Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 181750 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 150 PM EDT TUE JUN 18 2013 .SYNOPSIS... WARM AND HUMID CONDITIONS WILL PREVAIL AHEAD OF AN APPROACHING COLD FRONT...WHICH WILL MOVE THROUGH THE AREA EARLY ON WEDNESDAY. HIGH PRESSURE WILL BUILD IN FROM THE NORTH THEREAFTER...WITH A DRYING TREND BEGINNING TOWARDS THE END OF THE WEEK. THE DRYING TREND WILL LAST INTO EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 12:30 PM TUESDAY...NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS: ANALYSIS OF MORNING SOUNDINGS AND A LOOK AT THE LATEST SYNOPTIC SITUATION CONFIRMS EARLIER THINKING THAT CONVECTION IS LIKELY TO DEVELOP THIS AFTERNOON AND LAST WELL INTO THE EVENING HOURS. STRONGEST CONVECTION POSSIBLE LATE THIS AFTERNOON AND EARLY EVENING AS A VORTICITY MAX TRANSITS THE AREA FROM WEST TO EAST. PREVIOUS DISCUSSION FOLLOWS: A COLD FRONT WILL APPROACH FROM THE NW TODAY AND MOVE INTO THE AREA TONIGHT. IN ADVANCE OF THE FRONT EXPECT TO SEE SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS...PARTICULARLY DURING THE AFTERNOON AND EVENING HOURS. ONCE CURRENT ACTIVITY CLEARS THE COAST...PLAN ON CHC POPS THROUGH THE PERIOD EXCEPT FOR LIKELY POPS FROM ABOUT MIDDAY INTO THE EVENING HOURS. MAX TEMPERATURES TODAY SHOULD REACH THE MID 80S WITH LOWS TONIGHT WITHIN A COUPLE DEGREES OF 70. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 AM TUESDAY...FRONT IN THE AREA AT THE START OF THE PERIOD WILL BE PUSHED FARTHER EAST BY WESTERLY FLOW ALOFT AND SURFACE HIGH RIDGING DOWN THE COAST DURING THE PERIOD. GFS/WRF/ECMWF ALL SHOW DRIER MID LEVEL AIR MOVING INTO THE REGION AS EARLY AS WED AFTERNOON BUT MORE LIKELY WED EVENING. SOUNDINGS SHOW DEVELOPMENT OF MID LEVEL STABLE LAYER AS SUBSIDENCE DEVELOPS BEHIND EXITING 5H TROUGH AXIS. AS A RESULT PRECIPITABLE WATER VALUES ARE FORECAST TO DROP UNDER 1.5 INCH BY EVENING LIMITING PRECIP COVERAGE TO EARLIER IN THE DAY. STILL HOLDING ONTO CHC POP BUT FURTHER REDUCTION MAY BE REQUIRED. ALTHOUGH THERE WILL BE DRY AIR IN THE MID LEVELS WED INTO THU THE HIGH BUILDING IN FROM THE NORTH WILL RESULT IN LOW LEVEL NORTH TO NORTHEAST FLOW. LOW LEVEL MOISTURE UNDER MID LEVEL INVERSION COULD TRANSLATE TO INCREASED CLOUD COVER WED AND EARLY THU. LOW LEVEL FLOW BECOMES EAST AND POSSIBLY SOUTHEAST THU INTO THU NIGHT. AT THE SAME TIME FLOW ALOFT VEERS TO NORTH-NORTHEAST IN RESPONSE TO WEAK 5H RIDGE BUILDING OVER THE CENTRAL US. THIS HELPS WEAKEN THE CAP WHICH MAY ALLOW FOR SOME ISOLATED CONVECTION BUT MID LEVEL DRY AIR REMAINS A BIG OBSTACLE. WILL CARRY SLIGHT CHC POP THU AFTERNOON BUT THIS MAY BE GENEROUS. LOSS OF HEATING SHOULD END ANY PRECIP THREAT SO WILL CARRY NO MENTIONABLE POP THU NIGHT. TEMPERATURES WILL BE NEAR TO SLIGHTLY BELOW CLIMO THROUGH THE PERIOD. && .LONG TERM /FRIDAY THROUGH TUESDAY/... AS OF 3 AM TUESDAY...MID LEVEL RIDGING SHIFTS EAST DURING THE PERIOD WHILE AT THE SURFACE ELONGATED HIGH MOVES SOUTH OF NEW ENGLAND. SUBSIDENCE UNDER THE BUILDING RIDGE MAINTAINS DEEP DRY AIR OVER THE CAROLINAS. FORECAST SOUNDINGS SHOW PWATS DROPPING UNDER 1 INCH FRI MORNING AND REMAINING UNDER 1 INCH THROUGH THE WEEKEND. ALTHOUGH THERE WILL BE A SEA BREEZE EACH AFTERNOON THINK VERY LITTLE IF ANY CU WILL DEVELOP WITH PRECIP CHANCES BEING QUITE LIMITED. LOW LEVEL AND UPPER LEVEL MOISTURE STARTS TO INCREASE ON MON AS SURFACE HIGH SHIFTS TO THE MORE TYPICAL BERMUDA LOCATION AND MID LEVEL RIDGE AXIS CONSOLIDATES OFF THE SOUTHEAST COAST. INCREASE IN MOISTURE IS NOT ENOUGH TO WARRANT ANYTHING OTHER THAN A SILENT POP BUT IS LIKELY TO RESULT IN AN INCREASE IN HIGH CLOUD AS THE PERIOD ENDS. TEMPERATURES START OUT NEAR TO SLIGHTLY BELOW CLIMO BUT STEADILY INCREASE THROUGH THE PERIOD AS MID LEVEL RIDGING MOVES OVERHEAD AND SUBSIDENCE INCREASES. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/...
