Area Forecast Discussion
Issued by NWS Wilmington, NC

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579 FXUS62 KILM 070627 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 127 AM EST SUN FEB 7 2016 .SYNOPSIS... A LOW PRESSURE SYSTEM WILL RAPIDLY INTENSIFY AS IT TRACKS NORTHEAST OFFSHORE OF THE CAROLINAS OVERNIGHT THROUGH SUNDAY. THIS SYSTEM MAY BRING SNOWFALL TO INLAND LOCATIONS SUNDAY. THE STRONG LOW WILL TRACK FARTHER OUT TO SEA SUNDAY NIGHT THRU MONDAY. WEAK HIGH PRESSURE WILL PREVAIL MONDAY FOLLOWED BY A COLD FRONTAL PASSAGE MONDAY NIGHT. A DRY ARCTIC AIR MASS WILL FOLLOW INTO MID WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 945 PM SATURDAY...FORECAST CONTINUES AS BEFORE. MONITORING 00Z GUIDANCE AS IT COMES IN TO SEE HOW IT INITIALIZES WITH CURRENT REALITY AND TO SEE IF WE NEED TO MAKE ANY ADJUSTMENTS TO OUR THINKING. LATEST OBS SHOW MID 40S ABOUT EVERYWHERE WITH LIGHT RAIN OR DRIZZLE FALLING OVER LARGE PORTIONS OF THE FORECAST AREA. PREVIOUS DISCUSSION FOLLOWS: HAVE RAISED POPS FOR THIS EVENING GIVEN LATEST RADAR REFLECTIVITY TRENDS...WHICH SHOW A GRADUAL INCREASE IN COVERAGE. HOWEVER...PRECIP IS STILL VERY LIGHT DESPITE INCREASED COVERAGE...SO HAVE NOT CHANGED QPF VALUES SIGNIFICANTLY. OTHERWISE FORECAST REMAINS ON TRACK. PREVIOUS DISCUSSION FOLLOWS: DETERIORATING WEATHER CONDITIONS TO PREVAIL LATE TONIGHT INTO SUNDAY AS WIND...RAIN...AND SNOW DEVELOP IN RESPONSE TO AN EVOLVING UPPER LOW AND ATTENDANT...BOMBING SURFACE LOW OFF THE CAROLINA COAST. ISENTROPIC OMEGA WAS ALREADY UNDERWAY THIS AFTERNOON OVER E GA AND SC AND THE CAROLINA COASTS...WHERE LIGHT PCPN AMOUNTS WERE NOTED. SURFACE TEMPERATURES ACROSS NE SC AND SE NC WILL NOT ALLOW FROZEN PCPN UNTIL THE PRE- DAWN HOURS SUNDAY MAINLY ALONG AND WEST OF I-95. TEMPERATURES SUPPORT A MIX OF RAIN AND SNOW...OR WET SNOW WITH LOW SNOW-RATIO VALUES. THROUGH 12Z SUNDAY SNOW AMOUNTS OF A 1/4 INCH ARE POSSIBLE WEST OF I- 95. NORTH WINDS WILL REMAIN IN PLACE TONIGHT AND INCREASE TO 10-20 MPH BY DAYBREAK OVER LAND WITH STRONGER GUSTS AT THE COAST EARLY SUNDAY...AS A RAPIDLY DEEPENING LOW BECOMES POSITIONED A FEW HUNDRED MILES OFF CHARLESTON SC. THROUGH 12Z SUNDAY UP TO A HALF OF RAIN IS POSSIBLE ALONG THE COAST...ESPECIALLY SOUTH OF CAPE FEAR. MINIMUM TEMPERATURES AT DAYBREAK SUNDAY 32-38...COLDEST WEST AND MILDEST AT THE COAST. && .SHORT TERM /6 AM THIS MORNING THROUGH MONDAY NIGHT/... AS OF 300 PM SATURDAY...DEEPENING LOW PRESSURE SYSTEM OFF THE SOUTH CAROLINA COAST SUN MORNING WILL TRACK NORTH DEEPENING FURTHER AS IT REACHES WITHIN 200 MILES EAST OF CAPE