Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 281450 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 1050 AM EDT MON JUL 28 2014 .SYNOPSIS... HIGH HEAT AND HUMIDITY WILL PREVAIL TODAY AHEAD OF AN UNSEASONABLY STRONG COLD FRONT. THE FRONT IS EXPECTED TO BRING THUNDERSTORMS LATER THIS AFTERNOON AND EVENING...AND SOME MAY BE SEVERE. DRIER AND COOLER AIR WILL SETTLE INTO THE REGION IN WAKE OF FRONT MUCH OF THIS WEEK...AS CANADIAN HIGH PRESSURE DROPS INTO THE REGION. RAIN CHANCES WILL RETURN BY NEXT WEEKEND AS HIGH PRESSURE OFFSHORE BUILDS WEST AND BRINGS A RETURN OF MOISTURE TO THE EAST COAST. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1045 AM MONDAY...MORNING CLOUD COVER HAMPERING OTHERWISE RAPID MORNING TEMPERATURE CLIMBS ACROSS THE AREA...BUT THE DEBRIS CLOUD COVER IS THINNING AND SOON SURFACE-BASED CAPES WILL RAMP UP. H5 TEMPS HAVE DROPPED ONLY SLIGHTLY AND WILL REMAIN AROUND -7 DEGREES MUCH OF THE DAY. STRONGER HEIGHT FALLS AND COOLING ALOFT FOLLOW MAINLY INTO EARLY TUESDAY. STILL...THESE FACTORS COULD BRING MORE OF A HAIL THREAT INTO EARLY EVENING ...AS HIGH SFC CAPES AND UPPER COOLING OVERLAP. SPC RETAINS A SLIGHT RISK OVER OUR AREA DUE TO GOOD FORCING ALOFT WITH THE APPROACHING AND UNUSUALLY AMPLIFIED UPPER TROUGH...AND ASSOCIATED ROBUST BULK SHEAR PARAMETERS. WITH INCREASING SUN...IGNITION OF STORMS IS EXPECTED. THE SEA BREEZE WILL ALSO INTERTWINE IN THE MIX TO ADD LOW-LEVEL BOOSTS SO THIS FEATURE WILL ALSO SERVE AS A FOCAL POINT FOR STORM INITIATION. STORM MOTION AND DOWNDRAFT CAPE PARAMETERS WILL ENHANCE POTENTIAL FOR DAMAGING WINDS GUSTS...THROUGH A FORWARD MOTION CLOSE TO 30 MPH AND EVAPORATIVE COOLING TO INCREASE DOWNDRAFT POWER. ANYTIME AFTER 18Z SEEMS FAIR GAME FOR DISCREET STRONG STORMS...THEN A MORE ORGANIZED SQUALL OR BROKEN LINE OF STORMS WITHIN THE MAIN VORT SPOKE EMBEDDED IN THE UPPER TROUGH THIS EVENING. ACTUAL FRONTAL PASSAGE SLATED LATE TONIGHT AND A WIND-SHIFT TO THE NORTH LOOKS TO CLEAR THE COAST BY DAYBREAK TUESDAY. HEAT ADVISORY CONTINUES FOR PORTIONS OF SC FOR MAXIMUM APPARENT TEMPERATURES OF 105-108 THIS AFTERNOON. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 3 AM MONDAY...COLD FRONT WILL BE OFF THE COAST BY THE START OF THE PERIOD WITH A MARKEDLY DIFFERENT AIR MASS BUILDING OVER THE REGION. FLAT MID LEVEL TROUGH WILL REMAIN JUST WEST OF THE AREA DURING THE PERIOD. LOW LEVEL NORTHERLY FLOW AND MID LEVEL WEST-NORTHWEST FLOW WILL USHER IN MUCH DRIER AIR. PRECIPITABLE WATER VALUES DROP TO AROUND 1 INCH TUE/WED WITH DEWPOINTS IN THE UPPER 50S TO LOWER 