Area Forecast Discussion
Issued by NWS Wilmington, NC

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911 FXUS62 KILM 042003 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 303 PM EST THU FEB 4 2016 .SYNOPSIS... SEVERAL WAVES OF LOW PRESSURE WILL CAUSE A COLD FRONT TO DRIFT SLOWLY ACROSS THE EASTERN CAROLINAS AND OFFSHORE THIS EVENING. THE LAST OF THESE WAVES WILL INTENSIFY OFF THE NORTH CAROLINA COAST OVERNIGHT. COOL HIGH PRESSURE WILL ARRIVE FRIDAY AND PERSIST THROUGH SATURDAY. LOW PRESSURE WILL DEVELOP OFFSHORE LATE SATURDAY AND QUICKLY MOVE OFF TO THE NORTHEAST. THIS SYSTEM WILL BRING A QUICK BOUT OF RAIN WITH JUST A SMALL CHANCE OF SNOW MIXING IN. ARCTIC AIR WILL ARRIVE FOR THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 3 PM THURSDAY...THE SURFACE COLD FRONT HAS FINALLY REACHED THE SOUTH CAROLINA COAST BUT HAS YET TO SHOW UP IN THE WILMINGTON/ CAPE FEAR AREA WHERE WINDS ARE STILL SOUTH WITH MID 60S DEWPOINTS. THE FRONT IS CURRENTLY WEAKENING ALTHOUGH IT SHOULD SURVIVE AS A TRACKABLE FEATURE THIS EVENING DESPITE THE WEAK WINDS AND MODIFYING AIRMASSES ON EITHER SIDE OF THE BOUNDARY. A STREAM OF DEEP MOISTURE AND RAINFALL EXTENDING FROM FLORIDA CONTINUES TO MOVE NORTHWARD ACROSS THE AREA. WE`VE HAD A WIDESPREAD 2-4 INCHES OF RAIN OVER THE PAST 24 HOURS...WITH THE HEAVIEST TOTALS IN A STRIPE JUST WEST AND NORTH OF WILMINGTON. AN IMPRESSIVE UPPER LEVEL DISTURBANCE CURRENTLY OVER THE MID MISSISSIPPI VALLEY WILL WHIP EASTWARD TONIGHT...REACHING THE CAROLINAS BY SUNRISE FRIDAY. SLOWLY VEERING MID-LEVEL WINDS IN ADVANCE OF THIS DISTURBANCE _WOULD_ PUSH THE RAIN GRADUALLY OFF THE COAST THIS EVENING...HOWEVER THERE ARE SOME NON-LINEAR PROCESSES AT WORK WHICH WILL DELAY THE ENDING OF THE PRECIP. FOR ONE...THE BAROCLINIC ZONE ALONG THE COAST SHOULD TIGHTEN WITH THE APPROACH OF THE VORTICITY MAXIMUM ALOFT. THE RIGHT-ENTRANCE REGION OF A 300 MB JET STREAK OVER NEW YORK STATE WILL HELP ENHANCE DEEP LIFT OVER THE EASTERN CAROLINAS THIS EVENING AND WILL HELP SURFACE LOW PRESSURE DEEPEN ALONG THE FRONT JUST OFF THE SC COAST. ISENTROPIC LIFT THROUGH THE 300K-310K LAYER SHOULD INCREASE SUBSTANTIALLY FROM 6 PM UNTIL MIDNIGHT WITH RAINFALL RATES LIKELY BECOMING QUITE HEAVY ALONG THE COAST. ADDITIONAL RAINFALL LATE THIS AFTERNOON AND TONIGHT SHOULD RANGE FROM LESS THAN HALF AN INCH WEST OF INTERSTATE 95 TO 1.5 TO 2.5 INCHES FOR SOUTHPORT AND WILMINGTON. THIS IS THE REASON FOR THE FLOOD WATCH. AFTER 06Z/2 AM EST...DEEP ASCENT SHOULD SHIFT OFFSHORE AND TOWARD THE OUTER BANKS. A DRY SLOT ARRIVING IN THE MID LEVELS SHOULD ALSO HELP END THE SUBSTANTIAL PRECIP ALTHOUGH A FEW LIGHT SHOWERS COULD PERSIST. COMPARED TO MODELS 12 HOURS AGO SURFACE AND IN-CLOUD TEMPERATURES SHOULD BE WARMER LATE TONIGHT AND THE POTENTIAL FOR SNOW FLURRIES APPEARS TO BE DIMINISHING. FORECAST LOWS RANGE FROM THE UPPER 30S ACROSS THE PEE DEE REGION TO THE LOWER 40S ALONG THE COAST. