Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 010642 AFDILN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 142 AM EST SUN FEB 1 2015 .SYNOPSIS... LOW PRESSURE TRAVELING UP THE OHIO VALLEY WILL BRING WIDESPREAD SNOW AND RAIN TONIGHT INTO MONDAY. MUCH COLDER AIR WILL ARRIVE MONDAY NIGHT WITH HIGH PRESSURE MOVING IN FROM THE WEST. SNOW AND RAIN WILL BE POSSIBLE WEDNESDAY WHEN A DISTURBANCE IS FORECAST TO CROSS THE GREAT LAKES. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... THE FIRST CONCERN FOR THE NEAR TERM OF THE FORECAST WAS TO ADD SOME MORE SLEET. THIS IS BASED PARTLY ON SEVERAL REPORTS IN SOUTHEASTERN INDIANA...BUT ALSO BASED ON THE WAY CONDITIONS HAVE EVOLVED TONIGHT AS EVIDENCED BY OBSERVATIONS. DEWPOINT DEPRESSIONS ARE STILL RATHER HIGH...WITH WET BULB TEMPERATURES BELOW ZERO. THE KILN SOUNDING INDICATED QUITE A BIT OF DRY AIR BELOW 900MB...BUT ALSO INDICATED THAT THE WARM LAYER IN THE LOWEST 2KM WAS SLIGHTLY WARMER THAN THE CURRENT FORECAST HAD SUGGESTED WAS GOING TO HAPPEN. WITH A SLIGHTLY WARMER STARTING POINT...THE ZONE OF MIXED PRECIP AND ICE ACCUMULATIONS HAS BEEN SHIFTED SLIGHTLY NORTHWARD. HOWEVER...THESE ACCUMULATIONS SHOULD STILL REMAIN FAIRLY LIGHT. THE SOUTHERN TIER OF THE WINTER WEATHER ADVISORY WILL COVER THE THREAT NICELY...AND IN FACT...THE FAR SOUTHERN COUNTIES IN THE ADVISORY MAY NOT GET COLD ENOUGH TO SUPPORT MUCH OF A THREAT FOR ANY GLAZE ACCUMULATION (PERHAPS JUST SOME SLEET MIXING IN NEAR THE ONSET OF PRECIPITATION). BASED ON A FULL ANALYSIS OF 18Z MODEL RUNS...RECENT RAP/HRRR RUNS...AND THE 00Z NAM...ANOTHER SLIGHT ADJUSTMENT WAS MADE TO THE OVERALL FORECAST ARRANGEMENT FOR SUNDAY. THERE ARE NO SIGNS AT ALL OF A REVERSAL OF THE GRADUAL NORTHWARD (WARMER) TREND...AND THE 02Z RAP / 00Z NAM ARE PERHAPS AS FAR NORTH WITH THE WARM AIR AS ANY MODEL HAS BEEN THROUGH THE FORECAST OF THIS EVENT. IT IS STILL VERY CLEAR THAT ANY LOCATION THAT REMAINS PURELY SNOW WILL RECEIVE A VERY LARGE AMOUNT (AROUND A FOOT)...BUT THE TRANSITION ZONE SEEMS TO BE CREEPING NORTHWARD WITH EACH NEW MODEL CYCLE. THUS...WHILE SNOW TOTALS IN THE FAR NORTHERN CWA (MERCER THROUGH HARDIN) REMAIN AS HIGH AS BEFORE (UP TO 12 INCHES)...A MODEST DOWNWARD ADJUSTMENT WAS MADE FURTHER SOUTH. THE NEW WSW PRODUCT ACCOUNTS FOR THIS CHANGE WITH SOME REFINED AND SLIGHTLY LOWER NUMBERS FOR SOME OF THE COUNTY SEGMENTS. HOWEVER...IT WOULD BE PREFERRED TO SEE THE ENTIRE 00Z MODEL SUITE BEFORE MAKING A MORE SUBSTANTIAL CHANGE (AS WOULD BE SUGGESTED BY THE LATEST MODELS). PREVIOUS DISCUSSION > SURFACE LOW PRESSURE WILL DEVELOP OVER THE GREAT PLAINS TONIGHT IN RESPONSE TO A DIGGING 500 MB TROUGH OVER THE ROCKIES. WHILE JET STREAM ENERGY INCREASES AS IT ROUNDS THE BASE OF THE UPPER TROUGH...THE SURFACE LOW WILL DEEPEN...AND THE PRESSURE GRADIENT WILL TIGHTEN...INCREASING MOISTURE ADVECTION TOWARD THE OHIO VALLEY. DURING THIS PROCESS...A BAND OF ISENTROPIC LIFT WILL SET