AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC ISSUED BY NATIONAL WEATHER SERVICE CHARLESTON SC 328 PM EDT FRI JUL 8 2011 .SYNOPSIS... BERMUDA HIGH PRESSURE WILL MAINTAIN A MOIST SOUTHERLY FLOW ACROSS THE EASTERN CAROLINAS INTO THE WEEKEND. TROPICAL MOISTURE MOVING NORTHWARD ACROSS THE EASTERN CAROLINAS WILL BRING SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS INTO THE WEEKEND. SOME OF THIS RAIN WILL BE HEAVY AT TIMES. BERMUDA HIGH PRESSURE WILL BUILD BACK ACROSS THE AREA EARLY NEXT WEEK. A COLD FRONT MAY APPROACH THE AREA DURING THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... STILL KEEPING A CLOSE WATCH ON POSSIBLE STRONG OR SEVERE STORMS THAT MAY FIRE UP ALONG A DIFFERENTIAL HEATING BOUNDARY OVER OUR FAR WESTERN COUNTIES WHERE THE BACK EDGE OF THE DEEP MOISTURE IS INTERACTING WITH CONVECTIVE CUMULUS THAT CONTINUE TO FORM. THIS IS IN AN AREA WHERE SURFACE BASED LIFTED INDICES ARE DOWN NEAR -6...LOW LEVEL LAPSE RATES ARE -7 OR -8C/KM AND MUCAPES ARE NEAR 2000 J/KG. WIND GUSTS WOULD BE THE MAIN WEATHER HAZARD WITH DCAPES OF 800-1000 J/KG. BUT WITH PWATS SO HIGH THERE IS ALSO A RISK OF MINOR FLOODING AND FLOOD ADVISORIES MAY BE REQUIRED. WE WILL MAINTAIN POPS AS HIGH AS 50-60 PERCENT INLAND THROUGH SUNSET AS A RESULT. THE TROPICAL PLUME OF MOISTURE WILL SKIRT THE FORECAST AREA TONIGHT...WITH PWATS OF 2 INCHES OR MORE...WHICH IS ABOVE THE 75TH PERCENTILE FOR THIS TIME OF YEAR. SHORT WAVES EMBEDDED WITHIN THIS SOUTHERLY FLOW OF EXTREMELY MOIST AIR AND ITS ASSOCIATED UPPER DIVERGENCE WILL REMAIN MAINLY OVER THE ATLANTIC WATERS AND EAST. HOWEVER...ANOTHER MORE PRONOUNCED SHORT WAVE TROUGH WILL MOVE THROUGH THE APPALACHIANS THIS EVENING AND WILL TRIGGER AN AREA OF LOW PRESSURE AT THE SURFACE OVER CENTRAL NC THAT MOVES EAST OVERNIGHT. AHEAD OF THIS LOW AND A TRAILING COLD FRONT TO THE SW WILL BE A 30-40 KT LOW LEVEL JET THAT WILL PREVAIL THE FIRST PART OF TONIGHT...BEFORE LIFTING OUT LATE. BUT AT THE SAME TIME A LOW LEVEL THETA-E RIDGE MEANS IN AFTER MIDNIGHT. ALOFT WE SEE A SPLITTING OF THE UPPER LEVEL JET...BUT THE BEST UPPER DIVERGENCE STAYS JUST NORTH AND NW OF THE FORECAST AREA. ALTHOUGH WE HAVE SEVERAL FORCING FACTORS TONIGHT...THEY ARE ALL OUT OF SYNC WITH EACH OTHER...SO WE ARE HESITANT TO GO ANY HIGHER THAN 40-50 PERCENT THROUGH MIDNIGHT...AND 30-40 PERCENT OVERNIGHT. EXTENSIVE CLOUD COVER...WARMER LOW LEVEL THICKNESS VALUES WITHIN A SOUTH TO SW SYNOPTIC FLOW AND MIXING WITH THE LOW LEVEL JET WILL PREVENT TEMPS FROM FALLING ANY LOWER THAN THE LOWER AND MIDDLE 70S. && .SHORT TERM /SATURDAY THROUGH MONDAY/... SATURDAY...A WET PATTERN WILL SET UP AS A WEAK SFC LOW SHIFTS THROUGH THE OHIO VALLEY AND BECOMES ENHANCED WITHIN A LEE TROUGH OVER THE MID ATLANTIC STATES WHILE THE MID/UPPER LVL FLOW PATTERN CONTINUES TO STEER SIGNIFICANT MOISTURE OVER THE REGION FROM THE SOUTH. ALTHOUGH MODEST ISENTROPIC ASCENT WILL LEAD TO SOME CLOUD COVER SATURDAY MORNING