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 3 PM THURSDAY...RAPIDLY DEEPENING OFFSHORE LOW WILL BE MOVING SWIFTLY NORTHEAST AT THE BEGINNING OF THE PERIOD...PULLING MOISTURE AWAY WITH IT BUT ALSO BRINGING IN A STRONG SURGE OF COLD ADVECTION. MODEL CONSENSUS HAS JUST A SLIGHT CHANCE FOR LIGHT RAIN IN THE CAPE FEAR REGION FRIDAY MORNING WITH HIGHS MAINLY IN THE UPPER 40S AND RAPIDLY CLEARING SKIES. EXPECT MAINLY CLEAR SKIES FRIDAY NIGHT AND LOWS A DEGREE OR SO EITHER SIDE OF 30. THE APPROACH OF A VERY POTENT AND DEEP SHORT WAVE OVERNIGHT SATURDAY WILL SPAWN CYCLOGENESIS OFF THE COAST IN THE EARLY MORNING HOURS OF SUNDAY. MOISTURE WRAPPING AROUND THE BACK-SIDE OF THE LOW WILL INCREASE CLOUD COVER OVERNIGHT SATURDAY...WITH RAIN LIKELY ALONG THE COAST...POSSIBLY ENDING BY DAYBREAK ON SUNDAY. MODEL SOUNDINGS SHOW FROZEN PRECIP UNLIKELY AT THIS POINT...ANOTHER CASE OF COLD AIR CHASING MOISTURE. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 3 PM THURSDAY...PRIMARY WEATHER CAPTION FOR THIS PERIOD READS SEASONABLY COOL EARLY FEBRUARY AIR CHARACTERIZED BY NEAR TO BELOW NORMAL VALUES COMPARED TO CLIMATOLOGY. ATMOSPHERIC DYNAMICS OFFERS 2 PRECIPITATION CHANCES...SUNDAY MORNING ALONG AND NEAR THE COAST AS AN ENERGETIC CLIPPER SHORT-WAVE SPURS OFFSHORE CYCLOGENESIS. ECMWF OFFERS A STRONGER AMPLIFICATION OF THIS FEATURE BUT FOR SENSIBLE WEATHER OUTCOMES IT IS SIMILAR TO THE GFS IN TERMS OF A LOW-QPF SYSTEM RELIANT ON ATLC MOISTURE. MONDAY NIGHT A REINFORCING COLD FRONT PASSAGE FOLLOWED BY AN UPPER COLD POOL TUESDAY WILL BRING A CHANCE OF SHOWERS. AGREEMENT IS GOOD AMONG GLOBAL SOLUTIONS THAT A BROAD AND COLD UPPER TROUGH WILL TRANSLATE EAST ACROSS THE EASTERN SEABOARD EARLY TO MID-WEEK. ENOUGH LOW AND MID-LEVEL MOISTURE LOOKS PRESENT TO INTERACT WITH THE LAPSE RATES ALOFT TO WARRANT SHOWERS. TEMPERATURE PROFILES AT THIS TIME SUGGEST THE PRECIPITATION WOULD BE OF LIQUID FORM. && .AVIATION /19Z THURSDAY THROUGH TUESDAY/... AS OF 18Z...A FRONTAL BOUNDARY AND A SHORTWAVE FROM THE WEST MOVING ACROSS THE REGION LATER THIS AFTERNOON AND OVERNIGHT WILL COMBINE TO PRODUCE A DEVELOPING SURFACE LOW OFF THE COAST. THE COASTAL TAF SITES WILL BE BOUNCING BETWEEN MVFR AND IFR EARLY THEN IFR FOR BOTH CEILINGS AND VISIBILITIES OVERNIGHT. THE SITES ARE EXPECTED TO LIFT TO MVFR BY LATE MORNING ON FRIDAY. AT KFLO AND KLBT WITH THE DEVELOPING LOW FARTHER TO THE EAST...THESE SITES SHOULD SEE MORE MVFR THROUGH THE PERIOD BUT IFR IS EXPECTED AS RAIN...LOW CEILINGS PERSIST UNTIL THE MID-OVERNIGHT PERIOD. IF THE LOW DEVELOPS AS EXPECTED MAY SEE VFR CONDITIONS AT THE KFLO AND KLBT JUST AFTER 12UTC. STRONG NORTHWEST LOW-LEVEL WINDS ARE EXPECTED TO DEVELOP AFTER 00 UTC AND GUST WINDS WILL FOLLOW THROUGH