FEAR EARLY AFTN SUNDAY. THE MID TO UPPER TROUGH DIGS DOWN AND CUTS OFF OVER FL/GA LINE HELPING TO SLOW AND PULL SFC LOW SLIGHTLY WEST BEFORE CAPTURING IT INTO LATE AFTN EARLY EVE BEFORE MOVING OFF TO THE EAST NORTHEAST. MOISTURE SPREADS FARTHER INLAND AS LOW GETS PULLED TO THE WEST A BIT AS UPPER LOW DEEPENS. THIS DEEP LOW WILL PRODUCE A VERY TIGHT GRADIENT AND STRONG GUSTY WINDS ESPECIALLY ACROSS COASTAL COUNTIES WHERE A WIND ADVISORY HAD BEEN ISSUED FOR SUNDAY. CONFIDENCE IS GREATEST WHEN IT COMES TO IMPACTS ASSOCIATED WITH STRONG WINDS AND HEAVY RAIN ALONG THE COAST. WILL LIKELY ISSUE FLOOD WATCH AS MANY AREAS STILL HAVE SATURATED GROUNDS FROM PREVIOUS STORM. THE UNCERTAINTY GROWS WHEN LOOKING AT CHC OF SNOW AND MORE SPECIFICALLY THE CHC OF ANY ACCUMULATING SNOW. AS THE LOW DEEPENS AND UPPER DYNAMICS INCREASE ACROSS THE AREA EXPECT EXTREME LIFT AND MOISTURE EXTENDING WESTWARD TO COVER PORTIONS OF FORECAST AREA ESPECIALLY ALONG THE COAST. AS FOR THE COLD AIR...SOUNDING DATA SHOWS DEEP WARM NOSE FROM 2K FT UP TO 7K FT CLOSER TO THE COAST AND ALTHOUGH COOLING WILL OCCUR ALOFT...EXPECT MAINLY RAIN. MAY SEE SOME WET SNOW FALL BUT NOT CONCERNED WITH ACCUMULATING SNOW CLOSE TO THE COAST. MOVING INLAND AND LOOKING AT SOUNDING DATA FROM FLO TO LBT OR I-95 CORRIDOR...PROFILE BECOMES FULLY SATURATED OVERNIGHT AND HEADING INTO EARLY MORNING SHOWS ENOUGH COLD AIR ALOFT ESPECIALLY IN DENDRITIC GROWTH ZONE TO PRODUCE SOME SNOW. FOR NOW HAVE LEFT THE SNOW AMOUNTS THE SAME ALTHOUGH INCREASED POPS FARTHER INLAND. TOO MUCH UNCERTAINTY BETWEEN MODELS TO ISSUE A WINTER WEATHER ADVISORY AT THIS POINT...BUT CAN NOT RULE OUT ONE AT A LATER TIME. WOULD THINK THAT COLD AIR AND ENOUGH MOISTURE WILL COME TOGETHER TO PRODUCE A BURST OF SNOW THAT COULD ACCUMULATE. NOT CONFIDENT AS TO EXACT LOCATION OR HOW MUCH. MAY SEE PCP MIX WITH MORE SNOW ALONG COAST AS IT WINDS DOWN INTO THE EVENING. FOR NOW EXPECT RAIN MODERATE TO HEAVY AT TIMES ALONG THE COAST WITH QPF UP OVER AN INCH IN PLACES AND POSSIBLY UP TO 2 TO 3 INCHES IN SPOTS. AS FOR SNOW...WITH INCLUDE RAIN AND SNOW MIX WITH UP TO A HALF INCH POSSIBLY ACCUMULATING...MAINLY ALONG THE I95 CORRIDOR BUT WOULD NOT BE SURPRISED TO SEE SNOW MIX IN ALONG THE COAST. ALTHOUGH TEMPS REMAIN ABOVE FREEZING AT THE SFC...WITH SUCH A DEEP SYSTEM THE POTENTIAL FOR WINTRY PCP COULD BE MORE WIDESPREAD AS TEMPS COOL RAPIDLY ALOFT WITH VERY STRONG DYNAMICS IN PLACE AND PLENTY OF COLD AIR IN DENDRITIC GROWTH ZONE. THE ATMOSPHERE BEGINS TO DRY OUT FROM SOUTHWEST TO NORTHEAST THROUGH LATE SUNDAY AS LOW TRACKS OFF TO THE EAST TO