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SYNOPSIS

A trough lingers near Lake Erie through Sunday. A ridge will build into the Ohio Valley and into our region Sunday night through Monday before departing to the East Coast midweek.

NEAR TERM /THROUGH SUNDAY NIGHT/

- Portage County upgraded to a Lake Effect Snow Warning through 7 AM EST Monday morning. - Lake-Effect Snow Warning remains in effect for the primary snowbelt of NEOH and NWPA, including Cuyahoga County, until 7 AM EST Monday morning. - Winter Weather Advisory remains in effect for the rest of the secondary snowbelt of NEOH until 7 AM EST Monday morning. - Winter Weather Advisory remains in effect for Stark and Mahoning Counties until 7 PM EST Sunday evening. - Winter Weather Advisory across portions of northern and central Ohio remains in effect until 7 AM EST Sunday morning.

10:25 PM Update:

Clipper snow is on the downtrend. Preliminary reports generally range widely between near 0" in Toledo to 1-4" elsewhere, with a couple of 5-6" reports down in Marion/Knox Counties. Additional snow from the clipper will be an inch or less though many roads, especially secondary and more rural ones, will remain snow covered and slick through the overnight. Wind chills will dip to 0 to -10 degrees area-wide overnight.

The attention is quickly shifting towards the lake effect snow. With this late evening update, went ahead and upgraded Portage County to a Lake Effect Snow Warning. We may upgrade at least a couple of additional counties over the next several hours, though Portage County is the county with the most consistent model signal for organized and likely intense banding on Sunday, which is why we jumped on that upgrade before any others.

Lake enhanced snow has lost a bit of organization over the last hour as winds have veered behind a trough passage...a bit of subsidence and drier air behind the trough and clipper are also currently moving over the lake. However, there still is some (rather disorganized) enhancement present from northern Lorain County across Cuyahoga County and into parts of southern Lake, Geauga, inland Ashtabula, and while not seen well on radar, presumably much of Erie County PA south of I-90. While the lake snow will not entirely stop, this general lull may continue for the next few hours into the overnight. Winds may veer *slightly* more west-northwest into the overnight and push the lake snow a few miles farther south, but in general it likely will remain fairly steady state in terms of location overnight.

Lake effect likely begins re-organizing and intensifying pre- dawn Sunday, peaking in intensity during the daytime hours. Winds will start west-northwest early Sunday, gradually veering more northwest through the afternoon and even briefly north- northwest Sunday evening. Peak instability, moisture, and synoptic support will be realized during the daytime on Sunday before decreasing quickly Sunday night. Gradually shifting winds due to a few different trough passages on Sunday, along with strong flow and a shorter fetch, may make it hard for banding to lock into one location for too long at once and will certainly push heavier snow well inland. Still, the good synoptic support and moderate to extreme lake-induced instability suggest snow bands will be very intense where they setup, with ties to upstream Great Lakes (including Lakes Michigan, St. Clair, Superior and Huron) likely dictating where those bands develop. There is some indication of a WNW-ESE oriented band late tonight through early Sunday afternoon cutting across parts of Lorain, Medina, Summit, and into Portage. There are also hints of a band extending from eastern Cuyahoga/western Geauga into Portage for several hours on Sunday. The Lake Huron connection will likely largely focus in Northwest PA, but may drift into eastern Ashtabula and Trumbull for a few hours late Sunday. The greatest signal for banding into the secondary snowbelt is Portage, hence the higher confidence and LES Warning upgrade...though we will also be closely evaluating Medina, Summit, and Trumbull tonight into Sunday for any additional warning upgrades.

Given the strong instability and synoptic support, cold temperatures, and strong winds, lake effect snow squalls will be intense with rates of 1 to 2 inches per hour and produce near- zero visibility on Sunday, with these conditions likely to carry far inland. Those who will be traveling or out and about on Sunday will need to be prepared for these very changeable, and within lake effect bands potentially dangerous, conditions.

Previous Discussion...

The coldest weather of this winter season so far is moving into our region this weekend. There is a large and strong upper level trough that is currently digging out across the Great Lakes and much of the eastern U.S. This upper level trough is bringing down another Arctic Blast and will crank up the lake effect snow machine today through Sunday night and Monday morning.

A rather decent clipper system is currently rounding the base of the upper level and tracking through the Ohio Valley this afternoon into tonight. Widespread system snow will impact the entire area this afternoon into tonight. 1 to 3 inches of snowfall is expected for locations outside of the snowbelt and areas that are not in the winter weather advisory from the clipper system. On the backside of the clipper system tonight, Arctic airmass will move over the Great Lakes tonight. The widespread system snow will transition to Lake Snow shower and squalls later tonight and continue through Sunday night or Monday morning. 850 mb temps will fall tonight into Sunday to around -22C if not a little colder. Both the primary and secondary Snowbelt will see the lake effect snow later tonight through early Monday morning. Overall the areas of the Snowbelt that have Winter Weather Advisories will see generally 3 to 7 inches of snowfall total from both the system snow and lake effect snow through Sunday night. For areas of the Snowbelt that have a Lake Effect Snow Warning will see generally 6 to 12 inches of snowfall today from both system snow and the lake effect through Monday morning. There could be few spots in the Snowbelt of NWPA that end up over a foot of snowfall total through Monday morning.

