ALOFT TO BECOME PREDOMINATE ACROSS THE ILM CWA AFTER 08Z. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 PM FRIDAY...HOT AND DRY CONDITIONS CONTINUE SAT WITH DEEP WESTERLY FLOW IN PLACE...BUT IT WILL LIKELY BE THE LAST DURING THE RECENT STRETCH. DRY AIR REMAINS PREVALENT THROUGH ALL LAYERS...FORECAST PRECIPITABLE WATERS ARE RIGHT AROUND AN INCH SAT. DEEP MIXING...BETWEEN 6K AND 7K FT...WILL QUICKLY ERODE LIMITED BOUNDARY LAYER MOISTURE. HIGHS GENERALLY IN THE LOW 90S WITH DEWPOINTS IN THE LOW 60S. FLOW BECOMES SOUTHERLY SAT NIGHT AS SHORTWAVE TROF AND ASSOCIATED SURFACE FEATURE MOVE OUT OF THE MIDWEST AND INTO THE TN VALLEY. STILL SOME QUESTION AS TO STRENGTH OF SHORTWAVE AND SURFACE FEATURE...FEEDBACK MAY BE AN ISSUE...BUT THE SHORTWAVE AND LOW CAN ALREADY BE SEEN IN IN WATER VAPOR AND SURFACE ANALYSIS RESPECTIVELY. WAVE SPAWNS A CONVECTIVE COMPLEX SAT NIGHT THAT PASSES WELL NORTH OF THE AREA. CHANGES BEGIN SUN WITH MOISTURE INCREASING AHEAD OF FRONTAL SYSTEM MOVING INTO THE CAROLINAS. FORECAST SOUNDINGS INDICATE PRECIPITABLE WATER JUST UNDER 2 INCHES SUN AND OVER 2 INCHES SUN NIGHT. LOW LEVEL CONVERGENCE AHEAD OF THE FRONT AND DIURNAL HEATING/MOISTURE WILL YIELD AFTERNOON CONVECTION. THINK COVERAGE WILL BE AROUND 40 PERCENT FOR THE AFTERNOON WITH BEST LIFT/DYNAMICS STILL NORTHWEST OF THE AREA. BEST PRECIP CHANCES...THOUGH ONLY SLIGHTLY BETTER...WILL BE SUN NIGHT AS FRONT DROPS INTO THE AREA. LOSS OF DIURNAL HEATING AND LACK OF SIGNIFICANT UPPER FEATURE WILL KEEP PRECIP COVERAGE AROUND 50 PERCENT FOR THE EVENING AND EARLY OVERNIGHT HOURS. HIGHS SUN WILL BE DEPENDANT ON CLOUD COVER AND PRECIP COVERAGE...UPPER 80S TO LOW 90S EXPECTED. CLOUD COVER AND LOW LEVEL MOISTURE SUN NIGHT WILL KEEP LOWS IN THE LOWER 70S. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 3 PM FRIDAY...FRONTAL BOUNDARY WILL BE MAKING ITS WAY THROUGH THE CWA ON MONDAY WITH CHC OF PCP AND CLOUDS DECREASING BY THE END OF THE DAY. TUES WILL START OUT DRIER BUT LINGERING MOISTURE FROM THE FRONT MAY BE PULLED BACK NORTH BY LATE TUES INTO WED AS GFS SHOWS A LOW RIDING ACROSS THE GULF COAST STATES AND THEN MOVING UP THE SOUTHEAST STATES THROUGH THE CAROLINAS WED INTO THURS. 00Z ECMWF JUST SHOWS A HINT OF A LOW BUT MUCH LESS INTENSE AND SUPPRESSED FARTHER SOUTH. PCP WATER VALUES START OUT ABOVE 2 INCHES BUT DECREASE THROUGH THE DAY ON MON AND SHOULD REACH DOWN BELOW 1.25 INCHES BY TUES MORNING. OVERALL WILL SHOW LINGERING CHC OF SHWRS/TSTMS MON ESPECIALLY OVER SOUTHEAST COAST AS FRONT MAKES ITS WAY THROUGH. LATE MON INTO TUES SHOULD BE DRIER WITH CHC OF PCP ALONG SEA BREEZE IN THE AFTN AND THEN GREATER CHC OF PCP THROUGH MID WEEK...WED AND THURS WITH UNCERTAINTY IN MODEL RUNS. BY FRIDAY SHOULD SEE DRIER WEATHER RETURN IN NORTHERLY FLOW ON THE BACK END OF UPPER TROUGH AS IT MOVES OFF THE EAST COAST. TEMPS SHOULD START OUT AROUND CLIMO WITH LINGERING CLOUDS AND PCP AS FRONT MOVES THROUGH AND SHOULD HOLD AROUND CLIMO THROUGH MOST OF THE PERIOD. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... VFR EXPECTED THROUGH THE TAF VALID PERIOD. LIGHT AND VARIABLE WINDS EXPECTED THROUGH SUNRISE. WINDS WILL BECOME LIGHT SOUTHWEST BY MID MORNING. WINDS WILL THEN BECOME SOUTH IN THE WAKE OF THE SEA BREEZE AT THE COASTAL TERMINALS BY LATE MORNING. NO CONVECTION EXPECTED TODAY WITH A STABLE AIRMASS AND DRY AIR IN THE MID LEVELS. COULD STILL GET A FEW FLAT CU TO DEVELOP 5K-7K BY AFTERNOON...ESPECIALLY ALONG THE SEA BREEZE BOUNDARY. EXTENDED OUTLOOK THROUGH WEDNESDAY...SCATTERED THUNDERSTORMS SUNDAY AND MONDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 930 PM FRIDAY...SFC FRONTAL BOUNDARY NOW FURTHER OFFSHORE AND A BIT MORE DIFFICULT TO RECOGNIZE BUT NEVERTHELESS STILL HAVING BNDRY PROPERTIES. FOR THE REMAINDER OF THE OVERNIGHT...THE WEAK SUB-1020 HIGH CENTERED ACROSS THE CENTRAL CAROLINAS WILL RIDGE ACROSS THE WATERS. SPECIFICALLY...THE RIDGE AXIS SLICES ACROSS THE CAPE FEAR AREA AND WILL PRODUCE WIND DIRECTIONS OF NW THRU N FROM CAPE FEAR NORTHWARD...AND N THRU NE SOUTH OF THE CAPE. SPEEDS BASICALLY LESS THAN 10 KT. TWO TO OCCASIONALLY 3 FOOT SEAS IN THAT WIND DRIVEN 5 TO 6 SECOND PERIOD WILL PRIMARILY BE YOUR SEAS. THE 3 FOOTERS WILL LIKELY OCCUR ACROSS F.P.S. .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 PM FRIDAY...LIGHT WINDS SAT MORNING WILL BECOME SOUTH TO SOUTHEAST AS SEA BREEZE BECOMES MAIN FACTOR IN AN OTHERWISE DIFFUSE GRADIENT. GRADIENT BEGINS TO TIGHTEN UP SAT NIGHT AS FRONTAL SYSTEM DROPS INTO THE CAROLINAS...BUT BETTER GRADIENT DEVELOPS SUN WHEN SEA BREEZE AND TIGHT SW GRADIENT COMBINE TO PUSH SPEEDS OVER 15 KT. SEAS WILL RUN 2 TO 4 FT THROUGH SAT NIGHT INCREASING TO 3 TO 5 FT SUN AND SUN NIGHT. LONG TERM /MONDAY THROUGH WEDNESDAY/... AS OF 3 PM FRIDAY...WINDS MAY BECOME QUITE VARIABLE ON MON AS THEY SHOULD BECOME LIGHTER AND VEER AROUND TO THE NORTH BEHIND FRONTAL BOUNDARY...BUT SHOULD STAY SOUTHERLY AHEAD OF BOUNDARY. OVERALL WEAKER FLOW 10 KTS OR LESS EXPECTED ON MON BEHIND FRONT WITH SHIFTING WINDS AND DECREASING SEAS THROUGH THE DAY DEPENDING ON HOW FAST FRONT PROGRESSES THROUGH THE AREA FROM NW TO SE. SEAS SHOULD START OUT IN THE 3 TO 5 FT RANGE BUT DECREASING TREND THROUGH EARLY TUES DOWN TO 3 FT TUES THROUGH EARLY WED. MAY SEE INCREASE IN SEAS IF LOW MATERIALIZES AS THE GFS HAS IT..BUT FOR NOW WILL KEEP SEAS IN THE 2 TO 4 FT RANGE INCREASING SLIGHTLY TOWARD THE END OF THE PERIOD. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...HOEHLER NEAR TERM...HOEHLER SHORT TERM...III LONG TERM...ZOUZIAS AVIATION...ROSS/RJD