122 FXUS62 KILM 240539 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 139 AM EDT SUN JUN 24 2012 .SYNOPSIS... A WEAK FRONT WILL SLOWLY DISSIPATE ACROSS THE AREA THROUGH SUNDAY. HEAT AND HUMIDITY WILL PREVAIL AHEAD OF AN APPROACHING COLD FRONT MONDAY NIGHT. DRIER AND COOLER AIR WILL SPREAD ACROSS THE REGION TUESDAY AND WEDNESDAY. A BUILDING RIDGE OF HIGH PRESSURE WILL BRING VERY HOT TEMPERATURES LATE NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 826 PM SATURDAY...A WEAK FRONTAL BOUNDARY AND A MYRIAD OF OUTFLOW BOUNDARIES ACROSS THE REGION WILL SUSTAIN SHOWERS AND A FEW THUNDERSTORMS THROUGH EVENING...BUT LOSS OF HEATING IS BEGINNING TO TAKES ITS TOLL ON CONVECTIVE STRENGTH. THEREFOR DWINDLING POP VALUES OVERNIGHT REMAINS REASONABLE...FAVORED ACROSS THE NORTH COINCIDENT WITH THE WEAK BOUNDARY AND COLDER AIR ALOFT. FREEZING LEVELS WERE AROUND 2500 FEET LOWER ACROSS NC COMPARED TO SC DUE TO THE COOL POOL TROUGH SWEEPING ACROSS NEW ENGLAND AND THE MIDDLE ATLANTIC. A FEW TSTM WARNINGS WERE ISSUED FROM PENDER COUNTY WESTWARD TO EASTERN BLADEN COUNTY MAINLY BETWEEN 6PM-8PM...AND HAIL UP TO 3/4 INCH WAS REPORTED. PATCHY FOG AND STRATUS IS POSSIBLE OVERNIGHT...ESPECIALLY WHERE GROUNDS ARE WET FROM RAINFALL. BALMY OVERNIGHT LOWS ANTICIPATED WITH LOW/MID 70S ALONG THE COAST AND AROUND 70 OVER MUCH OF THE INTERIOR ZONES. && .SHORT TERM /6 AM THIS MORNING THROUGH MONDAY NIGHT/... AS OF 230 PM SATURDAY...AFTERNOON CONVECTION WILL DEVELOP SUN WITH SEA BREEZE...DIURNAL HEATING...AND OUTFLOW FROM STORMS ALONG REMAINS OF DISSIPATING FRONT TO THE NORTHWEST ACTING AS TRIGGERS. FAVORED AREAS WILL BE WELL INLAND WHERE TEMPS WILL BE WARMEST AND ARRIVAL OF SURFACE BOUNDARIES WILL BE LATER IN THE DAY...COINCIDENT WITH PASSAGE OF SHORTWAVE TROUGH. FORECAST SOUNDINGS SHOW A VERY WEAK MID LEVEL CAP...BUT LIKELY NOT ENOUGH TO COMPLETELY SUPPRESS UPWARD MOTION. IT APPEARS THE LIMITING FACTOR COVERAGE WISE...ESPECIALLY CLOSER TO THE COAST...MAY BE DRY AIR ABOVE 700MB. PRECIPITABLE WATER VALUES START OUT AROUND 1.5 INCH...ON THE LOW SIDE GIVEN THE TIME OF YEAR...BUT DO INCREASE LATE IN THE DAY AS SHORTWAVE AND ITS MOISTURE ARRIVE. INCREASE IN MOISTURE MAY BE TOO LATE TO INCREASE CONVECTION ALONG THE COAST...SO WILL MAINTAIN SLIGHT CHANCE POP FOR THESE AREAS. WELL INLAND ENVIRONMENT APPEARS TO BE A LITTLE MORE FAVORABLE SO WILL CONTINUE TO CARRY CHANCE POP WITH ONLY A FEW SLIGHT CHANGES. DEEP NORTHWEST FLOW WILL PUSH A COLD FRONT ACROSS THE AREA LATER MON...WITH STRONG SOUTHWEST FLOW AHEAD OF IT PUSHING TEMPS ABOVE CLIMO AND KEEPING THE SEA BREEZE CLOSER TO THE COAST. HEATING AHEAD OF THE FRONT WILL CREATE AN UNSTABLE AIR MASS WITH STEEP LAPSE RATES SUGGESTING A MARGINAL DAMAGING WIND THREAT...HENCE SPC HAS THE AREA IN A SEE TEXT FOR DAY 3. AREA WIDE CHANCE POP WILL COVER IT WITH MID AFTERNOON INTO THE EARLY EVENING BEING THE FAVORED HOURS. AT THIS POINT IT IS WORTH NOTING THAT THE GFS SOLUTION IS BEING DISCOUNTED. THE 12Z SOLUTION HAS A CYCLONE OFF THE GA COAST MON MORNING WHICH TRACKS EAST-NORTHEAST. GIVEN LOW CONFIDENCE WITH THE SYSTEM CURRENTLY IN THE GULF