The other impact from this Arctic Blast will the very cold weather and wind chills to deal with. Overnight low temperatures tonight will drop down into the single digits away from the immediate lakeshore. Most areas tomorrow will not make it out of the teens for daytime high temperatures. Sunday night low temperatures will be back down in the single digits and lower teens. Wind chill values will be -10F to 10 F later tonight through Monday morning.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/

There will be break in this recent active winter pattern for early next week. The deep upper level trough over the Great Lakes and Ohio Valley will lift out and the weather pattern will become will more zonal from west to east. A large high pressure system will slowly track across the eastern U.S. Monday and Tuesday before exiting the East Coast late Tuesday evening. The cold airmass over the Ohio Valley and Great Lakes region will slowly modify early next week. High temps on Monday will still be very cold in the lower to middle 20s. The high temps by Tuesday will crack the freezing mark for most locations into the lower and middle 30s.

LONG TERM /WEDNESDAY THROUGH SATURDAY/

The slow warming trend will continue for the middle and end of next week. The fast pace and active weather pattern will be somewhat zonal with several more storm systems riding the jetstream from west to east along or near the U.S./Canada border. On the front end these weather systems will be a brief warm up to above temperatures followed by another shot of colder air brought from Canada. We actually have more potential and higher chances of rain rather than wintry weather with these systems late next week into next weekend.

AVIATION /06Z Sunday THROUGH Thursday/

Steady snow from the clipper that affected much of the area Saturday afternoon and evening has exited, leaving mainly MVFR ceilings and shifting the focus to lake effect snow. Most sites will hang on to an MVFR ceiling through the TAF period, though some temporary clearing may occur at TOL, FDY, and MFD at times on Sunday. Lake effect will be most prominent at CLE and ERI, though will push well inland across Northeast OH and Northwest PA during the day Sunday with impacts likely at CAK and YNG later Sunday morning through the afternoon. The heaviest lake effect will likely focus south of ERI, though banding may impact CLE at times between overnight tonight and Sunday afternoon with periods of vsby under 1/2SM and potential for quick snow accumulations, especially during the day Sunday...though, it's possible the most persistent banding is slightly west or southwest of the CLE airfield. Lake effect loses intensity and focuses closer to the lakeshore east of CLE Sunday night.

West to northwest winds of 6-12kt with a few 20kt gusts along the Lake Erie shoreline continue tonight, shifting a bit more northwesterly and increasing to 10-18kt with gusts 25-30kt late Sunday morning and afternoon.

Outlook...Non-VFR conditions are possible with lake effect snow showers in northeastern Ohio and northwestern Pennsylvania through Monday night.

MARINE

Westerly winds across the lake have diminished slightly to 15-20 knots, with gusts around 25 knots, and waves to 5-8 feet. A Small Craft Advisory remains in effect for the entire nearshore zones of Lake Erie due to the elevated winds and waves. Water temperatures remain at, or below, 40 degrees across much of the lake, with air temperatures in the upper teens to low 20s. As a result, there is a minor risk for freezing spray through Sunday morning.

Winds will become northwesterly overnight and increase to 20-25 knots on Sunday. Winds may briefly increase to 30 knots across the central basin, but will decrease to 10-15 knots by the evening and becoming westerly. Waves will steadily subside from 2-4 feet Sunday to 1-3 feet Sunday night. Winds will become southwesterly on Monday and increase to 25-30 knots. Waves build to 3-6 feet in the nearshore zones, and 6-9 feet the open water zones. Occasional waves 11-15 feet are possible. These condition will continue through Wednesday, with potential for gales across the lake on Thursday.

CLE WATCHES/WARNINGS/ADVISORIES

OH...Winter Weather Advisory until 7 AM EST Monday for OHZ010-020- 021-023. Lake Effect Snow Warning until 7 AM EST Monday for OHZ011>014- 022-089. Winter Weather Advisory until 7 AM EST Sunday for OHZ029>031- 036>038-047. Winter Weather Advisory until 7 PM EST Sunday for OHZ032-033. PA...Lake Effect Snow Warning until 7 AM EST Monday for PAZ001>003. MARINE...Small Craft Advisory until 1 AM EST Monday for LEZ142-143. Small Craft Advisory until 7 AM EST Monday for LEZ144>149.