textproduct: Cleveland

SYNOPSIS

Low pressure moving through the northern Great Lakes will extend a warm front across the area today. Strong low pressure will pass north of Lake Erie on Wednesday and extend a cold front across the area. A trough will set up over the lake on Thursday and brief high pressure will enter for Thursday night. The pattern will continue to be unsettled going into the weekend.

NEAR TERM /THROUGH WEDNESDAY/

Plenty of active weather on tap over the next 36 hours as a series of upper level troughs and surface low pressure systems move through the Great Lakes region. For the local area, the main concerns will be light widespread snow across the northern half of the area today, accumulating snow in NW PA tonight into Wednesday, and elevated winds with the second system moving through the region.

A low pressure system is entering Lake Superior this morning with an associated warm front well to the south over Illinois. This front will continue to progress east overnight into Tuesday. On the cold side of the front, snow is expected with support from an upper trough also moving through the Great Lakes region. Overall, the trend with this low and snow has been further north and less impactful, but will continue to time out a band of categorical PoPs for the northern third of the area and a daytime accumulation of up to 0.5" to 1" for areas closest to Lake Erie. Behind the warm front, expecting temperatures to warm considerably from recent days into the 30s for most. There will be a break in precipitation this afternoon and evening, as this first system races away from the forecast area.

The more impressive of the two low pressure systems will arrive tonight and pass north of Lake Erie on Wednesday with an associated cold front tailing through the area Wednesday afternoon and evening. Given moderating temperatures across the region ahead of this system, most precipitation will begin as a rain/snow mix or all rain across the forecast area. The lone exception will be in NW PA, where some trapped near-surface freezing temperatures will remain and the initial precipitation type may be freezing rain/drizzle. Eventually, the residual warm nose will get wiped out and there will be a transition to all snow in NW PA. For much of the area, the rain or rain/snow mix will likely not be too impactful, other than melting some of the snow pack that has lasted a couple of weeks. However, for NW PA, the timing of the system is coming together where there may be an intense band of snow during the pre-dawn hours of Wednesday into the Wednesday morning commute. This will be due in large part to the strong lift from the incoming upper trough and support from the left exit region of the upper jet. The snowfall trend for NW PA continues to trend higher with 3-5" of snow expected before snow mixes with rain late Wednesday morning ahead of the cold front. Therefore, have hoisted a Winter Weather Advisory for Southern Erie and Crawford Counties in PA from 1 AM to 10 PM on Wednesday.

As snow is falling in Northwest PA, the surface low will be passing north of Lake Erie and extending a cold front across the area. Ahead of this front, a strong low level jet will be moving through the region and should do fairly well mixing to the surface and suspect that there will be southwest wind gusts in the 40 to 45 mph range. There are some probabilities suggesting that surface wind gusts could reach 50 mph for NW OH and the Lake Erie shoreline areas and a wind advisory would be needed if trends increase. With the frontal passage itself, there will be a quick drop in temperatures and a rapid change to snow for the area. Snow accumulations for areas outside of NW PA with the front would be up to 0.5" of new snow. High temperatures on Wednesday will be earlier in the day before the front in the 30s and perhaps some lower 40s.

SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/

The main forecast question for Wednesday night through Thursday night will be how much lake effect snow will there be in Northeast Ohio and Northwest PA before winds back ahead of the next system on Friday. The thermodynamics for lake effect snow appear pretty good early on with -12 to -14 C at 850 mb and some residual remaining across the region. There will also be northwest flow over the area, which will be a shorter fetch for Lake Erie but allow for Lake Huron to potentially get involved for a stronger multi-band setup. At this point, there is uncertainty on where a stronger band would be with the average location likely on the NW/PA border. Backing winds with time would shift these bands further east and snow activity within the forecast area would shrink with time and become just light snow showers. If a more dominant band appears likely to to impact NE OH/NW PA, the Winter Winter Advisory will likely need to be extended/expanded as needed for Wednesday night into Thursday.

A weak low pressure system will move through the Ohio Valley on Friday and bring a band of widespread snow to the forecast area. Right now, believe that there could be an inch or so of new snow for the entire area. This system will bring a touch warmer low level temperatures and this may allow for any lake effect behind this system to be slower to start until later into the weekend.