OF MEXICO HAVE FAVORED A SOLUTION SIMILAR TO THE HPC/NAM/ECMWF SOLUTIONS. SHOULD THE GFS BE CORRECT THE MON FORECAST WOULD END UP DRIER AND SEVERAL DEGREES COOLER. TEMPERATURES WILL RUN NEAR TO SLIGHTLY ABOVE CLIMO SUN AND SUN NIGHT. RANGING FROM UPPER 80S ALONG THE COAST TO LOWER 90S INLAND. SLIGHTLY WARMER TEMPS EXPECTED MON...ESPECIALLY ALONG THE COAST WHERE SEA BREEZE IMPACT SHOULD BE LESS. HIGHS IN THE LOW TO MID 90S. LOWS WILL RUN WARMER SUN NIGHT...LOWER 70S...COMPARED TO UPPER 60S TO LOWER 70S MON NIGHT. && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 230 PM SATURDAY...RELATIVELY COOLER AND DRIER HIGH PRESSURE WILL BUILD IN TUESDAY THROUGH WEDNESDAY MAKING FOR A REFRESHING START TO THE LONG TERM PERIOD. A DEEP NW FLOW WILL USHER IN MUCH DRIER AIR WITH PCP WATER VALUES DROPPING DOWN CLOSE TO A HALF INCH BY TUES AFTN. ALTHOUGH THEY RECOVER SOME THROUGH MID WEEK VALUES REMAIN BELOW AN INCH THROUGH EARLY THURS. ALTHOUGH JUNE SUNSHINE WILL ALLOW TEMPS TO REACH UP INTO THE MID 80S TUES AND MID TO UPPER 80S BY WED. THE OVERALL DRIER AIR MASS WILL ALLOW GREATER DIURNAL SWINGS WITH TEMPS OVERNIGHT DROPPING DOWN INTO THE LOW TO MID 60S. OVERNIGHT TUES TEMPS MAY DROP CLOSER TO 60. THE HEAT RETURNS WITH A VENGEANCE ACCORDING TO THE LONGER RANGE ECMWF AND GFS. A WARMING TREND WILL OCCUR BEGINNING THURS AS THE RIDGE BUILDS ALOFT ACROSS THE SOUTHEAST. H5 HEIGHTS RISE UP TO NEAR 590 DEM. THE LATEST 850 TEMPS FROM BOTH THE ECMWF AND GFS SHOW READINGS PEAKING UP AROUND 26 TO 27 C ON FRI. THIS WOULD BRING DAYTIME MAX TEMPS CLOSE TO 100 OR SO MAKING FOR THE HOTTEST WEATHER SO FAR THIS YEAR. THE MEX GUIDANCE SHOWS TEMPS 95 TO 100 AND WITH THE GUIDANCE TENDING TOWARD CLIMO...THESE VALUES SHOULD INCREASE AS WE GET CLOSER IN TIME. AFTER MENTIONING THIS HEAT...I HAVE TO ADD THAT THIS IS VERY FAR OUT IN TIME AND THINGS COULD CHANGE. LASTLY...THERE STILL REMAINS MUCH UNCERTAINTY WITH THE MODELS WHEN IT COMES TO THE TROPICAL SYSTEM IN THE GULF. THE GFS STILL SHOWS H5 TROUGH PICKING UP THE SYSTEM AND GUIDING IT OFF TO THE E-NE WHILE ECMWF MOVES IT WESTWARD TOWARD TEXAS THROUGH MID WEEK. THE CMC NOW BRINGS IT UP INTO THE GULF COAST. SEEMS MORE LOGICAL THAT IT WOULD HOLD BELOW THE RIDGE BUILDING ACROSS THE CONUS. EITHER WAY...AS OF NOW...LOOKS LIKE LOCAL AREA SHOULD SEE LITTLE TO NO EFFECTS FROM THIS TROPICAL SYSTEM. AS FOR PCP CHANCES...WITH RIDGE BUILDING ALOFT AND PLENTY OF SUBSIDENCE...WILL KEEP OUT ANY MENTION OF PCP THROUGH THE LONG TERM PERIOD. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... AS OF 06Z...PLENTY OF LOW LEVEL MOISTURE AROUND COMPLIMENTS OF THE SCATTERED SHOWERS AND STORMS FROM LAST NIGHT. WITH IDEAL RADIATIONAL COOLING CONDITIONS EXPECT INLAND TERMINALS AT FLO AND LBT TO DROP TO IFR-LIFR WITH ILM DROPPING TO IFR AS WELL. WILL HOLD MYR AND CRE AT MVFR SINCE THEY DID NOT GET ANY RAINFALL LAST NIGHT. CONDITIONS STAY DOWN TO AROUND 12Z WHEN CONDITIONS START TO IMPROVE AND SHOULD SEE RETURN TO VFR AFTER 14Z. VFR CONDITIONS TO DOMINATE THROUGHOUT SUNDAY WITH THE THREAT OF ISOLATED SHOWERS AND STORMS DURING THE AFTERNOON INTO EARLY