UP OVER THE ILN AREA WELL AHEAD OF THE SURFACE LOW TO THE WEST. LATEST MODELS SHOW THE BAND AFFECTING LOCATIONS MAINLY NORTH OF CINCINNATI. PRECIP WILL START AROUND MIDNIGHT...WITH TYPE VARYING WITH RESPECT TO ATMOSPHERIC TEMPERATURE PROFILES. EXPECT DEFINITE SNOW FOR THE NORTH HALF OF THE FA INCLUDING DAYTON...COLUMBUS AND WAPAKONETA. FOR LOCATIONS ROUGHLY NEAR WILMINGTON...WARMER AIR ALOFT SHOULD ALLOW A WINTRY MIX. FARTHER SOUTH FROM CINCINNATI TO PORTSMOUTH AND ACROSS NORTHERN KENTUCKY...THERE WILL BE A CHANCE FOR A LIGHT WINTRY MIX OF FZRA AND RA. DUE TO THE SIGNIFICANT NATURE OF SNOW ACCUMULATIONS BASED ON QPF AND MODEL SOUNDINGS...WENT WITH A WINTER STORM WARNING FOR SNOW NORTH OF DAY AND CMH. FARTHER SOUTH WENT WITH A WINTER WEATHER ADVISORIES FOR LIGHTER SNOW AND ICE ACCUMULATIONS. SEE CLEWSWILN FOR FURTHER DETAILS. && .SHORT TERM /6 AM THIS MORNING THROUGH MONDAY NIGHT/... SURFACE LOW WILL PROGRESS UP THE OHIO VALLEY TO SOUTHERN INDIANA ON SUNDAY. WHILE SNOW PERSISTS NORTH OF DAYTON...CONTINUED MOISTURE ADVECTION ALONG THE WARM CONVEYOR BELT AHEAD OF THE LOW WILL ALLOW PRECIP TO OVERSPREAD THE AREA BY SUNDAY EVENING. WITH MODELS PRESENTING A WARMER SOLUTION...RAIN IS THE ANTICIPATED PRECIP TYPE SOUTH OF I-70...WITH SNOW NORTH. A BAND OF FRONTOGENETIC FORCING WILL ENHANCE PRECIP ESPECIALLY ACROSS THE NORTH WHERE SIGNIFICANT SNOW WILL ACCUMULATE. THE SURFACE LOW WILL BE MOVING FROM EASTERN OHIO TO PENNSYLVANIA BY MONDAY MORNING. PRECIP WILL TRANSITION TO ALL SNOW AREA WIDE BEFORE DIMINISHING IN COLD ADVECTION BEHIND THE DEPARTING LOW. SNOW IN THE NORTH WILL BE ENHANCED BY STRONG DEFORMATION IN THE NW QUADRANT OF THE LOW. TOTAL SNOW AMOUNTS WILL VARY GREATLY...WITH OVER 10 INCHES POSSIBLE OVER WEST CENTRAL OHIO...A FEW INCHES NEAR DAYTON AND COLUMBUS...AND UNDER AN INCH AT CINCINNATI...PORTSMOUTH AND NORTHERN KENTUCKY. COLD TEMPERATURES AND WIND CHILLS ARE IN STORE FOR MONDAY AND MONDAY NIGHT. HIGHS IN THE TEENS AN 20S MONDAY WILL BE FOLLOWED BY LOWS RANGING FROM THE NEGATIVE SINGLE DIGITS NORTH TO THE MID TEENS SOUTH MONDAY NIGHT. THE COLD TEMPS WILL COMBINE WITH BRISK WINDS TO PRODUCE WIND CHILLS BELOW MINUS 10 OVER THE NORTH HALF OF THE FA. WILL MENTION WIND CHILLS IN HWO FOR NOW...AND A WIND CHILL ADVISORY MAY EVENTUALLY BE ISSUED ACROSS THE NORTH. && .LONG TERM /TUESDAY THROUGH SATURDAY/... NORTHWEST MID/UPPER LEVEL FLOW WITH THE CENTER OF SPRAWLING SURFACE HIGH PRESSURE SLIDING OFF TO THE EAST COAST BY TUESDAY EVENING. THIS HIGH WILL PROVIDE COLD AND DRY WEATHER CONDITIONS. AFTER A COLD START TO THE DAY...TEMPERATURES WILL WARM TO HIGHS 5 TO 10 DEGREES BELOW NORMAL. TUESDAYS HIGHS TO RANGE FROM THE MID 20S NE TO THE UPPER 30S SW. FLOW BACKS WESTERLY A HEAD OF DIGGING TROF OVER THE GREAT LAKES... WITH A QUICK MORNING SYSTEM MOVING THRU THE REGION TUESDAY NIGHT/WED. WILL HAVE CHANCE POPS FOR THIS PERIOD WITH THE BEST CHANCE ACRS THE NORTH. PCPN WILL LKLY