Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 272007 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 307 PM EST SAT DEC 27 2014 .SYNOPSIS... THE CENTER OF DRY HIGH PRESSURE WILL MOVE OFFSHORE TONIGHT. RETURN FLOW BEHIND THIS HIGH WILL BRING INCREASING MOISTURE AND WARMER TEMPERATURES FOR SUNDAY AND MONDAY. A COLD FRONT WILL CROSS THE AREA ON MONDAY...INCREASING RAIN CHANCES. COOL AND DRY HIGH PRESSURE WILL FOLLOW FOR THE MID-WEEK PERIOD AND THE BEGINNING OF THE NEW YEAR. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... AS OF 300 PM SATURDAY...LATEST SATELLITE IMAGERY TRENDS CONTINUE TO HIGHLIGHT A MOSTLY SUNNY SKY ACROSS THE ILM CWA...THAT SHOULD CONTINUE AFFECTING THE FA THRU THIS AFTERNOON. UPSTREAM CI AND/OR AC ON THE LEE SIDE OF THE APPALACHIANS...WILL AT TIMES PUSH ACROSS THE ILM CWA THROUGH TONIGHT. THE INITIAL DOWNSLOPE TRAJECTORY OFF THE MOUNTAINS WILL HELP SCOUR OUT MUCH OF THIS MOISTURE THIS AFTN BEFORE REACHING THE ILM CWA. HOWEVER FOR TONIGHT...THE FLOW ALOFT BECOMES MORE ORIENTED FROM THE SW AFTER THE MID TO UPPER LEVEL RIDGE AXIS MOVES OFF THE SE U.S. COAST. IN ADDITION...THERE WILL BE AN INCREASE IN THE TAPPING OF GULF OF MEXICO MOISTURE AS THE SW FLOW ALOFT PICKS UP. OVERALL...LOOKING AT AN INCREASE AND THICKENING OF MID AND UPPER LEVEL LAYER OF CLOUDINESS TONIGHT. LOW LEVEL ATLANTIC MOISTURE COULD FUEL SC/ST CLOUDINESS CLOSER TO THE COAST DURING TONIGHT... ESPECIALLY IN THE VICINITY OF CAPE FEAR. MODELS HINT AT A SLIGHT CHANCE FOR PCPN IN THE VICINITY OF CAPE FEAR...AND WILL HIGHLIGHT ITS OCCURRENCE...JUST NOT QUITE MAKING IT ONSHORE. LOCATIONS ALONG AND WEST OF THE I-95 CORRIDOR AFTER MIDNIGHT TONIGHT...WILL ALSO BE ON THE RECEIVING END OF POSSIBLE LIGHT PCPN AS THE FRONT MAKES SOME PROGRESS TOWARD BOTH CAROLINA COASTS...ALTHOUGH NOT VERY ORGANIZED. WILL REMAIN ON THE HIGHER SIDE OF MODEL MOS GUIDANCE FOR THIS AFTERNOON HIGHS...WHICH IN THIS CASE IS THE GFS MOS GUIDANCE. LOW TO MID 60S SHOULD COVER IT. WITH ADJACENT ATLANTIC SSTS IN THE 50S...THE IMMEDIATE COAST AND/OR BEACHES MAY HAVE A TOUGH TIME BREAKING ABOVE 60. FOR TONIGHTS LOWS...WILL LEAN TOWARD THE SLIGHTLY MILDER GFS MOS OVER NAM...WITH MID 40S INLAND TO AROUND 50 AT THE COAST. IF CLOUDS HOLD OFF UNTIL LATE TONIGHT...THEN RADIATION FOG WILL HAVE A CHANCE TO OVERSPREAD THE FA ESPECIALLY ALONG AND EAST OF THE I-95 CORRIDOR. HAVE KEPT FOG PATCHY DUE TO THE MANY VARIABLES THAT HAVE YET TO COME TOGETHER FOR FOG TO BECOME MORE WIDESPREAD. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... AS OF 300 PM SATURDAY...NO LESS THAN 4 DISTINCT FEATURES WORKING TOGETHER WILL CREATE AN UNSETTLED SHORT TERM PERIOD. HIGH PRESSURE OFFSHORE WILL CONTINUE TO PUSH TO THE EAST INTO EARLY NEXT WEEK...DRIVEN BY A SLOWLY DEAMPLIFYING MID-LEVEL RIDGE OFF THE EAST COAST. THIS LEAVES DEEP SW FLOW AND MOIST ADVECTION ACROSS THE SOUTHEAST. EMBEDDED WITHIN THIS DEEP SW FLOW...2 SHORTWAVES...A WEAK ONE