NORTHEAST FARTHER INTO THE ATLANTIC. TEMPS WILL DROP INTO THE 30S OVERNIGHT SUNDAY AS SKIES CLEAR OUT. MOVING INTO MONDAY...DEEP LOW PRESSURE SYSTEM WILL BE MOVING FARTHER AWAY WITH DIMINISHING NW FLOW THROUGH EARLY MORNING. WINDS WILL QUICKLY BACK TO THE SW THROUGH THE AFTERNOON THOUGH AS NEXT SYSTEM APPROACHES. DEEPENING SHORTWAVE WILL PIVOT AROUND THE GREAT LAKES AND DEEPEN EXTENDING DOWN INTO THE SOUTHEAST. THE MAIN SURFACE LOW WILL MOVE OVER THE GREAT LAKES ASSOCIATED WITH UPPER LOW BUT A SECONDARY LOW WILL DEVELOP OFF THE DELMARVA COAST DEEPENING AS IT SHIFTS EAST. A COLD FRONT WILL EXTEND FROM THIS SYSTEM AND ALONG WITH UPPER LEVEL SUPPORT WILL PROVIDE SOME ENHANCED LIFT OVER THE AREA LATE MONDAY. PLENTY OF COLD AIR WILL BE IN PLACE ALOFT BUT MOISTURE WILL BE LACKING. FOR NOW HAVE INCLUDED MAINLY SLIGHT CHC OF LIGHT RAIN FOR MON AFTN WITH SFC TEMPS IN THE 50S BUT WOULD NOT DISCOUNT SOME LIGHT SNOW MIXING IN LATE...BUT AGAIN THE MOISTURE WILL BE LACKING WITH THIS SYSTEM AND NOT COUNTING ON MUCH IN THE WAY OF QPF. TEMPS WILL FALL JUST BELOW FREEZING MOST PLACES OVERNIGHT MON INTO EARLY TUES. && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 300 PM SATURDAY...COLD AND WINDY AS ARCTIC AIR INVADES THE REGION THROUGH THURSDAY. COLD FRONT WILL BE OFFSHORE TO START THE PERIOD...WITH A VERY DEEP MID-LEVEL TROUGH DIGGING ACROSS THE EAST BEHIND IT. 500MB HEIGHTS FALL TO AROUND -4 SD`S IN THE SOUTHEAST...A SIGNAL OF THE VERY COLD INTRUSION OCCURRING THROUGH MID-WEEK. AT THE SURFACE...STRONG LOW PRESSURE MOVING INTO THE CANADIAN MARITIMES WILL LEAVE A BROAD TROUGH INTO THE SOUTHEAST THROUGH WEDNESDAY BEFORE HIGH PRESSURE BEGINS TO RIDGE NORTHEAST FROM THE GULF COAST...MAXIMIZING IN AMPLITUDE ON FRIDAY. THE COMBINATION OF THE DEEP MID-LEVEL TROUGH AND SHARP GRADIENT WITH NW WINDS WILL PROMOTE STRONG COLD ADVECTION THROUGH WEDNESDAY. HIGHS TUE/WED/THU WILL LIKELY FALL BELOW GUIDANCE...WITH WEDNESDAY BEING THE COLDEST DAY WHEN HIGHS WILL STRUGGLE TO 40 DEGREES. VERY COLD NIGHTTIME MINS ARE NOT FORECAST AS MIXING REDUCES RADIATIONAL COOLING...BUT LOWS WILL ALSO BE WELL BELOW NORMAL IN THE MID TO UPR 20S. THESE COLD TEMPS WILL COMBINE WITH WINDS POTENTIALLY GUSTING TO 30 MPH TUE AND WED TO PRODUCE VERY COLD WIND CHILLS FALLING INTO THE MID TEENS AT NIGHT...AND REMAINING STILL COLD DURING THE DAY. SUBTLE WARMING OCCURS THURSDAY AND THEN MORE SIGNIFICANTLY FRIDAY WITH HIGHS RISING TO AROUND NORMAL. THIS WILL BE SHORT LIVED HOWEVER AS ANOTHER COLD FRONT DROPS INTO THE CWA ON SATURDAY BRINGING A RETURN TO BELOW NORMAL TEMPERATURES AND THE ONLY CHANCE FOR RAINFALL THIS PERIOD. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... AS OF 06Z...SHOULD BE AN INTERESTING NEXT 24 HOURS TO SAY THE LEAST. CURRENTLY...SURFACE CYCLOGENESIS OCCURRING OFFSHORE FROM THE FLORIDA EAST COAST. A STRONG UPPER TROF WILL CATCH UP WITH THE SFC LOW THIS MORNING...RESULTING IN EXPLOSIVE DEEPENING OF THE SFC LOW JUST OFFSHORE FROM THE NC AND SC COASTS THRU THIS AFTERNOON AND EVENING. LOOK AT INITIALLY REDUCED VISIBILITY FROM LIGHT RAIN...VFR TO MVFR...WITH POCKETS OF MODERATE TO HEAVY RAIN...MVFR TO IFR... REDUCING VSBY TO LESS THAN 1 MILE AND ASSOCIATED CEILINGS AT OR BELOW 1200 FT. THE HEAVIEST PCPN WILL OCCUR DURING DAYTIME SUNDAY MORNING THRU MID-AFTERNOON. THE HIGHER PCPN AMOUNTS WILL OCCUR CLOSER TO THE COAST...IE MYR...CRE AND ILM. SFC TEMPS AND THE LOW LEVELS REMAIN MILD ENOUGH TO KEEP THE PCPN TYPE TO JUST PLAIN RAIN. THE ENDING OF THIS PCPN COULD BE A MIXTURE OF RAIN OR SNOW OR POSSIBLY ALL SNOW DEPENDING ON HOW MUCH WRAP AROUND COLD AIR MAKES IT INTO THE AREA PRIOR TO THE DEPARTURE OF THE MOISTURE. FOR NOW...ENDING THE PCPN AS PLAIN RAIN. THE MAJOR EFFECTS FROM THIS STORM SYSTEM WILL BE THE GUSTY NE WINDS INITIALLY...BACKING TO THE NORTH TODAY...AND NW LATE THIS AFTERNOON AND EVENING. THE SFC PG WILL TIGHTEN RAPIDLY THIS MORNING AS THE SFC LOW NEARLY BOMBS JUST OFFSHORE FROM THE CAROLINAS LATER THIS MORNING AND AFTERNOON...AND PASSES BY CAPE FEAR EARLY THIS EVENING...AND OFF CAPE HATTERAS BY SUNRISE MON. PEAK GUSTS WILL RUN 20 TO 30 KT ACROSS THE INLAND TERMINALS... AND 30-40 KT ACROSS THE COASTAL TERMINALS...AND OCCUR LATE THIS MORNING THRU EARLY THIS EVENING. EXTENDED OUTLOOK...CONDITIONS IMPROVE TO VFR SUNDAY EVENING AND OVERNIGHT...AND CONTINUING THRU MON. A CHANCE OF PRECIPITATION WITH MVFR CONDITIONS POSSIBLE LATE MONDAY INTO TUESDAY. ARCTIC AIR MASS WILL PROVIDE VFR CONDITIONS WEDNESDAY AND THURSDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 945 PM SATURDAY...WE CONTINUE TO SEE A GRADUAL INCREASE IN WINDS AND SEAS...WITH 5 FT SEAS NOW REACHING THE NEAR-SHORE WATERS. GALE WARNING CONTINUES FOR ALL WATERS. PREVIOUS DISCUSSION FOLLOWS: MARINE CONDITIONS WILL BECOME PERILOUS INTO EARLY SUNDAY AS N WINDS RAPIDLY INTENSIFY AS A SURFACE LOW DEEPENS QUICKLY OFFSHORE OF SC EARLY SUNDAY. GALE WARNINGS ARE POSTED FOR SUNDAY AND ADVISORY CONDITIONS WILL CERTAINLY PRECEDE THE GALE STARTING TONIGHT. MARINERS ARE DISCOURAGED FROM VENTURING OFFSHORE THE NEXT 36 HOURS AS CONDITIONS WILL TURN DANGEROUS. ALTHOUGH SUNDAY WILL SEE THE WORSE OF CONDITIONS...WAVE HEIGHTS DAYBREAK SUNDAY WILL REACH 4 TO 7 FEET AND GROWING...WITH DOMINANT WAVE PERIODS OF 5-6 SECONDS...MAKING FOR STEEP-FACED WAVE-SETS. WIND-DRIVEN RAIN LATE TONIGHT AND EARLY SUNDAY WILL REDUCE VISIBILITIES TO 2NM OR LESS AT TIMES. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 300 PM...DANGEROUS MARINE CONDITIONS WILL EVOLVE DURING THE SHORT TERM PERIOD AS AN AREA OF LOW PRESSURE INTENSIFIES AS IT TRANSLATES ACROSS THE ADJACENT OFFSHORE WATERS DURING SUNDAY. A GALE WARNING WILL REMAIN IN EFFECT DUE TO WINDS REACHING CRITERIA DURING SUNDAY ALONG WITH FREQUENT GUSTS TO GALE FORCE. WINDS ARE EXPECTED TO BE STRONGEST DURING THE DAY SUNDAY AND INTO THE EVENING. SPEEDS WILL DIMINISH AS THEY BACK TO A WESTERLY DIRECTION EARLY MONDAY MORNING. WIND SPEED WILL INCREASE AGAIN DURING MONDAY OUT OF A WEST- SOUTHWEST DIRECTION WITH LIKELY SMALL CRAFT CONDITIONS PERSISTING INTO MONDAY NIGHT. THERE WILL BE A LARGE RANGE IN SEAS DEVELOPING ONCE THE WINDS BACK TO THE NORTHWEST. BLOW-OUT TIDES ARE POSSIBLE ALONG THE TIDAL CREEKS AND OTHER NAVIGABLE CHANNELS WITH THE STRONG OFFSHORE FLOW AND WITH THE ASTRONOMICAL AFFECTS FROM THE NEW MOON MONDAY. LONG TERM /TUESDAY THROUGH THURSDAY/... AS OF 300 PM SATURDAY...SMALL CRAFT CONDITIONS EXPECTED TUESDAY AND WEDNESDAY BEHIND A DEPARTING STRONG LOW PRESSURE SYSTEM. ALTHOUGH THIS LOW PULLS AWAY TO THE NORTHEAST QUICKLY ON TUESDAY...LINGERING TROUGH ACROSS THE AREA WILL KEEP A PINCHED GRADIENT AND STRONG W/NW WINDS OF 20-25 KTS...WITH GUSTS POSSIBLY TO GALE FORCE...TUESDAY AND WEDNESDAY. AN SCA WILL BE NEEDED...AND IT IS STILL POSSIBLE A GALE WARNING MAY BE REQUIRED...PRIMARILY ON WEDNESDAY. THESE WINDS WILL DRIVE SEAS TO 4-8 FT...BUT LOWER IN THE NEAR SHORE WATERS DUE TO THE OFFSHORE COMPONENT. THEREAFTER...HIGH PRESSURE BEGINS TO RIDGE IN FROM THE WEST AND THIS WILL CAUSE THE GRADIENT TO SLACKEN...ALLOWING WINDS TO FALL TO 10-15 KTS AND THEN VARIABLE LATE...WITH SEAS DROPPING TO 2 FT BY THE END OF THE PERIOD. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...FLOOD WATCH FROM 6 AM EST THIS MORNING THROUGH THIS EVENING FOR SCZ053>056. WIND ADVISORY FROM 10 AM THIS MORNING TO 8 PM EST THIS EVENING FOR SCZ053>056. NC...FLOOD WATCH FROM 6 AM EST THIS MORNING THROUGH THIS EVENING FOR NCZ099-105>110. WIND ADVISORY FROM 10 AM THIS MORNING TO 8 PM EST THIS EVENING FOR NCZ105>110. MARINE...GALE WARNING FROM 6 AM THIS MORNING TO 10 PM EST THIS EVENING FOR AMZ250-252-254-256. && $$ SYNOPSIS...RGZ NEAR TERM...MJC SHORT TERM...RGZ LONG TERM...JDW AVIATION...DCH

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