138 FXUS62 KILM 191914 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 314 PM EDT TUE MAR 19 2013 .SYNOPSIS... AN ARCTIC COLD FRONT WILL MOVE ACROSS THE CAROLINAS WEDNESDAY NIGHT. WELL-BELOW NORMAL TEMPERATURES ARE EXPECTED THE LATTER HALF OF THE WEEK. RAIN CHANCES WILL INCREASE THIS WEEKEND INTO EARLY NEXT WEEK AS A STORM SYSTEM MOVES UP THE MISSISSIPPI VALLEY WHILE A COASTAL TROUGH DEVELOPS ALONG THE COAST. && .NEAR TERM /THROUGH TONIGHT/... AS OF 300 PM TUESDAY...COLD FRONT PUSHING FARTHER OFFSHORE AND TAKING CLOUDS ALONG WITH IT. COLD AIR ADVECTION IN ITS WAKE TO MAINTAIN STRENGTH THROUGH 00Z BEFORE WEAKENING AT 06Z AND TURNING NEUTRAL TO POSSIBLY WEAKLY WARM OVER FAR SRN ZONES BY END OF PERIOD/12Z. WEAK 8S-1 VORT MAX ALSO SLIDING BY VERY LATE IN THE PERIOD AND GUIDANCE SHOWING A LITTLE BIT OF CLOUD COVER ASSOC WITH THIS FEATURE. AXIS OF HIGH DOES NOT BUILD IN TIL JUST BEYOND THE PD KEEPING A FEW MPH OF WINDS IN THE FCST AND PREVENTING IDEAL RAD COOLING AS WILL ANY OF THE POSSIBLY OVERFORECAST CLOUDS INDICATED. EITHER WAY FAIRLY MODEL GUIDANCE SHOWING GOOD AGREEMENT IN LOWS GENERALLY MID TO UPPER 30S AND 40 NR COAST. FROST...IF ANY...TOO PATCHY AND SHORT LIVED AT THIS POINT IN TIME TO WARRANT BEING IN FCST UNLESS FUTURE SHIFTS DEEM COLDER TEMPS AND/OR LIGHTER WINDS IN THE OFFERING. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 300 PM TUESDAY...UNCHARACTERISTICALLY COLD WEATHER FOR MARCH WILL OCCUR AS A STRONG UPPER LEVEL LOW JUST NORTH OF THE GREAT LAKES MAINTAINS A LONGWAVE TROUGH OVER THE EASTERN UNITED STATES. A SOUTHERN STREAM SHORTWAVE GETTING INGESTED INTO THE BIG EAST COAST UPPER TROUGH WILL BRING A LOAD OF MID AND UPPER LEVEL PACIFIC MOISTURE ACROSS THE EASTERN CAROLINAS TOMORROW. THIS WILL LEAD TO MOSTLY CLOUDY SKIES AND PERHAPS SNOW VIRGA ALOFT AS RESPECTABLE ISENTROPIC LIFT BETWEEN 600-450 MB DEVELOPS DURING THE EARLY AFTERNOON. EXTREMELY DRY AIR WITHIN THE DEEP SUB-CLOUD LAYER SHOULD PREVENT ANY OF THIS PRECIPITATION FROM MAKING IT TO THE GROUND AS DEWPOINT DEPRESSIONS AS LARGE AS 55 DEGREES F AT 900 MB MAY EXIST IF 12Z MODEL CONSENSUS IS CORRECT. SOME LATE-DAY SUN IS POSSIBLE INLAND...BUT OVERALL LACK OF INSOLATION SHOULD LEAD TO WELL-BELOW NORMAL HIGHS WITH 56-61 EXPECTED NORTH TO SOUTH. A SURFACE COLD FRONT ACCOMPANYING THE UPPER TROUGH WILL PUSH THROUGH THE AREA WEDNESDAY NIGHT AS SKIES BECOME CLEAR. LIGHT WINDS DURING THE EVENING WILL KICK BACK UP TO 5-10 MPH IN THE POST-FRONTAL COLD ADVECTION WITH LOWS IN THE MID 30S INLAND AND UPPER 30S AT THE COAST. THE NASTY ARCTIC AIR ARRIVES DURING THE DAY THURSDAY WITH 1000-500 MB THICKNESSES FALLING AS LOW AS 529 DAM ACROSS SE NORTH CAROLINA...ACCOMPANIED BY 850 MB TEMPERATURES PLUNGING TO -8C. THESE ARE AMONG THE 4 OR 5 COLDEST READINGS OF THIS ENTIRE WINTER! EVEN