textproduct: Cleveland

WHAT HAS CHANGED

Potential for a few heavier snow showers or squalls along and just ahead of a cold front on Saturday has increased, especially east and southeast of the I-71 corridor.

KEY MESSAGES

1) Scattered snow showers are expected this evening through Saturday. Isolated snow squalls are possible on Saturday, which could briefly create hazardous travel conditions.

2) A prolonged period of frigid weather is expected through Tuesday night with highs in the 10s and lows in the single digits. Dangerous wind chills near -20 are possible Monday into Tuesday.

3) Scattered snow showers are possible early next week, with a chance for more impactful lake effect snow Monday into Tuesday across far Northeast Ohio and Northwest Pennsylvania. Confidence in the lake effect is low to medium.

4) Light snow and breezy conditions are possible Wednesday into Wednesday night. Some lake effect snow may linger into Thursday across the snowbelt, though confidence is low.

DISCUSSION

KEY MESSAGE 1... A broad longwave trough with various embedded shortwaves and vort maxes will drift across the Great Lakes into this weekend, with slow-moving surface low pressure moving east through the upper Great Lakes and pushing a cold front east across the local area between early Saturday morning and late Saturday afternoon.

A band of low-mid level warm air advection and isentropic lift will quickly lift east-northeast across the area through early this evening. A band of snow with this feature is ongoing across Northwest OH and will continue east, producing a brief period of snow across northern portions of the area (lower confidence farther south due to drier low-levels and weaker lift). Snow accumulations through this evening will be under 1", though brief visibility drops to 1/2 of a mile have been observed upstream...these brief embedded bursts of moderate snow may continue to occur as the snow progresses across the area, especially north of a Findlay to Akron to Meadville line. A short-lived period of reduced visibility and snow coated roads is possible through early this evening with any moderate bursts.

A shortwave rotating through the broader Great Lakes trough will lift across the Upper Ohio Valley tonight. Lift and enhanced moisture ahead of this shortwave will graze our southeastern counties tonight, bringing a brief period of light snow overnight into early Saturday morning. The greatest potential for a light accumulation of up to around an inch tonight will be southeast of a Mt. Vernon to Erie, PA line, with any accumulations northwest of that minimal.

A fairly strong cold front will enter Northwest OH early Saturday morning and progress east across the area through the afternoon. Scattered to numerous snow showers will accompany this feature, especially during the late morning and afternoon hours as the front moves east of the I-71 corridor. During this time, modest destabilization in the low-levels will contribute to a more convective flavor to the snow showers with some increase in large-scale lift occurring ahead of the next embedded shortwave. This results in a lower chance (20-40%) chance for snow showers west of I-71 increasing to 50-60% farther east/southeast. Forecast snow amounts are under an inch across the board, though the chance does exist for a few more convective snow showers or squalls (especially east/southeast of I-71) to drop locally over an inch, sharply reduce visibility, and quickly accumulate on roads producing a brief travel hazard. Above-freezing temperatures ahead of the front across the eastern half of the area may try to limit the potential for road impacts, though temperatures do quickly fall with the frontal passage and the ground is colder after this morning. So, certainly don't want to rule out potential for impactful snow squalls if particularly intense activity can play out. Forecast soundings depict weak CAPE up to about 12k feet/-25C ahead of the front east of I-71 with mean boundary layer winds of about 30kt, so snow showers will certainly be convective (with a very low but non-zero chance for a rumble of thunder across far eastern OH) and produce brief gusty (up to 40 MPH) winds.

After a "milder" night tonight with lows ranging from the mid 20s to lower 30s, highs on Saturday will range from the upper 20s in Toledo to the mid 30s in Youngstown, with temperatures beginning to drop from west to east during the afternoon.

