Area Forecast Discussion
Issued by NWS Wilmington, NC

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476 FXUS62 KILM 271027 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 627 AM EDT WED APR 27 2016 .SYNOPSIS... WARM WEATHER IS EXPECTED THROUGH FRIDAY AHEAD OF AN APPROACHING COLD FRONT. WARM AND UNSTABLE AIR AHEAD OF THE FRONT WILL BRING SCATTERED SHOWERS AND THUNDERSTORMS THURSDAY AND THURSDAY NIGHT WITH DRIER AND MILD CONDITIONS FRIDAY. HIGH PRESSURE WILL BUILD IN ON SATURDAY BRINGING A BIT OF A COOL DOWN. A RAINY START TO THE MONTH OF MAY IS LOOKING MORE LIKELY...AS A LOW PRESSURE SYSTEM IMPACTS THE AREA LATE SUNDAY THROUGH TUESDAY OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 615 AM WEDNESDAY...WEAK UVVS FROM THE LOW LEVEL JET AND AVBL MOISTURE HAS RESULTED IN MY WIDESPREAD SC ACROSS THE COASTAL COUNTIES AND THE NEAR SHORE WATERS. EXPECT THIS CLOUDINESS TO PERSIST THRU THE MID TO POSSIBLY LATE MORNING HRS. THE MESOSCALE SEA BREEZE WILL DEVELOP BY LATE MORNING AND BEGIN PUSHING INLAND WITH BULK OF CLOUDINESS TRANSITIONING ALONG AND WEST OF THE SEA BREEZE. SFC HIGH PRESSURE CENTERED WELL OFFSHORE FROM THE SE U.S. WILL CONTINUE TO RIDGE BACK WESTWARD WITH ITS AXIS ONSHORE IN THE VICINITY OF GA. THUS...WARM SW FLOW WILL CONTINUE ACROSS THE FA THIS PERIOD. THE ADVERTISED BACKDOOR COLD FRONT WILL ONLY DROP OR SNAKE FROM THE VA CAPES TO THE VA-NC BORDER BY DAYBREAK THU. THE MAIN CONVECTION ALONG AND AHEAD OF THIS FRONT WILL REMAIN JUST NORTH OF THE FA. HOWEVER...THE ATM ACROSS THE ILM CWA NO LONGER IS STRONGLY CAPPED. THIS DUE TO THE SUBSIDENCE INVERSION ALOFT NOT AS PRONOUNCED LIKE PREVIOUS DAYS THAT BASICALLY PREVENTED DEVELOPING CU TO REACH MDT OR TOWERING CU STATUS. PWS INCREASE TO 1.25+ INCHES ACROSS THE FA AS MOISTURE ESPECIALLY IN THE LOWER LEVELS INCREASES VIA VARIOUS MODEL RH TIME HEIGHT DISPLAYS. MODEL PROGGED INSTABILITY INDICATES 1300-1900 CAPE WHICH HAS BEEN LACKING THE PAST SEVERAL DAYS. THE INLAND PROGRESSION SEA BREEZE WILL PROVIDE SOME FORCING TO AID INITIATION OTHER THAN THE PLAIN OLD DIFFERENTIAL HEATING AIR MASS TYPE CONVECTION. BEHIND THE SEA BREEZE...POPS WILL BECOME NULL AND VOID DUE TO THE STABLE MARINE LAYER. IN ALL...COULD ONLY MUSTER UP 15 TO 24 POPS OR ISOLATED CONVECTION FOR THIS AFTN INTO THIS EVENING. AS FOR TEMPS...USED A BLEND OF NAM AND GFS MOS BUT STILL TWEAKED TONIGHTS MINS SLIGHTLY HIER. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 400 AM WEDNESDAY...BACKDOOR COLD FRONT WILL SINK A BIT FURTHER SOUTH BEFORE TEMPORARILY STALLING JUST NORTH OF THE FA DURING THU. MID-LEVELS EMBEDDED S/W TROFS OR VORTS TO PUSH ACROSS THE FA LATE THU AND THU NIGHT. THIS WILL RESULT IN A WEAK LOW TO DEVELOP ALONG THIS FRONT...MOVING OFF THE OUTER BANKS LATE THU NIGHT. POPS WILL GENERALLY RUN IN THE GOOD CHANCE CATEGORY THU AFTN AND WELL INTO THU NIGHT. THE FORCING AND UVVS FROM THE MID