THE LATE OVERNIGHT INTO FRIDAY. EXTENDED OUTLOOK...BECOMING VFR FRIDAY AND SATURDAY. RAIN POSSIBLE SUNDAY WITH MVFR. VFR MONDAY INTO TUESDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 3 PM THURSDAY...A COLD FRONT HAS REACHED THE SOUTH CAROLINA COAST AND SHOULD DRIFT OFF THE NORTH CAROLINA COAST LATE THIS AFTERNOON. WEAK WINDS ARE INITIALLY EXPECTED BEHIND THE FRONT. THE APPROACH OF A STRONG UPPER LEVEL DISTURBANCE OVERNIGHT WILL CAUSE SURFACE LOW PRESSURE TO DEVELOP ALONG THE FRONT...RAPIDLY DEEPENING AS IT MOVES NORTH ALONG THE BOUNDARY. THIS SHOULD CAUSE A SUBSTANTIAL INCREASE IN WIND SPEED LATE TONIGHT...REACHING 20-25 KT WITH GUSTS OVER 30 KT LATE TONIGHT. LATEST MODELS SUGGEST THE POTENTIAL FOR GALE FORCE WINDS IS TOO LOW FOR A GALE WARNING...AND WE HAVE ELECTED TO GO WITH A SMALL CRAFT ADVISORY INSTEAD. SEAS CURRENTLY 3-5 FEET MAY DIMINISH BY ABOUT A FOOT THIS EVENING...BUT WILL INCREASE AGAIN LATE TONIGHT DUE TO STRONG OFFSHORE WINDS. DOMINANT WAVE PERIODS WILL SHORTEN CONSIDERABLY DURING THE PERIOD OF STRONG WINDS. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 3 PM THURSDAY...PERIOD STARTS OUT WITH VERY STRONG WINDS AND DANGEROUSLY HIGH SEAS IN THE WAKE OF A RAPIDLY DEEPENING LOW PRESSURE SYSTEM. EXPECT A STRONGLY-WORDED SMALL CRAFT ADVISORY WILL BE IN PLACE FRIDAY MORNING FOR WINDS OF 20 TO 30 KTS AND 5 TO 8 FT SEAS. HOWEVER...CONDITIONS WILL RAPIDLY IMPROVE DURING THE DAY ON FRIDAY AS HIGH PRESSURE NOW CENTERED OVER TEXAS MOVES RAPIDLY EAST OVER EASTERN CONUS. ANOTHER RAPIDLY DEEPENING LOW WILL MOVE EAST OF THE WATERS SUNDAY MORNING...ALLOWING CONDITIONS TO ONCE AGAIN DETERIORATE AND LIKELY NECESSITATING THE ISSUANCE OF A SMALL CRAFT ADVISORY. LONG TERM /SUNDAY THROUGH MONDAY/... AS OF 3 PM THURSDAY...CHALLENGING MARINE CONDITIONS START THE EXTENDED PERIOD AS STRONG OFFSHORE N-NW WINDS GREET SUNDAY DUE TO SURFACE LOW PRESSURE DEEPENING OFFSHORE. 25 KT WINDS AND ELEVATED SEAS OFFSHORE WILL LIKELY RESULT IN A SMALL CRAFT ADVISORY ON SUNDAY. IMPROVEMENT WILL FOLLOW SUNDAY NIGHT INTO MONDAY AS THE LOW PULLS NE AWAY FROM THE WATERS. THE IMPROVEMENT WILL BE SHORT- LIVED AS A STRONG COLD FRONT CROSSES THE WATERS MONDAY NIGHT INTO TUESDAY. THE ADVERTISED PRESSURE GRADIENT SUPPORTS 20-25 KT SW-W WINDS BY TUESDAY AND HIGHER GUSTS OUTER PORTION. THUS IT APPEARS ANOTHER ADVISORY MAY BE NEEDED LATE MONDAY AND TUESDAY...AFTER AN ADVISORY SUNDAY. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...FLOOD WATCH THROUGH LATE TONIGHT FOR SCZ053>056. NC...FLOOD WATCH THROUGH LATE TONIGHT FOR NCZ096-099-105>110. MARINE...GALE WATCH FROM 1 AM EST FRIDAY THROUGH FRIDAY AFTERNOON FOR AMZ250-252-254-256. && $$ SYNOPSIS...REK NEAR TERM...TRA SHORT TERM...REK LONG TERM...MJC AVIATION...SGL MARINE...MJC/REK/TRA

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