SUNDAY MORNING...AND A STRONGER IMPULSE MONDAY MORNING...WILL TRAVERSE OVERHEAD THE AREA. THE FORMER WILL BE ACCOMPANIED BY SOME VERY LIGHT RAINFALL SUNDAY MORNING...FOCUSED MOSTLY ACROSS INLAND ZONES. A BREAK IN PRECIP IS ANTICIPATED SUNDAY AFTN/EVE THANKS TO SUBSIDENCE AND DRYING BEHIND THIS FEATURE...BEFORE RAIN RE-DEVELOPS LATE SUNDAY NIGHT. THE SECOND /STRONGER/ SHORTWAVE WILL BE ACCOMPANIED BY A SURFACE REFLECTION AND WIDESPREAD RAINFALL IS EXPECTED DURING MONDAY AS THE LOW PRESSURE MOVES ACROSS AND DRAGS A COLD FRONT BEHIND IT. AGAIN...TOTAL QPF LOOKS PRETTY LOW BUT AN AVERAGE OF ONE-QUARTER TO AS MUCH AS ONE-HALF INCH OF RAINFALL IS POSSIBLE MONDAY. THE COLD FRONT WILL SLOW OFFSHORE MONDAY NIGHT...KEEPING UNSETTLED AND DRIZZLY CONDITIONS GOING THROUGH THE END OF THE PERIOD. TEMPS SUNDAY WILL WARM WELL INTO THE 60S THANKS TO WAA AND AFTN INSOLATION...AND LOWS WILL STRUGGLE TO FALL MUCH DUE TO CLOUDS AND THE CONTINUED WARM SW FLOW. EXPECT LOWS SUNDAY NIGHT TO DROP ONLY INTO THE MID 50S - VALUES MORE TYPICAL OF LATE-DECEMBER HIGHS. HIGHS MONDAY WILL STILL BE WARM AHEAD OF THE COLD FRONT...BUT A FEW DEGREES COOLER THAN SUNDAY. A BIGGER DROP IN TEMPS IS FORECAST FOR MONDAY NIGHT THANKS TO DEVELOPING CAA BEHIND THE FRONT...AND LOWS WILL FALL INTO THE LOW/MID 40S...COOLEST FAR NW. && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 300 PM SATURDAY...TUESDAY`S WEATHER MAP WILL FEATURE AN UNUSUALLY LARGE AREA OF HIGH PRESSURE COVERING JUST ABOUT THE ENTIRE NATION, IT`S CENTER OVER MONTANA. AT IT`S CORE IT IS A VERY CHILLY AIRMASS BUT WITH THE CAROLINAS ONLY ON THE SOUTHEASTERN PERIPHERY TEMPERATURES WILL ONLY BE A LITTLE BIT BELOW CLIMO. OVER THE NEXT SEVERAL DAYS THIS AIRMASS WILL BLEED SLOWLY SOUTHWARD INTO THE PLAINS. CONFLUENT MID AND UPPER LEVEL FLOW OVER THE EASTERN U.S. WILL ALSO DRAW A RIDGE AXIS INTO THE MIDATLANTIC FROM THE PARENT HIGH. THIS SETS UP VERY LITTLE IN THE WAY OF THERMAL ADVECTION ACROSS THE SOUTHEAST AND MID ATLANTIC AS LOW LEVEL THICKNESSES AND ISOTHERMS ALIGN WITH THE ZONAL FLOW ALOFT. RAD COOLING TUESDAY NIGHT WILL HELP TO MAKE WEDNESDAY COOLER THAN TUESDAY AS FAIRLY SHALLOW MIXING OCCURS EACH DAY AND FAIRLY GOOD RADIATIONAL COOLING OCCURS EACH NIGHT. THINGS BECOME QUITE PROGRESSIVE FRIDAY AND SATURDAY WITH RETURN FLOW SETTING UP AND MOISTURE RETURNING ALONG WITH IT. CLOUDS AND TEMPERATURES SHOULD BOTH BE ON THE RISE. THE GFS HAS COASTAL TROUGHINESS AS WELL THAT WOULD IMPLY SOME MINOR RAIN CHANCES, BUT THIS FEATURE IS LARGELY ABSENT IN THE ECMWF AND CANADIAN. WILL CAP POPS AT SLIGHT CHANCE/20S LATE IN THE PERIOD. && .AVIATION /20Z SATURDAY THROUGH THURSDAY/... AS OF 18Z...OTHER THAN SOME PASSING CIRRUS...VFR CONDITIONS ARE EXPECTED THROUGH THIS EVENING. MID-LEVEL RIDGE AND SFC HIGH WILL BOTH PUSH OFF THE CAROLINA COASTS THIS AFTN AND EVENG. THIS WILL ALLOW INCREASING HIGH LEVEL CLOUDS THIS AFTERNOON...THICKENING UP THIS EVENING...WITH MID-LEVEL