textproduct: Cleveland

WHAT HAS CHANGED

A couple strong to sever thunderstorms are possible this evening into the overnight with large hail possible. Strong gusty winds are likely behind a cold front on Friday. A colder weather pattern will return this weekend and continue into next week with scattered chances for light snow.

KEY MESSAGES

1) A developing storm system over the Ohio Valley will bring the scattered showers and thunderstorms this evening into overnight. A couple strong to severe storms may be possible with large hail as the main threat.

2)Strong gusty winds from the West will follow the passage of a cold front Friday morning.

3) Colder and seasonable-like temperatures will return this weekend through next week along with chances for scattered snow showers.

DISCUSSION

KEY MESSAGE 1... The unseasonable mild weather over the region will give fuel to a developing storm system over the Ohio Valley this evening into overnight. There is a stalled frontal boundary that stretches from NWOH eastward along southern lakeshore of Lake Erie this afternoon. North of this boundary, temperatures are stuck in the 30s. South of this surface boundary, temps have climbed into the upper 50s and lower 60s. A developing surface low is currently over the Cornbelt region of the Midwest. This low pressure system will deepen as it track northeastward towards Lake Michigan tonight.

Our attention later this evening into the overnight will be watching the strong to severe convection that is currently developing over the lower and central Ohio Valley this afternoon. The better thermodynamics and setup for severe weather will remain southwest of our local area down closer to the Ohio River this afternoon and evening. That area of stormy weather will eventually move northeast into northern Ohio and northwest Pennsylvania late this evening through very early Friday morning. We are expecting this convection to weaken for the most part as it moves into our local area later tonight. Scattered "general" thunderstorms are very possible tonight. There is a limited or marginal threat for a couple stronger storms with large hail as the main severe weather hazard. Average QPF expected this evening through early Friday morning will be a quarter to half an inch of rainfall.

KEY MESSAGE 2... A strong low pressure system will deepen to around 988 mb by later Friday morning over central Lake Michigan. A rather strong cold front will sweep from west to east across the area Friday morning. The cold frontal passage will be around 12z for NWOH and quickly push eastward and pass through NWPA before noon. Temperatures will start off mild in the 50s Friday morning and steadily fall after the cold front passage into 30s by late afternoon and evening. Later in the Friday afternoon and evening, scattered snow flurries or snow showers will be possible as the cold air advection and wrap around moisture from the storm system pushes into the area. There will likely be a good push of gusty winds up to 45 mph with the actual cold front pushing through. Gusty west winds will follow the frontal passage through the rest of the day Friday 20 to 30 mph with gusts over 40 mph for NEOH and NWPA. We have issued a Wind Advisory for areas along and west of I-71 for strong winds of 25 to 35 mph with gusts up to 50 mph possible on Friday.

KEY MESSAGE 3... Forecast model guidance shows a big weather pattern change with an upper level trough developing over the Great Lakes and eastern U.S. this weekend into next week. This pattern with the trough over the region will bring colder but seasonable temperatures for the middle and end of February. The trough over the Great Lakes will favor colder air moving over the lakes which will develop scattered lake effect snow showers this weekend continuing through Monday night or early Tuesday. Light snowfall accumulations of a few inches could be possible for the favor Snowbelt region. High temperatures will generally be in the 30s and overnight low temperatures in the teens and 20s.

AVIATION /06Z Friday THROUGH Tuesday/

Shield of rain/decaying thunderstorms will move across the region tonight with IFR effects expected as it does so. Occluded/cold front moves through in the wake of this precipitation with ceilings improving to MVFR, and even scattering out to VFR for a few hours possibly in the afternoon Friday. Clouds move back in with MVFR, and possibly light snow for CLE/CAK east for a few hours after 21Z in the cold air advection and returning low level moisture. Winds will also increase with gusts 30-40kts in the wake of the front through much of the remainder of the TAF period.

Outlook...Expect periods of non-VFR conditions throughout the weekend, with the snow returning Sunday and Monday enhanced by a vigorous coastal low pressure system exiting the Mid Atlantic. High pressure will build across the region Tuesday.

MARINE

A nearly-stationary front should linger near the southern shore of Lake Erie through tonight. Just north of the front, the air mass at and near the surface is exhibiting small dew point depressions and is slightly warmer than ~32F Lake Erie. As a result, fog is lingering over Lake Erie, especially west of Vermilion, OH, where the Dense Fog Advisory is now in effect until 4 AM EST Friday. Easterly winds around 10 knots late this evening become easterly to southeasterly and freshen to around 10 to 20 knots during the predawn hours of Friday morning. These freshening winds and the arrival of rain are expected to scour-out any lingering fog during the first few predawn hours of Friday morning.

For Friday, a low pressure system will advance the stationary front north again with some oomph in a 45 kt low level jet and some warm advection once again to get temperatures into the 50s. This will allow for ice to continue to weaken across the lake and strong southwest winds around 25 to 30 kts will allow for movement of the ice fields. Any ice floes will be hazardous to folks on Lake Erie and may block or close established shipping channels. People are urged to stay off the Lake Erie.

The low pressure system will weaken over the region on Saturday and southwest flow will fall to around 10 to 15 kts. A strong low pressure system will move up the East Coast on Sunday into Monday and enhance the pressure gradient of the trough over the region, allowing for 15 to 20 kts of northwest flow on Sunday and Monday.

CLE WATCHES/WARNINGS/ADVISORIES

OH...Wind Advisory from 7 AM to 7 PM EST Friday for OHZ003-006>012- 017>020-027>030-036-037. PA...None. MARINE...Dense Fog Advisory until 4 AM EST Friday for LEZ142>144- 162>164.