Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 260829 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 329 AM EST THU FEB 26 2015 .SYNOPSIS... LOW PRESSURE WILL MOVE OFF TO THE NORTHEAST TODAY BRINGING A SLOW END TO THE RAINFALL. SOME LIGHT FREEZING RAIN OR FREEZING DRIZZLE IS POSSIBLE EARLY THIS MORNING FAR INLAND. A WEDGE OF HIGH PRESSURE WILL BUILD DOWN THE COAST FRIDAY AND THROUGH THE WEEKEND BRINGING DRIER WEATHER BUT WITH VERY COLD TEMPERATURES. MOISTURE WILL RETURN EARLY NEXT WEEK BUT WITH MORE SEASONABLE TEMPERATURES. && .NEAR TERM /THROUGH TONIGHT/... AS OF 130 AM THURSDAY...NEW UPDATES SENT TO REMOVE ALL MENTION ALL SNOW OR SLEET FROM THE FORECASTS. WILL CONTINUE TO MENTION LIGHT FREEZING RAIN OR LIGHT FREEZING DRIZZLE POSSIBLE FROM ROUGHLY DAYBREAK THU THRU MID-MORNING FOR THE COUNTIES WITHIN THE WINTER WX ADVISORY. TEMPS SHOULD BE ABOVE 32 BY LATE MORNING...ELIMINATING THE THREAT FOR ANY ICING. PREVIOUS DISCUSSION........................... AS OF 820 PM WEDNESDAY...SLEET IS FALLING AS FAR EAST AS WILMINGTON THIS EVENING...WITH A MIX OF SLEET AND SNOW REPORTED AS FAR EAST AS WHITEVILLE. THIS APPEARS TO BE DUE TO A POCKET OF VERY DRY AIR BETWEEN 2,000 AND 10,000 FEET AGL--MUCH DRIER THAN ANY MODEL FORECAST. THE 00Z SOUNDINGS FROM MHX AND GSO SHOWED DEWPOINT DEPRESSIONS ANOTHER 10 DEGREES F WIDER THAN THE 18Z NAM OR GFS THROUGH THAT LAYER. EVAPORATIONAL COOLING WITH THIS INITIAL WAVE OF PRECIPITATION COOLED THE COLUMN SUFFICIENTLY TO MAKE A WRECK OF MY PREVIOUS FORECAST. STRONG WARM ADVECTION IN THE 850-700 MB LAYER SHOULD RAISE AIR TEMPERATURES WELL ABOVE FREEZING IN THE NEXT 1-2 HOURS...ALONG WITH A CONSIDERABLE INFLUX OF GULF AND ATLANTIC MOISTURE WHICH WILL REMOVE ANY REMAINING EVAPORATIONAL COOLING POTENTIAL. BY LATE EVENING I ANTICIPATE FROZEN PRECIPITATION TO BE CONFINED TO WESTERN PORTIONS OF MARLBORO AND DARLINGTON COUNTIES...PERHAPS AFFECTING MAXTON IN WESTERN ROBESON COUNTY AS WELL. I AM GROWING MORE CONCERNED ABOUT THE POTENTIAL FOR WRAP-AROUND COLD AIR AROUND SUNRISE THURSDAY MORNING CHANGING THE LAST OF THE RAIN OVER TO FREEZING RAIN. I HAVE ADDED A CHANCE OF FREEZING RAIN TO THE FORECAST ACROSS NORTHERN FLORENCE...MARION AND COLUMBUS COUNTIES...AND MAY NEED TO CONSIDER RAISING AN ADVISORY FOR FREEZING RAIN IF THIS THREAT GROWS OVERNIGHT. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 300 AM THURSDAY...DRY BUT COLD FOR THE SHORT TERM AS A WEDGE OF HIGH PRESSURE BECOMES ENTRENCHED ALONG THE EAST COAST. THIS HIGH DEVELOPS BEHIND A COLD FRONT FROM THURSDAY...AND IS INTENSIFIED BY PERSISTENT CONFLUENCE ALOFT. FORECAST PROFILES SUGGEST A LOT OF SUNSHINE FRI/SAT...BUT THESE STRONG WEDGES ARE FREQUENTLY ACCOMPANIED BY A LOT OF LOW-LEVEL MOISTURE ON THE NE FLOW...WHICH MANIFEST AS LOW LEVEL CLOUDS. THUS...WILL NOT BE AS OPTIMISTIC AS THE GUIDANCE WITH SUNSHINE