CLOUDS BECOMING DOMINANT OVERNIGHT. A SFC FRONTAL BOUNDARY WILL BECOME ORIENTED ENE TO WSW ACROSS THE WESTERN CAROLINAS...WITHIN A GSO TO GSP LINE...BY MIDDAY SUNDAY. SHRA-/R- WILL FOR THE MOST PART REMAIN JUST OUTSIDE THE ILM CWA...AND THE LOCAL TERMINALS. CEILINGS WILL SLOWLY COME DOWN THRU THIS TIME PERIOD...DROPPING TO A MID-LEVEL AC/AS TONIGHT...AND WILL FURTHER AND PARTIALLY DROP TO A LOW LEVEL SC/CU CLOUD DECK. MOS GUIDANCE HAS BEEN ILLUSTRATING IR/LIFR CEILINGS BY DAYBREAK SUN AND THERE-AFTER. WILL HOLD OFF WITH THESE CEILINGS UNTIL THE VARIOUS MODELS MOS GUIDANCE AGREE WITH ONE ANOTHER. EXTENDED OUTLOOK...MODERATE CONFIDENCE FOR RAIN WITH MVFR/IFR CONDITIONS MONDAY...POSSIBLY LINGERING INTO TUE. VFR WED AND THU. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 300 PM SATURDAY...NICE DOCILE DAY ON TAP FOR WFO ILM COASTAL WATERS. SFC PG TO REMAIN RATHER LOOSE AS THE CENTER OF HIGH PRESSURE LIES NEARLY OVERHEAD AT THE MOMENT...BEFORE BEING PROGGED TO SLIDE OFF THE CAROLINA COASTS LATER THIS AFTERNOON AND OFFSHORE TONIGHT. INITIALLY...EXPECT AN ONSHORE WIND THAT COULD POSSIBLY GO VARIABLE IN DIRECTION THIS AFTERNOON AND EVENING. WITH A LACK OF A SFC PG...WIND SPEEDS WILL RUN 10 KT OR LESS. BY LATE TONIGHT...RETURN FLOW AROUND THE DEPARTING SFC HIGH CENTERED OFFSHORE FROM THE CAROLINAS...WILL PRODUCE A SW-WSW WIND AROUND 10 KT. SIGNIFICANT SEAS ARE NOW A COMBINATION OF THE LOCALLY PRODUCED WIND DRIVEN WAVES...AND AN EASTERLY 1-3 FOOT BONAFIDE GROUND SWELL WITH PERIODS AT 11-13 SECONDS. LOCAL BUOYS SUCH AS 41013 ARE PICKING UP ON THIS GROUND SWELL. AND FOR THE MOST PART...THIS GROUND SWELL WILL LIKELY DOMINATE THE SIGNIFICANT SEAS AFFECTING THE LOCAL WATERS. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 300 PM SATURDAY...OFFSHORE HIGH PRESSURE WILL DRIVE SW RETURN FLOW INTO THE AREA SUNDAY AND THE FIRST PART OF MONDAY...BEFORE A COLD FRONT DROPS SOUTH ACROSS THE WATERS MONDAY EVENING. THIS CREATES TWO DISTINCT WIND REGIMES DURING THE SHORT TERM...SW AROUND 10 KTS AHEAD OF THE COLD FRONT...QUICKLY BECOMING NE AT 10-15 KTS MONDAY NIGHT. WAVE HEIGHTS WILL BE 2-4 FT THROUGH THE PERIOD...WITH THE HIGHEST SEAS OCCURRING SUNDAY AFTN AND AGAIN MONDAY NIGHT BEHIND THE COLD FRONT. LONG TERM /TUESDAY THROUGH THURSDAY/... AS OF 300 PM SATURDAY...SPRAWLING HIGH PRESSURE COVERING MOST OF THE NATION THROUGH THE PERIOD. INITIALLY CENTERED OVER MONTANA, IT WILL BOTH BLEED SOUTH AND EXTEND A RIDGE AXIS EASTWARD AS TIME WEARS ON. THIS KEEPS WIND MORE OR LESS OUT OF THE NORTH TUESDAY THROUGH WEDNESDAY. UNCERTAINTY CRAWLS INTO THE FORECAST ON THURSDAY AS THE HIGH MAY STILL BE BRINGING A NORTHERLY/OFFSHORE FLOW OR A SURFACE TROUGH MAY DEVELOP OFFSHORE AND TURN WINDS MORE EASTERLY. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...JDW NEAR TERM...DCH SHORT TERM...JDW LONG TERM...MBB AVIATION...DCH/DL MARINE...DCH/JDW/MBB

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