Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 291744 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 144 PM EDT FRI APR 29 2016 .SYNOPSIS... A WEAK COLD FRONT WILL DISSIPATE ACROSS SOUTH CAROLINA TODAY. DRY WEATHER IS EXPECTED THROUGH SATURDAY AS HIGH PRESSURE RIDGES IN FROM THE NORTH. LOW PRESSURE MOVING ACROSS THE MID-ATLANTIC STATES MAY BRING SEVERAL DAYS OF UNSETTLED WEATHER WITH PERIODS OF RAINFALL SUNDAY THROUGH TUESDAY...WITH SHOWERS BECOMING MORE ISOLATED BY WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1230 PM FRIDAY...MORNING STRATUS HAS DISSIPATED OVER ALL MY THE IMMEDIATE COAST OF PENDER COUNTY. A FEW CUMULUS WERE VISIBLE ON SATELLITE IMAGERY ALONG THE SEABREEZE IN NEW HANOVER AND BRUNSWICK COUNTIES. SMALL ADJUSTMENTS WERE MADE TO TEMPERATURES AND WINDS BASED ON CURRENT OBSERVATIONS...MAINLY UPWARD WITH WINDS NEAR THE COAST AND WITH COASTAL TEMPERATURES SOUTH OF CAPE FEAR WHERE THE OFFSHORE WIND TRAJECTORY APPEARS IT WILL SUSTAIN ITSELF A COUPLE MORE HOURS BEFORE THE SEABREEZE ARRIVES. DISCUSSION FROM 1000 AM FOLLOWS... THE COLD FRONT IS RAPIDLY BECOMING TOO DIFFUSE TO LOCATE AS NORTHWEST WINDS ARE OBSERVED ALL THE WAY DOWN TO THE GEORGIA COAST CURRENTLY. LOW STRATUS CLOUDS HAVE ADVANCED AS FAR SOUTH AS FLORENCE AND CONWAY...BUT SINCE THEIR DEPTH IS LESS THAN A THOUSAND FEET AND VISIBLE SATELLITE ALREADY SHOWS THE EDGES BURNING OFF...I DON`T THINK THESE CLOUDS WILL SURVIVE MORE THAN ANOTHER 1-2 HOURS BEFORE YIELDING TO DEEP MIXING AND STRONG LATE APRIL SUNSHINE. COMPARING ALL THE VARIOUS MODELS 12Z WIND FORECASTS VERSUS REALITY IT APPEARS HIGH-RES AND RAPID UPDATE IS THE WAY TO GO TODAY. LIGHT NORTHERLY WINDS SHOULD TURN ONSHORE AT THE BEACHES WITH A WEAK SEABREEZE THIS AFTERNOON...DELAYED AN HOUR OR TWO FROM ITS TYPICAL GENESIS TIME DUE TO THE BACKGROUND NORTH WIND. FOR TEMPERATURES...IT APPEARS THE 06Z GFS IS MUCH TOO COOL AND ITS OUTPUT IS LARGELY BEING IGNORED. THE 06Z NAM PLUS HIGH-RES NMM AND ARW VERSION OF THE WRF WERE BLENDED WHICH GIVES UPPER 80S TO NEAR 90 ACROSS THE SC PEE DEE REGION...AND LOWER TO MIDDLE 80S ACROSS MOST OF SE NORTH CAROLINA. THE BEACHES SHOULD INITIALLY WARM TO 80-83 BY NOON BUT WILL THEN COOL BACK INTO THE 70S THIS AFTERNOON WITH THE SEABREEZE. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 330 AM FRIDAY...THE MID-LEVEL RIDGE AXIS WILL MOVE OFF THE CAROLINA COAST EARLY SAT...WITH WINDS IN THE MID LEVELS BECOMING SW-WSW FOR THE REMAINDER OF THE SHORT TERM PERIOD. THIS WILL ENABLE MOISTURE TO INCREASE ACROSS THE FA BOTH IN THE MID AND UPPER LEVELS. AT THE SFC...RIDGING WILL TEMPORARILY PUSH SOUTHWARD FROM THE NE STATES ACROSS THE FA EARLY SAT. ITS RIDGE AXIS BY SAT EVENING WILL EXTEND OFF THE CAROLINA COAST FROM ITS CENTER WHICH WILL HAVE MOVED OFF THE COAST FROM THE NE STATES. A STALLED FRONTAL BOUNDARY IS PROGGED TO RETURN