FOR THE WEEKEND. IT WILL BE DRY HOWEVER. THIS IS GOOD BECAUSE TEMPERATURES WILL BE SOLIDLY 15-20 DEGREES BELOW NORMAL...WITH SATURDAY THE COLDER DAY. HIGHS FRIDAY WILL STRUGGLE INTO THE LOW-TO-MID 40S ON FRIDAY...AND A FEW DEGREES COOLER ON SATURDAY WHEN SOME PLACES WON`T EVEN CRACK 40. LOWS BOTH NIGHTS WILL BE SIMILARLY COLD...FALLING INTO THE 20S MOST LOCATIONS...WITH A FEW MORE LOW 30S SATURDAY NIGHT AS CLOUD COVER INCREASES. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 300 AM THURSDAY...PATTERN CHANGE DEVELOPS...FINALLY...AS BROAD RIDGING ENVELOPS THE SOUTHEAST. THERE IS CONSIDERABLE UNCERTAINTY INTO HOW LONG THIS RIDGING WILL PERSIST...AND 2 SEPARATE COLD FRONTS NEXT WEEK COULD QUICKLY BRING US BACK TO BELOW NORMAL TEMPS...BUT FOR THIS FORECAST WILL BE SOMEWHAT OPTIMISTIC. ONE LAST WELL BELOW NORMAL DAY EXPECTED SUNDAY AS THE SURFACE WEDGE SLOWLY BEGINS TO BREAK DOWN IN RESPONSE TO MID-LEVEL DEVELOPING RIDGE. AT THE SAME TIME...A COLD FRONT WILL APPROACH FROM THE NW...AND MOISTURE WILL INCREASE WITHIN THE COLUMN. THERE DOES NOT APPEAR TO BE A LOT OF FORCING FOR SHOWERS SUNDAY...BUT THE INHERITED INCREASING POP SUNDAY NIGHT SEEMS WARRANTED. WARMER TEMPS MONDAY IMMEDIATELY AHEAD OF THE COLD FRONT IN A PRE-FRONTAL AIR MASS WILL BE ACCOMPANIED BY BETTER SHOWER CHANCES THANKS TO A SHORTWAVE MOVING OVERHEAD. THIS FRONT WILL BECOME ALIGNED PARALLEL TO THE FLOW LATE MONDAY INTO TUESDAY...AND WILL STALL IN THE VICINITY BEFORE LIFTING BACK NORTH BY WEDNESDAY. THIS LEAVES TUESDAY AS THE BIGGEST QUESTION MARK WITH RESPECT TO TEMPS...BUT EXPECT JUST BELOW NORMAL TEMPS WITH CONTINUED POTENTIAL FOR SHOWERS. A MORE SIGNIFICANT WARMUP IS ON TAP FOR WEDNESDAY ON RETURN FLOW AND CONTINUED MID-LEVEL RIDGING...BUT UNSETTLED WEATHER WILL PERSIST AS ANOTHER COLD FRONT APPROACHES THE AREA. && .AVIATION /09Z THURSDAY THROUGH MONDAY/... AS OF 06Z...MODERATE TO HEAVY PRECIPITATION CONTINUES ACROSS THE TERMINALS EARLY THIS THU AM...WITH ALL TERMINALS FLUCTUATING WITH MVF AND IFR...AND EVEN OCCASIONALLY VFR CONDITIONS. FORECAST THAT! RELATIVELY HIGH CONFIDENCE THAT THE AREA TERMINALS WILL BE TOTALLY DOMINATED BY IFR THROUGH DAYBREAK FROM BOTH CEILINGS AND VSBY...AND MAINLY FROM CEILINGS THERE-AFTER THRU SUNSET THU. HAVE REMOVED ALL MENTION OF -SN AND -PL FROM THE FORECAST AS MODEL SOUNDINGS AND OOZ LOCAL RAOBS AND MODEL DATA INDICATE A DEEP WARM LAYER IN THE LOWER LEVELS. AFTER THE PASSAGE OF THE LOW TO THE EAST OF THE ILM CWA...WINDS BACK TO THE NW-N WITH A RETURN OF SOME COLD AIR AT THE SFC. MAY BE COLD ENOUGH TO INCLUDE A PERIOD OF FZRN OR FZDL TOWARD DAYBREAK...AND UP TO SEVERALS THERE-AFTER. ALL PCPN SHOULD END BY MID TO LATE MORNING...WITH THE LOWER LEVELS REMAINING MOIST DOWN TO THE SFC...RESULTING IN A LOW CLOUD DECK THRUOUT DAYLIGHT THU...AND PARTIALLY INTO THE EVENING BEFORE SOME DRY AIR MIXES IN TO