textproduct: Cleveland

WHAT HAS CHANGED

A low end potential for severe weather remains for much of the area today. The best window for strong to severe thunderstorms is 3 to 10 PM today. Sunday night is trending a bit warmer, likely limiting frost potential, but Monday night is trending cooler and widespread frost/freeze conditions are becoming more likely.

KEY MESSAGES

1) An initial round of rain will exit east this morning. Another round of showers and thunderstorms are expected this afternoon and evening. Storms could reach strong to severe limits.

2) Dry weather with below normal temperatures are expected early next week with frost/freeze chances increasing for Monday night.

3) Another system will enter for the middle of next week, bringing additional rain chances to the region. Some storms and moderate rainfall could be possible on Tuesday night into Wednesday.

DISCUSSION

KEY MESSAGE 1... Shower activity will continue across the southeastern half of the forecast area this morning, bringing another 0.10-0.30" of rain from Mansfield to Meadville and southeast. Behind this rain, there should be a dry window for much of the area through the early afternoon hours. This will allow for the atmosphere to recover well in the warm sector with temperatures returning into the 60s and even lower 70s for some, mainly where the sun can find its way through the clouds for a couple of hours. There should also be some decent mixing in the warm sector as well with southwest winds gusting 25 to 30 mph. This improved air mass will be present later today ahead of a cold front that will approach the region from the northwest. A new round of convective activity should develop well ahead of the front by mid-afternoon, as a stronger shortwave moves through the broader trough aloft. This activity will tap into a marginally unstable air mass and allow for widespread showers and some thunderstorms to move across the region later today.

The main question is: Could storms become organized and pose a strong to severe weather risk today? The answer to that question will fully rely on the atmosphere recovery this morning and early afternoon. If temperatures trend warmer into the 70s, suspect that there will be more storm activity and potential for severe weather as MLCAPE values can get over 1000 J/kg. If recovery is slower with more cloud cover across the region, then temperatures may not reach 70 degrees and instability would be less conducive for severe weather. Outside of instability factors, there will be good jet support aloft and broader shear to sustain thunderstorms if they can get going this afternoon. If storms do develop, the main threats would be damaging wind gusts and large hail, especially with fairly low freezing levels across the region. A Marginal Risk of Severe Weather from the Storm Prediction Center remains across the area for today and continues to convey the conditional storm threat.

Rain will continue across the area tonight into Sunday with support from the upper trough aloft and the main cold front sweeping through the region. The loss of daytime heating should allow for convection to switch to just rain tonight. QPF totals could be up to a half inch of rainfall for this afternoon into tonight with a low potential for more where rain persists.

KEY MESSAGE 2... Cool high pressure will enter the region starting on Sunday afternoon and remain over the area through Tuesday morning, allowing for 36-48 hours of dry weather across the region. This will also promote several periods of below normal temperatures. Clouds will remain across the region on Sunday night with the Saturday system departing to the east. This may keep low temperatures more in the lower 40s vs. mid-to-upper 30s and may limit the overall frost threat across the area. High pressure solidly across the area on Monday night and should allow for a clear, calm, and decoupling atmosphere and low temperatures in the 30s should be anticipated. Frost, if not freeze, headlines are becoming more likely on Monday night for a large portion of the forecast area. High temperatures on Monday will be in the 50s. Highs on Tuesday will be in the 50s and 60s with high pressure moving out and some return flow entering the region.

KEY MESSAGE 3... The pattern will return to unsettled for the middle of next week with a low pressure moving through the Great Lakes region. Rain chances will be expected from Tuesday night through Thursday with the system. The initial arrival of the system during the night on Tuesday should limit thunderstorm activity but will continue some slight chances of thunder, mainly out west. Otherwise, just rain will be expected for Wednesday and Thursday at this time. There could be some moderate rain on Tuesday night into Wednesday morning and will need to watch for trends with that part of the forecast for any future flood concern. Rain will be lighter later with the system.

AVIATION /06Z Saturday THROUGH Wednesday/

Cyclonic W'erly flow aloft and embedded disturbances affect our region through 06Z/Sun. At the surface, net troughing lingers for the time being and a cold front should sweep generally SE'ward across northern OH and NW PA between ~22Z/Sat and ~05Z/Sun. Behind the front, a high pressure ridge builds slowly from the Canadian Prairies and vicinity through 06Z/Sun. Ahead of the cold front, our regional surface winds trend S'erly to SW'erly around 5 to 15 knots and should gust up to 20 to 25 knots at times, especially late this morning through early evening. The cold front passage will cause our regional surface winds to veer to W'erly and be around 5 to 10 knots for several hours. Farther behind the surface front, surface winds should become light and variable as the MSLP gradient weakens in response to the building surface ridge.

Scattered light to moderate rain showers associated with one of the aforementioned disturbances aloft continue to exit generally E'ward from our region through ~10Z/Sat. Visibility will vary between VFR and IFR in this rain. Otherwise, widespread ceilings are expected to range between about 5kft AGL and IFR through ~14Z/Sat. Behind this morning's rain, subtle breaks in the low-level cloud cover, weak surface winds, and sufficient low-level moisture should allow radiation mist with visibility in the MVFR to IFR range to form through ~12Z/Sat. The mist and low ceilings are then expected to give way to widespread VFR by ~14Z/Sat, following the onset of diurnal convective mixing of the boundary layer. Scattered rain showers and thunderstorms along and ahead of the surface cold front should impact our region between ~19Z/Sat and ~05Z/Sun as the convection persists generally E'ward. These showers and storms should be accompanied by brief MVFR to LIFR and generate brief/erratic surface wind gusts up to 30 to 50 knots. Following the surface cold front passage, additional scattered rain showers associated with the upper-reaches of the front remain possible through 06Z/Sun. Widespread ceilings near 3.5kt to 6kft AGL are expected along the upper-reaches of the front.

Outlook...Scattered rain showers with non-VFR are possible overnight Saturday night into Sunday morning. Periodic showers and thunderstorms with non-VFR are expected this Tuesday afternoon through Wednesday.

MARINE

S'erly to SW'erly winds around 5 to 15 knots are expected on Lake Erie through this afternoon as the axes of subtle troughs advance E'ward across the lake. These winds may flirt with 20 knots at times this afternoon. During this evening through tonight, a cold front should sweep SE'ward across Lake Erie and cause SW'erly winds around 5 to 15 knots to veer toward NW'erly. However, these winds may flirt with 20 knots at times early this evening. Waves should trend 3 feet or less, but occasional 4 footers are possible this afternoon and evening.

Behind the cold front, a ridge should affect Lake Erie as the embedded high pressure center moves from the Canadian Prairies toward Atlantic waters near NC on Sunday through Tuesday. Primarily NW'erly to N'erly winds around 5 to 15 knots on Sunday through Monday should become variable in direction Monday night through Tuesday. Waves should trend 3 feet or less.

The ridge should exit E'ward Tuesday night through Wednesday as a low wobbles ESE'ward from the northwestern Great Lakes toward Lake Ontario and weakens gradually. Accordingly, a warm front should sweep NE'ward across Lake Erie Tuesday night through Wednesday morning and cause SE'erly winds around 15 to 25 knots to veer to S'erly to SW'erly. A cold front should then sweep E'ward across Lake Erie late Wednesday morning through Wednesday evening and cause winds to veer to W'erly to NW'erly as wind speeds ease to around 10 to 20 knots. Waves should primarily be 4 feet or less, but occasional 5 to 6 footers are possible and forecast trends may eventually require a Small Craft Advisory.

CLE WATCHES/WARNINGS/ADVISORIES

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