Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 250909 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 409 AM EST WED FEB 25 2015 .SYNOPSIS... A STRENGTHENING LOW PRESSURE SYSTEM WILL MOVE OUT OF THE GULF OF MEXICO TODAY...AND OFF THE SOUTH CAROLINA COAST TONIGHT. THIS WILL BRING PERIODS OF RAIN TO THE AREA TONIGHT...WITH SOME SNOW POSSIBLE WELL INLAND. THIS LOW PRESSURE WILL PULL AWAY ON THURSDAY...LEAVING SOME LIGHT DRIZZLE OR FREEZING DRIZZLE THURSDAY MORNING BEFORE CONDITIONS DRY OUT. A WEDGE OF HIGH PRESSURE WILL BUILD DOWN THE COAST FRIDAY AND INTO THE WEEKEND BRINGING DRY BUT COLD CONDITIONS. A WARMING TREND WILL DEVELOP NEXT WEEK ALONG WITH INCREASING RAIN CHANCES. && .NEAR TERM /THROUGH TONIGHT/... AS OF 930 PM TUESDAY...PRECIP IS COMPLETELY OFFSHORE AND CLOUDY SKIES ARE ANTICIPATED TO CONTINUE OVERNIGHT. LATEST HIGH-RES MODELS SHOW WITH THE LACK OF ADVECTION ACROSS SOUTH CAROLINA TEMPERATURES MAY NOT FALL MUCH (IF ANY) OVERNIGHT. IN FACT WITH TEMPERATURES NOW ABOVE FREEZING AT BOTH MYRTLE BEACH AND KINGSTREE I AM NOT CERTAIN THERE`S MUCH CONCERN FOR ICE ON ROADS ACROSS SOME PARTS OF NE SOUTH CAROLINA. I HAVE RE-WRITTEN THE SPECIAL WEATHER STATEMENT TO FOCUS CONCERN ON SE NORTH CAROLINA WHERE WE ARE SEEING REPORTS OF MULTIPLE CLOSED BRIDGES AND ELEVATED ROADS IN WILMINGTON. DISCUSSION FROM 645 PM FOLLOWS... ITS BEEN A HECTIC FEW HOURS HERE. A BAND OF MODERATE FREEZING RAIN THAT EXTENDED AS FAR WEST AS THE SC MIDLANDS EARLIER THIS AFTERNOON IS FINALLY PUSHING OFF THE COAST NEAR CAPE FEAR THIS EVENING. THIS PRECIPITATION FELL PRIMARILY ACROSS SE NORTH CAROLINA WHERE AIR TEMPERATURES WERE IN THE 28-31 RANGE...PRODUCING LARGE AMOUNTS OF FREEZING RAIN BETWEEN 2-6 PM. THE FREEZING RAIN SENSOR AT THE ILM (WILMINGTON) ASOS REPORTED 0.40 INCHES OF ICE ACCRETION TODAY. NORMALLY OUTPUT FROM THIS SENSOR AGREES QUITE WELL WITH HUMAN-OBSERVED ACCRETION ON ELEVATED OBJECTS AT THE NWS OFFICE...BUT THE ASOS SENSOR APPEARS TO HAVE RUN A LITTLE HIGH WITH ITS TOTALS TODAY AS WE ARE ESTIMATING CLOSER TO 0.25 INCHES OF ICE ACCRETION HERE. REPORTS RECEIVED VIA FACEBOOK AND TWITTER CONFIRM WIDESPREAD 0.25 INCH ICE ACCUMULATIONS AROUND THE CAPE FEAR AREA TODAY...VERIFYING THE ICE STORM WARNING THAT WAS ISSUED EARLIER. RADAR ECHOES ARE PUSHING OFFSHORE AT 40 KNOTS...HOWEVER ASOS/AWOS OBSERVATIONS AND A PHONE CALL FROM THE NCDOT IN LUMBERTON EARLIER CONFIRMS THAT A COUPLE HOURS OF FREEZING DRIZZLE CONTINUES BEHIND THE RADAR-OBSERVED BACK EDGE OF THE PRECIP SHIELD. FOR THIS REASON I WILL MAINTAIN THE WATCHES AND ADVISORIES UNTIL 8 PM