Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 060207 AFDILN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 907 PM EST THU MAR 5 2015 .SYNOPSIS... A LARGE AREA OF HIGH PRESSURE WILL MOVE INTO THE OHIO VALLEY AND THE SOUTHERN STATES TONIGHT...BRINGING DRY BUT VERY COLD CONDITIONS FOR FRIDAY MORNING. AFTER THAT...A GRADUAL WARMING TREND WILL BEGIN FOR THE NEXT WEEK...WITH ONLY LOW CHANCES OF PRECIPITATION. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... HIGH PRESSURE IS MOVING INTO THE REGION...SKIES HAVE CLEARED...AND WINDS HAVE BECOME LIGHT. A VERY SHALLOW INVERSION IS EXPECTED TO DEVELOP IN THE FAVORABLE RADIATIONAL COOLING REGIME...AND TEMPERATURES IN MOST LOCATIONS ARE EXPECTED TO DROP BELOW ZERO. WITH DEWPOINTS CURRENTLY IN THE POSITIVE SINGLE DIGITS...THERE IS CERTAINLY SOME POTENTIAL FOR VISIBILITY REDUCTIONS OR EVEN STRATUS...AS TEMPS RADIATE BEYOND THE DEWPOINT VALUES. SREF PROBABILITIES SUGGEST THIS WOULD BE MOST LIKELY NEAR THE MORE SIGNIFICANT SNOW PACK...COVERING ONLY A SECTION OF THE CWA. WITH CONFIDENCE NOT TERRIBLY HIGH IN THIS SCENARIO...MOSTLY CLEAR CONDITIONS WILL BE KEPT IN THE FORECAST. MINIMUM TEMPS TONIGHT ARE GOING TO BE VERY COLD...AND RECORD LOWS WILL BE POSSIBLE FOR ALL THREE CLIMATE LOCATIONS. THE AIR MASS IS ABNORMALLY COOL (THOUGH NOT EXTREME BY THE STANDARDS THIS WINTER HAS ALREADY SET)...BUT IT IS THE GROUND CONDITIONS (LIGHT WINDS / CLEAR SKIES / FRESH SNOW) THAT WILL ALLOW TEMPERATURES TO GET INTO RECORD-BREAKING TERRITORY. THIS WILL BE ESPECIALLY TRUE WITH THE THICK SNOW IN THE SOUTHERN AND SOUTHEASTERN SECTIONS OF THE FORECAST AREA. FORECAST VALUES IN THIS AREA RANGE FROM -5 TO -8 DEGREES...AND IT IS LIKELY THAT THESE GENERALIZED VALUES WILL NOT COVER ALL OF THE VALLEYS AND COOL SPOTS...WHERE TEMPS WILL BE LIKELY TO DROP BELOW -10 IN SOME LOCATIONS. HERE ARE THE PREVIOUS RECORD LOWS FOR THE THREE PRIMARY AIRPORTS. CVG...+2 DEGREES...1960 CMH...+2 DEGREES...1901 DAY....0 DEGREES...1901 && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... THE CORE OF THE COLDEST AIR ALOFT WILL STILL BE IN PLACE OVER THE MIDDLE OHIO VALLEY ON FRIDAY MORNING...WITH WARM ADVECTION OFF THE SURFACE ONLY REALLY BEGINNING LATER IN THE AFTERNOON. EVEN THOUGH SURFACE FLOW WILL BE SWITCHING TO THE SSW...AND SKIES WILL BE MOSTLY SUNNY...THE SNOW PACK AND COOL CONDITIONS ALOFT DO NOT SUPPORT A SIGNIFICANT OR RAPID WARMING FOR FRIDAY. MAX TEMPS WERE REDUCED FROM THE PREVIOUS FORECAST...AND ARE NOW GENERALLY IN THE MID 20S FOR THE ENTIRE FORECAST AREA. THESE FORECAST VALUES ARE ABOVE THE RECORD LOW MAX TEMPERATURES FOR THE THREE PRIMARY AIRPORTS...BUT HERE ARE THE VALUES JUST FOR REFERENCE. CVG...22 DEGREES...1920 AND 1932 CMH...18 DEGREES...1920 DAY...19 DEGREES...1920 AS SURFACE HIGH PRESSURE SETTLES IN OVER THE SOUTHERN STATES...VERY BROAD