Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 271518 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 1118 AM EDT FRI MAR 27 2015 .SYNOPSIS... A STRONG COLD FRONT WILL CROSS THE AREA TODAY WITH SHOWERS. MUCH COLDER AIR WILL FILTER IN BEHIND THE FRONT. TEMPERATURES NEAR TO BELOW FREEZING REMAIN POSSIBLE EARLY SUNDAY. A WEAKER COLD FRONT WILL PASS THROUGH LATE MONDAY...WITH SEASONABLE TEMPERATURES INTO MID- WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1015 AM FRIDAY...TIMING ISSUES REMAIN WITH THE EVENTUAL CFP. MODELS IN GENERAL CONTINUE WITH A MUCH FASTER CFP THAN WHAT REALITY IS CURRENTLY DICTATING AT THE MOMENT. IN ADDITION...THE MAJORITY OF THE PRECIP SHOWN BY 88DS IS NOW OCCURRING POST CFP. IN ADDITION...AREAL COVERAGE OF THE PCPN HAS SHOWN A DECREASING TREND. AS A RESULT...HAVE HAD TO RE-ALIGN AND LOWER POPS BY 1 TO 2 CATEGORIES FOR THE REMAINDER OF THIS MORNING...AND CONTINUING THRU THIS AFTERNOON...AND WELL INTO THIS EVENING. LATEST VIS SATELLITE IMAGERY INDICATES BREAKS IN THE CURRENT OVERCAST...WHICH SHOULD EVENTUALLY FILL BACK IN THIS AFTERNOON. AS A RESULT OF THE BREAKS IN THE OVC...ESPECIALLY CLOSER TO THE COAST AND AWAY FROM THE MAIN PCPN SHIELD...MAX TEMPS LATE THIS MORNING AND EARLY THIS AFTN MAY BREAK THE 70 DEGREE MARK PRIOR TO THE CFP. PREVIOUS DISCUSSION............................................ AS OF 630 AM FRIDAY...A STRONG COLD FRONT CURRENTLY EXTENDING FROM RALEIGH TO SOUTHERN PINES...AND WADESBORO INTO UPSTATE SOUTH CAROLINA WILL SWEEP SOUTHEASTWARD AND OFF THE COAST THIS AFTERNOON. SOUTHWEST WINDS OUT AHEAD OF THE FRONT WILL MAINTAIN THE MILD SUBTROPICAL AIRMASS JUST LONG ENOUGH AFTER 12Z/8 AM EDT TO KEEP TODAY`S DAYTIME HIGHS IN THE 60S...ALTHOUGH ALONG THE INTERSTATE 95 CORRIDOR TEMPERATURES WILL DIVE INTO THE 50S BY 10 AM...NOT TO RECOVER DURING THE AFTERNOON AS STRONG COLD ADVECTION OVERWHELMS WHAT LITTLE HEAT IS ABLE TO FILTER THROUGH THE CLOUDS. MOS GUIDANCE TYPICALLY STRUGGLES IN THESE SITUATIONS AND MY FORECAST IS A LARGELY BLEND OF THE RAW 00Z NAM...00Z WRF-NMM AND 07Z HRRR MODELS. PRECIPITATION OVER THE NEXT 24 HOURS SHOULD COME IN THREE WAVES. WAVE #1 IS EXITING THE CAPE FEAR AREA NOW AND SHOULD BE OUT OF OUR FORECAST AREA BEFORE DAYBREAK. WAVE #2 COVERS THE WESTERN HALF OF NC AND IS ON THE COLD FRONT ITSELF AND SHOULD BEGIN IN LUMBERTON AND FLORENCE WITHIN A COUPLE HOURS AFTER SUNRISE...SPREADING DOWN TOWARD THE COAST BY EARLY AFTERNOON. THIS SHOULD BE THE MOST SIGNIFICANT OF THE PRECIP WAVES...WITH FORECAST POPS 80-100 PERCENT AND QPF .10 TO .20 INCHES. WAVE #3 OF SHOWERS MAY OCCUR TONIGHT AS THE COLDEST PORTION OF THE UPPER TROUGH CROSSES OVERHEAD AND ENCOUNTERS A LITTLE 800-700 MB MOISTURE THAT SNEAKED SOUTH OF THE APPALACHIANS...AVOIDING THE DOWNSLOPING FLOW. ALTHOUGH I AM CAPPING POPS TONIGHT AT 20 PERCENT...THE BEST CHANCE FOR MEASURABLE RAIN WILL BE ACROSS EASTERN