textproduct: Wilmington

SYNOPSIS

A system will move across the area Saturday into Saturday night which will result in accumulating snow area wide. Bitterly cold air will come in behind the snow and last into Monday. This will be followed by a substantial warm up through midweek.

NEAR TERM /THROUGH TONIGHT/

Weak surface ridging between systems will persist through much of the period. That will get nudged southwards towards daybreak Saturday as the next system approaches. While there are breaks in the clouds in central Ohio to start the period, these will fill in with considerable cloud cover area wide from late afternoon through the night. Temperatures will fall into the 20s.

SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/

Cold front will slide across the area on Saturday, laying out in a more west southwest-east northeast orientation through the day. This will result in falling temperatures through the afternoon. Robust short wave will quickly move from the upper Mississippi Valley southeast across the area through the period. Mid level frontogenesis out ahead of this system will spread a shield of snow across the forecast area from late morning through the afternoon, primarily north of the Ohio River. This will then sag southeast across the rest of the area during the evening and end towards midnight.

There continue to be some minor variations in the guidance suite, but overall there is pretty good consensus that heaviest snowfall amounts will occur between I-70 and the Ohio River with an axis of 3" to 5". This is pretty close to where the previous winter storm watch was oriented. Opted to upgrade at this time. That is a little bit complicated because winter storm warning criteria changes from south to north within this axis. Outside of the former watch area, we have gone ahead and issued a winter weather advisory. There still could be some fluctuations in amounts that could cause the warning area to be adjusted as the event gets closer. Even though snow tapers off through the evening, impacts will likely continue through the overnight, so the warning/advisory extends all of the way through 7 am Sunday.

Arctic airmass will pour into the region in the wake of the snow. Air temperatures will drop into the single digits. With winds of 10 to 15 mph, apparent temperatures will fall below zero with much of the Whitewater and Miami Valleys getting to 10 below or colder. Will likely need a cold weather advisory for these conditions, but there still is a bit of time before needing to make that decision.

LONG TERM /SUNDAY THROUGH THURSDAY/

Arctic high pressure will build into the area Sunday and Sunday night. Very high confidence of temperatures being at least 20 degrees below normal. Coldest part of the airmass will be across eastern Indiana and western Ohio counties. These areas have a greater than 80 percent chance of apparent temperatures 10 below or colder Sunday morning. Probabilities of reaching this threshold drop off to 20 percent or less from the Scioto Valley into northeast Kentucky.

Frigid temperatures will persist into Monday. Air temperatures Monday morning will be similar to those of Sunday morning but the apparent temperature will not be as cold Monday morning since there will be little, if any, wind at that point.

Once the high moves off, there will be an extended period of southerly low level flow with the mid level flow becoming zonal. This will result in a substantial warming trend. Temperatures will warm around 10 degrees both Tuesday and Wednesday and another 5 degrees or so on Thursday. Probability of having above normal temperatures by Thursday is over 70 percent. Highs 50 or greater probabilities range from 30 to 80 percent.

A cold front is forecast to cross the area on Thursday bringing rain showers. There is some variability within the guidance suite concerning timing and strength. Most guidance pushes the front through the area by Thursday night with high pressure building in for Friday, dropping temperatures back closer to or slightly below normal.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/

While a few sites have popped up to VFR to start the period, expect this to be short lived. MVFR ceilings will prevail, primarily below 2kft except at the Columbus terminals. Ceilings are forecast to lower after 06Z, although there is uncertainty exactly when that will happen. This will bring IFR conditions to all but KCMH/KLCK. Snow may spread into KDAY and KILN at the very end of the period with a substantial deterioration in conditions just beyond these TAFs.

OUTLOOK...Snow with IFR to LIFR conditions expected Saturday afternoon and evening. Ceilings will lift to MVFR after the snow ends late Saturday night. These ceilings may linger into Sunday.

ILN WATCHES/WARNINGS/ADVISORIES

OH...Winter Weather Advisory from 1 PM Saturday to 7 AM EST Sunday for OHZ026-034-035-042>046-051>056-060>062. Winter Storm Warning from 1 PM Saturday to 7 AM EST Sunday for OHZ063>065-070>074-077>082-088. KY...Winter Weather Advisory from 1 PM Saturday to 7 AM EST Sunday for KYZ089-090-094>100. Winter Storm Warning from 1 PM Saturday to 7 AM EST Sunday for KYZ091>093. IN...Winter Weather Advisory from 1 PM Saturday to 7 AM EST Sunday for INZ050-058-059-080. Winter Storm Warning from 1 PM Saturday to 7 AM EST Sunday for INZ066-073>075.