Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 161720 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 1220 PM EST TUE DEC 16 2014 .SYNOPSIS... TEMPERATURES WILL RISE WELL ABOVE NORMAL THIS AFTERNOON AHEAD OF AN APPROACHING COLD FRONT THAT WILL CROSS THE COAST TONIGHT. SEASONABLY COOL AND FAIR WEATHER WILL FOLLOW WEDNESDAY THROUGH FRIDAY. AN APPROACHING STORM SYSTEM COULD BRING WET CONDITIONS DURING THE UPCOMING WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1230 PM TUESDAY...PRE FRONTAL BAND OF BROKEN SHOWERS CONTINUES TO MOVE EASTWARD AND IS A LITTLE MORE CONCENTRATED TO THE NORTH AS EXPECTED. BASED ON THE NAM...I HAVE BUMPED POPS UP SLIGHTLY FOR LATER THIS AFTERNOON FOR THE CAPER FEAR REGION. THERE IS JUST ENOUGH MOISTURE POOLING AND A SHORTWAVE ALOFT TO GIVE A BRIEF BOOST TO THE FORCING. THERE IS A LITTLE QPF ASSOCIATED WITH THE ACTUAL FRONT LATER AND HAVE EXTENDED POPS A LITTLE LATER IN THE EVENING. USED THE COOLER MET NUMBERS FOR THE OVERNIGHT LOWS. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 AM TUESDAY...PROGRESSIVE MID LEVEL PATTERN AND LOW LEVEL DRY AIR WILL KEEP THE SOUTHEAST DRY THROUGH THE PERIOD. INCREASING MOISTURE ALOFT WILL MANIFEST AS AN INCREASE IN CLOUD COVER LATE WED NIGHT AND THU BUT DRY AIR BELOW 700MB AND LOW LEVEL SUBSIDENCE RULE OUT ANY PRECIP CHANCES. WEAK SHORTWAVE PASSES NORTH OF THE AREA ON THU AND THE RESULTING INCREASE IN MOISTURE BETWEEN 600 AND 700MB SHOULD PRODUCE A MID CLOUD DECK DURING THE AFTERNOON. THIS CLOUD...WHILE NOT RAIN BEARING...WILL COOL TEMPS A BIT AND HIGHS ARE LIKELY TO END UP A DEGREE OR 2 SHORT OF CLIMO IN MOST PLACES. COOLEST AREAS WILL BE ACROSS THE NORTHERN TIER WHERE CLOUDS LIKELY TO BE THICKEST AND MOST PREVALENT. HIGH CLOUDS WILL HELP KEEP LOWS NEAR CLIMO BOTH NIGHTS. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 3 AM TUESDAY...SOUTHERN STREAM SYSTEM STILL PROGGED TO AFFECT THE SOUTHEAST FRI NIGHT THROUGH SAT NIGHT. A LOT ABOUT THIS SYSTEM REMAINS UNCERTAIN AND CONFIDENCE CONTINUES TO RUN LOW. GUIDANCE CONTINUES TO HAVE RUN TO RUN CONSISTENCY PROBLEMS WITH SOLUTIONS RANGING FROM INTERACTION WITH A NORTHERN STREAM SHORTWAVE AND A WELL DEVELOPED SURFACE LOW CROSSING THE LOCAL AREA AND THEN TRAVELING UP THE EAST COAST TO A WEAK WAVE OPENING UP AS IT LIFTS NORTHEAST AND DRAGS A COLD FRONT ACROSS THE AREA. DESPITE THE UNCERTAINTY SOME DETAILS CAN BE GLEANED FROM THE CHAOS. MID LEVEL FLOW OVER THE SOUTHERN CONUS WILL TRANSITION FROM PROGRESSIVE TO AMPLIFIED WITH DEEP SOUTHWEST FLOW ADVECTION MOISTURE OVER THE CAROLINAS. EVEN THE DRIEST SOLUTIONS SHOW ABUNDANT DEEP MOISTURE WITH PRECIPITABLE WATER VALUES APPROACHING 1.25 INCH. IT ALSO APPEARS THAT REGARDLESS OF THE TRACK OR INTENSITY OF THE SURFACE AND MID LEVEL FEATURES THERE WILL NOT BE ANY PRECIP TYPE ISSUES. BEST PRECIP CHANCES REMAIN LATE FRI NIGHT INTO SAT EVENING WHEN ISENTROPIC LIFT AND MOISTURE ARE ON THE INCREASE. THERE SHOULD ALSO BE SOME ENHANCEMENT FROM PVA AHEAD OF THE SHORTWAVE ALONG WITH THE POSSIBILITY OF SURFACE CYCLOGENESIS. INHERITED FORECAST THINKING REMAINS VALID AND PLAN ONLY MINIMAL CHANGES TO PRECIP FORECAST. NEXT WEEK STARTS OFF DRY AS THE SOUTHERN STREAM SYSTEM EXITS. MEDIUM RANGE GUIDANCE IS HINTING AT TRAILING COLD FRONT ENDING UP PARALLEL TO STEERING FLOW WITH THE BOUNDARY STALLED SOMEWHERE OFF THE SOUTHEAST COAST. AS HAS BEEN THE CASE LATELY THERE ARE BIG DIFFERENCES BETWEEN THE GFS/ECMWF