textproduct: Cleveland

WHAT HAS CHANGED

No major changes to the upcoming forecast.

KEY MESSAGES

1) Cooler weather with occasional lake effect rain showers across parts of Northeast OH and Northwest PA into early this week. Locally heavy rainfall is possible, mainly this evening. Elsewhere, scattered showers are possible this afternoon and evening before a prolonged period of drier weather arrives.

2 Scattered showers and thunderstorms return to the forecast Wednesday night through Thursday night. Currently, the potential for severe weather and/or heavy rainfall appears minimal.

DISCUSSION

KEY MESSAGE 1... Surface low pressure across southern Ontario and an upper-level trough over the Great Lakes are expected to become closed off and more vertically stacked while drifting east through tonight. The system will begin to gradually weaken starting on Monday while only slowly exiting through southeast Canada and New England. High pressure will gradually build into the Ohio Valley and eventually across the local area early this week, though lingering influence from the departing closed low won't totally exit our northeastern counties until Tuesday.

The primary weather impact from the departing system will be lake effect/enhanced rain showers occasionally streaming off of Lake Erie into parts of Northeast OH and Northwest PA. Lake water temperatures are near 25C on average, so as 850mb temperatures bottom out at 6-8C late today and tonight, with 700mb temperatures dipping to just below 0C and 500mb temperatures bottoming out around -20C, impressive and deep instability will be in place over the late summer lake waters. Flow will generally waiver between the west and northwest through early Tuesday before shifting more firmly offshore.

We are seeing a flareup of lake effect showers and a few storms during the pre-dawn hours this Sunday morning as an initial vort max and surface trough axis works across the region. There will likely be a lull for several hours later this morning into this afternoon, before another impressive vort max and surface trough cross the lake the first half of tonight. This is expected to bring another, likely more widespread, flareup of lake effect showers and thunderstorms. Lake effect activity is possible as far west as the Islands and Sandusky through early tonight. Thereafter, activity will continue mainly from near the Cleveland metro points east-northeast (and will be most organized across Northwest PA) Monday into early Tuesday, though will likely shut-off farther west of Cleveland as high pressure gradually builds from the west-southwest. Lake effect is not expected to be as intense/organized (and will have decreasing thunder potential) starting late tonight, and may completely stop at times. However, coverage/intensity may briefly increase Monday morning, Monday evening, and perhaps early Tuesday as additional spokes of mid-level energy and surface troughs rotate around the backside of our departing closed low.

After this morning's flareup, the main concern for organized activity that could produce locally heavy rain downwind of Lake Erie in short order is the first half of tonight. Rain amounts will need to be monitored for localized flooding potential if any more stationary bands of lake effect play out, especially over areas that saw heavy rain on Saturday. Lower overall confidence in impactful flooding and a likely limited potential areal scope of any flooding that occurs precludes a Flood Watch at this time. Some storms coming off the lake may produce small hail through early tonight, with the potential for gusty winds with any storms coming off the lake this evening as well. QPF amounts from the eastern Cleveland suburbs and across the core "snowbelt" of far Northeast OH and Northwest PA generally range from 0.50-2.00", which is manageable on its own, though given the very convective nature amounts will vary more than shown in the forecast and can locally end up in the 2-4" range. That would be where an isolated flooding concern can develop.

Across the rest of the area a good scattered of showers is likely late this afternoon and evening as the vort max and surface trough work through. Otherwise, a drying trend is favored into the first half of the week as high pressure builds.

Highs will range from the upper 60s to mid 70s today and Monday, coolest across Northeast OH and Northwest PA (the hills of PA may be stuck in the low-mid 60s most of Monday), with overnight lows largely in the 50s the next few nights. A few outlying areas may get into the 40s Monday night where skies clear. A gradual warming trend begins on Tuesday.

KEY MESSAGE 2.. The next upper trough digs into the Great Lakes Wednesday and Thursday, with weak low pressure tracking well to our north and pulling a cold front through the local area likely on Thursday. This does not look like a very dynamic system, but will bring the next potential for scattered showers and storms. The greatest potential for rain appears to be late Wednesday night into Thursday. Given weaker dynamics and amounts of instability and moisture that appear modest, the risk for severe weather and/or heavy rain with this system is currently minimal.

AVIATION /06Z Sunday THROUGH Thursday/

The main weather message for aviation over the next 24 hours will be impacts from lake effect clouds and lake enhanced showers with isolated thunder possible for NEOH and NWPA. Clouds will increase and ceilings will lower between 3500 and 5000 feet downwind of Lake Erie later this morning for CLE, YNG, CAK, and ERI. Scattered rain showers with isolated thunder possible will come off Lake Erie into NEOH and NWPA starting later this morning. This cloudy and showery weather will continue off and on through tonight for the sites just mentioned. There is general mention of -shra 6sm for most the TAF time period. We did try to highlight the time window of MVFR ceilings and visibility reductions of 3sm to 5sm for the showers later this afternoon into this evening as well as a mention of VCTS. Outside of the favored lake effect impacts to aviation, NWOH will see mostly VFR conditions and ceilings. Winds will be westerly to west- northwesterly increasing 10 to 15 knots later this morning through the evening with gusts up to 20 or 25 knots possible, especially closer to the lakeshore. The gusty winds will relax to 10 knots or less by late evening.

Outlook...Non-VFR conditions will be likely through Monday afternoon with lake effect clouds and lake enhanced rain showers with isolated thunder possible for areas downwind of Lake Erie in Northeast Ohio and Northwest Pennsylvania. VFR conditions will return Tuesday and Wednesday as high pressure builds across the region.

MARINE

Rough marine conditions are expected on Lake Erie today through Monday with gusty northwest winds and higher waves as well as the risk for rip currents along the beaches/lakeshore. West to Northwest winds will be between 15 and 25 knots with gusts up to 30 knots today through Monday afternoon. Waves will increase 3 to 8 feet today through Monday. Waterspouts will be very possible on Lake Erie today through Monday as well. Small Craft Advisories and Beach Hazard Statements for rip currents have been issued through Monday afternoon and evening. High pressure will slowly build in Monday night into Tuesday with conditions on Lake Erie improving. By Tuesday, winds will be westerly to southwesterly 5 to 15 knots and waves decreasing to 1 to 2 feet. The southerly winds will linger into Wednesday 5 to 12 knots and waves of 1 to 2 feet as well. The next weather system to possibly impact marine weather will be a cold front moving through the Great Lakes region by Thursday.

CLE WATCHES/WARNINGS/ADVISORIES

OH...Beach Hazards Statement through Monday afternoon for OHZ009- 010. Beach Hazards Statement through Monday evening for OHZ011-012- 089. PA...Beach Hazards Statement through Monday evening for PAZ001. MARINE...Small Craft Advisory until 5 PM EDT Monday for LEZ144-145. Small Craft Advisory until midnight EDT Monday night for LEZ146>149.