Area Forecast Discussion
Issued by NWS Wilmington, OH

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000
FXUS61 KILN 010312
AFDILN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
1012 PM EST SAT JAN 31 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 SUNDAY 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 SUNDAY 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 /03Z SUNDAY THROUGH THURSDAY/...
AN INITIAL ROUND OF PRECIPITATION IS EXPECTED TO BEGIN AT THE TAF
SITES IN THE NEXT FEW HOURS. A MIX OF PRECIPITATION TYPES WILL BE
POSSIBLE...WITH RAIN MOST LIKELY FOR CINCINNATI...AND SNOW MOST
LIKELY FOR DAYTON AND COLUMBUS. HOWEVER...THERE COULD BE A BRIEF
MIX WITH FREEZING RAIN OR SLEET AT ANY OF THE LOCATIONS. IFR
CONDITIONS ARE EXPECTED IN THE HEAVIER PRECIPITATION FOR DAYTON
AND COLUMBUS.

THERE WILL BE SOMEWHAT OF A LULL IN ACTIVITY ON SUNDAY
MORNING...THOUGH CEILINGS AND VISIBILITIES MAY REMAIN IN THE MVFR
RANGE. BY AFTERNOON...A MORE SIGNIFICANT AREA OF PRECIPITATION
WILL SPREAD INTO THE REGION. THIS PRECIPITATION IS EXPECTED TO BE
RAIN FOR CINCINNATI...WITH A MIX OF RAIN AND SNOW FOR COLUMBUS AND
DAYTON. CEILINGS AND VISIBILITIES WILL ALMOST CERTAINLY DROP TO
THE IFR RANGE FOR A LENGTHY PERIOD OF TIME...PERSISTING BEYOND THE
END OF THE TAF PERIOD INTO SUNDAY NIGHT.

OUTLOOK...IFR CEILINGS AND VISIBILITIES WILL OCCUR SUNDAY NIGHT
IN RAIN CHANGING TO SNOW. MVFR CEILINGS ARE EXPECTED TO CONTINUE
INTO MONDAY. MVFR CEILINGS ARE POSSIBLE TUESDAY NIGHT INTO
WEDNESDAY.

&&

.ILN WATCHES/WARNINGS/ADVISORIES...
OH...WINTER WEATHER ADVISORY UNTIL 9 AM EST SUNDAY 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 SUNDAY FOR KYZ089>093.
IN...WINTER WEATHER ADVISORY UNTIL 9 AM EST SUNDAY 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...HATZOS






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