LEVEL TROFS WILL BE WANING AS THEY PUSH ACROSS THE FA LATE THU...BUT COMBINED WITH THE DAYS HEATING AND RESULTING INCREASED INSTABILITY IE. PROGGED 2000-2500 CAPE...ISOLATED STRONG WIND GUST UP TO 45 MPH WILL REMAIN POSSIBLE. THE EXITING LOW OFF THE OUTER BANKS WILL HELP DRAG THE COLD FRONT ACROSS AND SOUTH OF THE FA DURING FRIDAY. SOUTHEASTERN CANADIAN HIGH WILL BEGIN TO RIDGE DOWN THE EAST COAST OF THE U.S FRI NIGHT. USED A BLEND FOR MAX AND MIN TEMPS THIS PERIOD...AND DISREGARDED THE HIGH GFS MAX TEMPS FOR THU...IE. 90 FOR LBT. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 330 AM WEDNESDAY...SFC HIGH PRESSURE WILL EXTEND INTO NC FROM THE NORTH ON SATURDAY WITH COOLER AND DRIER WEATHER HOLDING ON WHILE MID TO UPPER RIDGE BUILDS UP THROUGH THE SOUTHEAST. THIS RIDGE WILL SHIFT EAST THROUGH THE WEEKEND AS LOW PRESSURE MAKES ITS WAY TOWARD THE CAROLINAS FROM THE WEST. ENOUGH DRY AIR AND SUBSIDENCE THROUGH THE MID LEVELS SHOULD BE PRESENT TO KEEP SHOWERS AT BAY ON SATURDAY. WESTERLY FLOW ALOFT WILL BACK TO THE S-SW THROUGH SUNDAY AS RIDGE AXIS SHIFTS EAST OF THE CAROLINAS AND SHORTWAVE REACHES THE AREA. THE ASSOCIATED SFC LOW SHOULD AFFECT THE CAROLINAS WITH INCREASED SHOWER ACTIVITY SUNDAY NIGHT THROUGH MONDAY. MOISTURE WILL INCREASE THROUGH THE COLUMN SUN INTO MONDAY WITH PCP WATER VALUES INCREASING FROM AN INCH EARLY SUNDAY UP TO 1.5 INCHES BY LATE SUN INTO MON. OVERALL EXPECT A GENERAL INCREASE IN CLOUDS ON SUNDAY AND BEST CHC OF SHWRS SUN NIGHT INTO MONDAY. WOULD NOT RULE OUT SOME LOCALIZED SHWRS SUN AFTN AHEAD OF SYSTEM...BUT MOST SHWRS/TSTMS WILL COME ON MONDAY. LOOKS LIKE THIS SYSTEM WILL BE MOVING OFF OF THE MID ATLANTIC COAST LATE MONDAY DRAGGING A COLD FRONT EAST. MAY BE SOME LINGERING CLOUDS AND SHWRS ON TUES AS SHORTWAVE PASSES THROUGH BUT OVERALL EXPECT SLIGHTLY COOLER BUT MAINLY DRIER AIR FOR TUES INTO WED. TEMPS SHOULD STAY BETWEEN 75 AND 80 MOST PLACES THROUGH THE WEEKEND THEN WARMING AHEAD OF FRONT MONDAY AND RELATIVELY COOLER AGAIN TUES INTO WED. && .AVIATION /10Z WEDNESDAY THROUGH SUNDAY/... AS OF 06Z...EXPECT A HIGH LIKELIHOOD OF VFR THROUGH THE 06Z TAF ISSUANCE PERIOD. CLEAR SKIES EARLY THIS MORNING WITH MID/HIGH TSTM DEBRIS CLOUDS DROPPING SE MAY SPREAD ACROSS THE TERMINALS DURING THE PRE-DAWN HOURS. STRATOCU 4-5K MAY ALSO BEGIN TO DEVELOP AS DAWN APPROACHES. ALL TAF SITES WILL SEE SW WINDS AT 5 TO 10 KT WITH OCNL GUSTS TO 15 KT IN RESPONSE TO A SW LLJ AT 30-35 KT AT 1100 TO 1400 FT AGL. APPEARS SITES WILL REMAIN JUST BELOW LLWS CRITERIA ATTM...BUT THIS MAY CHANGE AS SURFACE WINDS DECREASE SLIGHTLY TOWARD DAYBREAK WED...AND ALSO VEER TO THE SW-WSW AT 5 TO 10 KT. THE SEA BREEZE WILL AGAIN DEVELOP BY NOON AT THE IMMEDIATE COASTAL TERMINALS...REACHING ILM BY 18Z...OVERALL WINDS BACKING TO THE SSW AND GUSTING TO 20 KTS. ALONG AND WEST OF THE SEA BREEZE DURING THIS AFTERNOON...80+ DEGREE TEMPS AND