400 FXUS62 KILM 161601 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 1201 PM EDT TUE APR 16 2013 .SYNOPSIS... HIGH PRESSURE WILL RIDGE ACROSS THE ATLANTIC OCEAN INTO THE CAROLINAS THROUGH FRIDAY...BRINGING ABOVE NORMAL TEMPERATURES THROUGH THE WEEK. A COLD FRONT WILL CROSS THE AREA LATE FRIDAY NIGHT INTO SATURDAY...ACCOMPANIED BY SHOWERS AND THUNDERSTORMS. MUCH COOLER TEMPERATURES WILL FOLLOW FOR NEXT WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF NOON TUESDAY...VERY LOW TOPPED LIGHT SHOWERS HAVE POPPED UP ALONG THE SEABREEZE IN SOUTHEAST NC. MID LEVEL INVERSION WILL PREVENT SHOWERS FROM BECOMING OTHER THAN A NUISANCE SPRINKLE BUT HAVE UPDATED POP GRIDS AND FORECAST TO REFLECT THIS ACTIVITY. SOME OF THE HIGH RES 12Z GUIDANCE HAS LOCKED ONTO THE SEABREEZE SHOWERS AND SHOW THEM SLOWLY MOVING WEST BEFORE WEAKENING AND DISSIPATING DURING THE AFTERNOON. ACTIVITY OFF THE COAST CONTINUES ITS SLOW SOUTHWEST DRIFT. IT APPEARS THIS ACTIVITY HAS STARTED THE EXPECTED WEAKENING AND IS BECOMING MORE DIFFUSE AS THE LOW LEVEL CONVERGENCE WEAKENS. HIGHS WILL RANGE FROM LOW TO MID 70S ALONG THE COAST TO AROUND 80 INLAND. FLAT BUT SIGNIFICANT CU FIELD WILL LIMIT INSOLATION BUT ANY EXTENDED PERIOD OF SUN AHEAD OF THE SEABREEZE COULD PUSH HIGHS INTO THE LOW 80S. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 300 AM TUESDAY...HIGH PRESSURE AT THE SURFACE AND ALOFT COMBINE TO MAKE FOR AN ABOVE NORMAL PERIOD WITH VERY LIMITED CONVECTIVE POTENTIAL. WHILE LOW-LEVEL MOISTURE WILL BE RATHER SIGNIFICANT BOTH DAYS...MORE SO ON THURSDAY...THIS WILL LIKELY BE CONFINED TO SCT/WIDESPREAD DIURNAL CU AS OPPOSED TO ANY SHOWERS/TSTMS. CONVECTIVE POTENTIAL WILL BE LIMITED THANKS TO VERY DRY MID-LEVEL AIR AND A PRONOUNCED CAP BETWEEN 850-750MB. AS NOTED BY PREVIOUS FORECASTER...THERE IS INCREASED MOISTURE THURSDAY AND THE CAP IS SLIGHTLY LESS ROBUST...WHICH MAY ALLOW FOR SOME ISOLATED CONVECTION. HOWEVER...ATTM OPT TO LEAVE ANY MENTION OUT OF FORECAST DUE TO SUBSIDENCE BENEATH THE RIDGE AND CONTINUED AMPLE MID-LEVEL DRY AIR. TEMPS THROUGH THE PERIOD WILL BE ABOVE NORMAL...LOW 80S AWAY FROM THE COAST ON WEDNESDAY...UPPER 70S AT THE BEACHES...AND ONLY SLIGHTLY COOLER ON THURSDAY. MINS EACH NIGHT WILL FALL TO A DEGREE OR TWO EITHER SIDE OF 60. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 300 AM TUESDAY...CONCERN FOR THE EXTENDED REVOLVES AROUND A STRONG...SLOW MOVING...COLD FRONT SLATED TO CROSS THE AREA OVERNIGHT FRIDAY INTO SATURDAY. WHILE FRIDAY WILL AGAIN FEATURE ABOVE-NORMAL TEMPS...CLOUDS WILL RAPIDLY INCREASE AHEAD OF THE COLD FRONT WITH PRECIP BREAKING OUT FROM WEST TO EAST DURING THE NIGHT. ECMWF/GFS ARE IN PRETTY GOOD AGREEMENT WITH TIMING ACTUAL FROPA FIRST THING SATURDAY MORNING. WHILE MUCAPE...LLJ...AND PRESENCE OF SIGNIFICANT THETA-E RIDGING SUGGESTS TSTMS...IT IS A NOCTURNAL FROPA WHICH WILL OF COURSE LIMIT OVERALL TSTM POTENTIAL. STILL...FEEL THERE IS ENOUGH SUPPORT TO CONTINUE WITH INHERITED WX TYPE OF TSTMS...AND WITH PWATS RISING TO 1.75 INCHES...HAVE BUMPED POP TO