textproduct: Cleveland

WHAT HAS CHANGED

Increased the snow forecast for today's lake-effect snow, and we're now looking at an additional 1-3 inches of snow across the snowbelt of Northeast Ohio and Northwest Pennsylvania. Also increased the snow forecast for Tuesday's clipper. Generally expecting most of the area to get at least a dusting of snow, with an additional 1-3 inches of snow across the snowbelt. Finally, the Extreme Cold Watch was upgraded to an Extreme Cold Warning, with wind chills forecast to reach -25 across much of the area tonight into Tuesday morning.

KEY MESSAGES

1) Lake-effect snow continues across Northeast Ohio and Northwest Pennsylvania, causing poor road conditions to linger through this evening.

2) Dangerous wind chills down to -25 F are expected to bring significant cold exposure risks to the entire area tonight into Tuesday morning.

3) Light snow is expected areawide on Tuesday, with lake- enhanced snow producing light snow accumulations across Northeast Ohio and Northwest Pennsylvania. This may produce minor travel impacts.

4) Prolonged cold is expected through the weekend creating elevated risks for cold exposure and damage to infrastructure.

DISCUSSION

KEY MESSAGE 1... Low-level moisture wrapping around the departing 850mb low continues to linger across the area. Cold air over lake effect has produced minor lake-induced CAPE, which along with orographic lift, has produced light, accumulating snowfall across the primary snowbelt of Northeast Ohio and Northwest Pennsylvania early this morning. Area cameras and traffic speed information indicates that travel impacts remain due to snow- covered roads, including on many major highways. For now, have left the Winter Storm Warnings active across parts of Northeast Ohio and Northwest Pennsylvania this morning until its clear the travel impacts have been minimized.

Upstream, and upper-level trough resides over the northern Great Lakes and Upper Midwest. This trough will move southeast across the Great Lakes, further producing lift and deeper moisture up 700mb. 850mb temperatures should further cool down this morning to around -18 C, which as the upper-level trough approaches, should re-intensify the lake-effect snow across the primary snowbelt. Despite Lake Erie being nearly ice-covered (latest analysis has Lake Erie at 92% ice-covered), additional moisture and warmth can be provided through thin ice, and cracks in the ice. Additional snow accumulations of around 1 to 3 inches are expected in the primary snowbelt with localized higher amounts of 3 to 4 inches possible in eastern Cuyahoga, southern Lake, northern Geauga, and Erie, PA south of I-90. Where it snows, expect minor travel impacts to persist through this evening. Once its clear that roadways have improved a little bit more, it's likely that the active Winter Storm Warnings will be downgraded to a Winter Weather Advisory and extended through this evening.

KEY MESSAGE 2... The upper-level trough departs to the east, and an arctic airmass associated with surface high pressure centered over Texas will extend northeastward towards the lower Great Lakes region. As the ridge builds in, should see an area of clearing skies, and aided by a deep snowpack, should see temperatures plummet below zero areawide. The temperature forecast trended lower with this forecast package, especially in central and east-central Ohio where low temperatures could dip to -5 or lower. Breezy southwest winds develop early Tuesday morning behind the departing surface ridge, which when combined with the cold air temperatures will produce dangerous wind chills down to -25. The Extreme Cold Watch was upgraded to an Extreme Cold Warning for the entire area from 7 PM this evening through 11 AM Tuesday morning.

KEY MESSAGE 3... A clipper system swings southeast across the Great Lakes on Tuesday with sufficient cold air and moisture depth for brief, light snow across the area Tuesday morning. Breezy southwest winds Tuesday morning may result in patchy blowing or drifting snow, especially west of I-71 where wind gusts of 30-35 mph will be possible. This will transition to lake effect snow showers for the primary snowbelt of Northeast Ohio and Northwest Pennsylvania where an additional 1 to 3 inches of snow and minor travel impacts are expected.

KEY MESSAGE 4... An upper-level trough remains over much of the eastern CONUS through the end of the week, with stubborn anomalously cold temperatures across the Great Lakes region through the weekend. The recent snow storm has produced a deep snowpack areawide, which should further enhance cold temperatures across the area. Air temperatures at or below zero will be common through Saturday with minimum wind chill values ranging between -10 and -25, increasing the risk of frostbite or hypothermia. Additional Cold Weather Advisories or Extreme Cold Warnings are likely.

Infrastructure impacts from cold air temperatures tend to increase for longer duration events, especially when the daily average temperature dips below 16 degrees (this is a local criteria) for multiple days. This results in increased likelihood of burst frozen pipes, dead car batteries, power outages, increased chances for carbon monoxide poisoning (from improper use of secondary sources of heat) and structure fires.

Additionally, we will likely start to see ice develop and thicken on area rivers.

AVIATION /06Z Monday THROUGH Friday/

At the surface, a ridge builds from the north-central United States through 06Z/Tues. Our regional surface winds will back from NE'erly to SW'erly through the TAF period and remain around 5 to 15 knots in magnitude. Gusts up to 20 knots are possible, especially between ~15Z/Mon and ~23Z/Mon. Scattered to widespread low clouds are expected through ~23Z/Mon and will have bases primarily in the range of 800 ft to 3.5kft AGL. After ~23Z/Mon, sky should clear considerably across most of our region. However, scattered to broken lake-effect stratocumuli with bases near 3kft AGL should stream generally E'ward across far-NE OH and NW PA through ~04Z/Tues and then shift offshore by 06Z/Tues as mean low-level flow backs from W'erly toward SW'erly.

Mainly dry weather and VFR visibility are expected through the TAF period. However, light lake-effect snow (LES) downwind of mainly ice-covered Lake Erie should impact NE OH and NW PA through ~04Z/Tues as mean low-level flow backs from N'erly toward SW'erly. After ~04Z/Tues, lingering LES should become located offshore our region. Visibility should vary between VFR and MVFR in the LES.

Outlook...Additional periods of snow with non-VFR are possible overnight Monday night through Friday. Greatest chances exist in NE OH and NW PA, where periodic lake-effect snow downwind of mainly ice-covered Lake Erie should occur.

MARINE

NW winds early this morning will gradually shift to WSW by this evening with speeds increasing to 10-20 knots. SW winds will further increase to 20-30 knots late tonight and Tuesday ahead of a clipper system and associated cold front dropping through the Great Lakes. Winds will turn WNW behind the front Tuesday evening and Tuesday night, with speeds decreasing to 10-15 knots. Another clipper approaching the region will back winds on the lake to SW at 10-20 knots Wednesday before turning NW and decreasing to 10-15 knots behind the associated cold front Wednesday night and Thursday. NW winds of 10-15 knots will then continue through Friday.

Lake Erie is mostly ice covered, and the ice will continue to thicken this week as a deep arctic airmass remains entrenched across the region. The shifting wind directions may also cause the ice to shift, especially during the periods of stronger SW winds tonight and Tuesday and again Wednesday.

CLE WATCHES/WARNINGS/ADVISORIES

OH...Extreme Cold Warning from 7 PM this evening to 11 AM EST Tuesday for OHZ003-006>014-017>023-027>033-036>038-047- 089. Winter Storm Warning until 10 AM EST this morning for OHZ010>014-020>023-089. PA...Extreme Cold Warning from 7 PM this evening to 11 AM EST Tuesday for PAZ001>003. Winter Storm Warning until 1 PM EST this afternoon for PAZ001>003. MARINE...None.