DEWPOINTS IN THE 60S WILL CREATE AMPLE INSTABILITY FOR POSSIBLE AIR MASS PULSE CONVECTION. HOWEVER...IT REMAINS TOO ISOLATED TO MENTION IN KFLO/KLBT TAFS ATTM. PRECIPITATION CHANCES SHOULD DECREASE RAPIDLY AFTER SUNSET. EXTENDED OUTLOOK...ISOLATED CONVECTION POSSIBLE WED AFTERNOON AND EVENING. INCREASED CHANCES FOR SCATTERED CONVECTION THURSDAY INTO FRIDAY DUE TO A BACK-DOOR COLD FRONT DROPPING SOUTHWARD. OTHERWISE EXPECT VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 615 AM WEDNESDAY...THE SFC HIGH CENTERED WELL OFFSHORE FROM THE SE U.S....WILL CONTINUE TO RIDGE WESTWARD ONSHORE INTO GA. THIS PRESSURE PATTERN WILL YIELD SW WINDS THRU THIS PERIOD. THE SFC PG TO REMAIN SOMEWHAT TIGHTENED YIELDING AROUND 15 KT WIND SPEEDS. GUSTS UP TO 20 KT POSSIBLE...ESPECIALLY NEAR SHORE THIS AFTN AND EVENING DUE TO THE FORMATION AND INLAND PROGRESSION OF THE SEA BREEZE. SIGNIFICANT SEAS WILL RUN 2 TO 4 FT...WITH THE 4 FOOTERS MAINLY ACROSS THE ILM NC WATERS. DOMINATING PERIODS WILL RUN 4 TO 5 SECONDS DUE TO WIND DRIVEN WAVES BEING THE PRIMARY DRIVER FOR SIGNIFICANT SEAS. AN UNDERLYING 1 TO POSSIBLY 2 FOOT ENE GROUND SWELL WILL REMAIN PRESENT ESPECIALLY NORTH OF FRYING PAN SHOALS. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 400 AM WEDNESDAY...THE BACKDOOR COLD FRONT WILL SINK TO CENTRAL NC DURING THU. SFC LOW IS PROGGED TO DEVELOP ALONG THE FRONT ACROSS THE WESTERN CAROLINAS AND TRAVEL ALONG THIS FRONT TO OFF THE OUTER BANKS BY LATE THU NIGHT. IT WILL AID IN FINALLY DRAGGING THE COLD FRONT ACROSS THE WATERS DURING FRIDAY...AND TO WELL SOUTH OF THE AREA WATERS DURING FRI NIGHT. A 1030+ MB HIGH CENTERED OVER SE CANADA WILL BEGIN TO NOSE DOWN THE EAST COAST OF THE U.S. IN THE WAKE OF THE CFP. SW FLOW AHEAD OF THE FRONT THU WILL BECOME NE-E AFTER THE CFP DURING LATE FRI. CONVECTION WILL BE MOST NUMEROUS THU AFTN AND NIGHT AND POSSIBLY PRODUCE STRONG ISOLATED WIND GUSTS UP TO 35 KT. SIGNIFICANT SEAS WILL RUN 2 TO 4 FT THRU THE PERIOD...WITH A CHANGE IN DIRECTION TO THE 4 TO 5 SECOND PERIOD WIND DRIVEN WAVES PART OF THE EQUATION OCCURRING AFTER THE CFP. A FADING EASTERLY 1 FOOT GROUND SWELL TO REMAIN PRESENT. LONG TERM /SATURDAY THROUGH SUNDAY/... AS OF 330 AM WEDNESDAY...EXPECT NE WINDS UP TO 15 KTS AS HIGH PRESSURE BUILDS IN BEHIND COLD FRONT FROM THE NORTH THROUGH SATURDAY. WINDS WILL VEER TO THE E THROUGH SAT NIGHT AND EVENTUALLY SE BY SUN AFTN AS HIGH PRESSURE SHIFTS OFF THE MID ATLANTIC COAST AND LOW PRESSURE APPROACHES THE CAROLINAS FROM THE WEST. SEAS WILL REMAIN IN THE 2 TO 4 FT RANGE THROUGH THE WEEKEND BUT WILL BEGIN TO INCREASE OVERNIGHT SUN INTO MON MORNING AS LOW PRESSURE MOVES INTO THE CAROLINAS TIGHTENING THE GRADIENT FLOW OUT OF THE S-SW. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...RGZ NEAR TERM...DCH SHORT TERM...DCH LONG TERM...RGZ AVIATION...DCH/MRR

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