LONG TERM /SATURDAY THROUGH MONDAY/

For the weekend into next week, the pattern returns to very cold with more lake effect snow for NE OH/NW PA. A strong upper trough will dig into the Great Lakes region and extend a cold front through the area on Saturday morning. This will allow for a more favorable air mass to tap into the residual moisture from Friday's low pressure system and allow for some accumulating lake effect snow in NE OH/NW PA. There is still plenty of uncertainty with the placement, timing, and intensity of snow, but the weekend will have some snow activity to be concerned about. The broader impacting feature will be temperatures returning to the teens/20s for highs and lows in the single digits/teens. Winds will be elevated over the weekend, so wind chills near or below zero are on the table. There could be some reprieve later next week with high pressure eventually entering the region and moderating some temperatures and allowing lake effect to break up a bit.

AVIATION /06Z Tuesday THROUGH Saturday/

High pressure over the area departs to the east, with VFR conditions continuing through the overnight hours. A warm front will be accompanied by a band of light to moderate snowfall tracking eastward across the area Tuesday morning through early Tuesday afternoon. There is some uncertainty with how far south this band of snow will extend, with confidence higher in a 1-2 hour period of IFR visibilities across the northern part of the forecast area (including KTOL, KCLE, and KERI). Visibility could briefly reach as low as 1/2 SM to 1 SM in the heart of the snow band across our the northern forecast area. There is lower confidence across the southern portion of the forecast area where visibilites may remain above 3 SM (or at least IFR visibilities will be more brief).

As the warm front crosses the area, strong southwest winds of around 15 knots with gusts to 25 knots expected areawide. Stronger peak wind gusts of up to 30-35 knots may be possible at western sites such as KTOL, KFDY, and KMFD and along the lakeshore (e.g. KERI). OVC/BKN will remain across much of the area, with FEW/SCT possible across the southern portion of the area. Cloud bases will be around 3500-5000 ft.

Precipitation associated with the main low pressure system will move in from the west Tuesday night, resulting in gradually lower ceilings to primarily MVFR initially. Precipitation type is going to be a forecast challenge for Tuesday night when precipitation will fall as a mix of rain and snow, with a low chance of freezing rain with the initial first few hours of precipitation. Warmer temperatures will exist to the southwest, which is where all rain is most likely (e.g. KFDY). The farther north and east you get, the more likely it is to mix in snow (KTOL, KCLE, KMFD, KCAK) and/or be all snow (KERI/KYNG). The low chance of freezing rain is most likely at KMFD, KCAK, and KYNG.

Outlook...Non-VFR is expected with snow Tuesday night which will gradually transition to rain by Wednesday morning. Rain will transition back over to snow Wednesday evening. Periods of snow will be possible Thursday through Saturday, especially in Northeast Ohio and Northwest Pennsylvania. Strong southwest to west wind gusts up to 30 to 40 knots are possible Wednesday.

MARINE

Unsettled and rough marine conditions are expected on Lake Erie today through the end of the week and possibly into the weekend. A low pressure system will track across the Upper Great Lakes region today increasing the southerly flow over Lake Erie 15 to 25 knots and waves building, especially in the open water. A stronger low pressure system will deepen to 29.20 inches as it tracks through the Great Lakes late tonight into Wednesday. Southwesterly winds will increase 35 to 40 knot Gales late tonight and Wednesday. Waves will build to 8 to 13 feet in the open water late tonight through Wednesday evening. There are Small Craft Advisories in effect today into tonight. Gale warnings will take in effect late tonight through Wednesday evening. As the strong low pressure system exits the region Wednesday night, the flow will become west-northwestlery 15 to 25 knots. Additional SCA will be needed after the Gale Warning expires Wednesday night through Thursday.

High pressure will build in over Lake Erie Thursday night into Friday with a brief lull in the winds and waves. Another clipper system and cold front will sweep across the Great Lakes on Saturday with a return of Westerly winds 15 to 30 knots and higher waves. Additional SCA will likely be needed this weekend.

CLE WATCHES/WARNINGS/ADVISORIES

OH...None. PA...Winter Weather Advisory from 1 AM to 10 PM EST Wednesday for PAZ002-003. MARINE...Small Craft Advisory from 7 AM this morning to 4 AM EST Thursday for LEZ142. Small Craft Advisory from 7 AM this morning to 4 AM EST Wednesday for LEZ143>149. Gale Warning from 4 AM to 7 PM EST Wednesday for LEZ143>149- 163>169.