MIX WITH AND CHANGE TO RAIN IN THE SOUTH PRIOR TO COLD FRONTAL PASSAGE WED AFTN. LOWS TUESDAY NIGHT TO RANGE FROM THE LOWER 20S NE TO THE UPPER 20S SW. HIGHS ON WED FROM THE LOWER 30S NORTH TO THE LOWER/MID 40S FAR SOUTH. REINFORCING SHOT OF COLD AIR WITH HIGH PRESSURE OF CANADIAN ORIGIN TO BUILD SE BECOMING CENTERED OVER OHIO THURSDAY. COLD AND DRY WEATHER ON TAP WITH WED NIGHT/S LOWS FROM THE SINGLE DIGITS ACRS THE NORTHWEST WHERE SNOW PACK WILL EXIST TO NEAR 20 SE. HIGHS ON THURSDAY TO BE AROUND 15 DEGREES BELOW NORMAL...RANGING FROM THE UPPER TEENS NW TO THE UPPER 20S SE. THIS SFC HIGH BUILDS SLOWLY EAST TO THE EAST COAST BY THE END OF THE WEEK. COLD TEMPERATURES TO CONTINUE WITH LOWS THURSDAY NIGHT FROM THE SINGLE DIGITS BELOW ZERO NW TO NEAR 10 SE. AS THE HIGH MOVES OFF TO THE EAST A RETURN FLOW DEVELOPS WITH SOME SOME MODERATION TO TEMPERATURES INTO THE WEEKEND. HIGHS ON FRIDAY FROM NEAR 20 NORTH TO THE LOWER 30S FAR SOUTH AND WARMING ON SATURDAY FROM THE UPPER 20S NORTH TO AROUND 40 SOUTH. MODEL SOLN SPREAD LARGE NEXT SATURDAY REGARDING TIMING AND PLACEMENT OF NEXT SYSTEM. HAVE KEPT FCST DRY THRU SAT AFTN ATTM MORE LIKE THE GFS SOLN BUT THIS MAY CHANGE WITH LATER UPDATES. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... A BAND OF SNOW AND MIXED PRECIPITATION IS LIFTING NORTH THROUGH THE REGION AND WILL CONTINUE TO AFFECT NORTHERN TAF SITES KDAY AND KCMH/LCK UNTIL ABOUT 9Z AT KDAY AND 12Z FOR KCMH/LCK. A DRY PUNCH WILL PULL IN WARM AIR AND PRECIP SHOULD SHUT OFF FOR A MAJORITY OF THE DAY TODAY AT MOST SITES...WITH KCMH/LCK HANGING ON TO THE LOWER CIGS IN SHOWERS THROUGH EARLY MORNING. IN THE AFTERNOON...TOWARDS 20Z...THE PREVAILING RAIN WILL RAPIDLY OVERSPREAD THE REGION FROM THE WEST. THE LOW WILL TRACK NORTH OF KCVG AFTER 0Z AND UNTIL THIS HAPPENS...THE WARM AIR WILL AFFECT ALL TAF SITES. TEMPERATURES WILL RAPIDLY DECREASE AS THE LOW CROSSES AND WEST WINDS GUSTING TO 25KT WILL ACCOMPANY A RAPID CHANGEOVER TO SNOW. WITH THE EXCEPTION OF THE RESPITE IN PRECIP DURING DAYLIGHT HOURS TODAY...CIGS WILL BE MVFR AND COULD DROP TO IFR IN HEAVIER RAIN AND/OR SNOW SHOWERS. OUTLOOK...MVFR CEILINGS ARE EXPECTED TO CONTINUE INTO MONDAY. MVFR CEILINGS ARE POSSIBLE WEDNESDAY THROUGH WEDNESDAY NIGHT. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...WINTER WEATHER ADVISORY UNTIL 9 AM EST THIS MORNING FOR OHZ063>065-070>074-077>080-082. WINTER STORM WARNING UNTIL 7 AM EST MONDAY FOR OHZ026-034-035- 042>046-051-052. WINTER WEATHER ADVISORY UNTIL 7 AM EST MONDAY FOR OHZ053>056- 060>062. KY...WINTER WEATHER ADVISORY UNTIL 9 AM EST THIS MORNING FOR KYZ089>093. IN...WINTER WEATHER ADVISORY UNTIL 9 AM EST THIS MORNING FOR INZ058- 059-066-073>075-080. WINTER WEATHER ADVISORY UNTIL 7 AM EST MONDAY FOR INZ050. && $$ SYNOPSIS...CONIGLIO NEAR TERM...CONIGLIO/HATZOS SHORT TERM...CONIGLIO LONG TERM...AR AVIATION...FRANKS

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