RAISE THE LOW STRATIFORM CEILINGS. WINDS INITIALLY WILL STAY ACTIVE AND GUSTY UP TO 20 KT FROM THE N-NE... THEN SLOWLY BACK TO NW-NNW AND DIMINISH LATER TODAY INTO TONIGHT. EXTENDED OUTLOOK...VFR CONDITIONS FRIDAY THRU SATURDAY...MVFR/IFR POSSIBLE LATE SUNDAY INTO MONDAY. && .MARINE... .NEAR TERM /THROUGH TONIGHT/... AS OF 630 PM WEDNESDAY...THE ONLY CHANGE TO THE FORECAST WAS TO SLOW DOWN THE RATE OF INCREASE IN FORECAST SEA HEIGHTS OVERNIGHT. OUR LOCAL SWAN WAVE MODEL HAS A WELL-KNOWN BIAS OF INCREASING SEAS MUCH TOO QUICKLY IN PERIODS OF STRENGTHENING WIND. NO OTHER SIGNIFICANT CHANGES ARE NECESSARY. DISCUSSION FROM 300 PM FOLLOWS... LOW PRESSURE WILL MOVE OUT OF THE GULF OF MEXICO THIS EVE AND THEN UP THE CAROLINA COAST...INTENSIFYING OFF THE NORTH CAROLINA COAST TOWARD DAYBREAK AND ON THU. THE PRESSURE GRADIENT IS EXPECTED TO BECOME SUFFICIENTLY TIGHT TO SUPPORT 20 TO 25 KT WINDS. THE DIRECTION WILL BE NE THROUGH THE EVE...BACKING TO THE N OVERNIGHT. SEAS WILL RESPOND TO THE INCREASING WINDS...BUILDING UP TO 6 TO 9 FT...10 FT SEAS ARE POSSIBLE AROUND FRYING PAN SHOALS. SEAS WILL BE LOWER ACROSS THE VERY NEAR SHORE WATERS. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 300 AM THURSDAY...WEDGE OF HIGH PRESSURE WILL DEVELOP AND STRENGTHEN ALONG THE COAST THROUGH THE SHORT TERM. THIS PRODUCES PERSISTENT N/NE WINDS BOTH FRIDAY AND SATURDAY...WITH SPEEDS INCREASING INTO SATURDAY WHEN THE WEDGE BECOMES MOST INTENSE. SPEEDS OF 10-15 KTS EARLY FRIDAY WILL RISE GRADUALLY...BECOMING STRONGEST ON SATURDAY WHEN SPEEDS WILL REACH 20-25 KTS. VERY LATE SATURDAY NIGHT WINDS WILL BEGIN TO EASE AS THE WEDGE STARTS TO BREAK DOWN. THE HIGHEST SEAS WILL OCCUR LATE FRIDAY NIGHT AND THROUGH MUCH OF SATURDAY...WHEN 4-6 FT SEAS WILL BE COMMON...AND AN SCA IS LIKELY. OTHERWISE...SEAS WILL BE 2-4 FT BOTH BEFORE THE SMALL CRAFT CONDITIONS...AND AGAIN AFTER IT SATURDAY NIGHT. LONG TERM /SUNDAY THROUGH MONDAY/... AS OF 300 AM THURSDAY...WEAKENING WEDGE JUST INLAND FROM THE COAST WILL LEAVE EASING NE WINDS MUCH OF SUNDAY...EVENTUALLY VEERING TO THE SOUTH AROUND 10 KTS BY MONDAY MORNING. WIND DIRECTION WILL VEER FURTHER TO THE SW AND INCREASE TO 10-15 KTS MONDAY AHEAD OF A COLD FRONT...BUT THEN SHIFT ABRUPTLY BACK TO THE NORTH AT THE END OF THE PERIOD BEHIND ITS PASSAGE. WAVE HEIGHTS THROUGH THE EXTENDED WILL HOVER AROUND 2-4 FT...BUT A NE WIND CHOP WILL DOMINATE THE SPECTRUM ON SUNDAY...WHILE A SOUTHERLY WIND WAVE WILL DEVELOP ON MONDAY. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR SCZ017-023- 024. NC...WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR NCZ087-096- 105. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR AMZ250- 252-254-256. && $$ SYNOPSIS...JDW NEAR TERM...DCH/TRA SHORT TERM...JDW LONG TERM...JDW AVIATION...DCH MARINE...DCH/TRA/JDW

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