EAST OF I-95. FOR THE REMAINDER OF THE OVERNIGHT PERIOD...IT APPEARS LOW CLOUDS WILL HOLD TOUGH FOR ALL BUT PERHAPS THE LUMBERTON-BENNETTSVILLE AREA WHERE SOME LIMITED CLEARING MAY DEVELOP LATE TONIGHT AS MOISTURE THINS FROM ALOFT. THIS WILL PREVENT ANY SIGNIFICANT RADIATIONAL COOLING AND LOWS SHOULD RANGE FROM 26-30...COOLEST NEAR LUMBERTON AND WARMEST NEAR GEORGETOWN. THE 12Z & 18Z GFS BOTH APPEAR TO BE UP THE SAME ANTICS PULLED DURING LAST WEEK`S ARCTIC COLD WHERE IT SEVERELY OVERESTIMATES RADIATIONAL COOLING POTENTIAL OVER MEAGER SNOWPACK ACROSS MUCH OF NORTH CAROLINA. THE 18Z NAM AND 22Z RUC LOOK MUCH MORE REASONABLE FOR TEMPERATURES OVERNIGHT. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 400 AM WEDNESDAY...BIGGEST CONCERN IN THE SHORT TERM INVOLVES DEPARTING LOW PRESSURE THURSDAY...AND THE CHANCE FOR WINTRY PRECIP ACROSS THE AREA. CENTER OF STRENGTHENING LOW PRESSURE WILL BE OFF THE OUTER BANKS OF NC TO START THURSDAY MORNING...AND WILL RAPIDLY PULL OFF TO THE NORTHEAST THROUGH THURSDAY AFTN. ALTHOUGH THE MAJORITY OF THE MOISTURE ASSOCIATED WITH THIS SYSTEM WILL FALL ON WEDNESDAY...LOW-LEVEL RESIDUAL MOISTURE BELOW 700MB WILL REMAIN INTO THURSDAY EVENING. THIS OF COURSE WILL NOT PRODUCE HEAVY PRECIP...BUT VERY LIGHT RAIN AND DRIZZLE...ALONG WITH WIDESPREAD LOW CLOUDINESS...WILL PERSIST INTO THURSDAY NIGHT. THE QUESTION IS HOW QUICKLY CAN SURFACE TEMPS FALL BELOW FREEZING DURING THURSDAY...WHICH WOULD CREATE A FREEZING DRIZZLE SCENARIO. GUIDANCE IS IN VERY GOOD AGREEMENT WITH TEMPS REMAINING JUST ABOVE FREEZING NEAR THE COAST...BUT DROPPING TO BELOW INLAND. FORTUNATELY...THE BETTER CHANCE FOR RESIDUAL PRECIP IS NEAR THE COAST...AND EVEN IN THOSE PLACES THAT DO ENCOUNTER SOME -ZL WILL DO SO ONTO GROUND THAT HAS EXPERIENCED RAIN ON WEDNESDAY. LOCAL TOP DOWN METHODOLOGY PRODUCED A SHORT PERIOD OF -ZR/-ZL ACROSS THE COUNTIES ALREADY WITHIN THE WSW - SO EXTENDED THE WSW UNTIL NOON THURSDAY FOR SOME VERY LIGHT FREEZING DRIZZLE WHICH MAY ACCRETE UP TO 0.01 OR 0.02 INCHES...MOSTLY ACROSS ROBESON/BLADEN COUNTIES. AS THE LOW PULLS AWAY THURSDAY NIGHT DRY ADVECTION COMMENCES AND SKY CONDITIONS WILL IMPROVE DRAMATICALLY FRIDAY...ALTHOUGH LOW CLOUD COVER WILL REMAIN AS A WEDGE OF HIGH PRESSURE BUILDS DOWN THE COAST. STILL...FRIDAY WILL BE DRY...A NICE BREAK FROM THE ACTIVE WEATHER RECENTLY. TEMPS THROUGH THE PERIOD WILL REMAIN WELL BELOW NORMAL AS THE CALENDAR APPROACHES MARCH. HIGHS BOTH THURSDAY AND FRIDAY WILL BE ONLY IN THE LOW 40S...A FULL 20 DEGREES BELOW NORMAL...ALTHOUGH FRIDAY WILL BE THE SLIGHTLY WARMER OF THE TWO. LOWS AT NIGHT WILL ALSO BE VERY COLD...DROPPING WELL INTO THE 20S BOTH NIGHTS...BUT IN THE DRIER COLUMN FRIDAY NIGHT MINS WILL LIKELY BE 2-3 DEGREES COOLER THAN THOSE EXPERIENCED ON THURSDAY NIGHT. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 400 AM WEDNESDAY...COLD AND DRY FOR THE WEEKEND...WITH A WARMUP EXPECTED NEXT WEEK BUT ACCOMPANIED BY UNSETTLED WEATHER. WEDGE OF HIGH PRESSURE WILL EXTEND DOWN THE EAST COAST DURING THE WEEKEND AS CONFLUENCE BETWEEN THE EASTERN CONUS TROUGH AND DEVELOPING SE RIDGE DRIVES RISING SURFACE PRESSURE. SATURDAY AND SUNDAY WILL BOTH LIKELY BE DRY DAYS...BUT NE FLOW WITHIN THE WEDGE WILL LEAD TO LOW CLOUDINESS THROUGH THE WEEKEND...BUT LIKELY IN A VARYING STATE. THIS SUGGESTS THE SUN WILL BE PRESENT AT TIMES. HOWEVER...TEMPS WILL...SHOCKINGLY...REMAIN WELL BELOW CLIMO THROUGH THE WEEKEND. WEDGE BREAKS DOWN ON MONDAY AND SURFACE HIGH PRESSURE SLIPS OFFSHORE LEADING TO A DRAMATIC WARMING TREND FOR EARLY NEXT WEEK. HOWEVER...THIS WARMTH WILL BE SOMEWHAT UNREALIZED AS UNSETTLED WEATHER WILL DEVELOP MONDAY AND PERSIST THROUGH THE REMAINDER OF THE PERIOD. LARGE TROUGH DEVELOPING WEST OF THE AREA WILL DRIVE VORTICITY IMPULSES JUST NORTH OF THE AREA...OVERTOP A STALLED COLD FRONT WHICH WILL HOVER ACROSS THE CAROLINAS. OVERALL...THERE APPEARS TO BE LIMITED FORCING LOCALLY FOR PRECIP...BUT INCREASING CLOUDS WITH AT LEAST PERIODS OF SHOWERS SEEM LIKELY MONDAY/TUESDAY. && .AVIATION /09Z WEDNESDAY THROUGH SUNDAY/... AS OF 05Z...IFR CONDITIONS WILL CONTINUE THROUGH THE PRE-DAWN HRS OF WED WITH THE LOW CEILINGS THE PRIMARY REASON. WILL SEE VSBYS DROP TO 2 TO 5 MILES IN FOG AT TIMES BUT THE LOW STRATUS WILL BE THE PRIMARY AVIATION ISSUE THROUGH SEVERAL HRS AFTER SUNRISE WED. NEXT SOUTHERN STREAM S/W TROF TO AFFECT THE FORECAST AREA WITH ANOTHER ROUND OF WINTRY PCPN. DIFFERENCE WITH THIS NEXT SYSTEM IS THAT COLD AIR WILL BE A LIMITING FACTOR THUS LEAVING ONLY THE INLAND TERMINALS...FLO AND LBT...THAT COULD FACE POSSIBLE FROZEN/FREEZING PCPN LATER TONIGHT INTO DAYTIME THU. AT THIS TIME...THE CONSENSUS IS THAT THE COASTAL TERMINALS WILL BE JUST PLAIN RAIN. THUS...LOW CEILINGS AND REDUCED HORIZONTAL VSBY TO RETURN LATE IN THE TAF ISSUANCE PERIOD FOR ALL TERMINALS. EXTENDED OUTLOOK...MVFR/IFR CONDITIONS EXPECTED AS LOW PRESSURE WILL MOVE ACROSS THE TERMINALS TONITE INTO EARLY THU...THEN ACCELERATE NE OFF THE CAROLINA COASTS AND OFFSHORE DURING THE DAY ON THURSDAY. FINALLY...A RETURN TO VFR CONDITIONS FRI THROUGH SAT. MVFR/IFR POSSIBLE SUNDAY. && .MARINE... .NEAR TERM /THROUGH TONIGHT/... AS OF 930 PM TUESDAY...NO