EVENING. A FRONTAL BOUNDARY ACROSS THE REGION ON SUNDAY WILL ACT AS A TRIGGER FOR ISOLATED CONVECTION BUT THIS BOUNDARY IS NOT THAT DYNAMIC AND WASHES OUT BY EARLY MONDAY. DRYER AIR MOVES INTO THE REGION BY MONDAY AS A STRONGER COLD FRONT APPROACHES THE AREA. EXTENDED OUTLOOK...CHANCE OF SHOWERS/THUNDERSTORMS THROUGH MONDAY... OTHERWISE VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 826 PM SATURDAY...A WEAK COLD FRONT WILL SLOWLY DISSIPATE WEST OF THE WATERS THROUGH SUNDAY. THE PRESSURE PATTERN ACROSS THE WATERS WILL REMAIN SLACK WITH THE SEABREEZE BEING THE MAIN DRIVER OF WINDS. THE WIND DIRECTION WILL BE FROM THE SSW FOR THE REMAINDER OF THE AFTERNOON...BUT S ALONG THE NEAR SHORE WATERS DUE TO SEABREEZE INFLUENCES. AS THE SEABREEZE DISSIPATES DURING THE MID AND LATE EVE...WEAK SW WINDS WILL DOMINATE. HIGHEST WINDS WILL BE THROUGH THIS EVE...BUT NO HIGHER THAN 10 TO 15 KT. SEAS WILL REMAIN RATHER CONSTANT...2 TO 3 FT THROUGH THE PERIOD...WITH MORE 3 FOOTERS THROUGH THIS EVE AND MORE 2 FOOTERS OVERNIGHT. THERE WILL BE CONSIDERABLE SE SWELL... ALBEIT WEAK...ONE WITH A PERIOD OF 7 TO 9 SECONDS AND A STILL WEAKER SWELL OF 12 TO 14 SECONDS. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 230 PM SATURDAY...BERMUDA HIGH WILL MAINTAIN LIGHT SOUTHWEST FLOW OVER THE WATERS SUN INTO MON. SPEEDS WILL BE AROUND 10 KT...SLIGHTLY HIGH ALONG THE COAST IN THE AFTERNOON WITH SEA BREEZE DEVELOPMENT. A STRONG COLD FRONT DROPPING IN FROM THE NORTHWEST LATER MON PINCHES THE GRADIENT...INCREASING SOUTHWEST FLOW. FRONT PUSHES ACROSS THE WATERS LATE MON NIGHT...BUT BEFORE IT PASSES SUSTAINED WINDS WILL APPROACH 20 KT WITH HIGHER GUSTS. HEADLINES FOR MON AFTERNOON/NIGHT SEEM LIKELY...BUT UNSURE WHETHER IT WILL BE SCA OR SCEC. WINDS SHOULD REMAIN BELOW 25 KT AND SEAS WILL LIKELY DETERMINE IF SCEC OR SCA IS REQUIRED. DURATION OF STRONG SOUTHWEST FLOW IS LIMITED...BUT THERE MAY JUST BE ENOUGH TIME TO BUILD SEAS TO 4 TO 6 FT LATER MON. AT THE START OF THE PERIOD SEAS WILL BE 2 TO 3 FT MAINLY AS A COMBINATION OF SMALL SOUTHERLY WIND WAVE AND A SOUTHEAST SWELL. LONG TERM /TUESDAY THROUGH THURSDAY/... AS OF 230 PM SATURDAY...WILL SEE A NORTHERLY SURGE UP AROUND 15 KTS EARLY TUES AS COLD FRONT MOVES FURTHER OFF SHORE AND HIGH PRESSURE BUILDS IN. RIDGE BUILDS ALOFT WHILE RELATIVELY WEAK HIGH PRESSURE DOMINATES AT THE SURFACE WED AND THURS. OVERALL WILL SEE GRADIENT FLOW WEAKEN AND VEER AROUND FROM NORTH TO THE E ON WED AND SE TO S BY THURS. AS THE PREVAILING FLOW WEAKENS THE LAND/SEA BREEZE WILL DOMINATE WITH GREATER ON SHORE FLOW IN THE AFTERNOON AND SLIGHTLY OFF SHORE AT NIGHT. SEAS INITIALLY CLOSER TO 5 FT IN THE OUTER WATERS IN A MODERATE OFF SHORE FLOW WILL SUBSIDE THROUGH LATE TUES INTO WED AS WINDS DIMINISH. EXPECT SEAS 3 FT OR LESS TUES NIGHT THROUGH THURS. AS OF NOW...LOOKS LIKE TROPICAL SYSTEM IN GULF MAY NOT BE TOO MUCH OF AN INFLUENCE TO OUR MARINE CONDITIONS...BUT GUIDANCE STILL DIFFERS AS TO THE EXACT TRACK AND INTENSITY AND THEREFORE CAN NOT COMPLETELY RULE OUT POTENTIAL IMPACTS. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ AVIATION...MAC