textproduct: Cleveland

WHAT HAS CHANGED

Based on latest trends in observations and NWP model guidance, made the following changes to our forecast: decreased forecast cloud cover through the first several predawn hours of Tuesday morning; decreased forecast low temperatures slightly for early Tuesday morning. Please see key messages and discussion for further details.

KEY MESSAGES

1) Lake-effect snow across the Cleveland metro and Snowbelt will wind down from west to east this evening into tonight as snow showers occurring farther inland also exit, leaving mainly dry weather across the area for tonight.

2) Minimum wind chills of -20 to -30 degrees are in the forecast tonight into early Tuesday. An Extreme Cold Warning remains in effect for the entire area until 11 AM Tuesday.

3) Light snow is expected areawide on Tuesday, with lake- enhanced snow producing slightly higher snow accumulations across Northeast Ohio and Northwest Pennsylvania. Some blowing snow is also likely due to wind gusts of 25-35 MPH, especially west of the I-71 corridor Tuesday morning. The light snow accumulations and blowing snow may result in travel impacts.

4) Prolonged cold is expected through the weekend creating elevated risks for cold exposure and damage to infrastructure. Additional cold weather headlines will be needed.

5) Generally limited precipitation chances after Tuesday

DISCUSSION

KEY MESSAGE 1...

Light to locally moderate lake-effect snow has been ongoing amid west-northwest flow from Lorain and northern Medina Counties points east across Northeast OH much of today and has expanded east into Northwest PA this afternoon. This snow is driven by some synoptic lift and moisture associated with a shortwave moving through this afternoon, shoreline convergence and upslope, and limited but still-present fluxes off the icy lake. The snow is not particularly intense but is very efficient/ high-ratio, and has been causing some roadway accumulations when it's been more intense. This lake effect is not going to last too much longer, with a notable downtrend expected through this evening as the shortwave moves east and low-level ridging builds in. It's possible a few spots see another inch or two of fluffy snow late this afternoon into this evening. For now the Winter Wx Advisory expires at 4 PM, and it will be a "game time decision" regarding if part of that needs to be extended at all.

Outside of the snowbelt, some very modest low-level instability is combining with weak synoptic lift from the shortwave and moisture from Lake Michigan to generate flurries and a few snow showers. This activity has increased early-mid afternoon across the Akron/Canton and Youngstown areas as the shortwave moves through and is beginning to diminish farther west. Overall, this activity is also expected to end through this evening, leaving a dry rest of the night across the area. There will be a short window for some clearer skies tonight before clouds increase from the northwest into early Tuesday morning.

KEY MESSAGE 2...

There has been little change to the temperature, wind, and wind chill forecast for tonight into early Tuesday. While conditions aren't ideal for radiational cooling, a period of relatively lighter winds through the first half of tonight and a window of clearer sky (especially outside of any lingering lake effect clouds) over our fresh and deep snowpack will support low temperatures between about 2F and -8F, with the coldest values across our southern and southeastern counties. Winds will shift to southwesterly overnight and increase to 12-22 MPH (strongest west of the I-71 corridor) late tonight into early Tuesday. This all yields minimum wind chills tonight in the range of about -20F to -30F prior to sunrise. Thus, Extreme Cold Warning criteria (wind chills of -25F or colder) are expected to be reached in a large portion of our CWA. Note: the prolonged frigid conditions support an increased risk of infrastructure damage (such as burst pipes and dead batteries).

KEY MESSAGE 3...

A lobe of the tropospheric polar vortex will swing southeast through the Great Lakes tonight and Tuesday. In response at the surface, a weak surface low will track through the upper Great Lakes. A warm front extending from this low will lift into the area Tuesday morning, quickly followed by the low's trailing cold front late Tuesday afternoon and evening. These features will help bring snow chances and gusty winds to the local area.

Mid-level warm air advection and isentropic lift will drive an initial batch of snow that will spread in from the northwest between ~5 AM and ~9 AM. Much of the area stands a chance to see a light amount of snow (up to an inch) with this initial batch of snow, with potential for a few spots in Northeast OH to see an inch or two of snow through midday. This snow will not be much, but with the cold will try to stick to roads and bring some minor travel impacts. It will remain mainly cloudy behind this initial batch of snow, with some continued weak warm air advection in the low-mid levels supporting continued potential for off/on flurries or light snow into the afternoon. Snow potential ramps back up later in the afternoon and into the early evening along and ahead of the cold front. As the front moves through, the combination of low-level convergence with the front itself and weak instability in the lowest ~7k feet may support some briefly moderate to heavy snow showers/squalls... particularly from Lorain County points east across the snowbelt, where limited fluxes off the lake combined with some shoreline convergence/upslope will give activity along the front a boost. The primary hazard with the cold front will be a short-lived but quick visibility drop and accumulation of snow on roads during the late afternoon or early evening, especially across parts of Northeast OH and Northwest PA. Overall snowfall Tuesday into Tuesday evening will range from an inch or less across the western half of the area to 1-3" across Northeast OH and Northwest PA. While not enough for an advisory, do plan on some snow accumulations on roads and slower travel at times.

