198 FXUS62 KILM 120739 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 339 AM EDT WED MAR 12 2014 .SYNOPSIS... SPRING LIKE WARMTH WILL CONTINUE TODAY AHEAD OF A STRONG COLD FRONT WHICH WILL CROSS TONIGHT. MUCH COLDER TEMPERATURES EXPECTED THURSDAY AND FRIDAY AS CANADIAN HIGH PRESSURE BUILDS INTO THE AREA. A GRADUAL WARMING TREND TO SEASONABLE TEMPERATURES WILL OCCUR OVER THE WEEKEND. A LOW PRESSURE SYSTEM MAY BRING UNSETTLED WEATHER LATE IN THE WEEKEND AND ON MONDAY. COOL HIGH PRESSURE WILL FOLLOW FOR TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1100 PM TUESDAY...NO SIGNIFICANT CHANGES WITH THIS LATE EVENING UPDATE. PREVIOUS DISCUSSION FROM 730 PM FOLLOWS... LOW PRESSURE ALREADY BELOW 1000 MB ACROSS MISSOURI WILL REMAIN WELL NORTH OF THE CAROLINAS AS IT MOVES EAST OVERNIGHT INTO WEDNESDAY. A COLD FRONT EXTENDING SOUTH THROUGH TEXAS WILL MOVE INTO THE AREA TOMORROW. UNTIL THEN...WE ARE ENJOYING THE LAST DAY OF DRY MILD WEATHER IN THE WARM SECTOR BEFORE GULF MOISTURE ARRIVES. AN UPPER LEVEL DISTURBANCE OVER THE CENTRAL GULF COAST WILL DE-AMPLIFY AS IT MOVES EAST-NORTHEASTWARD TOWARD THE CAROLINAS. THE 15Z SREF MEAN LOOKED SIMILAR TO THE 18Z NAM AND GFS WITH REGARDS TO THE ONSET OF PRECIPITATION POTENTIAL OVERNIGHT. BEFORE DAYBREAK ODDS ARE LESS THAN 50% THAT ANY OF OUR FORECAST AREA WILL SEE RAINFALL... HOWEVER MY HIGHEST FORECAST POPS (30-40 PERCENT) ARE IN THE FLORENCE-DARLINGTON-KINGSTREE AREA JUST BEFORE SUNRISE. AT THE COAST POPS RANGE FROM 20 PERCENT ALONG THE GRAND STRAND TO LESS THAN 10 PERCENT IN WILMINGTON. CIRRUS-LEVEL CLOUD COVER SHOULD SLOWLY INCREASE LATE THIS EVENING AND SHOULD DESCEND INTO A MID DECK AFTER MIDNIGHT AHEAD OF THE INCOMING DISTURBANCE. A RATHER IMPRESSIVE LOW LEVEL JET WITH 1000 FOOT WIND SPEEDS 25-30 KNOTS SHOULD DEVELOP SHORTLY WITH ENOUGH INDUCED BOUNDARY LAYER TURBULENCE TO KEEP TEMPERATURES FROM DROPPING TOO FAR THIS EVENING. THE ADDITION OF THICKENING CLOUD COVER AFTER MIDNIGHT SHOULD PRODUCE A NEARLY STEADY TEMPERATURE CURVE THEN. FEW ADJUSTMENTS HAVE BEEN MADE TO FORECAST LOWS WHICH RANGE FROM 55-58 ACROSS THE AREA. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 300 AM WEDNESDAY...HARSH RETURN TO REALITY THURSDAY AS STRONG CAA BEHIND AN ARCTIC FRONT DRIVES TEMPS TO WELL BELOW NORMAL FOR MID MARCH...WITH HIGHS ABOUT 30 DEGREES COOLER THAN THE PAST FEW DAYS! EVEN THE INCREASINGLY STRONG SUN ANGLE WILL DO LITTLE TO HELP WARM THINGS UP THURSDAY...AND EXPECT HIGHS TO REMAIN SUB-50 ACROSS NC THURSDAY...WITH SOME LOW 50S POSSIBLE IN THE PEE DEE REGION AND TOWARDS THE SANTEE RIVER. IN ADDITION...GUSTY NW WINDS THROUGH THE DAY WILL KEEP APPARENT TEMPS ONLY IN THE MID/UPR 40S...SO JUST A BRUTALLY COLD MARCH DAY...ESPECIALLY AFTER THE WARMTH OF THE PAST WEEK. AS ARCTIC HIGH MOVES OVERHEAD THURSDAY NIGHT...TEMPS WILL PLUMMET AFTER DARK...AND A WIDESPREAD SUB-FREEZING EVENT IS LIKELY. WHILE THE OFFICIAL LOCAL GROWING SEASON HAS NOT BEGUN AS OF YET...EARLY AND SENSITIVE PLANTS WILL NEED TO BE PROTECTED THURSDAY NIGHT AS TEMPS FALL INTO THE