textproduct: Wilmington

SYNOPSIS

Brisk, cold, and mainly dry conditions will continue through Friday. A wintry mix of precipitation is likely Saturday into early Sunday as a system moves through the Ohio Valley. Below normal temperatures are expected to continue into next week with another threat for winter precipitation on Tuesday.

NEAR TERM /THROUGH FRIDAY/

Highly amplified mid level flow with a ridge over the west and a mean longwave trof over the eastern CONUS. Cyclonic flow across the area with an embedded shortwave dropping south through the region this afternoon thru this evening. Behind this shortwave the flow becomes more northwesterly and with more favorable fetch off Lake Michigan. This will keep the area mostly cloudy thru the day and into tonight. Some flurries or snow showers will be observed with the best threat for scattered snow showers across the far north late in the day into this evening. Brisk conditions with west wind gusts up to 30 mph this afternoon relax some overnight but continue up to 20 mph at times - mainly this evening.

Expansive cloud cover observed across the area will persist north of of I-70 tonight, with some breaks developing during the evening south and then likely increasing early Friday.

Temperatures drop to cold lows from 20 to 25 as colder air settles into the region.

SHORT TERM /FRIDAY NIGHT/

Northwest mid level flow on Friday backs more westerly Friday night as broad ridging works in from the west. Surface high pressure begins to build into the area with the ridge axis moving thru Friday evening. Lingering clouds with the best coverage across north to decrease from the southwest Friday afternoon into Friday evening. Expect mostly clear skies Friday evening with an increase in high level clouds overnight. With a reinforcing shot of cold air Friday, highs to range from the lower to middle 30s from north to south. Cold lows Friday night to range from the upper teens to the lower 20s - with the warmest readings in urban locations.

LONG TERM /SATURDAY THROUGH THURSDAY/

All eyes will be on a rather robust system that is poised to impact the region this holiday weekend. A deepening shortwave to the west of the Great Lakes will bring a mix of rain and snow, in addition to renewed breezy conditions, to the region on Saturday into Sunday.

Given that we're still a couple of days out, we're heavily focused on trends in the global models. The The GFS and Canadian ensembles continue to suggest a southerly shift in the wave, which would limit the amount of warm air that is able to advect north of the Ohio River. Additionally, this morning's 12z NAM run follows this trend. Meanwhile, the ECMWF ensemble still holds onto the upper level wave digging in some 200 miles NORTH of the other guidance. This would favor a warmer solution/much more warm air working its way north. In fact, in the most recent runs, the ECMWF ens 850 rain snow line rides right along the Ohio River whereas the GFS ens keeps it down through Kentucky.

Right now, thinking is that snow will overspread the entire CWA on Saturday afternoon as the column saturates. Warm air encroaches north of the Ohio River in the lower levels of the atmosphere, aided by a strong 50+ knot LLJ. This will help transition p-types to a rain/snow mix and then to rain during Saturday overnight hours into Sunday. As the system wraps itself up, a brief transition back to rain/snow or snow will follow Sunday morning into early afternoon before precipitation tapers off. Given the uncertainty of where that rain/snow line will be, confidence in impactful accumulating snowfall is highest in west central and northwest Ohio. WPC ensemble plumes indicate QUITE the spread (0-5 inches) in snowfall totals for areas near Dayton, while plumes cluster a bit closer to the 0-3 inch range areas along I-71 down through the Ohio River region.

As such, have collaborated with neighboring offices/WPC and have issued a Winter Storm Watch for the far northwestern counties in our CWA. While these areas are currently right on the cusp of Watch criteria, we hedged toward being more cautious given the prolonged period of sub-freezing temperatures prior to precip onset and this being an impactful holiday travel weekend.

After the cold front is pulled through on Sunday, we'll have a non- diurnal temperature drop and temperatures will plummet throughout the daytime hours. Some lingering flurries or light snow showers are possible, thanks to northwesterly flow off of Lake Michigan. Trends continue to drop temperatures on Sunday night, now resolving into the teens north of I-70 and low 20s south. Any snowpack would exacerbate temps dropping further.

Weak surface high pressure moves in across the Great Lakes on Monday behind the low, resulting in mostly dry conditions across the region with cold high temperatures, around freezing. Attention then turns to the next upper level wave that will bring renewed chances for precipitation to the region. While details with this feature are also pretty limited given how far out we are, there does seem to be a current consensus that the majority of the CWA will remain on the colder side of this feature. After this second feature pulls east, we'll get a reinforced shot of cold air, keeping the first few days of December rather chilly.

AVIATION /23Z THURSDAY THROUGH TUESDAY/

Generally VFR conditions are expected through the TAF period. Some snow will continue to be observed at the KCMH/KLCK airports for another few hours, but this should remain light (mainly just flurries) with no expected impacts. Winds through the overnight hours may have some gusts to around 20kts.

A few periods of MVFR ceilings could occur at KCMH/KLCK in the morning, but otherwise, VFR conditions are expected through the day. Westerly winds will remain in place with gusts to around 20kts tomorrow morning and afternoon.

OUTLOOK...MVFR/IFR ceilings and visibilities with wintry precipitation likely late Saturday into early Sunday. LIFR ceilings and visibilities will be possible during this time. Snow may bring additional reductions to aviation conditions on Monday night into Tuesday.

ILN WATCHES/WARNINGS/ADVISORIES

OH...Winter Storm Watch from Saturday morning through Sunday morning for OHZ034-042. KY...None. IN...Winter Storm Watch from Saturday morning through Sunday morning for INZ050.