WITH FULL SUNSHINE HIGHS WILL STRUGGLE INTO THE LOW TO MID 50S WITH A GUSTY NORTHWEST BREEZE 15-20 MPH. THE REALLY TROUBLESOME NIGHT WILL BE THURSDAY NIGHT AS WINDS WILL DIMINISH WITH THE ANOMALOUSLY COLD ARCTIC AIRMASS STILL PRESENT. GFS AND NAM MOS MIGHT BE A TOUCH TOO COLD...BUT SUB-FREEZING TEMPERATURES OF 27-31 APPEAR LIKELY ALL THE WAY DOWN TO THE COAST. THE OFFICIAL 2013 GROWING SEASON HAS BEEN DETERMINED TO START FOR OUR AREA THURSDAY...SO EXPECT THE ISSUANCE OF A FREEZE WATCH PERHAPS TOMORROW FOR THURSDAY NIGHT. WE WILL ACTUALLY BE WITHIN A COUPLE DEGREES OF RECORDS FOR THURSDAY NIGHTS... LOW TEMPERATURE RECORDS FOR THURSDAY NIGHT (FRI MORNING) MARCH 21: WILMINGTON 27 IN 1885 FLORENCE 26 IN 1965 MYRTLE BEACH 28 IN 1956 && .LONG TERM /FRIDAY THROUGH TUESDAY/... AS OF 300 PM TUESDAY...MANY OF US WILL BE ASKING, "IS IT JANUARY OR MARCH"...AS A DEEP-WINTER-LIKE PATTERN TAKES HOLD THROUGH EARLY NEXT WEEK WITH WELL BELOW NORMAL TEMPS AND UNSETTLED CONDITIONS. LARGE UPPER TROUGH SLOWLY WEAKENS FRIDAY IN RESPONSE TO AN UPPER LOW DROPPING INTO THE MTN STATES AND BOWLING ACROSS THE MIDDLE OF THE COUNTRY. FRIDAY WILL BE MOSTLY DRY THANKS TO HIGH PRESSURE RIDGING DOWN FROM THE NW. THIS WILL HELP SUPPRESS MOST MOISTURE TO THE SOUTH...BUT MAX TEMPS WILL STILL STRUGGLE ONLY INTO THE MID/UPPER 50S...MORE TYPICAL OF JANUARY THAN LATE MARCH. LOWS FRIDAY NIGHT WILL FALL INTO THE MID/UPPER 30S WHILE CLOUD COVER INCREASES FROM THE SOUTH. STILL QUESTIONS INTO THE EXTENDED DUE TO MODEL FLUCTUATIONS AND TIMING ISSUES...BUT IT APPEARS A COLD AND WET WKND/EARLY WEEK IS IN STORE FOR THE CAROLINAS. WARM FRONT/TROUGH WILL LIFT SLOWLY NORTH DURING SATURDAY...WITH INCREASINGLY MOIST ISENTROPIC LIFT OVERRUNNING THE COLD DOME OF HIGH PRESSURE WHICH WILL BEGIN TO WEDGE DOWN THE COAST. WHILE GFS BRINGS RAIN INTO THE AREA SATURDAY...THE WPC FAVORED ECMWF AND ITS ENSEMBLES KEEP MUCH OF SATURDAY DRY. WILL HEAD IN THIS DIRECTION BASED OFF SLOW ADVECTION OF THE THETA-E RIDGE. THIS WARM FRONT LIFTS NORTH AHEAD OF SURFACE CYCLOGENESIS BENEATH THE EASTWARD MOVING UPPER LOW. ALL EXTENDED GUIDANCE NOW SUPPORTS A MILLER-B TYPE SETUP...WITH A SURFACE LOW DEVELOPING ALONG THE COAST SUNDAY WHILE THE MID-WEST LOW FILLS. DEEP/NEGATIVELY TILTED UPPER TROUGH SUPPORTS THIS AS WELL...SO EXPECT A COASTAL LOW TO MOVE BASICALLY RIGHT ALONG THE COAST SUNDAY INTO MONDAY...FURTHER ENHANCING THE RAINFALL ALREADY ONGOING DUE TO THE INCREASED ISENTROPIC LIFT. THE POTENTIAL IS THERE FOR A SIGNIFICANT RAINFALL AS WELL...AND WPC PAINTS 1-1.5 INCHES OVER THE AREA. WILL CARRY HIGH CHC POP SUN-MON WITH TEMPS THROUGH MONDAY BEING VERY MUCH BELOW CLIMO...LIKELY AVERAGING A DEPARTURE OF -10 TO -15 DEGREES FOR MAX TEMPS. COLD FRONT CROSSES MONDAY...BUT LITTLE CAA BEHIND THIS SO TEMPS WILL ACTUALLY RECOVER FOR THE EARLY PART OF NEXT WEEK WITH A MUCH DRIER AIRMASS IN PLACE...BUT STILL REMAIN WELL BELOW NORMAL...AND THE CPC 6-10 DAY TEMPERATURE GRAPHIC IS QUITE CHILLING...NO PUN INTENDED...WITH 90% CHANCE FOR BELOW NORMAL ACROSS MOST OF THE SE/MID-ATLANTIC. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... AS OF 18Z...LOW CLOUDS HAVE SCATTERED...AND THE CIRRUS WILL BE OFFSHORE SHORTLY. HIGH CONFIDENCE FOR VFR CONDITIONS THROUGH THE FORECAST PERIOD WITH HIGH PRESSURE BUILDING IN. WEST NORTHWEST WINDS AT 10-15 KTS WILL CONTINUE THROUGH THE AFTERNOON HOURS...DIMINISHING OVERNIGHT. HIGH LEVEL MOISTURE WILL WORK BACK INTO THE PICTURE ON WEDNESDAY...WITH A MORE NORTHEASTERLY WINDS. EXTENDED OUTLOOK...SLIGHT CHANCE OF RAIN FRIDAY. RAIN MOVING IN THE LATTER PART OF SATURDAY...CONTINUING THROUGH SUNDAY WITH INTERMITTENT IFR CONDITIONS. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 300 PM TUESDAY...OFFSHORE/NWRLY POST-COLD FRONTAL WINDS THROUGH THE PERIOD WITH HIGH PRESSURE BUILDING IN FROM POINTS NORTH AND WEST. ADDITIONAL VEER TO MORE NRLY APPROX 06Z AS THE RIDGE AXIS GETS CLOSER...WHICH SHOULD ALSO ACT TO KNOCK A FEW KTS OFF THE WIND SPEEDS. SEAS FCST GENERALLY COMPRISED OF A WIND WAVE GIVEN THE ABSENCE OF SWELL ENERGY. THE FLOW BEING LARGELY OFFSHORE WILL OPEN UP A SMALL RANGE IN WAVE HEIGHT AS THE LANDMASS SHADOWS WAVE HEIGHTS SLIGHTLY WHILE SEAS STAY CLOSE TO 4 FT AWAY FROM THE WATER. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 300 PM TUESDAY...THE MAIN FOCUS OF THE MID WEEK PERIOD WILL BE THE ARRIVAL OF AN ARCTIC COLD FRONT WEDNESDAY NIGHT...AND A SUBSEQUENT PERIOD OF MODERATE NORTHWEST BREEZES BEHIND THE FRONT EXTENDING INTO THURSDAY EVENING. AT THIS TIME IT APPEARS WE MAY BE ABLE TO GET THROUGH THE PERIOD WITHOUT SMALL CRAFT ADVISORIES...BUT MARINE WEATHER CONDITIONS WILL NOT EXACTLY BE FAVORABLE. VERY COLD AIR RELATIVE TO NORMALS FOR THE MONTH OF MARCH WILL CREATE WIND CHILLS IN THE 30S EVEN OUT AT 10 AND 20 MILES FROM SHORE. LONG TERM /FRIDAY THROUGH SATURDAY/... AS OF 300 PM TUESDAY...HIGH PRESSURE RIDGING ACROSS THE WATERS FRIDAY CREATES LIGHT AND VARIABLE WINDS...ONLY DEVELOPING A PREDOMINANT NE DIRECTION LATE. THIS KEEPS WAVE HEIGHTS MINIMAL...REMAINING 1-2 FT THROUGH THE DAY. A COMPLEX FRONTAL SYSTEM AND COASTAL LOW THEN BEGIN TO IMPACT THE WATERS SAT/SUN WITH DETERIORATING MARINE CONDITIONS. NE WINDS WILL DEVELOP SATURDAY AND MAINTAIN THIS DIRECTION THROUGH THE EXTENDED WITH MINIMAL FLUCTUATIONS TO EAST OR NORTH AT TIMES...AT SPEEDS OF 10-15 KTS. SEAS BUILD GRADUALLY...FROM 1-2 FT EARLY SATURDAY...UP TO 4-6 FT SUNDAY AND A SMALL CRAFT ADVISORY MAY BE NEEDED MUCH OF SUNDAY. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...TRA NEAR TERM...MBB SHORT TERM...TRA LONG TERM...JDW AVIATION...MBB/HDL