SIGNIFICANT CHANGES ARE NEEDED TO THE FORECAST THIS EVENING AS WINDS AND SEAS ARE BEHAVING NICELY. DISCUSSION FROM 645 PM FOLLOWS... LOW PRESSURE WELL EAST OF THE SOUTH CAROLINA COAST WILL CONTINUE TO PUSH NORTHEAST AND AWAY FROM THE AREA OVERNIGHT. THIS WILL ALLOW WEAK HIGH PRESSURE INLAND TO SPREAD DOWN TO THE COAST OVERNIGHT...WITH VEERING WINDS AND WEAKENING WIND SPEEDS. THE SMALL CRAFT ADVISORY WILL REMAIN IN EFFECT FOR THE NC WATERS WHERE THE FRYING PAN SHOALS BUOY IS STILL REPORTING 7.5 FOOT SEAS. WEST OF FRYING PAN SHOALS CONDITIONS APPEAR TO BE IMPROVING A LITTLE FASTER. NOTE THAT SOME WIND SENSORS NEAR THE COAST APPEAR TO HAVE FROZEN ANEMOMETER CUPS AND ARE NOT TO BE TRUSTED. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 400 AM WEDNESDAY...DEEPENING LOW PRESSURE WILL BE MOVING AWAY FROM THE COAST DURING THURSDAY...BUT THE GRADIENT WILL REMAIN PINCHED THE FIRST PART OF THE SHORT TERM. GUSTY NORTH WINDS WILL REACH OVER 20 KTS FIRST THING THURSDAY...BUT WILL EASE QUICKLY THROUGH THE AFTN TO BECOME 10-15 KTS THURSDAY NIGHT WHILE REMAINING FROM THE NORTH. HIGH PRESSURE WILL BEGIN TO WEDGE DOWN THE COAST ON FRIDAY...CAUSING RENEWED TIGHTENING OF THE GRADIENT...AND WINDS WILL INCREASE SLOWLY...BECOMING 20-25 KTS ONCE AGAIN BUT FROM MORE OF A NE DIRECTION FRIDAY NIGHT. SEAS THURSDAY MORNING WILL BE 5-8 FT...BUT WILL FALL QUICKLY THROUGH THE DAY AND THE ONGOING SCA SHOULD BE ALLOWED TO EXPIRE LATE THURSDAY. SEAS WILL REMAIN BELOW 6 FT THURSDAY NIGHT AND FRIDAY...BUT WILL RISE ONCE AGAIN TO 4-6 FT FRIDAY NIGHT WHEN A RENEWED SCA MAY BE NEEDED. LONG TERM /SATURDAY THROUGH SUNDAY/... AS OF 400 AM WEDNESDAY...WEDGE OF HIGH PRESSURE WILL STRENGTHEN SATURDAY...AND AN EXTENDED PERIOD OF GUSTY 20-25 KT NE WINDS WILL OCCUR THROUGH SATURDAY. THIS DRIVES WAVE HEIGHTS TO 4-6 FT...AND AN SCA WILL LIKELY BE NEEDED THROUGH SATURDAY. SATURDAY NIGHT...GRADIENT SLOWLY BEGINS TO WEAKEN AS THE WEDGE BREAKS DOWN. THIS CAUSES WINDS TO EASE TO 10-15 KTS BY SUNDAY MORNING WHILE REMAINING FROM THE NE. WINDS WILL EASE FURTHER AND THEN VEER TO THE SOUTH AS THE WEDGE DISSIPATES LATE SUNDAY. WAVE HEIGHTS FALL ON THE DECREASING WINDS...FROM 4-6 FT LATE SATURDAY...TO 2-4 FT SUNDAY. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO NOON EST THURSDAY FOR SCZ017-023-024. NC...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO NOON EST THURSDAY FOR NCZ087-096-105. MARINE...NONE. && $$ SYNOPSIS...JDW NEAR TERM...DCH/TRA SHORT TERM...JDW LONG TERM...JDW AVIATION...DCH MARINE...DCH/TRA/JDW

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