NORTHWARD...ACROSS THE FA SAT NIGHT TO NORTH OF THE FA DURING SUNDAY. MODELS THERE-AFTER ARE SOMEWHAT DIFFERENT IN HOW FAR SOUTH AND EAST AND DEEP THE MOISTURE BECOMES ACROSS THE FA. EMBEDDED MID-LEVEL S/W TROUGHS OR VORTS WILL SPORADICALLY PUSH ACROSS THE FA SUN THRU SUNDAY NIGHT. THEIR DYNAMICS AND AN UNSTABLE ATM WILL YIELD SHOWERS AND THUNDERSTORM ACTIVITY FROM LATE SUN MORNING THRU DAYBREAK MON. AM CONCERNED THAT POPS EXHIBITED BY THE MODELS ARE RUNNING TOO HIGH ACROSS THE ILM CWA. HAVE TWEAKED THEM LOWER TO 50 PERCENT OR LESS...AND KEPT THE HIGHER POPS NORTH OF THE ILM CWA. AS FOR TEMPS...STAYED ACTUALLY CLOSER TO THE WARMER GFS MOS GUIDANCE DUE TO LOWER POPS AND LESS CLOUDS ESPECIALLY ON SAT. THE ONSHORE AND VEERING WINDS THIS PERIOD...NE-E SAT VEERING TO SE-S SUN...WILL KEEP MAX TEMPS IN CHECK ALONG THE COAST. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 330 AM FRIDAY...NORTHERN STREAM SHORTWAVES WILL ROTATE AROUND A BROADER TROUGH OVER THE GREAT LAKES MON INTO TUES. LOW PRESSURE WILL SHIFT OFF THE NORTHEAST COAST DRAGGING A COLD FRONT INTO THE CAROLINAS ON MONDAY. SOUTHWESTERLY FLOW OF WARM AND MOIST AIR AHEAD OF THIS FRONT WILL PRODUCE SHOWERS/TSTMS ON MONDAY. A SHORTWAVE DIGS DOWN MON NIGHT PUSHING THIS FRONT SOUTH AND EAST ON MONDAY WITH WEAK HIGH PRESSURE BUILDING IN BEHIND IT. THE ECMWF IS LESS AGGRESSIVE WITH DIGGING SHORTWAVE AND DOES NOT PUSH THE FRONT SOUTH...BUT INSTEAD IT LINGERS OVER NC/SC AS LOW PRESSURE DEVELOPS ALONG IT PRODUCING UNSETTLED WEATHER THROUGH MID WEEK. THE GFS KEEPS THE FRONT WELL SOUTH AS LOW PRESSURE MOVES ALONG IT TOWARD THE SOUTHEAST COAST BRINGING CLOUDS AND PCP BACK IN THE FORECAST FOR TUES NIGHT INTO WED. THEREFORE GFS MAINTAINS A DRIER AIR MASS WITH WEAK HIGH PRESSURE OVER THE AREA LATE MON INTO TUES WHILE THE ECMWF KEEPS WETTER WEATHER FOR TUES. WILL KEEP SOME CLOUDS AND LOWER END POPS MON NIGHT INTO TUES TO ACCOUNT FOR THE UNCERTAINTY AT THIS POINT. BY WED A MUCH MORE AMPLIFIED MID TO UPPER LEVEL PATTERN EVOLVES WITH A DIGGING TROUGH ACROSS THE EAST PUSHING A COLD FRONT EAST BY THURSDAY NIGHT. THIS SHOULD PRODUCE COOLER AND DRIER WEATHER HEADING INTO NEXT WEEKEND. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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AS OF 18Z...A WARM FRONT IS LIFTING NORTH OF THE AREA WITH WINDS VEERING FROM THE NORTH TO NORTHEAST THIS AFTERNOON. EXPECT VFR THROUGH THE REMAINDER OF THE DAYLIGHT HOURS. MODEL SOUNDINGS SHOW AMPLE LOW LEVEL MOISTURE ADVECTING IN OVERNIGHT THAT WILL LEAD TO STRATUS DEVELOPMENT AND ASSOCIATED IFR CIGS IN THE EARLY MORNING HOURS. HAZE/FOG WILL ALSO DEVELOP OVERNIGHT WITH THE GREATEST VISIBILITY RESTRICTIONS LIKELY AT KFLO WHERE WINDS WILL BE THE LIGHTEST. KILM MAY HAVE THE BEST OVERALL VISIBILITIES DUE TO STRONGER MIXING. EXTENDED OUTLOOK...BRIEF MVFR/IFR POSSIBLE FROM CONVECTION SUNDAY INTO TUESDAY. OTHERWISE VFR.