textproduct: Cleveland

WHAT HAS CHANGED

The conditional severe weather threat remains on track for today, depending on how our area recovers from incoming rain and clouds this morning. There is very high confidence in the need for frost/freeze headlines on Sunday and Monday nights.

KEY MESSAGES

1) Showers with some thunderstorms with severe potential are expected this afternoon, mainly between Noon and 6 PM. Damaging wind gusts, large hail, and a tornado or two are all possible with storms. The greatest potential for severe storms is in Northeast Ohio and Northwest Pennsylvania.

2) A cold air mass enters for Sunday and Monday, bringing below normal temperatures to the area. Residual rain will be in place on Sunday with some changeover to snow on Sunday night. The colder air will allow for frost/freeze potential on Sunday and Monday nights.

DISCUSSION

KEY MESSAGE 1... Early this morning, a QLCS line of storms is moving across Indiana, weakening as it pushes east into a more stable atmosphere. Storms are beginning to transition to an elevated status as a strong outflow boundary is developing and pushing ahead of the main convective cores. The remnants of this line of thunderstorms will enter Northwest Ohio later this morning and continue eastward, modifying the air mass ahead of the cold front today.

The main show for today will begin closer to the Noon hour as a new round of showers with some thunderstorms will develop with energy moving aloft ahead of the main cold front. This boundary will be the feature where showers and storms focus on redeveloping in North Central Ohio. The wind field ahead of the front will be favorable for severe weather with 40-50 kts of southerly 925 mb flow and 60-70 kts of westerly 500 mb flow aloft that will sustain storms. However, the question of the day just comes down to thermodynamics of the atmosphere for the amount and intensity of thunderstorms. The region dried out significantly on Friday and surface dew points are barely reaching 50 degrees early this morning. The remnant convection entering this morning will add some moisture to the region, but there will be some dependency on the southerly low level jet to try and advect better moisture into the region. The other question will then be how much instability will be in place. The remnant convection this morning will introduce clouds and may taper afternoon temperatures. Therefore, mid-to-upper 70s may only be achieved in the eastern third of the forecast area, which is where any activity could pick up later today.

In short, the severe threat for today remains conditional for the eastern two-thirds of the area with the potential for an organized severe weather threat or busting to just be some perky showers and some embedded thunder with the cold front. The area remains outlooked with a Slight Risk from SPC and all severe hazards remain possible, although damaging winds will be the most likely threat. The timing for the strongest storms remains focused in the Noon to 6 PM time frame. Rain chances will persist behind the main convection tonight with the upper trough moving through the region.

KEY MESSAGE 2... This evening's cold frontal passage will be a jolting change after several days of 70 and 80 degree high temperatures. Once clouds and precipitation move out of the region, temperatures will fall into the 30s across the area tonight. If winds can settle down a bit, there is even a small chance for the need for additional frost mention in the forecast and maybe a Frost Advisory for western areas.

For Sunday, a residual trough over the area will allow for light, scattered rain showers to continue, mostly focused in the upslope areas, downwind of Lake Erie in NE OH and NW PA. On Sunday night, colder air aloft along with some lake enhancement will allow for rain to persist in NE OH and NW PA with some changeover to snow becoming more likely and have push more snow mentions in the forecast. Overall, accumulations will be negligible, given warm surface/pavement temperatures that will need to be overcome. High temperatures on Sunday will be a mix of upper 40s to mid 50s. Low temperatures on Sunday night will be in the upper 20s and lower 30s with widespread frost expected. The growing season is in effect for the entire forecast area and Frost/Freeze headlines will be needed for a large portion of the forecast area.

Dry conditions are expected for Monday with incoming high pressure. High temperatures will be cool in the 40s. Lows on Monday night will be in the 20s and 30s with widespread frost expected again. Another round of Frost/Freeze headlines will be needed for the area.

AVIATION /12Z Saturday THROUGH Wednesday/

The main concerns for aviation weather over the next 24 hours will be the scattered convection associated with the cold front moving through the area today. Conditions will eventually become MVFR later this morning through the afternoon. The timing of the potential for scattered convection is mentioned in the TAFs from east to west during this morning through the afternoon. TEMPO groups are highlighting the timing of potential impacts of MVFR to Lower end MVFR due to the convection. Behind the front, MVFR ceilings and scattered showers are expected through this afternoon and evening. Winds will increase through this morning 10 to 15 knots with gusts up to 25 knots. By midday into the afternoon, winds will become southwesterly 15 to 20 knots with gusts up to 30 knots. The gusts will relax after 00z this evening but remain westerly around 10 to 12 knots.

Outlook...Brief/spotty non-VFR possible in scattered rain and snow showers early Sunday morning through the first half of Sunday night. Non-VFR possible Tuesday night and Wednesday in rain showers.

MARINE

Southerly to southwesterly winds will increase Saturday morning through the afternoon 15 to 20 knots ahead of a cold front. Behind the cold front Saturday night, winds will become westerly 15 to 20 knots. A Small Craft Advisory will likely be needed Saturday night into Sunday. Winds on Sunday will be westerly 15 to 20 knots then oscillate between westerly to northwesterly while dissipating to 10-15 knots by Sunday night as high pressure builds overhead. By Monday, winds will be northwesterly around 10 knots. A southerly flow of winds 10 to 20 knots will return late Monday night into Tuesday.

CLE WATCHES/WARNINGS/ADVISORIES

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