textproduct: Cleveland

WHAT HAS CHANGED

Scattered showers with isolated thunder have developed across portions of the Mahoning Valley this evening. Increased the potential for showers through sunset in this area. No severe weather is expected.

KEY MESSAGES

1) Chances for showers and thunderstorms increase today with severe weather potential late tonight and late Monday evening. Afterwards, periodic showers possible across NE OH and NW PA into Wednesday.

DISCUSSION

KEY MESSAGE 1... The upper level ridge across the Central CONUS continues to build as a series of shortwaves move around the northern periphery through the middle of the week. Firstly, there is a slight chance for diurnal showers and thunderstorms this afternoon into the evening, though coverage should be minimal. Late tonight into early Monday morning, the first of the shortwaves will move just west of the region and precipitation chances will increase. Current guidance has an MCS tracking along a thermal gradient that is situated northwest to southeast across Indiana. Recent trends have this feature not impacting northwestern Ohio until Monday morning, if the precipitation does reach this far east. Any storms that do reach the area have the potential for strong to severe winds, and as a result, much of the region is under a Marginal Risk (level 1 out of 5) for severe weather on SPC's Day 1 Severe Weather Outlook.

There will be a lull in precipitation into the afternoon on Monday before the second shortwave ahead of a surface low pressure tracks through the Great Lakes region to the southeast. The upper level ridge, and thermal gradient will have shifted to the east a little more as well. Out ahead of the surface low, bulk shear vectors will be out of the northwest at 40-50 knots that will support strong to severe thunderstorms Monday evening. As the front approaches late Monday night, storms will develop into a more linear mode. Damaging winds will be the main threat throughout the event, especially with the linear mode, but can't rule out any large hail given the strength of the deep layer shear and instability in any cells developing ahead of the line. There is still some uncertainty given how the 12Z models have handled this feature, with the HRRR keeping it well to the west and the NAM Nest developing it across central Michigan and moving into northern Ohio. In addition, how long precipitation lingers through the morning and coverage of any late evening storms may inhibit storm development with the front. Highest confidence currently is in northwestern Ohio to Cleveland, south through the Mansfield area for damaging wind impacts. SPC currently has the entire area in a Slight Risk (level 2 out of 5) for severe weather with the main driver being the damaging wind threat.

Behind the cold front Tuesday morning, a surface trough will linger across the eastern portion of the region with strong northerly flow expected. Residual moisture is expected, primarily across Northeastern Ohio and Northwestern Pennsylvania that will aid in lake effect showers developing. Periodic showers are possible across the aforementioned area through at least Wednesday when drier air moves into the region from the west with high pressure.

AVIATION /18Z Sunday THROUGH Friday/

VFR conditions will persist over the next few hours with mostly clear skies with the exception across the Mahoning Valley where some diurnal cu and associated showers are currently moving south. These scattered cloud decks are ranging between 3500-5000 ft but any further lowering may result in a brief period of MVFR at KYNG and KCAK, but given low confidence did not include in the TAF. Tonight the potential for patchy fog returns across inland terminals as moisture values continue to creep up. Opted to lower those terminals to 5SM with this update, but in isolated areas visibilities may be reduced to 3-4SM at times. Near sunrise, the fog should quickly lift as temperatures and winds increase. There is a non-zero chance for additional showers and storms across the northern terminals, especially KTOL as a decaying MCS sags south. Confidence in spatial extent remains low and may be isolated west of the area. Additional storms and non-VFR conditions will once again be possible Monday late afternoon into the evening, but given low confidence in timing and extent opted to handle this potential with MVFR PROB30.

Light and variable winds tonight will become southwesterly at 7-11 knots by Monday afternoon with isolated gusts up to 20 knots possible at western terminals.

Outlook...Non-VFR possible with periodic showers and thunderstorms Monday morning through Tuesday.

MARINE

Mainly light winds and waves will continue on Lake Erie through Monday, except for locally higher in and near any thunderstorms that drop across the lake tonight through early Tuesday morning. Confidence in thunderstorms tonight is low, but confidence and potential is higher Monday and especially Monday night as one or two clusters may drop across the lake.

Otherwise, W winds will increase to 10-15 knots Monday night as a strong cold front crosses Lake Erie, with winds becoming NNW and increasing to 15-25 knots Tuesday. NNW winds will continue at 15-25 knots at times through Wednesday, so Small Craft headlines and Beach Hazard Statements for rip currents are likely Tuesday through Wednesday. NNW winds will gradually diminish to 5-10 knots by early Thursday, becoming light and variable Friday as high pressure settles overhead.

CLE WATCHES/WARNINGS/ADVISORIES

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