WITH RESPECT TO THE LOCATION OF THE BOUNDARY AND ITS IMPACT ON THE CAROLINAS. FOR NOW DO NOT PLAN ANY MAJOR CHANGES TO INHERITED DRY FORECAST FOR NEXT WEEK. TEMPS NEAR CLIMO EARLY IN THE PERIOD WILL TREND BELOW CLIMO NEXT WEEK. THERE WILL BE POTENTIAL FOR TEMPS ABOVE AND BELOW CLIMO DEPENDING ON HOW THE WEEKEND PLAYS OUT. THE POSSIBILITY OF SURFACE LOW CROSSING THE AREA SAT INTO SAT NIGHT COULD LEAD TO A WIDE RANGE IN TEMPS ACROSS THE AREA. A STRONGER LOW WOULD ENHANCE WARMING AHEAD OF THE LOW AS WELL AS ENHANCING COLD ADVECTION IN ITS WAKE SUN. ONCE AGAIN FEEL MAKING LARGE CHANGES GIVEN THE LOW CONFIDENCE AND LACK OF PREFERRED SOLUTION WOULD BE POINTLESS SO WILL CONTINUE WITH INHERITED FORECAST. && .AVIATION /17Z TUESDAY THROUGH SATURDAY/... AS OF 18Z...MODERATE SOUTHWEST FLOW THIS AFTERNOON AHEAD OF THE WEAK COLD FRONT. SCATTERED CONVECTION WILL CONTINUE TO MOVE INTO THE REGION THROUGH THE AFTERNOON HOURS. THE NAM IS MORE PESSIMISTIC...PARTICULARLY AT THE INLAND TERMINALS. THERE WILL BE ABOUT A TWO HOUR WINDOW FOR PRECIP AS THE FRONT PUSHES TO THE COAST THIS EVENING. NOT A LOT OF DEEP MOISTURE...WITH INTERMITTENT MVFR CONDITIONS WORST CASE. POST FRONTAL...LOOK FOR A GRADUAL WIND SHIFT TO THE WEST NORTHWEST...LIKELY STAYING BELOW 10 KTS...CONTINUING THROUGH THE END OF THE FORECAST PERIOD. EXTENDED OUTLOOK...VFR WED THROUGH FRIDAY. A CHANCE OF RAIN ON SATURDAY AND SUNDAY WITH POSSIBLE MVFR/IFR CONDITIONS. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1230 PM TUESDAY...SOUTHWESTERLY WINDS STARTING TO PICK UP AT THE MOMENT ACROSS THE WATERS. BUOY OBSERVATIONS SHOW SPEEDS CURRENTLY AROUND 10-12 KNOTS. SPEEDS WILL CONTINUE TO INCREASE THROUGHOUT THE AFTERNOON ENDING UP IN THE MIDDLE OF A 20-25 KNOT RANGE BRIEFLY THIS EVENING. FOR LATER TONIGHT...THE FRONT PUSHES THROUGH AROUND 0300 UTC WITH A WEST TO NORTHWEST FLOW ENSUING. WILL RAISE A SCEC AS CONDITIONS SHOULD REMAIN BELOW SMALL CRAFT CRITERIA. SEAS WILL INCREASE FROM CURRENT 1-2 FT. VALUES TO 3-5 FEET LATER THIS EVENING. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 AM TUESDAY...WINDS WILL RETAIN AN OFFSHORE COMPONENT FOR THE DURATION OF THE PERIOD WITH WATERS ON EAST SIDE OF ELONGATED SURFACE HIGH EXTENDING SOUTH FROM CANADA. WINDS WILL VARY FROM WEST TO NORTHWEST ON WED/WED NIGHT AND NORTHWEST TO NORTH THU/THU NIGHT. GRADIENT WILL BE ON THE WEAK SIDE WITH SPEEDS AROUND 10 KT FOR MUCH OF THE PERIOD. COMBINATION OF LIGHT WINDS AND OFFSHORE FLOW WILL KEEP SEAS 2 FT OR LESS. LONG TERM /FRIDAY THROUGH SATURDAY/... AS OF 3 AM TUESDAY...HIGH PRESSURE FRI WILL YIELD TO A DEVELOPING STORM SYSTEM SAT. SURFACE RIDGE AXIS TO THE WEST-NORTHWEST AND WEAK GRADIENT WILL KEEP NORTH TO NORTHEAST FLOW 10 KT OR LESS THROUGH FRI NIGHT. DEVELOPING LOW WILL MOVE ACROSS OR IN THE VICINITY OF THE WATERS SAT. ALTHOUGH DETAILS REMAIN HAZY GRADIENT WILL TIGHTEN WITH THE PASSING LOW AND WINDS WILL BE ON THE INCREASE...ESPECIALLY LATE IN THE PERIOD AS THE LOW PULLS AWAY AND STRENGTHENS. CURRENT FORECAST HAS WINDS HIGHLY VARIABLE SAT WITH OFFSHORE FLOW APPROACHING A SOLID 20 KT LATE SAT NIGHT. SEAS AROUND 2 FT FRI COULD BUILD AS HIGH AS 5 FT LATER SAT. ALTHOUGH NOT CURRENTLY FORECAST CANNOT RULE OUT HEADLINE CRITERIA DEVELOPING LATE SAT OR SAT NIGHT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...III NEAR TERM...SHK SHORT TERM...III LONG TERM...III AVIATION...DL

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