textproduct: Cleveland

WHAT HAS CHANGED

The low pressure has trended weaker over the past couple of forecast runs leading wind gusts tending lower for Friday.

KEY MESSAGES

1) There will be a chance for thunderstorms as a warm front lifts north across the region tonight. A few storms could produce strong gusts upwards of 50 MPH.

2) A cold front will sweep through the region early Friday as low pressure moves through the Great Lakes bringing the chance for rain and gusty winds.

3) Coldest air of the season is expected Friday night and Saturday night with frost/freeze conditions expected on Sunday morning.

DISCUSSION

KEY MESSAGE 1... Low pressure will begin to develop in the Mid-Mississippi Valley midday today and deepen to the northeast into the Great Lakes by late this evening. Ahead of this low, a warm front will lift north across the region late tonight into the early overnight hours. The majority of the region should remain dry through much of the day as showers and thunderstorms will enter Northwestern Ohio by 6-8PM this evening and move eastward. The chances of thunderstorms will decrease further east as we move into the late overnight hours and instability will wane. On the note of instability, temperatures through out the day will warm into the low 70s with dewpoints climbing into the low 60s by late this evening. This will lead to marginal instability, in the for of a few hundred J/kg along and behind the warm front. Additionally, a strong low level jet of 40-50 knots out of the southwest will accompany the warm front as it moves north. 0-6km Bulk shear of around 50 knots is also expected with the low level jet. With this, there is potential for a few stronger thunderstorms to produce wind gusts of 50 MPH or greater. Though poor lapse rates across the region will limit how much of the low level winds mix down and limiting the overall severe weather threat. Currently, SPC has much of North-Central Ohio within a Marginal Risk for this time period. Severe weather threat should dissipate later into the overnight as precipitation chances decrease as well with the departing warm front.

KEY MESSAGE 2... The associated cold front from the low pressure system will sweep through the region west to east Friday morning into the afternoon. Showers and scattered thunderstorms are expected with the front as it moves through with widespread accumulation expected. Currently expecting around 0.25-.50" of accumulation with higher amounts possible within thunderstorms. The low level jet and low pressure itself has trended weaker over the past couple of model runs. This is leading to wind gusts and winds overall being lower, even with the strong CAA behind the front. Winds are still expected to be 15- 20 MPH with gusts over 30 MPH possible. The strongest timeframe for winds will be after midnight Friday through early Saturday morning when the winds shift to be out of the north with a secondary trough moving through. The strongest winds are expected to be along the lakeshore, generally from the Islands east through Lake County with gusts around 35-40 MPH. Winds will begin to subside Saturday morning as high pressure begins to build in from the west.

With the secondary trough moving through and winds shifting to be out of the north, lake effect showers are possible across Northeastern Ohio and Northwestern Pennsylvania. An additional couple tenth of rain is possible with these linger showers, primarily around Cleveland and south through Akron due to the connection from Lake Huron with the northerly winds. The lake effect showers should linger into Saturday afternoon and begin to dissipate as drier air moves in with the upper level ridge. Dry weather is expected through the remainder of the weekend into early next week.

KEY MESSAGE 3... Behind the cold front, much colder air will be advected into the region with the northwest the north flow Saturday into early Sunday. Temperatures Friday night into Saturday morning will drop down into the mid to upper 30s with areas near the lakeshore staying in the 40s. Temperatures have trended a few degrees warmer for the region, so there is less confidence in needing frost headlines for Saturday morning. Northwestern Pennsylvania will be the coldest location in the CWA with temperatures in the mid 30s, but winds being 10-15 MPH throughout the night may inhibit frost formation.

Saturday night into Sunday morning will have more widespread temperatures at 36 degrees or lower. High pressure will have built in across much of the region at this point with only some lingering cloud cover and winds becoming light at less than 5 MPH allowing for decent radiational cooling. Trends still have the areas east of the I-71 corridor away from the lakeshore with an over 50% chance of seeing temperatures below freezing. Frost conditions are likely elsewhere with lower probability near the lakeshore given the lake is still relatively warm. Temperatures will begin to moderate to more seasonal highs and lows starting Sunday as the high pressure builds to the east and southwesterly flow moves into the region.

AVIATION /12Z Thursday THROUGH Monday/

A warm front is expected to lift across the area this evening, quickly followed by a cold front early Friday. Most sites remain MVFR due to ceilings this morning. MVFR ceilings will be most common today, though they'll bounce up and down some and there will likely be a period of modest improvement this afternoon in which some sites will try going VFR. MVFR ceilings become more widespread this evening as the warm front sweeps through, with showers likely as well. Some heavier showers can bring brief MVFR visibility with isolated thunder also possible. Have some PROB30 groups for lower vis and/or TSRA potential for a few hours late this evening into the overnight at most sites. The cold front will likely sweep through TOL/FDY near the end of the TAF period (12z Friday) and the remaining sites shortly thereafter. Showers with some vis restrictions will likely fill in along and behind the cold front, with ceilings mainly remaining MVFR but perhaps briefly IFR at a few sites.

Winds will gradually shift to the east-southeast through the day today, and then more south-southwest behind the warm front this evening into tonight. Winds shift west-northwest behind the cold front into Friday. Speeds will generally remain 10 knots or less through today before increasing to 10-15kt with some 25-30kt gusts behind the warm front tonight. A 40-50kt low-level jet will overspread the area overnight tonight. Forecast soundings do no show a strong low-level inversion so it's unclear if we'll see true low-level wind shear or if gusts/turbulence will be more common. For now left the LLWS out of TAFs, though future cycles may need to include it and either way conditions will be noticeable on takeoff/landing.

Outlook...Occasional non-VFR expected to continue in periods of rain showers and lower ceilings through Friday night. Winds may gust over 30kt at times Friday afternoon through early Saturday.

MARINE

Winds and waves from the Islands through Willowick, OH will continue to decrease over the next few hours so the Small Craft Advisory has been canceled early. Winds throughout today will be out of the east at 10-15 knots, then shifting to the south-southeast and increasing to 20-25 knots as a warm front lifts north across the lake late this evening. A low pressure system will move north of the lake tonight into Friday sweeping a cold front though early Friday morning. Winds will shift around to be out of the northwest at 20-25 knots Friday morning through the afternoon. Waves will build to 6-9 feet across the lake as a result.

A secondary trough will move across the lake Friday evening and winds will shift to be out of the north at around 25-30 knots and waves will build to 7-11 feet. The probability of gales across the central basin as decrease due to the low pressure system trending weaker than previously. Though, wind gusts exceeding 34 knot gales are still possible and Small Craft Advisories will be needed for Friday and Saturday. Elevated winds will persist through Saturday morning when they diminish to around 15-20 knots by midday. Winds will continue to diminish into Saturday evening to around 5-15 knots and shift to be out of the northwest with waves diminishing as well with high pressure builds into the region. Winds will increase out of the southwest early Sunday morning to 10-15 knots and persist through Monday.

CLE WATCHES/WARNINGS/ADVISORIES

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