Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 042355 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 655 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 FRIDAY/... AS OF 7 PM THURSDAY...CURRENTLY ONLY WIDESPREAD LIGHT RAIN MAINLY EAST OF A ELIZABETHTOWN TO ANDREWS LINE. PRECIPITATION MORE SCATTERED TO THE WEST OF THIS LINE. THE SURFACE ANALYSIS IS SHOWING THE SURFACE LOW SOUTHEAST OF CHARLESTON JUST BELOW 1013 MB ALONG THE COLD FRONT. THE 22 UTC RAP/HRRR MODELS SHOW THE LOW SLOWLY SHIFTING TO THE NORTH BUT REMAINING AT OR ABOVE 1010MB. THE 22 UTC HRRR INITIALIZES THE WESTERN EXTENT OF THE RAIN TO FAR WEST...AND IT WANTS TO INCREASE INTENSITY OF THE PRECIPITATION OVER THE FLOOD WATCH AREA IN THE NEXT HOUR OR SO. THE SIGNIFICANT FORCING IS SUPPOSE TO BE THE ISENTROPIC LIFT. THIS LIFT SHOULD BECOME STRONG WITH THE NEXT HOUR OR TWO. WILL CONTINUE TO MONITOR AND IF THE HEAVY RAIN DOESN`T MATERIALIZE IN THE NEXT FEW HOURS MAY HAVE TO CONSIDER DROPPING THE FLOOD WATCH. ...PREVIOUS DISCUSSION... 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 NIGHT 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 /00Z FRIDAY THROUGH TUESDAY/... AS OF 00Z...THE SLOW MOVING FRONTAL BOUNDARY THAT WAS MOVING ACROSS EASTERN NC HAS FINALLY REACHED THE COAST AND WILL BE PULLING OFF THE COAST DURING THE NEXT FEW HOURS. SURFACE LOW PRESSURE ALONG THE SC COAST WILL BE LIFTING NEWD DURING THIS TIME FRAME AS WELL. HRRR AND RAP40 SHOWED HEAVY RAIN ALONG THE COASTAL TERMINALS FROM 00Z-04Z WITH DRYING MOVING ACROSS THE INLAND TERMINALS. NOT SEEING THAT HEAVY PRECIP MATERIALIZING FOR SC TERMINALS BUT WILL LEAVE THE CHANCE ACROSS KILM FOR THAT PERIOD ALTHOUGH CONFIDENCE IS LOW. WILL FORECAST MVFR ACROSS KLBT/KFLO AND KEEP IN IFR ACROSS KILM/KCRE/KMYR THROUGH 03Z-04Z THEN MVFR. LOOK FOR TERMINALS TO BECOME VFR FIRST INLAND THEN COASTAL TERMINALS AFTER 10Z-13Z INLAND AND AFTER 15Z-16Z COAST. MAIN AVIATION ISSUE WILL TRANSITION FROM RAIN/CEILINGS/VSBY TO WIND AS PRESSURE GRADIENT TIGHTENS WITH SURFACE LOW EXITING AREA AND HIGH PRESSURE BUILDING IN. PRESSURE GRADIENT WILL PRODUCE STRONG N-NW WINDS ACROSS THE TERMINALS OF 15-20KTS WITH SOME GUSTS OF 25-30KTS. WINDS WILL START TO ABATE AFTER 06/00Z. EXTENDED OUTLOOK...BECOMING VFR FRIDAY AND SATURDAY. RAIN POSSIBLE SUNDAY WITH MVFR. VFR MONDAY INTO TUESDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 630 PM THURSDAY...A SURFACE LOW IS SOUTH OF 41004 AND THIS LOW WILL MOVE UP ALONG THE COLD FRONT WHICH IS OVER THE SOUTH CAROLINA WATERS AND INTERSECTS THE SOUTHEAST NORTH CAROLINA COAST IN BRUNSWICK COUNTY. AS THE LOW MOVES NORTHEAST ALONG THE FRONT IT WILL BE PULLED OUT OFF THE NEAR SHORE WATERS AND A STRONG NORTHWEST WIND WILL DEVELOP OVER ALL THE WATERS BRINGING SMALL CRAFT CONDITIONS THROUGH FRIDAY EVENING. 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 TUESDAY/... 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 UNTIL 2 AM EST FRIDAY FOR SCZ053>056. NC...FLOOD WATCH UNTIL 2 AM EST FRIDAY FOR NCZ096-099-105>110. MARINE...SMALL CRAFT ADVISORY FROM 1 AM TO 6 PM EST FRIDAY FOR AMZ250- 252-254-256. && $$ NEAR TERM...HAWKINS SHORT TERM...REK LONG TERM...MJC AVIATION...MAC

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