60S EACH DAY. PRECIP CHANCES WILL BE CLOSE TO ZERO EACH DAY. ALTHOUGH GRADIENT WILL BE VERY WEAK THERE WILL NOT BE MUCH IF ANY SEA BREEZE GIVEN WATER TEMPS WITHIN A FEW DEGREES OF HIGHS...MID 80S. TUE SHOULD BE THE WARMER DAY...MAINLY DUE TO A WARMER START. LOWS WILL DROP INTO THE MID TO UPPER 60S EACH NIGHT. THERE WILL BE POTENTIAL FOR RADIATIONAL COOLING WITH LIGHT WINDS...CLEAR SKIES...AND DRY AIR ALOFT. TYPICAL COLD SPOTS COULD DROP INTO THE LOWER 60S. && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 3 AM MONDAY...MID LEVEL TROUGH HANGING OVER THE EASTERN CONUS FOR MUCH OF THE PERIOD WILL KEEP COLD FRONT STALLED OFF THE SOUTHEAST COAST INTO THE WEEKEND. ALTHOUGH DEEP MOISTURE IS LACKING THERE COULD BE A FEW SHORTWAVES ROTATING AROUND THE BASE OF THE TROUGH THU INTO FRI...EACH PROVIDING A BRIEF INCREASE IN MID LEVEL MOISTURE. THESE COULD SPAWN SOME ISOLATED AFTERNOON/EVENING SHOWERS...IF TIMING IS FAVORABLE. COVERAGE WOULD BE FAIRLY LIMITED SO AT MOST PLAN TO CARRY A SILENT POP. DEEPER SOUTHWEST FLOW DEVELOPS FRI AND CONTINUES THROUGH THE WEEKEND AS 5H TROUGH DIGS. GULF MOISTURE ADVECTED INTO THE SOUTHEAST LATE IN THE WEEK PUSHES PRECIPITABLE WATER VALUES OVER 1.5 INCHES LATER FRI AND CLOSE TO 2 INCHES BY THE END OF THE PERIOD. INCREASING DEEP MOISTURE...POSSIBILITY OF SHORTWAVES AND DIURNAL INSTABILITY WILL ALL CONTRIBUTE TO AN INCREASE IN POP FRI-SUN. THERE ALSO REMAINS THE SPECTER OF POTENTIAL LOW PRESSURE DEVELOPMENT ALONG THE FRONT STALLED OFF THE SOUTHEAST COAST. FOR NOW THE MAJOR MEDIUM RANGE GUIDANCE KEEPS THIS FEATURE QUITE WEAK BUT DEVELOPMENT OF SAID FEATURE WOULD NOT BE UNPRECEDENTED AND IS SOMETHING TO WATCH. TEMPERATURES THROUGH THE PERIOD WILL REMAIN BELOW CLIMO WITH HIGHS IN THE MID TO UPPER 80S AND LOWS IN THE MID TO UPPER 60S. && .AVIATION /14Z MONDAY THROUGH FRIDAY/... AS OF 14Z...SHORT-LIVED MVFR/IFR POSSIBLE IN ISOLATED STRONG STORMS LATER THIS AFTERNOON AND EVENING. OTHERWISE EXPECT VFR. LATEST SATELLITE IMAGERY DEPICTS OVERALL SCT SKIES THIS MORNING...MAINLY HIGH CLOUDS...AS A DISTURBANCE CONTINUES TO WEAKEN ACROSS THE CAROLINAS. CHANCES INCREASE FOR ISOLATED STRONG TO SEVERE STORMS LATER THIS AFTERNOON AND EVENING AS A COLD FRONT APPROACHES THE AREA. AHEAD OF THE FRONT...WE WILL SEE SOUTHWEST WINDS INCREASE THROUGHOUT THE MORNING HOURS...WITH SUSTAINED WINDS 10 TO 12 KTS AND GUSTS UP TO 20 KTS BY EARLY AFTERNOON. COULD NOT ENTIRELY RULE OUT SHORT-LIVED PERIODS OF MVFR/IFR WITH THE CONVECTION AS STRONGER STORMS MAY PRODUCE HEAVY DOWNPOURS AT TIMES. THE FRONT WILL PUSH