LIKELY OVERNIGHT INTO SATURDAY MORNING. BEST UPPER DYNAMICS HANG BACK BEHIND SURFACE FRONT...AND THIS WILL ALLOW THE CHANCE FOR PRECIP TO CONTINUE INTO SATURDAY AFTN...BEFORE DRYING BEGINS IN EARNEST THROUGH THE COLUMN SAT NIGHT...PERSISTING THROUGH MONDAY. WHILE THE END OF THE EXTENDED WILL BE DRY WITH A LOT OF SUNSHINE...TEMPS WILL FALL TO BE MUCH COOLER THAN THE PREVIOUS WEEK. GUIDANCE IS DIFFERING ON INTENSITY OF THIS COOLER AIR...BUT IT SEEMS LIKELY THAT TEMPS WILL FALL TO BELOW NORMAL SUN/MON AT THE END OF THE PERIOD. && .AVIATION /16Z TUESDAY THROUGH SATURDAY/... AS OF 12Z...EASTERLY FLOW IS ADVECTING STRATA CU ONSHORE...WITH A CEILING MAINLY FROM 2-3K FEET. LOOK FOR THIS SCENARIO TO CONTINUE ALONG THE COAST THROUGH THE MORNING HOURS...AS THE WEAK WEDGE CONTINUES TO WANE. INLAND TERMINALS WILL SEE THE IFR CONDITIONS LIFT TO MVFR SOMETIME AROUND 13-14Z. WINDS WILL BE NORTHEASTERLY THIS MORNING...VEERING TO EAST BY AFTERNOON WITH THE GRADIENT AND RESULTANT IN SYNC. LIGHT WINDS TONIGHT WITH ANOTHER ROUND OF STRATUS/FOG TOWARD MORNING. MODELS ARE ADVERTISING SOME DECENT MOISTURE JUST TO OUR WEST...BUT IT WILL NOT APPROACH THE CWA UNTIL AFTER THE TAF TIME WINDOW. EXTENDED OUTLOOK...CHANCE OF SHOWERS ON FRIDAY...OTHERWISE VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1030 AM TUESDAY...NORTHEAST FLOW CONTINUES TODAY WITH HIGH PRESSURE RIDGING IN FROM THE NORTHEAST. GRADIENT WILL SLOWLY WEAKEN THROUGH THE DAY WITH SPEEDS DROPPING FROM AROUND 15 KT TO 10 TO 15 KT BY AFTERNOON. SEAS WILL CONTINUE TO SLOWLY SUBSIDE FROM 3 TO 5 FT TODAY TO 2 TO 4 FT OVERNIGHT. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 300 AM TUESDAY...HIGH PRESSURE EXTENDING WEST FROM THE ATLANTIC OCEAN CREATES A WEAK GRADIENT WEDNESDAY...BEFORE TIGHTENING THURSDAY THANKS TO A SLOWLY APPROACHING COLD FRONT. THIS PRODUCES LIGHT E/SE WINDS WEDNESDAY...10 KTS OR LESS...BEFORE VEERING TO THE SOUTH WHILE STEADILY INCREASING THURSDAY TO 15-20 KTS. SEAS 2-4 FT EARLY WEDNESDAY WILL BECOME 1-3 FT MUCH OF THE DAY...CREATED BY SEVERAL LOW AMPLITUDE E/SE SWELLS. WHILE THESE WEAK SWELL GROUPS PERSIST ON THURSDAY...A GROWING SOUTHERLY WIND WAVE WILL GAIN MORE OF A CONTRIBUTION TO THE SEA SPECTRUM...HELPING TO BUILD WAVES TO 3-5 FT BY THE END OF THE PERIOD. LONG TERM /FRIDAY THROUGH SATURDAY/... AS OF 300 AM TUESDAY...SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED FOR MUCH...IF NOT ALL...OF THE EXTENDED AS A COLD FRONT CROSSES THE WATERS VERY EARLY SATURDAY. AHEAD OF THIS BOUNDARY...STRONG SOUTHERLY WINDS OF 15-25 KTS WILL VEER TO SW FRIDAY NIGHT...THEN DECREASE AND BECOME NW SATURDAY MORNING BEHIND THE FRONT. HIGH PRESSURE BUILDING IN BEHIND THIS FRONT SATURDAY WILL TURN WINDS TO THE N/NE...WITH SPEEDS INCREASING AGAIN TO AROUND 15 KTS LATE. SEAS WILL BE PRIMARILY WIND-WAVE DRIVEN...RANGING FROM 3-7 FT THROUGH THE PERIOD WITH THE PREDOMINANT WIND-WAVE GROUP FOLLOWING THE PRIMARY WIND DIRECTION. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...III SHORT TERM...JDW LONG TERM...JDW AVIATION...43