textproduct: Cleveland

WHAT HAS CHANGED

No major changes to the forecast for this update.

KEY MESSAGES

1) Showers and isolated thunderstorms are expected early this morning with the passage of a cold front.

2) Strong low pressure expected Friday bringing widespread rain, strong winds, and the coldest air of the season so far. Frost/freeze headlines possible Friday night and likely Saturday night.

DISCUSSION

KEY MESSAGE 1... A weak low pressure system has moved off to the northeast this morning with the associated cold front moving across Northern Ohio currently. Along this front, showers and thunderstorms have moved eastward into Northern Ohio and should continue east-southeast through the morning hours. Temperatures and dewpoints across the region are in the mid to upper 60s and upper 50s to low 60 respectively. Current Mesoanalysis has MUCAPE of around 500 J/kg or less across the region and 0-6km bulk shear of 45-55 knots where the thunderstorms are located. There's ample DCAPE out ahead of the front of around 1000, including a plume over the central basin of Lake Erie. With the lake being fairly warm still, around 18C, this may assist in some thunderstorms over the lake becoming more organized in the coming hours. With that being said, severe chances are fairly low for this event and if a storm or two does become more organized then strong winds will be the main impact.

The cold front will sag southward over the next several hours before settling across the Ohio Valley by midday today. There will be potential of moderate to heavy rain with it as it does push south, though should be isolated. As the front settles, areas south of the US30 corridor may see periodic showers through this evening. Overall, not expecting much in terms of rain accumulation for the region, with most areas staying around a few tenths to 0.25 inch. Exception would be the areas south of the US30 corridor which could see up to 0.50 inch. Rain will trend further south throughout the day as high pressure begins to build in from the north. Brief period of dry weather is expected until Thursday afternoon.

KEY MESSAGE 2... An upper level trough will begin to deepen across the Canadian Prairies Thursday night into Friday and push eastward into the Great Lakes region by Friday afternoon. The associated surface low pressure system will develop across the Mid-Mississippi Valley Thursday evening morning northeast towards the Great Lakes. The cold front that settled across the Ohio Valley today will lift north as a warm front Thursday evening into Friday night. Showers and thunderstorms will develop along this warm front and move into Western Ohio by Thursday evening, moving eastward into Friday. Given the timeframe the warm front lifts north, there will be little instability across the region and a low level inversion setting up with weak lapse rates. Though, low level winds will be fairly strong behind the front as the surface low begins to rapidly deepen. Low level winds will be 40-50 knots with 0-6km bulk shear around 50-60 knots. With this, isolated strong to severe wind gusts will be possible into early Friday morning.

The surface low pressure will continue to deepen throughout the day Friday as it moves eastward through the Great Lakes. The associated cold front will pass west to east across the region during the day Friday as well and should be clear of the CWA by Friday evening. Severe weather is not expected with the cold front as it moves through. There may be some lingering lake effect rain across Northeastern Ohio and Northwestern Pennsylvania into early Saturday morning with the northerly flow. Some snowflakes could be mixed in as well depending on how quickly the precipitation moves out. Though, given the rapidly deepening low pressure system, the pressure gradient will increase behind and winds increase as well. Winds will be 15-25 MPH with gusts over 40 MPH from midday Friday through the early overnight hours behind the cold front. CAA across the region will help in mix down the strong low level winds. Winds may reach advisory criteria briefly Friday evening, main areas will be along the lakeshore from Lorain County eastward and in Northwestern Ohio. Will need to assess the need for an advisory in in the coming days.

With the strong CAA behind the cold front and low pressure system, it will bring in the coldest air of the season so far. Overnight lows Friday night will be in the mid to upper 30s across much of the region. Areas across far Northeastern Ohio and Northwestern Pennsylvania may reach freezing temperatures. Widespread Frost Advisories and targeted Freeze Warnings will likely be needed for that night. Winds may be the a factor keeping frost from occurring widespread as they will still be elevated 10-15 MPH for most of the overnight period. Saturday night will bring more widespread temperatures of near or below freezing. Highest probabilities of temperatures at 32 degrees or below will be east of the I-71 corridor and away from the lakeshore. Winds will have calmed more at this point, and with high pressure building in with clearing skies, confidence is higher in widespread frost/freeze headlines for this period.

With the high pressure building into the region on Sunday, temperatures will begin to moderate back to a more seasonal level to start next week. Dry weather is also expected from Sunday through early next week.

AVIATION /06Z Wednesday THROUGH Sunday/

A cold front currently resides across northern Indiana, northwest Ohio and across Lake Erie. Showers and thunderstorms have developed near this cold front across parts of Northwest Ohio (and further west), and should continue expanding eastward towards the rest of the forecast area late tonight into Wednesday morning. Thunderstorms will be accompanied by visibilities down to 1-3 SM, and gusts up to 12-20 knots possible (but gusts are unlikely).

As the cold front sags southward, precipitation chances will as well, with low ceilings (700-1,500 ft) filling in north of the front. After the wave of thunderstorms clears out this morning, some scattered rain showers may persist into the afternoon hours, though it's pretty uncertain how far north. There is also uncertainty in the amount of IFR ceilings that develop north of the cold front but is most likely farther north and east within the forecast area. Ceilings should primarily becoming MVFR by late afternoon through the rest of the TAF period.

Outlook...Intermittent non-VFR is likely Thursday afternoon through Friday night with wind gusts exceeding 30 knots on Friday.

MARINE

Winds across Lake Erie are currently out of the north at 10-15 knots after a cold front passed north to south early this morning. Winds will increase throughout the day to 10-20 knots and veer to be more out of the northeast. Waves will briefly build as well to around 3 feet west of the Island to Lake County. By Thursday morning, winds will have shifted to be out of the east at 10-15 knots, then shift out of the south late Thursday evening as a warm front moves north over the lake. A strong low pressure system is expected to move north of Lake Erie early Friday morning dragging a cold front across the lake through Friday afternoon. Winds will shift to be out of the northwest behind the cold front and increase as the low pressure system deepens rapidly to the northeast. Winds will be 25-30 knots across the lake beginning Friday midday through Saturday morning. Gale force winds will be possible from the Islands eastward through Conneaut, OH late Friday afternoon through early Saturday morning. A combination of Small Craft and Gale Warning headlines will be needed beginning early Friday morning through Saturday afternoon.

High pressure will build in Saturday afternoon with winds and waves beginning to diminish. There will still be a moderate pressure gradient across the lake into early next week, so winds will stay between 10-20 knots out of the southwest through Monday.

CLE WATCHES/WARNINGS/ADVISORIES

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