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1230 PM FRIDAY...WINDS ARE ABOUT 5 KNOTS STRONGER THAN FORECAST ON THE LATEST OBSERVATIONS NEAR AND NORTH OF CAPE FEAR. ONCE YOU GET DOWN TO MYRTLE BEACH THE PIER OBSERVATIONS OF 10 KNOTS ARE IN-LINE WITH THE PREVIOUS FORECAST. WINDS SHOULD GRADUALLY DECREASE TO AROUND 10 KT OVER THE NEXT 3 HOURS AS THE SEABREEZE CIRCULATION DEVELOPS. DISCUSSION FROM 1000 AM FOLLOWS... THIS MORNING`S WEAK COLD FRONT IS RAPIDLY DISSIPATING AS NORTH TO NORTHWEST WINDS HAVE OVERSPREAD THE CAROLINAS AND GEORGIA COAST. LIGHT NORTH WINDS SHOULD CONTINUE THROUGH NOON FOLLOWING BY VEERING TO THE NORTHEAST. NEAR THE BEACHES WINDS WILL BECOME ONSHORE BY MID AFTERNOON WITH A WEAK SEABREEZE CIRCULATION. THE SEABREEZE SHOULD BE DELAYED AN HOUR OR TWO FROM ITS TYPICAL GENESIS TIME BY THE BACKGROUND WIND FIELD. SEAS ARE CURRENTLY 2-3 FEET WE MAY SEE THESE HEIGHTS DIMINISH BY A FOOT BY LATE AFTERNOON. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 400 AM FRIDAY...SFC RIDGING FROM THE CENTER OF HIGH PRESSURE OVER THE NE STATES...WILL PARTIALLY AFFECT THE ILM NC WATERS SATURDAY. THIS WILL PROVIDE A BRIEF NE-E 15 KT MINI SURGE ACROSS THE WATERS FROM CAPE FEAR NORTHWARD. THE PROGRESSION OF THE SFC RIDGE AXIS OFF THE CAROLINA COAST WILL OCCUR SAT NIGHT THRU SUN WITH WINDS VEERING TO THE E-SE THROUGHOUT SAT NIGHT. A WARM FRONT WILL LIFT NORTHWARD ACROSS THE WATERS EARLY SUN...RESULTING IN WINDS FURTHER VEERING TO THE S TO SW SUN THRU SUN NIGHT. THE SFC PG WILL TIGHTEN...RESULTING WITH 10 TO 15 KT SPEEDS...WITH GUSTS UP TO 20 KT SUN NIGHT. FOR SAT...SIGNIFICANT SEAS AT 2 TO 3 FT WILL BE DOMINATED BY WIND DRIVEN WAVES AT 3 TO 5 SECONDS ACROSS THE WATERS FROM CAPE FEAR NORTHWARD...AND AN EASTERLY GROUND SWELL AT 8 TO 9 SECOND PERIODS ELSEWHERE. WIND DRIVEN WAVES AT 4 TO 5 SECONDS WILL DOMINATE SAT NIGHT THRU SUN NIGHT...AND BUILD TO 3 TO 5 FT BY DAYBREAK MON. LONG TERM /MONDAY THROUGH TUESDAY/... AS OF 330 AM FRIDAY...SHOULD SEE SW FLOW AHEAD OF AN APPROACHING COLD FRONT ON MONDAY. LOW PRESSURE MOVING OFF THE NORTHEAST COAST SHOULD DRAG THIS COLD FRONT INTO THE WATERS BY MONDAY NIGHT. SHOULD SEE A PERIOD OF NORTHERLY WINDS BEHIND IT THROUGH TUES AS WEAK HIGH PRESSURE BUILDS DOWN FROM THE NORTH. THERE IS A POSSIBILITY THIS FRONT MAY LINGER ACROSS THE WATERS ON TUES POTENTIALLY KEEPING A MORE VARIABLE FLOW BUT FOR NOW WILL KEEP NORTHERLY WINDS ACROSS ALL WATERS ON TUES. SEAS GENERALLY 2 TO 4 FT WILL REACH UP TO 4 TO 5 FT IN OUTER WATERS MON AFTN AHEAD OF COLD FRONT BUT SHOULD DROP BACK DOWN SLOWLY IN NORTHERLY FLOW HEADING INTO TUES. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...RGZ NEAR TERM...TRA SHORT TERM...DCH LONG TERM...RGZ AVIATION...REK MARINE...DCH/TRA/RGZ

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