KEY MESSAGE 2... Saturday's cold front will usher in the first piece of colder air. Lows will generally dip to 10-15 by Sunday morning with minimum wind chills near or slightly above 0. Highs on Sunday will be on either side of 20 degrees with wind chills staying in the single digits. Sunday night will be similar to or slightly colder than Saturday night, with lows from the upper single digits to mid 10s and minimum wind chills near 0 to a few degrees below. An Arctic cold front will cross Monday, bringing a deeper chunk of very cold air to the region. Highs early Monday will range from 10-15 along the I-75 corridor to 15-20 across the eastern half of the area, with steady or falling temperatures behind the cold front through the afternoon. It will be quite brisk on Monday with west- southwest wind gusts of 30-40 MPH possible along and behind the Arctic front. The coldest night will be Monday night, with lows near to a bit below 0 across the area. Wind chills should fall to -5 to -15 during the day Monday and bottom out at -10 to -20 Monday night into Tuesday morning. Cold Weather Advisories will likely be needed Monday into Tuesday. Highs rebound into the 10s on Tuesday, with lows Tuesday night generally in the single digits.

Research has shown that average daily temperatures (taking the average of the high and low for a day) of 16 degrees or lower for 48 hours or longer yields increased infrastructure issues due to cold in our area...this includes things like dead car batteries and frozen pipes. We will reach these temperatures for a marginal duration of about 48 hours between Monday morning and Wednesday morning, which could be enough to cause some infrastructure issues due to the cold.

KEY MESSAGE 3... Some snow showers could accompany the Arctic frontal passage late Sunday night into Monday across the area. The greater forcing and moisture appear to stay to our north, so any accumulations with the Arctic front look minimal with parts of the area likely remaining entirely dry. A prolonged and potentially significant lake effect snow event is expected off the east end of Lake Erie late this weekend through the first half of next week. Predominantly southwest flow will keep the greatest accumulations and impacts into western NY...however, a period of more westerly flow remains possible behind the front from some point Monday into Tuesday. This could lead to a relatively brief period where impactful lake effect snow sinks into far Northeast OH and Northwest PA early next week. Confidence in this occurring is low to moderate, as some models and ensemble members are insistent on the southwest flow persisting. Those in far Northeast OH/Northwest PA should monitor the forecast as we gain confidence in the placement of any lake effect snow over the next few days.

Outside of the lake effect potential across a small portion of our forecast area and rather limited amounts of snow along the Arctic front, it will be mainly dry Monday and Tuesday.

KEY MESSAGE 4... A low pressure is expected to track through the Great Lakes Wednesday or Wednesday night and drag a cold front across the area. A brief spell of milder temperatures ahead of the cold front will give way to more below average weather behind it. This will be another breezy system, with some potential for a bit of snow area-wide followed by lower-confidence lake effect potential behind it Wednesday night into Thursday. The likely rapid development of ice on Lake Erie and uncertainty over wind direction lead to low confidence in that lake effect potential.

AVIATION /06Z Saturday THROUGH Wednesday/

A stratus deck with a mix of MVFR and VFR ceilings remains, though will trend towards lower ceilings through the night, especially in central and east-central Ohio where light snow is also possible.

A strong cold front will cross the region late Saturday morning through the afternoon, which will be accompanied by snow showers. Visibilities less than 2 SM will briefly occur with snow showers, especially east of I-77 where confidence is highest.

Conditions will quickly become VFR as a dry airmass builds in behind the front Saturday evening into the overnight hours.

South-southwest winds of around 10 knots or less will continue overnight. Winds become west while increasing to 10-15 knots and gusts up to 20-25 knots Saturday afternoon before decreasing to 10 knots or less overnight.

Outlook...Non-VFR possible in snow showers Sunday night into Monday. Non- VFR may linger in lake effect snow across Northeast Ohio and Northwest Pennsylvania Tuesday through Wednesday.

MARINE

Ice coverage continues to expand across the western basin of Lake Erie. Hazardous marine conditions across the central and eastern basins will persist into next week as multiple systems move across the Great Lakes.

Southerly to southwesterly winds 15 to 25 knots continue through this evening before diminishing to 10-15 knots. Maintained current Small Craft Advisories but a new set of advisories will need to be issued to cover the next round of elevated winds and waves on Lake Erie. Southwesterly winds will increase to 20-25 knots Saturday afternoon and remain elevated through Sunday. Southwesterly winds increase to 25-30 knots late Sunday into Monday. There remains the potential for gale force winds Monday into Tuesday as winds increase again to 30-35 knots. Given the Arctic airmass moving over the lake and strong winds, heavy freezing spray remains a concern early next week. Winds will gradually diminish to 15-25 knots late Tuesday into Wednesday.

CLE WATCHES/WARNINGS/ADVISORIES

OH...None. PA...None. MARINE...None.