SOUTH CAROLINA AFTER MIDNIGHT. FORECASTS EARLIER IN THE WEEK INCLUDED THE MENTION OF SNOW TONIGHT...BUT DESPITE THE VERY COLD 1000-500 MB THICKNESS VALUES ANALYSIS OF FORECAST SOUNDINGS SHOWS THE FREEZING LEVEL NEVER MAKES IT DOWN BELOW 2000-2500 FEET AGL...TOO DEEP A "WARM" LAYER FOR SNOW TO MAKE IT TO THE GROUND. GIVEN CLOUDS AND STEADY WINDS THROUGHOUT THE BOUNDARY LAYER OVERNIGHT I AM FORECASTING TEMPERATURES WELL ABOVE MOS NUMBERS...WHICH APPEAR TO BE TOO COOL GIVEN THE WELL-MIXED BOUNDARY LAYER. THE RAW GFS/NAM MODELS LOOK MUCH MORE REASONABLE WITH UPPER 30S INLAND AND AROUND 40 AT THE COAST. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 315 AM FRIDAY...CLEARING SKIES...BLUSTERY AND COLD CONDITIONS WILL DEVELOP SATURDAY AS THE FRONTAL SYSTEM AND MOISTURE PULLS OFF TO THE EAST/NORTHEAST. HIGHS SHOULD REACH THE MIDDLE 50S. THE FOCUS THEN SHIFTS TO SUNDAY MORNING LOWS. ALL GUIDANCE IS AT OR BELOW FREEZING FOR MOST OF THE AREA SUNDAY MORNING SANS A FEW ENSEMBLE MEMBERS OF THE SREF GUIDANCE. THERE IS STILL SOME WIND EXPECTED AS THE AXIS OF HIGH PRESSURE WILL RESIDE ALONG THE APPALACHIANS. MODEL FIELDS SHOW ONE FINAL DECENT VORT ROTATING ACROSS SUNDAY MORNING AS WELL. STILL ALL SIGNS POINT TO A SIGNIFICANT FREEZE. BASED ON COLLABORATION WITH ADJACENT OFFICES WILL LET THE DAY SHIFT RAISE THE FREEZE WATCH. I WOULD ANTICIPATE ALL AREAS BEING IN THE WATCH. NOT A LOT OF WARMING FOR SUNDAY AFTERNOON AS THE THERMAL PROFILES ARE SLOW TO RECOVER. WINDS WILL DROP OFF HOWEVER MAKING IT FEEL NICER. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 315 AM FRIDAY...EXTENDED FORECAST CONTINUES TO BE VOID OF ANY SIGNIFICANT WEATHER SYSTEMS AS A MOSTLY ZONAL FLOW ALOFT DEVELOPS ALOFT. A BACK DOOR FRONT WILL MOVE ACROSS THE REGION IN UNEVENTFUL FASHION TUESDAY MORNING. THERE ARE SOME SIGNALS OF FLEETING SHOWER ACTIVITY WITH THIS FEATURE AND WE CONTINUE TO ADVERTISE SLIGHT CHANCE POPS. BEYOND THIS THE PRESSURE PATTERN BECOMES VERY DIFFUSE AS THIS BOUNDARY LINGERS TO THE SOUTH THEN WASHES OUT WITH A RETURN FLOW LATE WEDNESDAY INTO THURSDAY. WE CONTINUE TO ADVERTISE LOW CHANCE POPS FOR LATE WEDNESDAY AND THURSDAY. TEMPERATURE FORECAST STARTS OUT ON THE COOL SIDE MONDAY AND TUESDAY WITH READINGS WARMING TO EXCEED CLIMATOLOGICAL VALUES WEDNESDAY AND THURSDAY. && .AVIATION /15Z FRIDAY THROUGH TUESDAY/... AS OF 12Z...MAIN DIFFICULTY TODAY WILL BE THE TIMING AND INTENSITY OF THE PRECIP...AS WELL AS THE CEILINGS. COLD FRONT WILL MOVE INTO THE CWA LATER THIS MORNING...REACHING THE COAST BY EARLY AFTERNOON. EXPECT CONVECTION TO DEVELOP AHEAD OF THE FRONT...BEST TIMING WILL BE BETWEEN 15-19Z TIME FRAME. THIS WINDOW COULD SEE THE HEAVIEST PRECIP WITH POSSIBLE IFR VISIBILITIES. LOW CONFIDENCE ON CEILINGS BUT COULD SEE IFR CONDITIONS AT AND JUST BEHIND THE FRONT. POST FRONTAL...LOOK FOR GUSTY NORTH WINDS WITH FAIRLY LOW CEILINGS LINGERING POSSIBLY INTO THIS EVENING. EXTENDED OUTLOOK...BECOMING VFR SATURDAY. A SLIGHT CHANCE OF SHOWERS MONDAY...OTHERWISE VFR CONDITIONS ARE EXPECTED. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1030 AM FRIDAY...BRIEF LULL IN THE SW-WSW WIND FIELD PRIOR TO THE CFP SLATED FOR THE MID TO LATE AFTERNOON HRS. AS A RESULT...SIGNIFICANT SEAS HAVE SUBSIDED BELOW THE CURRENT FCST AND THUS WILL HAVE TO BE AMENDED. ANY CHANGE IN THE WIND FIELD WILL BE QUICKLY REFLECTED IN THE SIG. SEAS. THIS DUE TO ONLY A SMALL PSEUDO GROUND SWELL COMPONENT TO THE SIG. SEAS...THUS RESULTING IN MAINLY SHORT PERIOD WIND DRIVEN WAVES IN THE SIG. SEAS MAKE-UP. AVERAGE PERIODS WILL RUN 4.5 TO 5.5 SECONDS. PREVIOUS DISCUSSION........................................... AS OF 630 AM FRIDAY...A STRONG COLD FRONT NOW IN CENTRAL NORTH CAROLINA WILL REACH THE CAROLINA COAST EARLY THIS AFTERNOON. SOUTHWEST WINDS OUT AHEAD OF THIS FRONT WILL SHIFT TO THE NORTH AS COLD AIR BLASTS OFFSHORE. FOCUS WILL THEN SHIFT TO HIGH PRESSURE UP OVER THE GREAT LAKES WHICH WILL BUILD ACROSS THE AREA THIS WEEKEND...MAINTAINING A VERY COLD AIRMASS FOR THIS LATE IN MARCH. SOUTHWEST WINDS THIS MORNING HAVE DIED DOWN TO 10-15 KT. LITTLE CHANGE IN WIND SPEED OR DIRECTION SHOULD OCCUR UNTIL THE ACTUAL FRONT ARRIVES...PROBABLY IN THE 1-3 PM TIMEFRAME. SEAS CURRENTLY 3-5 FT ACROSS THE SC WATERS AND 4-6 FT ACROSS THE NC WATERS WILL CHANGE LITTLE UNTIL THIS EVENING WHEN THE NORTH WINDS WILL ALLOW SEA HEIGHTS NEARSHORE TO DIMINISH. SMALL CRAFT ADVISORIES REMAIN IN EFFECT NORTH OF LITTLE RIVER INLET. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 315 AM FRIDAY...HEALTHY NORTHWEST WINDS WILL CONTINUE MOST OF THE DAY SATURDAY AS COLD HIGH PRESSURE CONTINUES TO BUILD SLOWLY ACROSS THE WATERS. SPEEDS WILL BE 15-20 KNOTS. SUNDAY WILL FEATURE MUCH LIGHTER WINDS AS THE HIGH MOVES OVERHEAD AND TO THE SOUTHEAST. EXPECT SPEEDS TO BE TEN KNOTS OR LESS. THE FLOW QUICKLY SHIFTS TO SOUTHWEST BY THE END OF THE PERIOD WITH THE RETURN FLOW AND AN APPROACHING BOUNDARY FROM THE NORTHWEST. SEAS WILL BE HIGHEST EARLY AND OFFSHORE WITH A RANGE OF 3-5 FEET. HEIGHTS BACK OFF CONSIDERABLY SUNDAY TO 1-3 FEET. LONG TERM /MONDAY THROUGH TUESDAY/... AS OF 315 AM FRIDAY...A DECENT SOUTHWEST FLOW WILL BE IN PLACE MONDAY AHEAD OF A COLD FRONT THAT MOVES ACROSS LATE MONDAY. SPEEDS WILL BE 15-20 KNOTS WITH SEAS 3-5 FEET. A MARGINAL SMALL CRAFT ADVISORY CANNOT BE RULED OUT. TUESDAY A NORTH TO NORTHEAST FLOW DEVELOPS AND IS BRIEFLY STRONG WITH 15-20 KNOTS AS WELL. UNDER A QUICK MOVING ZONAL PATTERN ALOFT THE HIGH IN THE WAKE OF THE FRONT QUICKLY MOVES OFF TO THE SOUTHEAST LEAVING LIGHTER WIND FIELDS. SEAS DROP BACK TUESDAY AS WELL. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR AMZ250- 252. && $$ SYNOPSIS...SHK NEAR TERM...DCH/TRA SHORT TERM...SHK LONG TERM...SHK AVIATION...DL

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