INTO THE AFTERNOON...SHOWERS AND THUNDERSTORMS ARE LIKELY AS SUFFICIENT SFC HEATING LEADS TO SBCAPES NEAR 2500 J/KG DURING PEAK HEATING HOURS. THERE WILL BE A CHANCE OF ISOLATED STRONG THUNDERSTORMS SATURDAY AFTERNOON AS AN H5 SHORTWAVE SLOWLY SHIFTS AROUND THE PERIPHERY OF A BUILDING RIDGE OVER CENTRAL UNITED STATES AND THEN THROUGH THE FORECAST AREA. ACTIVITY WILL LIKELY BE ENHANCED ALONG A REMNANT EAST/WEST SFC BOUNDARY DRAPED ACROSS THE CWA. GIVEN A WEAK WIND PATTERN...WEAK MID LVL LAPSE RATES AND PWATS NEAR 2.0 INCHES...PULSE TYPE CONVECTION IS ANTICIPATED WITH THE POSSIBILITY OF STRONG WIND GUSTS AND HEAVY RAINFALL DURING STRONGER STORMS. OVERALL HIGH TEMPS WILL BE AROUND 90 WITH CLOUD COVER ANTICIPATED. HIGH TEMPS WILL REACH THE UPPER 80S ALONG THE IMMEDIATE NC/SC COAST. OVERNIGHT LOWS WILL BE IN THE LOW 70S INLAND AND MID 70S ALONG THE NC/SC COAST. SUNDAY...SHOWER AND THUNDERSTORM ACTIVITY WILL PRIMARILY BE DRIVEN SOUTHEASTWARD TO SOUTHERN PORTIONS OF THE CWA WHERE AN H5 SHORTWAVE DRIFTS OFFSHORE WHILE AMPLE MOISTURE LINGERS NEAR THE VICINITY OF THE REMNANT EAST/WEST BOUNDARY. HAVE MAINTAINED 40 POPS OVER SOUTHERN COUNTIES WHERE PRECIP CHANCES ARE HIGHEST. CAN NOT RULE OUT AN ISOLATED STRONG STORM IN THE VICINITY OF THE REMNANT BOUNDARY...BUT THE OVERALL THREAT APPEARS LESS THAN SATURDAY. ACTIVITY WILL AGAIN BE PULSE TYPE IN NATURE WITH STRONG WIND GUSTS AND BRIEF HEAVY RAINFALL BEING THE MAIN THREATS SHOULD A STRONGER STORM DEVELOP. OVERALL HIGH TEMPS WILL REACH THE LOW 90S INLAND AND UPPER 80S ALONG THE NC/SC COAST. SUNDAY NIGHT THROUGH MONDAY MORNING...CONDITIONS WILL BEGIN TO DRY OUT LATE SUNDAY AS SFC HIGH PRESSURE SETTLES INTO THE REGION FROM THE NORTH WHILE MID LVL RIDGING EXPANDS OVER THE ATLANTIC STATES FROM THE WEST. HAVE MAINTAINED ISOLATED SHOWERS/THUNDERSTORMS MAINLY OVER SC COUNTIES WHERE WEAK AREAS OF LOW PRESSURE DEVELOP OVER THE STALLED BOUNDARY AND DRIFT OFFSHORE. OVERALL LOW TEMPS WILL REACH THE LOW/MID 70S WITH MID/UPPER 70S ALONG THE IMMEDIATE NC/SC COAST. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... EXTENDED FORECAST WARRANTS FEW CHANGES THIS AFTERNOON AS WHAT ELSE...A MASSIVE MID LEVEL RIDGE WILL BE THE MAIN FEATURE. HPC IS LEANING TOWARD THE ECMWF WITH THEIR NUMBERS AND WILL GENERALLY FOLLOW THIS FORECAST. MONDAY AND TUESDAY LOOK DRY AND WARM WITH ONLY ISOLATED SHOWERS AND THUNDERSTORMS. TUESDAY LOOKS TO BE THE WARMEST OF DAYS WITH MIDDLE 90S ALMOST EVERYWHERE SANS THE BEACHES. RIDGE MAY BREAK DOWN JUST ENOUGH LATER IN THE PERIOD TO ALLOW POPS TO INCREASE AS A FRONT SLIPS DOWN FROM THE NORTH. TEMPERATURES COOL SLIGHTLY AS WELL WITH THE SUBTLE INCREASE IN MOISTURE. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... CONDITIONS WILL VARY FROM VFR TO POSSIBLY IFR AT TIMES AS SHOWERS AND THUNDERSTORMS AFFECT THE REGION THIS AFTERNOON. WITH PLENTY OF LOW LEVEL MOISTURE...PERIODIC HEAVY DOWNPOURS ARE EXPECTED FOR ALL SITES. THUS...INCLUDED TEMPO GROUPS WITH REDUCED VISIBILITIES AND LOWERING CEILINGS. HOWEVER...CAN NOT RULE OUT BRIEF TIME PERIODS WHERE VISIBILITIES DROP BELOW IFR CONDITIONS. EXPECT CONVECTION ACTIVITY TO DECREASE SHORTLY AFTER SUNSET...ESPECIALLY FOR INLAND SITES. HAVE HELD ONTO CBS AFTER 01Z FOR ALL COASTAL SITES AS CONVECTION MAY LINGER OVER THE WATERS NEAR COASTAL AREAS. LOW LEVEL MOISTURE WILL LINGER OVERNIGHT WITH BOTH THE SREF MODEL AND MODEL SOUNDINGS HINTING AT EITHER A LOW STRATUS LAYER OR PATCHY FOG DEVELOPMENT EARLY SATURDAY MORNING. POTENTIAL FOR FOG DEVELOPMENT IN CONJUNCTION WITH LOW STRATUS APPEARS BETTER ACROSS INLAND SITES AS WINDS WILL REMAIN 5 KNOTS OR LESS AFTER 08Z. HOWEVER...STRONGER WINDS WILL REMAIN ACROSS COASTAL AREAS WHICH WILL LIKELY HINDER ANY FOG POTENTIAL. THUS EXPECT LOW STRATUS TO BE MORE LIKELY FOR THESE COASTAL AREAS. ANY REDUCED CONDITIONS WILL LIKELY IMPROVE TO IFR CONDITIONS BY LATE SATURDAY MORNING...HOWEVER ANOTHER ROUND OF CONVECTION COULD AFFECT ALL SITES TOWARD THE END OF THIS TAF PERIOD. EXTENDED OUTLOOK...WIDESPREAD SHOWERS AND THUNDERSTORMS LIKELY THROUGHOUT THE WEEKEND. PRECIP CHANCES DECREASE EARLY NEXT WEEK. && .MARINE... NEAR TERM /THROUGH TONIGHT/... THE SUB TROPICAL ATLANTIC RIDGE REMAINS SUPPRESSED FAR TO THE SE AS LOW PRESSURE FORMS IN NC AND MOVES EAST. AN ASSOCIATED COLD FRONT TRAILING SW FROM THE LOW WILL MOVE INTO CENTRAL NC AND NW SC LATE TONIGHT. THIS ALONG WITH A 30-40 KT LOW LEVEL JET THROUGH 06Z WILL KEEP THE PRESSURE GRADIENT PINCHED THROUGH 06-09Z. ALTHOUGH MIXING WILL BE SOMEWHAT RESTRICTED DUE TO WARM ADVECTION...SOUTH AND SW WINDS WILL STILL REACH AS HIGH AS 20-25 KT...WITH SEAS UP TO 4-7 FT. THUS WE HAVE INITIALIZED ALL COASTAL WATERS WITH SCA/S WITH THE AFTERNOON FORECAST. SHORT TERM /SATURDAY THROUGH SUNDAY/... A NEARLY STATIONARY FRONT WILL MEANDER NEAR THE CAROLINA COAST OVER THE WEEKEND INTO EARLY NEXT WEEK. PERIODS OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE AS WEAK AREAS OF LOW PRESSURE DEVELOP ALONG THE STALLED BOUNDARY AND DRIFT OFFSHORE. SEAS OF 4 TO 5 FEET WILL GRADUALLY SUBSIDE TO 2 TO 3 FEET SATURDAY THROUGH EARLY MONDAY. SOUTHWEST FLOW WILL BECOME LIGHT AND VARIABLE BY LATE WEEKEND WITH THE REMNANT BOUNDARY DIRECTLY OVER THE WATERS. WINDS AND SEAS WILL REMAIN BELOW SCA CRITERIA THROUGH EARLY NEXT WEEK. LONG TERM /SUNDAY NIGHT THROUGH TUESDAY/... ELONGATED TROUGH OF LOW PRESSURE WILL RESIDE JUST OFF THE COAST EARLY IN THE PERIOD WITH WEAK HIGH PRESSURE TO THE NORTH. THIS WILL LEAD TO AN EASTERLY FLOW MOST OF MONDAY. A MORE SOUTH TO SOUTHWESTERLY FLOW WILL DEVELOP LATE MONDAY AND PERSIST THROUGH WEDNESDAY. WIND SPEEDS WILL REMAIN TYPICAL OF SUMMER THROUGHOUT THE PERIOD WITH AROUND 10 KNOTS. WAVEWATCH SEAS OF 2-3 FEET LOOK GOOD AS WELL. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT SATURDAY FOR AMZ254-256. SMALL CRAFT ADVISORY UNTIL 6 AM EDT SATURDAY FOR AMZ250-252. && $$ SYNOPSIS...99