Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 021859 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 259 PM EDT THU JUL 2 2015 .SYNOPSIS... BERMUDA HIGH PRESSURE 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. A FRONT MAY STALL TO OUR NORTH OVER THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 2 PM THURSDAY...THUS FAR CONVECTION HAS BEEN SLOW TO DEVELOP ACROSS THE LOCAL AREA. APPEARS THE MARGINAL MID LEVEL LAPSE RATES AND LIMITED INSTABILITY ARE HELPING TO PREVENT ANY DEEPER CONVECTION. FARTHER SOUTH...WHERE ML CAPE HAS EXCEEDED 2000 J/KG...STORMS HAVE BEEN ABLE TO DEVELOP ALONG A WEAK SURFACE TROUGH PINNED CLOSE TO THE COAST. STORMS MAY TRY AND SPREAD NORTH ALONG THIS BOUNDARY BUT FOR THE TIME BEING WILL FIND THE MID LEVEL ENVIRONMENT LESS FAVORABLE. THERE IS ALSO SOME POST WAVE SUBSIDENCE EVIDENT IN FORECAST SOUNDINGS...SOMETHING WHICH HANGS AROUND INTO THE LATE AFTERNOON HOURS. SO WITHOUT MID LEVEL SUPPORT NOT SURE A LOT OF DEEPER CONVECTION WILL BE ABLE TO DEVELOP AND MAINTAIN ITSELF. BEST CHANCES APPEARS TO BE INLAND AS THE STORMS DOWNSTREAM...CURRENTLY IN NORTHERN GA/WESTERN SC...MOVE INTO THE REGION. CURRENT TIMING HAS THIS ACTIVITY REACHING THE AREA IN THE 4PM TO 6PM TIME FRAME. THINK BETTER EVENT WILL BE LATE TONIGHT. THE DIURNALLY DRIVEN CONVECTION IS LIKELY TO WEAKEN RATHER QUICKLY WITH THE LOSS OF HEATING. HOWEVER THERE IS A MORE POTENT SHORTWAVE APPROACHING THE AREA AS THE PERIOD ENDS. IF AFTERNOON ACTIVITY IS LIMITED THIS WAVE WOULD HAVE SOME MID LEVEL INSTABILITY AND ABUNDANT MOISTURE TO TAP INTO. IN FACT THE NUMERICAL GUIDANCE DEPICTS LIMITED PRECIP CHANCES THROUGH THE EVENING WITH AN INCREASE OVERNIGHT AS THE SHORTWAVE APPROACHES. HAVE TRENDED THE FORECAST IN THIS DIRECTION GIVEN RECENT RADAR TRENDS COMBINED WITH 12Z GUIDANCE. WORTH NOTING THAT EITHER ROUND OF CONVECTION WOULD HAVE SOME POTENTIAL TO PRODUCE DAMAGING WIND AND HAIL...THOUGH THE RISK REMAINS QUITE LOW. TEMPERATURES WILL BE TRICKY OVERNIGHT WITH A LOT DEPENDING ON HOW CONVECTION LATER THIS AFTERNOON/EVENING AND OVERNIGHT PLAYS OUT. MOST AREAS WILL REMAIN IN THE 70S WITH POTENTIAL FOR LOW TO MID 70S ACROSS A LARGE PORTION OF THE FORECAST AREA. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 3 PM THURSDAY...A BROADLY CYCLONIC PATTERN WILL PERSIST ALOFT THROUGH THE PERIOD...AS WILL THE BERMUDA HIGH/INLAND THERMAL TROUGH PATTERN AT THE SURFACE. TO OUR NORTH A FRONT WILL REMAIN STALLED ALONG THE NC/VA BORDER. COMBINE THESE FACTORS WITH A VERY MOIST AND MODERATELY UNSTABLE AIRMASS AND WE WILL CONTINUE TO SEE THE CHANCE FOR CONVECTION THROUGH THE PERIOD. THE USUAL SUSPECTS WILL BE IN PLAY AS FAR AS CONVECTIVE INITIATION GOES...DIURNAL HEATING...THE SEA BREEZE FRONT...THE INLAND THERMAL TROUGH...OLD OUTFLOW BOUNDARIES AND UPPER LEVEL DISTURBANCES. THIS LATTER FACTOR WILL BRING THE GREATEST POTENTIAL FOR STRONG CONVECTION AS A SERIES OF SHORT WAVES CYCLE THROUGH THE BASE OF THE UPPER TROUGH. EXACT TIMING OF THESE UPPER FEATURES IS...AS ALWAYS...AN IFFY PROPOSITION...BUT A CONSENSUS OF GUIDANCE SHOWS ONE SUCH SHORT WAVE MOVING THROUGH FRIDAY EVENING. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 3 PM THURSDAY...IN GENERAL...COASTAL CAROLINAS WILL REMAIN IN A MORE TYPICAL SUMMERTIME PATTERN IN SOUTHWESTERLY FLOW ON WESTERN PERIPHERY OF BERMUDA HIGH. THE LONGER WAVE TROUGH EXTENDING DOWN FROM THE GREAT LAKES IN THE MID TO UPPER LEVELS WILL PUSH A WEAKENING FRONTAL BOUNDARY SOUTH AND EAST THROUGH EARLY NEXT WEEK AND ALTHOUGH THIS BOUNDARY MAY NEVER REACH INTO OUR LOCAL AREA IT MAY ACT TO SHIFT LEE SIDE TROUGH FARTHER EAST. THEREFORE SHOULD SEE ENHANCED CONVERGENCE AND MOISTURE POOL SOUTH AND EAST OF THIS FRONT IN WARMER AND MORE MOIST AIR MASS. THIS IN COMBINATION WITH SHORTWAVE ENERGY ALOFT WILL ACT TO PRODUCE LOCALIZED CONVECTION EACH AFTERNOON. THE GFS ACTUALLY SHOWS A BROAD CUT OFF LOW DEVELOPING ALONG THE LEE OF THE APPALACHIANS BY MONDAY WHICH SEEMS TO OPEN UP BY TUES AND FINALLY LIFTS OFF TO THE NORTHEAST AND WEAKENS THROUGH MID WEEK. THIS SHOULD HELP TO ENHANCE CONVECTIVE DEVELOPMENT ON MONDAY BUT SHOULD DIMINISH UPPER LEVEL SUPPORT BY TUES INTO WED BUT LEE SIDE TROUGH WILL STILL REMAIN ACROSS INLAND CAROLINAS AND MODELS ARE SHOWING ANOTHER SHORTWAVE TO FOLLOW BY THURS. OVERALL...LOCAL AREA WILL REMAIN IN WARM AND HUMID SUMMERTIME AIR MASS AND THE SUBTLE PATTERN CHANGES FROM THE SURFACE THROUGH THE UPPER LEVELS WILL WILL MAKE THE BIGGEST DIFFERENCE EACH DAY IN TERMS OF BEHAVIOR OF SEA BREEZE FRONT AND PIEDMONT TROUGH AND OVERALL POTENTIAL AND FOCUS OF CONVECTION. && .AVIATION /19Z THURSDAY THROUGH TUESDAY/... AS OF 18Z...TERMINALS ARE VFR THIS AFTERNOON WITH SW WINDS AROUND 10KT. THE SEA BREEZE BOUNDARY WILL LIKELY REMAIN VERY NEAR THE COASTAL TERMINALS THIS AFTERNOON AS IT DID YESTERDAY. THIS LEADS TO LOW CONFIDENCE IN FORECAST WIND DIRECTIONS AT THE COASTAL TERMINALS WITH DIRECTIONS OF S-W POSSIBLE. PER VISIBLE SATELLITE LOOPS LOW CLOUDS ARE INCREASING WEST OF KFLO. SHOWERS/ISOLATED THUNDERSTORMS ARE POSSIBLE THIS EVENING AND OVERNIGHT. BEST CHANCE FOR VCTS WILL BE KFLO/KLBT EARLY EVENING AND COASTAL TERMINALS MID-LATE EVENING. OVERNIGHT THINK MOST ACTIVITY WILL BE JUST SHOWERS. AFTER SUNRISE EXPECT WEST WINDS AND VFR CONDITIONS. EXTENDED OUTLOOK...PREDOMINATELY VFR WITH A CHANCE OF SHOWERS AND THUNDERSTORMS EACH DAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 2 PM THURSDAY...SOUTHWEST FLOW CONTINUES OVER THE WATERS TODAY WITH SPEEDS 15 TO 20 KT. GRADIENT IS EXPECTED TO TIGHTEN UP A BIT THIS EVENING...PUSHING SPEEDS CLOSE TO 20 KT OVERNIGHT. THIS WILL PUSH SEAS...CURRENTLY RUNNING 3 TO 4 FT...TO 4 TO 6 FT ACROSS OUTER EDGES OF ALL ZONES EXCEPT AMZ256 WHERE WIND COMPONENT WILL BE MORE OFFSHORE. AS SUCH THE SCA CONTINUES UNALTERED STARTING THIS EVENING THROUGH ROUGHLY DAYBREAK FRI. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 3 PM THURSDAY...BERMUDA HIGH/INLAND TROUGH PATTERN WILL PERSIST THROUGH THE SHORT TERM...CONTINUING A SW FLOW IN THE 15 TO 20 KT RANGE FOR FRIDAY AND SATURDAY. A SMALL CRAFT ADVISORY IS POSSIBLE LATE FRIDAY INTO EARLY SATURDAY AS SEAS BRIEFLY BUILD INTO THE 4 TO 6 FT RANGE. LONG TERM /SUNDAY THROUGH TUESDAY/... AS OF 3 PM THURSDAY...LIGHT TO MODERATE SOUTHERLY FLOW AROUND WESTERN PERIPHERY OF BERMUDA HIGH THROUGH THE PERIOD. MAY SEE THE GRADIENT GET PINCHED AT TIMES AS LEE SIDE TROUGH MIGRATES CLOSER TO THE COAST OR GETS ENHANCED BY SHORTWAVE MOVING THROUGH...BUT OVERALL EXPECT A WEAKENING SFC FLOW THROUGH EARLY NEXT WEEK. WINDS WILL SPIKE UP AND BACK SLIGHTLY IN SEA BREEZE NEAR SHORE EACH AFTERNOON BUT OVERALL EXPECT WINDS MAINLY 10 KTS OR LESS. SEAS WILL ALSO DIMINISH THROUGH THE PERIOD STARTING OUT 2 TO 4 FT BUT DROPPING DOWN TO 3 FT OR LESS MON THROUGH TUES. A LONGER PERIOD SE SWELL UP TO 9 SEC WILL DOMINATE COME SUNDAY NIGHT AS SHORTER PERIOD WIND WAVES DIMINISH. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 AM EDT FRIDAY FOR AMZ250-252-254. && $$ SYNOPSIS...REK NEAR TERM...III SHORT TERM...REK LONG TERM...MBB AVIATION...MRR MARINE...REK/III/MBB

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