MID/UPR 20S...WITH MANY HOURS OF SUB-32 TEMPS EXPECTED. SURFACE HIGH SHIFTS OFFSHORE DURING FRIDAY...IN CONJUNCTION WITH MID-LEVEL THICKNESS INCREASE. THIS WILL DRIVE TEMPS FRIDAY CONSIDERABLY HIGHER THAN THOSE OF THURSDAY...BUT STILL REMAIN A SOLID 6-10 DEGREES BELOW NORMAL...WITH UPPER 50S COMMON ACROSS THE AREA...LOWER 60S IN THE FAR SOUTHERN ZONES. A COASTAL TROUGH WILL TRY TO DEVELOP ON THE WESTERN PERIPHERY OF THIS HIGH PRESSURE LATE IN THE PERIOD. GFS IS MOST AGGRESSIVE WITH SKY COVER/POP FRIDAY NIGHT...AND WILL LEAN ON THE NAM/ECMWF WHICH ARE WEAKER AND MORE REASONABLE IN RELATIVELY FAST MID-LEVEL FLOW AND WEAK MOIST ADVECTION. MINS FRIDAY NIGHT WILL FALL TO SEASONABLE LEVELS...LOW 40S MOST PLACES. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 300 AM WEDNESDAY...SOME UNCERTAINTY FOR THE WEEKEND...BEFORE A PERIOD OF UNSETTLED WEATHER DEVELOPS EARLY NEXT WEEK. ZONAL FLOW THROUGH THE WKND WILL HELP TEMPS RISE TO SEASONABLE LEVELS AHEAD OF A WEAK COLD FRONT DRIVEN BY A MID-LEVEL IMPULSE EARLY SUNDAY. GUIDANCE DIFFERS AS TO HOW MUCH MOISTURE WILL BE ACCOMPANIED BY THIS FEATURE...WITH THE GFS SHOWING DECENT RAIN CHANCES WHILE THE ECMWF IS PRIMARILY DRY. AS NOTED BY PREVIOUS FORECASTER...DEEP BAROCLINIC INSTABILITY ALL THE WAY TO THE GULF COAST WOULD SUPPORT SOME FORCING AND PRECIP WITH THIS FEATURE...BUT OVERALL MOIST ADVECTION IS LIMITED ON THE ZONAL FLOW. STILL...SCHC POP IS INHERITED AND WILL REMAIN LATE SAT NIGHT INTO SUNDAY WITH LITTLE QPF. A MORE SIGNIFICANT SYSTEM WILL EMERGE OUT OF THE GULF AS A STRONGER SOUTHERN STREAM IMPULSE DIVES INTO THE SOUTHEAST SPAWNING CYCLOGENESIS WHICH WILL THEN TRAVERSE NEAR OR OVER THE AREA INTO MONDAY. MUCH BETTER PRECIP CHANCES ASSOCIATED WITH THIS...AND THE SUN NIGHT INTO MONDAY TIMEFRAME COULD BE QUITE WET. COOL HIGH PRESSURE THEN BUILDS INTO THE AREA BEHIND THIS FEATURE...BUT TEMPS WILL FALL ONLY TO SEASONABLE OR SLIGHTLY BELOW FOR EARLY NEXT WEEK. && .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... AS OF 06Z...EXPECT INITIAL VFR EXCEPT MVFR AT THE COASTAL TERMS DUE TO SEA FOG...THROUGH MUCH OF THE PRE-DAWN WED HOURS. CONDITIONS WILL GRADUALLY DETERIORATE TO MVFR/POSSIBLE IFR AT ALL LOCATIONS TOWARD DAYBREAK WED DUE TO LOW CIGS AND RAINFALL IN ASSOCIATION WITH AN UPPER LEVEL S/W TROF AND AN APPROACHING SFC COLD FRONT. INCREASING HIGH CLOUDS AND SOUTHWEST WINDS AOB 8 KTS WILL PREVAIL THROUGH THE PRE-DAWN WED HOURS...WITH INCREASING MID-LEVEL CLOUDS AS WELL. A FEW MODELS ARE SUGGESTING THE POSSIBILITY OF BRIEF FOG DEVELOPMENT...BUT GIVEN WIND PROFILE AND INCREASING CLOUDS...DO NOT ANTICIPATE DEVELOPMENT. HOWEVER...SEA FOG IS A POSSIBILITY AT THE COASTAL TERMS THIS AM. AS WINDS VEER EVER SO SLIGHTLY TO THE SW FROM SSW...THE SEA FOG WILL REMAIN OVER THE ATL WATERS. AFTER DAYBREAK...CONDITIONS THRU THE MID-MORNING HOURS WILL CONTINUE TO DETERIORATE TO MVFR/IFR AS LOW CIGS INFILTRATE INTO THE AREA ALONG WITH INCREASING RAINFALL CHANCES FROM SOUTHWEST TO NORTHEAST ACROSS THE AREA. COULD NOT RULE OUT AN ISOLATED TSRA IN THE AFTERNOON