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AS OF 18Z...THIS AFTERNOON...SHOWERS DEVELOPED ALONG THE SEA BREEZE NEAR KILM EARLIER BUT HAVE SINCE DISSIPATED. SW-WSW FLOW THROUGH THE MID LEVELS SUGGESTS THE THE SEA BREEZE WILL NOT PENETRATE TOO MUCH FURTHER INLAND. MODELS SUGGESTS THE SIGNIFICANT LIFT NEAR KILM WILL SUBSIDE THIS AFTERNOON. WILL CONTINUE TO ONLY MENTION VCSH FOR THE COASTAL TERMINALS THROUGH THE AFTERNOON. SHOULD SEE A CONTINUED LIFT OF CLOUD BASES THUS DESPITE THE PROXIMITY OF THE SEA BREEZE BOUNDARY RESULTING IN LOW VFR CIGS. OTHER SHOWERS/ISOLATED THUNDERSTORMS ARE APPROACHING KFLO FROM THE WEST BUT CONVECTION IS NOT IMPRESSIVE. WILL INDICATE VCTS AT KFLO/KLBT 21-22Z. CONFIDENCE IS MODERATE SHOWERS/TSTMS WILL OCCUR 00-02Z. VCTS SHOULD DEVELOP AT THE COASTAL TERMINALS 01-02Z WITH MODERATE CONFIDENCE OF SHOWERS/TSTMS 02-04Z. PREDOMINATE MVFR/TEMPO IFR EXPECTED WITH THIS ACTIVITY. CONVECTION WILL MOVE SOUTH OF THE TERMINALS AFTER MIDNIGHT. MVFR CEILINGS WILL DEVELOP AS WINDS SHIFT TO THE NORTHWEST OVERNIGHT. MVFR CEILINGS WILL LIFT TO VFR AT KFLO/KLBT SHORTLY AFTER SUNRISE...BUT COULD PERSIST THROUGH THE END OF THE TAF VALID PERIOD AS SHOWER/TSTMS REDEVELOP AT THE COASTAL TERMINALS. EXTENDED OUTLOOK...SHOWERS AND THUNDERSTORMS LIKELY WEDNESDAY WITH MVFR/TEMPO IFR POSSIBLE. VFR THURSDAY THROUGH SATURDAY.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 12:30 PM TUESDAY...NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. PREVIOUS DISCUSSION FROM EARLIER THIS MORNING FOLLOWS: EXPECT S TO SW WINDS OF 10 TO 15 KT TODAY TO INCREASE TO 15 TO 20 KT TONIGHT BEFORE DIMINISHING SLIGHTLY LATE AS THE FRONT NEARS THE WATERS. SEAS OF 2 TO 3 FT EARLY TODAY WILL PEAK IN THE 3 TO 5 FT RANGE THIS EVENING BEFORE SUBSIDING SLIGHTLY TOWARD DAY BREAK. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 AM TUESDAY...COLD FRONT PUSHES EAST OF THE WATERS DURING WED AS HIGH PRESSURE BUILDS IN FROM THEN NORTH. AS A RESULT LIGHT OFFSHORE FLOW WILL VEER TO NORTH-NORTHEAST WED NIGHT INTO THU. GRADIENT INCREASES THU AS THE HIGH BUILDS SOUTH...PUSHING NORTHEAST FLOW AS HIGH TO 15 KT LATER THU AND THU NIGHT. OFFSHORE FLOW WILL KNOCK SEAS FROM 3 TO 5 FT AT THE START OF THE PERIOD TO 2 TO 3 FT BY THU MORNING. INCREASE IN NORTHEAST FLOW THU AND THU NIGHT WILL RESULT IN A MARGINAL INCREASE IN SEAS FOR THE SECOND HALF OF THE PERIOD...3 TO 4 FT. LONG TERM /FRIDAY THROUGH SATURDAY/... AS OF 3 AM TUESDAY...HIGH PRESSURE NORTH OF THE WATERS WILL REMAIN THE DOMINANT FEATURE THROUGH THE PERIOD. LACK OF GRADIENT WILL KEEP SPEEDS UNDER 15 KT AND ALLOW FOR DAILY SEA BREEZE WITH MORE OF AN ONSHORE WIND COMPONENT DEVELOPING NEAR SHORE. SEAS WILL RUN 2 TO 4 FT THROUGH THE PERIOD. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...REK AVIATION...MRR MARINE...REK

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