Outside of the snow accumulations, gusty winds will lead to some blowing and drifting of our fresh and deep snowpack late tonight and Tuesday. Southwest winds will turn gusty after 5 AM Tuesday, with 25-35 MPH gusts likely, strongest west of the I-71 corridor. Winds will gradually veer more westerly Tuesday afternoon with gusts 20-30 MPH continuing. Some blowing and drifting snow is likely area-wide, with the greatest impacts west of the I-71 corridor where stronger gusts and a more open landscape will encourage more blowing and drifting snow. Folks across Northwest and North Central OH west of I-71 should be prepared for some impacts to the Tuesday morning commute from the blowing and drifting. Would like more confidence in wind gusts over 35 MPH to go with an advisory for blowing snow impacts, so held off, though it was considered and will at the least add a mention to the Hazardous Weather Outlook.

KEY MESSAGE 4...

The continued story through this weekend will be our prolonged stretch of very cold/frigid temperatures. After a very slight "warm up" ahead of the cold front on Tuesday, more frigid air returns Tuesday night. A re-enforcing shot of frigid arctic air then arrives Thursday night. While we won't sniff freezing over the next week or more, some moderation in the temperatures does look likely by the start of next week.

In terms of daily highs...Tuesday will reach the mid 10s to near 20, cooling to the upper single digits/lower 10s Wednesday and Thursday, staying well into the single digits on Friday, and gradually moderating into the 10s this weekend. Overnight lows will generally range from 0 to -10 Tuesday night to -5 to 5 Wednesday night, before cooling to -5 to -15 Thursday night. Widespread lows of 0 to -10 are expected Friday night, with slow moderation Saturday and Sunday nights. At the least, parts of the area will likely get below 0 again on Saturday night. The deep snowpack will support low temperatures colder than guidance if we see a night with favorable conditions for radiational cooling (clear skies/light winds). Currently, the most likely nights for this to happen appear to be Tuesday and Thursday nights, with some potential Friday night as well if we don't see too many clouds. This ongoing and continued stretch of cold ambient temperatures averaging below 16 degrees will bring increased risk of infrastructure impacts due to the cold, such as burst pipes, water main breaks, and dead batteries. The prolonged nature of the cold will also pose a continued and increasing risk of exposure to more vulnerable populations.

Additional cold weather headlines will be needed beyond the current Extreme Cold Warning. Keeping in mind that advisory criteria is a wind chill or ambient temperature of -15 to -24, with a warning criteria of -25 or colder, most nights will be close to or in the range for an advisory from Tuesday night through Saturday night. There is some potential for warning- level cold Thursday night into early Friday. These cold wind chills bring risk for frostbite and hypothermia for those who are outside without proper cold weather gear, including pets.

KEY MESSAGE 5...

With a frozen lake and very cold, dry synoptic weather pattern, only small chances for light snow exist beyond Tuesday's system.

AVIATION /00Z Tuesday THROUGH Saturday/

Aloft, an E'ward-moving ridge axis approaches and then crosses our region through 12Z/Tues. Thereafter, a SE'ward-moving trough axis approaches and then traverses most of our region before it nears the eastern border of our area by 00Z/Wed. At the surface, the ridge continues affecting our region as a reinforcing cold front approaches from the north-central United States and vicinity. This front should sweep SE'ward through our region between ~19Z/Tues and 00Z/Wed. Behind the front, another ridge builds from the north-central United States and vicinity. Ahead of the front, our regional surface winds trend SW'erly to W'erly around 10 to 15 knots and should gust up to 20 to 25 knots at times, especially after ~12Z/Tues. Behind the front, W'erly to WNW'erly winds around 10 to 15 knots, gusting up to 25 knots, are expected.

Ahead of the cold front, isolated to broken low-level clouds with bases near 2kft AGL are expected. Lingering and light lake-effect snow (LES) should stream generally E'ward from Lake Erie and impact far-NE OH and NW PA, including KERI, through ~06Z/Tues. MVFR ceilings and mainly MVFR visibility are expected with the LES. The LES should then shift offshore our region after ~06Z/Tues as mean low-level flow backs from W'erly to SW'erly. Widespread light snow and associated MVFR ceilings/visibility preceding the aforementioned trough axis aloft should overspread our region generally from northwest to southeast between ~10Z/Tues and ~14Z/Tues. In addition, a band of steady to heavy snow with IFR or worse visibility should accompany the cold front passage. Behind the front, MVFR ceilings are expected with primarily dry weather and VFR visibility. However, LES showers should stream generally SE'ward from Lake Erie and impact much of NE OH and NW PA, including KCLE, KYNG, and KERI. Visibility as low as MVFR is expected with these LES showers.

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

MARINE

Winds will back to southwesterly tonight ahead of an approaching clipper system and increase to 30 knots on Tuesday. Winds will veer to westerly Tuesday evening and then decrease Tuesday night. Winds remain in the 15-25 knot range on Wednesday as another trough crosses Lake Erie. Winds will tend to decrease to 10-15 knots from Thursday into the weekend as ridging tries to expand east into the Great Lakes while remaining focused over the Upper Midwest.

Lake Erie is mostly ice covered, and the ice will continue to thicken this week as well below normal temperatures continue across the region. Some shifting of the ice is possible during periods of stronger winds which may close any remaining channels, especially tonight.

CLE WATCHES/WARNINGS/ADVISORIES

OH...Extreme Cold Warning until 11 AM EST Tuesday for OHZ003- 006>014-017>023-027>033-036>038-047-089. PA...Extreme Cold Warning until 11 AM EST Tuesday for PAZ001>003. MARINE...None.