TROUGHING ALOFT WILL SET UP OVER THE OHIO VALLEY...PROVIDING ALMOST-ZONAL FLOW (A LITTLE MORE FROM THE WNW THAN THE WEST). A FEW WEAK SHORTWAVES ARE FORECAST TO MOVE THROUGH THE GREAT LAKES...PERHAPS HAVING A MINOR IMPACT ON THE NORTHERN OHIO VALLEY. ONE SHORTWAVE APPEARS TO GET CLOSE ENOUGH TO WARRANT A CONTINUED 20 PERCENT CHANCE OF SNOW IN THE NORTHERN CWA ON SATURDAY MORNING...BUT THE SIGNALS FOR FORCING ARE VERY WEAK...AND DEEP-LAYER MOISTURE IS EXTREMELY LIMITED. HOWEVER...THE LOW-LEVEL MOISTURE WILL BECOME THICKER DURING SATURDAY...FORCING THE CLOUD FORECAST UP INTO THE 70-100 PERCENT RANGE. OTHERWISE...THE REMAINDER OF THE SHORT TERM FORECAST WILL BE ONE WITH GRADUAL WARMING ON SOUTHWESTERLY FLOW. IN FACT...NON-DIURNAL TEMPERATURES ARE EXPECTED EARLY SATURDAY MORNING...WITH MIN TEMPS CLOSER TO 06Z AND A GRADUAL RISE AFTER THAT. ALTHOUGH MAX TEMPS WERE REDUCED SLIGHTLY FOR SATURDAY...THE ENTIRE CWA IS EXPECTED TO CLEAR THE FREEZING MARK. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AFTER AN ACTIVE BEGINNING TO MARCH...THE EXTENDED WILL BE MORE TRANQUIL. WEAK SYSTEMS WILL PASS BY TO THE NORTH AND SOUTH OF THE REGION THROUGH EARLY WEEK. ATTM...WE SHOULD SEE JUST CLOUDS FROM TIME TO TIME. IT WILL BEGIN TO MODERATE THERMALLY IN THE ATMOSPHERE...BUT IT WILL BE DIFFICULT TO PINPOINT HIGHS/LOWS EARLY ON...ESPECIALLY ALONG AND SOUTH OF THE OHIO RIVER WHERE A GOOD SNOW PACK IS IN PLACE. THIS CALLS FOR USING A GENERAL BLEND OF MODELS WHICH HAVE HIGHS WARMING INTO THE 40S AND LOWS DROPPING INTO THE 20S. UPPER LEVEL FLOW BECOMES CONFLUENT BY MID WEEK AND THIS WILL RESULT IN A SPRAWLING AREA OF SURFACE HIGH PRESSURE ALONG WITH DRY WEATHER. AGAIN...TEMPERATURES WILL CONTINUE TO MODERATE THROUGH THE PERIOD AND SHOULD PUSH TO NEAR OR A LITTLE ABOVE NORMAL BY THE END OF THE EXTENDED. THIS MEANS THAT HIGHS WILL WARM INTO THE 50S WITH SOME 60S POSSIBLE ALONG AND SOUTH OF THE OHIO RIVER. LOWS WILL DROP INTO THE 30S. THE ECMWF AND GFS BEGIN TO DISAGREE BY THE END OF NEXT WEEK WITH THE UPPER LEVEL FLOW PATTERN. ECMWF IS STILL TRYING TO EJECT UPR LVL ENERGY FROM THE SRN STREAM WHILE THE GFS WANTS TO PUSH A WEAK FRONT THROUGH WITH A MORE DOMINATING NW FLOW PATTERN. WILL CONTINUE TO MONITOR WITH LATER MODEL RUNS. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... EXPECT VFR THROUGH THE PERIOD WITH ARCTIC HIGH PRESSURE MOVING IN. SKIES WILL BE MAINLY CLEAR...WITH CIRRUS INCREASING BY THE END OF THE FORECAST. NORTH WINDS WILL SUBSIDE TO NEAR CALM TONIGHT... BEFORE BECOMING SOUTH ON FRIDAY WHILE STAYING UNDER 10 KNOTS. OUTLOOK...MVFR CEILINGS AND VISIBILITIES POSSIBLE SATURDAY NIGHT AND SUNDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HATZOS NEAR TERM...CONIGLIO/HATZOS SHORT TERM...HATZOS LONG TERM...HICKMAN AVIATION...CONIGLIO

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