OFFSHORE TONIGHT ALLOWING FOR CONVECTION TO TAPER OFF AND SKIES BEGIN TO GRADUALLY CLEAR...GIVING WAY TO VFR WITH VEERING WINDS TO THE NORTHWEST...WITH SUSTAINED WINDS AOB 10 KTS THROUGH THE END OF THE VALID TAF PERIOD. EXTENDED OUTLOOK...MVFR DUE TO MORNING FOG POSSIBLE THURSDAY AND FRIDAY. OTHERWISE EXPECT VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1045 AM MONDAY...SMALL CRAFT EXERCISE CAUTION FOR ALL WATERS THROUGH TONIGHT. THE SFC PRESSURE PATTERN AND TIGHTENED GRADIENT AHEAD OF THE APPROACHING COLD FRONT REMAINS CONDUCIVE FOR SW-WSW WINDS AT A SOLID 15 TO 20 KT WITH SOME GUSTS UP TO 25 KT. DURING THE APPROACH AND PASSAGE OF THE COLD FRONT TONIGHT...WINDS WILL VEER FROM WSW TO NW INITIALLY...THEN FURTHER VEER TO THE N TO NNE BY DAYBREAK TUESDAY. THE SFC PG WILL BEGIN TO RELAX SOME TOWARD DAYBREAK TUESDAY...AND FURTHER RELAX EARLY IN THE SHORT TERM. WINDS WILL SUBSIDE TO AROUND 15 KT AFTER MIDNIGHT TONIGHT. SIGNIFICANT SEAS WILL RANGE BETWEEN 3 AND 5 FT TODAY INTO THIS EVENING...AND ONLY DROP TO 2 TO 4 FT LATE TONIGHT AFTER THE CFP. WIND DRIVEN WAVES OR CHOP WILL DOMINATE THE SIGNIFICANT SEAS SPECTRUM WITH DOMINATING PERIODS OF ONLY 5 TO 6 SECONDS. STRONG TO POSSIBLY SEVERE CONVECTION MAY AFFECT THE LOCAL WATERS LATE THIS AFTERNOON AND TONIGHT...AHEAD OF THE APPROACHING COLD FRONT. SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 3 AM MONDAY...BRIEF NORTHERLY SURGE FOLLOWING THE COLD FRONT WILL BE WANING AS THE PERIOD BEGINS. WINDS MAY BE 10 TO 15 KT TUE MORNING BUT BY MIDDAY NORTHEAST FLOW SHOULD BE 10 KT OR LESS. WINDS REMAIN 10 KT OR LESS WED BUT MAY BECOME SLIGHTLY MORE ONSHORE DURING THE AFTERNOON. SEA BREEZE IS NOT LIKELY TO BE A FACTOR EITHER DAY GIVEN THE BELOW NORMAL FORECAST HIGHS. HOWEVER...THERE WILL BE POTENTIAL FOR A WELL DEFINED LAND BREEZE EACH NIGHT AS LOWS OVERLAND DROP INTO THE 60S. SEAS WILL RUN 2 TO 3 FT THROUGH THE PERIOD...WITH HIGHEST SEAS EXPECTED DURING THE FIRST HALF OF TUE. LONG TERM /THURSDAY THROUGH FRIDAY/... AS OF 3 AM MONDAY...STALLED FRONT EAST OF THE WATERS AND HIGH PRESSURE TO THE WEST WILL MAINTAIN LIGHT NORTHEAST TO EAST FLOW OVER THE WATERS THROUGH THE PERIOD. SPEEDS WILL GENERALLY BE AROUND 10 KT WITH SEAS RUNNING 2 TO 3 FT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...HEAT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR SCZ032-033-039- 053>056. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...MJC NEAR TERM...MJC SHORT TERM...III LONG TERM...III AVIATION...SGL MARINE...DOUG/3

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