HOURS...BUT ANTICIPATE OVERALL TSTORMS CHANCES TO REMAIN NORTH OF THE AREA. WINDS WILL INCREASE THROUGHOUT THE DAY AS WELL...WITH SOUTHWEST WINDS NEAR 15-20 KTS SUSTAINED AND GUSTS NEAR 30 KTS POSSIBLE. INTO THE LATE EVENING HOURS...RAIN CHANCES WILL TAPER OFF AND THE COLD FRONT WILL PUSH THROUGH THE AREA. INCREASED WINDS WILL PERSIST AND VEER TO THE NORTHWEST JUST BY THE END OF THE TAF PERIOD WITH THE FRONTAL PASSAGE. EXTENDED OUTLOOK...VFR EXPECTED THURSDAY AND FRIDAY. CHANCE OF SHOWERS ON SATURDAY. VFR SUNDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1030 PM TUESDAY...NO SIGNIFICANT CHANGES WITH THIS LATE EVENING UPDATE. PREVIOUS DISCUSSION FROM 730 PM FOLLOWS... QUITE A SEABREEZE DEVELOPED THIS AFTERNOON AS INLAND TEMPERATURES SOARED TO AROUND 80 DEGREES WHILE MARINE AIR TEMPERATURES MADE IT NO HIGHER THAN THE UPPER 50S. THIS 20-25 DEGREE TEMPERATURE GRADIENT FUELED WIND GUSTS TO NEAR 20 KNOTS AT THE BEACHES. THESE WINDS ARE BEGINNING TO SUBSIDE AS INLAND TEMPERATURES COOL...BUT A MODEST PRESSURE GRADIENT AHEAD OF TOMORROW'S INCOMING COLD FRONT SHOULD MAINTAIN WINDS IN THE 12-15 KNOT RANGE THROUGH MOST OF THE NIGHT. BESIDES INCREASING FORECAST NEARSHORE WIND SPEEDS IN THE 0-3 HOUR RANGE...THE BIGGEST CHANGE TO THE FORECAST WAS TO REDUCE FORECAST SEA HEIGHTS LATER TONIGHT AS SEAS SHOULD NOT BUILD APPRECIABLY UNTIL WIND SPEEDS INCREASE LATE TOMORROW MORNING AHEAD OF THE COLD FRONT. CURRENT OBSERVATIONS SHOW 2-3 FOOT SEAS. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 300 AM WEDNESDAY...ARCTIC FRONT OFFSHORE TO START THE PERIOD LEAVES STRONG NW WINDS IN ITS WAKE...AND A SMALL CRAFT ADVISORY WILL LIKELY BE ONGOING THURSDAY MORNING. WINDS WILL BE 20-30 KTS THROUGH THE DAYLIGHT HOURS OF THURSDAY...EASING THURSDAY NIGHT TO AROUND 10 KTS WHILE BECOMING MORE NORTHERLY BY FRIDAY MORNING. SEAS OF 4-7 FT THE FIRST HALF THURSDAY WILL DROP QUICKLY THURSDAY NIGHT AS THE WINDS EASE WHILE STILL MAINTAINING AN OFFSHORE COMPONENT...WITH WAVE HEIGHTS BECOMING 1-3 FT FRIDAY MORNING. HIGH PRESSURE SHIFTS OFFSHORE ON FRIDAY...SO WINDS BECOME LIGHT AND VARIABLE MUCH OF THE DAY...EVENTUALLY TAKING ON A PREDOMINANT SW DIRECTION AROUND 10 KTS FRIDAY NIGHT. SEAS REMAIN LOW-AMPLITUDE HOWEVER...PERSISTING AT 1-3 FT INTO THE WKND. LONG TERM /SATURDAY THROUGH SUNDAY/... AS OF 300 AM WEDNESDAY...HIGH PRESSURE OFFSHORE SATURDAY LEAVES 10-15 KTS SW WINDS ACROSS THE WATERS ON RETURN FLOW. THESE WINDS WILL PERSIST INTO SUNDAY MORNING...BEFORE A WEAK COLD FRONT CROSSES THE WATERS AND TURNS THE WINDS TO THE NW...THEN NE...ON SUNDAY BUT AT SPEEDS OF ONLY 10 KTS OR LESS. SEAS WILL RISE BRIEFLY TO 3-5 FT DURING THE STRONGEST SW WINDS SATURDAY AFTN...BUT WILL OTHERWISE BE 2-4 FT THROUGH THE PERIOD. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 8 AM THIS MORNING TO 6 PM EDT THIS EVENING FOR AMZ250-252-254-256. GALE WARNING FROM 6 PM THIS EVENING TO 6 AM EDT THURSDAY FOR AMZ250-252-254-256. && $$ SYNOPSIS...JDW NEAR TERM...DCH/TRA SHORT TERM...JDW LONG TERM...JDW AVIATION...DCH/SGL MARINE...DCH/TRA/JDW