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SYNOPSIS

High pressure will build southeast tonight and Saturday before weakening Saturday night as another fast moving clipper system drops through the central and eastern Great Lakes. High pressure will return Sunday afternoon before exiting east Monday as a warm front lifts across the region. Another fast moving low pressure system will affect the region Tuesday into Wednesday.

NEAR TERM /THROUGH SATURDAY NIGHT/

Busy day today as Mother Nature threw us a curve ball with lake-effect snow showers being more widespread and organized than previously thought. This was due to a very subtle mid/upper shortwave and associated surface trough that crossed the southern Great Lakes from mid morning through early afternoon, leading to an uptick in synoptic moisture, inversion heights, and low-level convergence. Multiple bands of snow deposited 1 to 3 inches of fluffy snow (perhaps locally higher) across portions of Cuyahoga, Lake, Geauga, Ashtabula, Erie, and Crawford Counties. Lighter amounts also fell across Lorain, Medina, Summit, Portage, and Trumbull Counties.

Upstream visible satellite and regional radar loops finally show drier air working toward the region as the surface ridging approaches from the Upper Midwest. This is noted by diminishing clouds and lake-effect bands coming off Lakes Superior and Michigan. Expect the ongoing snow showers in NE Ohio and NW PA to slowly diminish through mid evening while also shifting northeast as this drier air, subsidence, and backing boundary layer flow work into the region. With this being said, extended all warning and advisory headlines through 00Z this evening since an additional 1 to 2 inches of snow (locally up to 3) is still expected where squalls persist.

As the ridging builds overhead tonight, lingering flurries in NW PA will end allowing all areas to dry out. This will set up a quiet and cold night, with lows in the low/mid teens. Mainly quiet and cold conditions will continue Saturday, with highs in the mid/upper 20s. The high will start to weaken and drift farther SE by Saturday afternoon as another fast moving mid/upper shortwave and associated surface low drop into the Upper Great Lakes. Increasing moisture and isentropic ascent ahead of this Clipper combined with continued lake induced instability and boundary layer flow across the lake starting to veer again could bring a few snow showers into NW PA and far NE Ohio, so added some chance POPS in the afternoon. The better chance of snow showers will be Saturday night as the Clipper crosses the central and eastern Great Lakes. The best forcing and moisture will stay north of our region, but enough mid-level ascent and low-level convergence as the associated trough crosses the lake combined with continued conditional instability and long fetch will bring a band of lake enhanced snow through far NE Ohio and NW PA. Given the short window, snow amounts at this time look to average 1-2 inches across Lake, Geauga, and Ashtabula Counties, with 1 to 3 inches (locally higher) in Erie and Crawford Counties. This period will continue to be evaluated for possible advisories. Otherwise, lows Saturday night will remain very cold, with mid/upper teens expected.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/

This period will gradually start a stretch of quieter weather that will last into next week, along with warming temperatures. Lingering lake-effect snow showers in far NE Ohio and NW PA will quickly end Sunday afternoon as broad surface ridging builds into the Ohio Valley. This will lead to mainly dry conditions through Sunday night. The broad mid/upper trough that has been sitting over eastern Canada and the Northeast U.S. over the past week will start to lift out Monday and Monday night, but one more Clipper system will drop from the Upper Great Lakes Monday through the eastern Great Lakes Monday night. The bulk of the forcing and moisture will stay to our north, but enough upper jet support will interact with a warm front lifting across the region Monday to generate some light snow across far northern areas.

Highs in the mid/upper 20s Sunday will warm into the low/mid 30s Monday. Lows Sunday night will range from the mid to upper teens, with much milder mid/upper 20s Monday night.

LONG TERM /TUESDAY THROUGH FRIDAY/

As hinted at above, a welcomed January thaw will arrive for next week as a quasi-zonal mid/upper flow pattern develops across the country. This will allow mild Pacific-based air to flood eastward, with high temperatures warming into the low 40s Tuesday and low/mid 40s Wednesday. Further warming will result in highs potentially reaching the mid 40s to around 50 Thursday and solid 50s Friday. A fast moving shortwave could bring a few rain showers Tuesday and Tuesday night, with better chances for rain Thursday into Friday as a stronger low lifts into the Great Lakes. As a heads up, this storm system for the end of the week will likely drag arctic air back into the region by next weekend, and long range Canadian, GEFS, and ECMWF ensembles suggest another cold pattern for mid and late January which is also supported by teleconnections in the eastern Pacific. Enjoy the thaw next week while it's here!

AVIATION /19Z FRIDAY THROUGH WEDNESDAY/

An expansive stratus deck encompasses the entire forecast area this afternoon with ceilings in the 1500-3500 ft range. Additionally, lake effect snow will persist across much of northeast Ohio and northwest Pennsylvania. Wide ranging visibilities will accompany lake effect snow to as low as 1 SM (though there have been a few occasional observations less than that even).

A dry airmass will accompany high pressure as it builds in from the west this evening and tonight. This should allow for gradual dissipation of cloud cover and lake effect snow from west to east tonight. Compared to the previous forecast, lake effect snow and clouds will hang around longer than expected. Confidence is lower than normal for when lake effect snow/clouds dissipate for sites downwind of Lake Erie in northeast Ohio and northwest Pennsylvania. In general though, should see lake effect gradually dissipate and end tonight, with no showers by 12Z Saturday.

West winds around 8-12 winds are expected with occasional gusts to 20 knots; slightly stronger winds to 15 knots with gusts near 25 knots close to the Lake Erie lakeshore. Winds become light and variable tonight.

Outlook...Non-VFR is expected across northeast Ohio and northwest Pennsylvania with snow showers Saturday night into early Sunday and again Monday morning. Additional non-VFR possible in rain showers Tuesday and Tuesday night.

MARINE

Small Craft Advisories remain in effect from Avon Point east through 4 AM EST Saturday morning. West winds 15 to 20 knots and waves of 3 to 6 feet (in ice free areas) are anticipated through this evening before winds diminish and waves subside late tonight into early Saturday morning.

High pressure builds across the region Saturday through Monday, with much quieter weather expected on Lake Erie during this period. Southerly winds develop on Monday, gradually becoming southwesterly on Tuesday and west on Wednesday, with wind speeds at or below 15 knots, and ice-free areas at or below 2 feet.

CLE WATCHES/WARNINGS/ADVISORIES

OH...Winter Weather Advisory until 7 PM EST this evening for OHZ012>014-089. PA...Winter Weather Advisory until 7 PM EST this evening for PAZ003. Lake Effect Snow Warning until 7 PM EST this evening for PAZ001-002. MARINE...Small Craft Advisory until 4 AM EST Saturday for LEZ146>149.