Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 301824 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 224 PM EDT TUE JUN 30 2015 .SYNOPSIS... BERMUDA HIGH PRESSURE WILL BECOME RE-ESTABLISHED ACROSS THE AREA TODAY AND WILL PERSIST THROUGH THE REMAINDER OF THE WEEK AND INTO THE UPCOMING HOLIDAY WEEKEND. THIS WILL CREATE SLIGHTLY ABOVE NORMAL TEMPERATURES...ALONG WITH TYPICAL SUMMERTIME THUNDERSTORM CHANCES EACH AFTERNOON AND EVENING. && .NEAR TERM /THROUGH TONIGHT/... AS OF 230 PM TUESDAY...SHORTWAVE ROUNDING BASE OF 5H TROUGH OVER NORTHERN AL/GA IS GENERATING SOME IMPRESSIVE CONVECTION TO THE SOUTHWEST. THUS FAR LOCALLY VERY LITTLE IN THE WAY OF DEEP CONVECTION HAS BEEN ABLE TO DEVELOP...LIKELY DUE TO AN ABUNDANCE OF LOW AND MID LEVEL DRY AIR. A LOOK AT DEWPOINTS DOWN STREAM SHOWS VALUES AS MUCH AS 10 DEGREES F HIGHER ACROSS INLAND GA/SC. THIS LOW LEVEL MOISTURE WILL ADVECT INTO THE FORECAST AREA LATER THIS AFTERNOON...JUST AS THE PVA AHEAD OF THE SHORTWAVE ARRIVES. THE COMBINATION OF INCREASING LOW LEVEL MOISTURE AND UPWARD MOTION ASSOCIATED WITH THE SHORTWAVE IN AN ALREADY UNSTABLE ENVIRONMENT SHOULD LEAD TO DEVELOPMENT OF SHOWERS AND THUNDERSTORMS. OVERALL COVERAGE WILL BE LIMITED AS THERE WILL STILL BE SOME DRY AIR PRESENT...ESPECIALLY ABOVE 600 MB. LOW LEVEL JETTING IS LIMITED AND SHEAR IS MARGINAL...25 KT OR SO. HOWEVER MID LEVEL DRY AIR DOES MAKE THE CASE FOR A FEW STRONG DOWNDRAFTS AND DAMAGING WIND WILL BE THE MAIN THREAT. SPC HAS MAINTAINED THE SLIGHT RISK FOR INLAND DARLINGTON/MARLBORO ALONG WITH A MARGINAL RISK FOR MUCH OF THE REMAINDER OF THE FORECAST AREA. ANY CONVECTION THAT DOES DEVELOP WOULD HAVE TROUBLE LINGERING PAST LATE EVENING. POST SHORTWAVE SUBSIDENCE AND LOSS OF DIURNAL HEATING WILL PLAY A LARGE PART IN ENDING STORMS. THERE WILL ALSO BE AN INFLUX OF DRIER MID LEVEL AIR LATER IN THE PERIOD. IF CONVECTION IS ABLE TO CONTINUE PAST MIDNIGHT IT WOULD BE ALONG THE NC COASTAL PLAIN AND OVER THE NEARSHORE WATERS. CONFIDENCE IN THIS IS LOW GIVEN A GENERALLY UNFAVORABLE ENVIRONMENT AND WILL ONLY CARRY A SLIGHT CHC POP. DEBRIS CLOUD AND SOUTHWEST BOUNDARY LAYER FLOW WILL KEEP LOWS ABOVE CLIMO OVERNIGHT. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 300 AM TUESDAY...BROAD TROUGH ACROSS THE EAST WILL KEEP ITS RIDGE AXIS WEST OF THE AREA THROUGH THE PERIOD. THIS DRIVES TEMPS TO ABOVE CLIMO...BUT WILL MAINTAIN SCATTERED CONVECTION EACH AFTN/EVE IN TYPICAL DIURNAL FASHION. WEAK SHORTWAVES MAY MOVE OVERHEAD AT ANY TIME DURING THE PERIOD WHICH COULD ENHANCE CONVECTION...ESPECIALLY ACROSS WESTERN ZONES WHICH WILL BE CLOSER TO THE TROUGH AXIS AND THE FORCING ASSOCIATED WITH ANY VORTICITY MAXIMUMS. CONVECTION WILL BE PRIMARILY DIURNALLY FORCED...AND THE GFS SHOWING WIDESPREAD SHOWERS ALONG THE COAST WEDNESDAY APPEARS TO BE OVERDONE. FOR THIS REASON WILL CUT BACK INHERITED POP A BIT WEDNESDAY AND JUST MAINTAIN LOW CHANCE BY DAY - SCHC/SILENT AT NIGHT. TEMPS WILL AVERAGE 3-5 DEGREES ABOVE CLIMO FOR HIGHS AND LOWS...WITH WIDESPREAD LOW 90S DURING THE AFTNS...AND MID 70S OVERNIGHT. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 300 AM TUESDAY...BERMUDA RIDGE WILL PERSIST THROUGH THE EXTENDED IN USUAL JULY FASHION...WITH THE ONLY SIGNIFICANT CHANGING FEATURE BEING THE DEAMPLIFICATION OF THE MID-LEVEL FLOW. TROUGH ACROSS THE EAST WILL FLATTEN INTO THE WKND...WITH SLIGHT RIDGING DEVELOPING BY EARLY NEXT WEEK. THIS WILL LEAD TO A WARMING TREND...AS WELL AS DECREASING POP EACH DAY. THE GFS IS SHOWING A STATIONARY BOUNDARY HOVERING ACROSS NC DURING THE WKND...BUT THIS IS NOT AGREED UPON BY OTHER GUIDANCE OR WPC...NOR IS IT SUPPORTED BY THE MID LEVEL PATTERN. FOR THIS REASON WILL HEDGE AGAINST THE GFS SOLUTION AND SHOW SLIGHT WARMING EACH DAY FROM JUST ABOVE CLIMO TO SEVERAL DEGREES ABOVE CLIMO FOR BOTH MAX AND MIN...WITH DECREASING CONVECTION CHANCES EACH DAY. HOWEVER...AS NOTED BY THE PREVIOUS FORECASTER...VERY DIFFICULT TO KEEP A DRY FORECAST THIS TIME OF YEAR...SO WILL SHOW AT LEAST SCHC POP EACH AFTN FOR THE SEA BREEZE AND PIEDMONT TROUGH CONVECTION. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... AS OF 18Z...THIS AFTERNOON WINDS WILL BE SW AT 10-15 KTS EXCEPT S- SSW AT 15-20 KTS AT THE COASTAL TERMINALS. VFR WILL CONTINUE WITH SCT SKIES CONSISTING OF LOW LEVEL CUMULUS AND HIGH LEVEL CIRRUS. THERE IS A CHANCE THAT VCSH COULD DEVELOP MAINLY SC TERMINALS MID- LATE AFTERNOON BUT CONFIDENCE IS LOW. PROGS ARE IN GENERAL AGREEMENT THAT SHOWERS AND THUNDERSTORMS WILL MOVE ACROSS THE TERMINALS THIS EVENING AS A SHORT WAVE MOVES THROUGH. CONFIDENCE OF COVERAGE IS LOW HOWEVER DUE TO MOISTURE AVAILABILITY. WILL INDICATE VCSH/VCTS IN TAFS BUT HIGHEST CONFIDENCE OF VCTS WILL BE A KFLO/KLBT. WINDS SPEEDS WILL DECREASE LATER IN THE EVENING AND EARLY MORNING HOURS TO SW 4-8 KT. VCSH COULD A BIT LONGER AFTER MIDNIGHT AT THE COASTAL TERMINALS THAN IS CURRENTLY INDICATED IN TAFS. AFTER SUNRISE VFR CONTINUES WITH WEST WINDS. EXTENDED OUTLOOK...PREDOMINATELY VFR WITH DECREASING CHANCES OF SHOWERS AND THUNDERSTORMS EACH DAY THROUGH SUNDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 230 PM TUESDAY...SOUTHWEST FLOW WILL BECOME MORE SOUTHERLY LATER THIS AFTERNOON AND EVENING WITH AN INCREASE IN SPEED AS GRADIENT BECOMES MORE DEFINED. SPEEDS CURRENTLY 10 TO 15 KT WILL PEAK ON THE HIGH END OF THE 15 TO 20 KT RANGE THIS EVENING THEN WEAKEN AND BECOME MORE WESTERLY AS GRADIENT RELAXES AFTER MIDNIGHT AND ANY LINGERING CONVECTION PUSHES OFF TO THE NORTHEAST. DO NOT EXPECT A LOT OF STORMS OVER THE WATERS BUT THERE WILL BE SOME POTENTIAL DURING THIS EVENING AND FIRST HALF OF THE OVERNIGHT. SEAS 3 TO 4 FT WILL PEAK AROUND 4 FT LATE TODAY...WITH ISOLATED 5 FT POSSIBLE NEAR 20 NM. SEAS WILL DROP BACK TO 3 TO 4 FT OVERNIGHT IN RESPONSE TO THE WIND SPEED REDUCTION. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 300 AM TUESDAY...TYPICAL SUMMERTIME PATTERN THROUGH THE PERIOD WITH BERMUDA HIGH PRESSURE OFFSHORE AND A PIEDMONT TROUGH LYING INLAND FROM THE COAST. THIS WILL DRIVE SW WINDS ACROSS THE WATERS THROUGH THE PERIOD AT 10-15 KTS...WITH ENHANCEMENTS EACH EVENING TO 20 KTS AS THE PIEDMONT TROUGH SHARPENS. BLEND OF INHERITED WAVE HEIGHTS WITH THE LATEST NWPS RUN BRINGS SEAS TO JUST BELOW 6 FT EACH EVENING AS THE WINDS INCREASE...BUT IT IS POSSIBLE THAT ADVISORY CONDITIONS WILL DEVELOP...ESPECIALLY THURSDAY AFTN/EVE. HAVE KEPT CURRENT FORECAST AT 3-5 FT THROUGH THE PERIOD...AND A SCEC IS PROBABLY THURSDAY...WITH THE SCA A POSSIBILITY. LONG TERM /FRIDAY THROUGH SATURDAY/... AS OF 300 AM TUESDAY...ENTERING THE TIME OF YEAR WHEN THE BERMUDA HIGH BECOMES A SEMI-PERMANENT FEATURE...AND THIS WILL BE THE CASE DURING THE EXTENDED. THIS MEANS LITTLE VARIATION IN MARINE CONDITIONS EACH DAY...WITH SW WINDS AROUND 15 KTS PRETTY MUCH CONSTANT. THESE WINDS WILL COMBINE WITH A SE SWELL TO PUSH WAVE HEIGHTS TO 3-5 FT...SLIGHTLY HIGHER AT TIMES IN THE EVENING AS THE GRADIENT GETS PINCHED IN THE LEE OF THE SHARPENING PIEDMONT TROUGH. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...III SHORT TERM...JDW LONG TERM...JDW AVIATION...MRR

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