946 FXUS62 KILM 121713 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 1213 PM EST THU JAN 12 2012 .SYNOPSIS... AN ARCTIC FRONT WILL SWEEP THROUGH THE CAROLINAS THIS EVENING. ARCTIC HIGH PRESSURE WILL BUILD INTO THE AREA FROM THE WEST ON FRIDAY...BRINGING MUCH DRIER AND COLDER AIR THAT WILL PERSIST INTO EARLY NEXT WEEK. HIGH PRESSURE WILL MOVE OFF THE COAST TUESDAY ALLOWING TEMPERATURES AND HUMIDITY LEVELS TO INCREASE. && .NEAR TERM /THROUGH TONIGHT/... AS OF 12 PM THURSDAY...LOWER CLOUDS HAVE MOVED IN A LITTLE SOONER THAN PREVIOUSLY THOUGHT. FOR THE REMAINDER OF THE DAYTIME HOURS... SKIES WILL BE MOSTLY CLOUDY...BECOMING PARTLY CLOUDY FROM S TO N AS THE AFTERNOON PROGRESSES AND CLOUD SHIELD LIFTS TO OUR N. SKIES WILL CLOUD UP AGAIN THIS EVE AS CLOUDS ASSOCIATED WITH ARCTIC FRONT CLOSE IN FROM THE W. THE CLOUDS WILL INHIBIT THE TEMP RISE AND HAVE BACKED OFF A FEW DEGREES ON MAXIMUMS FOR THIS AFTERNOON. IT SHOULD STILL BE WARMEST ACROSS SOUTHERN ZONES WHERE MORE AFTERNOON SUN IS EXPECTED. ARCTIC FRONT STILL EXPECTED TO SWEEP ACROSS THE FORECAST AREA THIS EVE. SW WINDS WILL BE GUST UP TO 30 MPH AHEAD OF THIS STRONG FRONT THROUGH THE AFTERNOON. COLUMN MOISTENS UP MODERATELY OVERNIGHT. HOWEVER...PRECIPITABLE WATER VALUES WILL NOT EXCEED ONE INCH. THE MID LEVELS WILL ALSO BE QUITE DRY. THAT BEING SAID...MODEL SOUNDINGS AND BUFKIT SHOW THAT THERE WILL BE ENOUGH MOISTURE AT THE LOW LEVELS AND WITH ADEQUATE FORCING...EXPECT ISOLATED SHOWERS TO MOVE ACROSS THE CWA OVERNIGHT. GIVEN DRYNESS OF COLUMN AND SPARSE COVERAGE EXPECT QPF TOTALS WILL BE MINIMAL...ON THE ORDER OF A FEW HUNDREDTHS OF AN INCH...IF THAT. BIGGEST EFFECT OF FROPA WILL BE STRONG COLD AIR ADVECTION AND GUSTY WINDS FOR THE OVERNIGHT HOURS. THIS WILL BRING TEMPERATURES BACK DOWN INTO THE 30S BY DAYBREAK FRIDAY. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 3 AM THURSDAY...FIRST ROUND OF COLD ADVECTION FOLLOWING ARCTIC FRONT WILL BE WINDING DOWN AS THE SHORT TERM PERIOD BEGINS. ALTHOUGH TEMPERATURES WILL BE BELOW CLIMO FOR THE PERIOD 850 TEMPS IN THE 00Z NAM/GFS/ECMWF AND THE 00Z NAM/GFS LOW LEVEL PARTIAL THICKNESS VALUES SUGGEST SLIGHTLY WARMER TEMPS...MAINLY HIGHS...THAN MOS WOULD SUGGEST. SO HAVE BUMPED HIGHS UP A BIT FOR FRI/SAT. SECOND SHOT OF COLD AIR ARRIVES FRI NIGHT WITH DEEP SOUTHWEST FLOW BECOMING MORE WESTERLY SAT. BREEZY CONDITIONS EXPECTED BOTH DAYS...WITH STRONGER WINDS FRI AS FULL SUN HELPS MIX STRONGER WINDS ALOFT TO THE SURFACE. ADDITIONALLY SURFACE GRADIENT IS TIGHTER FRI WITH LOW PRESSURE DEEPENING OVER NEW ENGLAND. DEEP DRY AIR IN PLACE THROUGH SAT NIGHT...PRECIPITABLE WATER VALUES REMAIN UNDER 0.30 INCH...AND WARMER AIR IN THE MID LEVELS PREVENT ANY PRECIP. FAST MOVING CLIPPER SYSTEM PASSING NORTH OF THE AREA SAT NIGHT MAY LEAD TO AN INCREASE IN MID/HIGH CLOUD BUT LITTLE ELSE. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 3 AM THURSDAY...MEDIUM RANGE GUIDANCE CONTINUES TO SHOW UPPER PATTERN FLATTENING OUT EARLY NEXT WEEK. IT NOW LOOKS LIKE SUN/SUN NIGHT WILL END UP BEING THE COOLEST DAY/NIGHT IN THE PERIOD. CLIPPER SYSTEM PASSING NORTH OF THE AREA STA NIGHT WILL HELPS SEND A FINAL SURGE OF COLD AIR INTO THE AREA FOR SUN. PREVIOUSLY IT LOOKED LIKE A BRIEF PERIOD OF SOUTHWEST FLOW WOULD DEVELOP...BUT NOW IT LOOKS LIKE LOW LEVEL FLOW WILL REMAIN WEST-NORTHWEST AS ANOTHER COLD SURGE ARRIVES VERY EARLY SUN. SURFACE HIGH MOVES OVERHEAD SUN NIGHT...ALLOWING FOR SOME RADIATIONAL COOLING. SURFACE RIDGE AXIS SHIFT OFFSHORE MON WHILE ALOFT WEAK RIDGING STARTS TO TAKE SHAPE. RETURN FLOW DEVELOPING MON IS NOT LIKELY TO IMPACT HIGHS AS NUMBERS WILL ONCE AGAIN FALL SHORT OF CLIMO. PRECIPITABLE WATER VALUES THROUGH MON REMAIN MEAGER...WELL UNDER HALF AN INCH...KEEPING THE EARLY PART OF THE FORECAST TEMPERATURES NEAR TO ABOVE CLIMO TUE WITH RETURN FLOW AROUND BACKSIDE OF HIGH PRESSURE AND WEAK RIDGING ALOFT. ALL THE MEDIUM RANGE GUIDANCE POINTS TO A SYSTEM DEVELOPING OVER THE CENTER OF THE COUNTRY...BUT SOLUTIONS VARY FROM WRAPPED UP LOW PRESSURE MOVING INTO THE GREAT LAKES AND DIGGING 5H TROUGH OVER THE CENTRAL/EASTERN CONUS...ECMWF...TO A FASTER MOVING MORE OPEN LOW IN THE GFS. THERE IS NOT A WHOLE LOT OF SUPPORT FOR ANYONE SOLUTION BUT ALL DO SUGGEST INCREASED RAIN POTENTIAL LATE IN THE PERIOD. SO WENT AHEAD AND ADDED A LOW CHANCE POP FOR TUE NIGHT...A COMBINATION OF 00Z GFS/ECMWF/CANADIAN TIMING. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... AS OF 18Z...STUBBORN AREA OF MVFR STRATA CU STILL AFFECTING A GOOD PORTION OF THE CWA. LOOK FOR MVFR CONDITIONS TO AFFECT THE TERMINALS FOR THE FIRST COUPLE OF HOURS THIS AFTERNOON. A DRY ARCTIC FRONT WILL MOVE THROUGH THE REGION TONIGHT. ONLY WEATHER ASSOCIATED WITH IT WILL BE A VFR STRATA CU CEILING AND A SLIGHT WIND SHIFT...WITH INCREASING WINDS FROM THE WEST AROUND MIDNIGHT. GUSTY WINDS WILL CONTINUE TO THE END OF THE FORECAST PERIOD. EXTENDED OUTLOOK...VFR THROUGH TUESDAY MORNING. LOW CONFIDENCE FOR PRECIPITATION LATE TUESDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 12 PM THURSDAY...LATEST OBSERVATIONS INDICATING 15 TO 20 KT WINDS WITH GUSTS TO 25 KT AND 4 TO 7 FT SEAS OVER THE COASTAL WATERS. WILL LIKELY SEE A RELATIVE LULL IN WINDS LATE THIS AFTERNOON BEFORE WINDS PICK UP AGAIN WITH THE APPROACH AND PASSAGE OF ARCTIC FRONT TONIGHT. STRONG COLD SURGE FOLLOWING FROPA WILL KICK WINDS UP FROM THE WEST INTO THE 25 TO 30 KT RANGE...WITH SEAS BUILDING BACK UP TO 6 TO 9 FT. WILL MAINTAIN SMALL CRAFT ADVISORY THROUGH THE PERIOD AND EVALUATE THE NEED FOR A GALE WARNING FOR FREQUENT GUSTS THIS AFTERNOON. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 3 AM THURSDAY...STRONG OFFSHORE FLOW FRI IN THE WAKE OF ARCTIC FRONT WILL LIKELY REQUIRE CONTINUATION OF SCA HEADLINES INTO THE AFTERNOON AND POSSIBLY LONGER. IN ADDITION TO SUSTAINED WINDS IN THE 20 TO 25 KT RANGE GUSTS IN EXCESS OF 30 KT CAN BE EXPECTED. INITIAL COMPONENT TO WIND WILL BE WEST-SOUTHWEST BUT BECOMING MORE WESTERLY LATER FRI. THIS WILL HELP KNOCK SEAS ALONG THE SC COAST DOWN PRETTY QUICK...BUT MAY RESULT IN SEAS GREATER THAN 6 FT ACROSS EXTREME EASTERN NC WATERS WELL INTO FRI NIGHT. A SECOND COLD SURGE ARRIVES EARLY SAT WITH A SLIGHT BUMP IN WEST TO NORTHWEST FLOW. OFFSHORE COMPONENT HELPS CONTINUE THE DECREASING SEA TREND...WITH SEAS DROPPING FRO 2 TO 4 FT SAT MORNING TO AROUND 2 FT BY AFTERNOON. GRADIENT RELAXES THROUGH THE DAY WITH SPEEDS DROPPING TO 10 TO 15 KT. WINDS BACK TO WEST- SOUTHWEST LATE SAT NIGHT AHEAD OF COLD SURGE EXPECTED IN THE AREA SUN MORNING. LONG TERM /SUNDAY THROUGH MONDAY/... AS OF 3 AM THURSDAY...NOW APPEARS COLD SURGE WILL ARRIVE A LITTLE EARLIER THAN EXPECTED...MOVING ACROSS THE WATER LATE SUN MORNING. SOLID 15 KT OFFSHORE FLOW SUN WILL KEEP SEAS UNDER 4 FT WITHIN 20 NM WITH NEAR SHORE SEAS LIKELY UNDER 2 FT. A SECOND COLD SURGE PUSHES SOUTH SUN NIGHT INTO MON AS SURFACE HIGH TO THE NORTH SHIFTS EAST. THIS SURGE WILL BE ACCOMPANIED BY NORTH TO NORTHEAST WINDS AROUND 15 KT. SEAS MAY BRIEFLY TOUCH 5 FT ON MON BUT AS RIDGE AXIS MOVES OVERHEAD IN THE AFTERNOON WINDS DROP BELOW 10 KT AND START TO VEER. && .TIDES... UNUSUALLY LOW TIDES MAY AFFECT THE AREA OVERNIGHT WITH TIDAL DEPARTURES AS MUCH AS 2 FT BELOW NORMAL POSSIBLE BETWEEN 2 AND 5 AM. WILL EVALUATE THE NEED FOR A LOW WATER ADVISORY WITH UPCOMING PACKAGE. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR AMZ250-252-254-256. && $$ NEAR TERM...RJD SHORT TERM...III LONG TERM...III AVIATION...DL TIDES...RJD