textproduct: Cleveland

WHAT HAS CHANGED

The forecast remains generally on track. The Marginal Risk for severe thunderstorms has been expanded to include the eastern lakeshore areas and includes more of Northwest Ohio.

KEY MESSAGES

1) Showers and thunderstorms return to the local area Thursday night and Friday. There is a Marginal Risk (level 1 of 5) for Northwest Ohio and extending east along the lakeshore Thursday evening/night.

2) Conditions dry out over the weekend with temperatures trending above normal early next week.

DISCUSSION

KEY MESSAGE 1... Water vapor imagery this afternoon shows a trough moving northeast through the Ohio Valley with moisture spreading north ahead of it. Meanwhile, a northern stream trough is moving into the Upper Midwest and will cross Lake Erie Thursday evening/night. The airmass remains very dry this afternoon with surface high pressure in place but the high is expected to weaken on Thursday as a cold front approaches from the north. Most of the day on Thursday will be dry but can not rule out an isolated afternoon shower or thunderstorm along the lake breeze in Northeast Ohio/Northwest Pennsylvania. Otherwise a chance for showers and thunderstorms will be possible in Northwest Ohio by late afternoon with coverage increasing Thursday night as the front approaches. ML CAPE values are forecast to reach 1500-2000 J/kg in NW Ohio along with shear increasing Thursday evening as the shortwave trough passes aloft. The Marginal Risk (level 1 of 5) for severe weather has been expanded slightly to include more of Northwest Ohio and now extends eastward along the lakeshore which seems reasonable. The primary concern will be wind gusts of 50-60 mph with thunderstorms Thursday evening.

Moisture advection will continue on Thursday night with PW values increasing to over 2 inches. Will continue with high pops for Thursday night as multiple rounds of showers and thunderstorms are possible. Will need to monitor for pockets of locally heavy rainfall with training of storms possible with the mean flow set up nearly parallel to the storm motion.

On Friday another shortwave will track through the Ohio Valley. Instability may be kept to modest values with higher cloud cover expected. Still expecting continued shower and thunderstorm activity on Friday as the surface front is slow to clear the area.

KEY MESSAGE 2... While a few showers may linger across the south on Saturday, the trend will be for drier conditions to develop over the weekend with high pressure building to the north. Low pops remain across the south into Saturday followed by a mostly dry forecast through the extended.

While temperatures will be near normal over the weekend, a strong upper level ridge tries to expand east into the Great Lakes early next week. Temperatures are forecast to surpass 90 degrees in portions of the area but will depend on the our proximity to the ridge. There is a larger spread in ensemble temperatures next week based on if the ridge is overhead or if we are on the downstream side of it. Will be monitoring the overall pattern evolution over the coming days.

AVIATION /18Z Wednesday THROUGH Monday/

Patchy MVFR ceilings are being observed across the Mahoning Valley this afternoon as diurnal cu have developed. These heights should continue to lift this afternoon, leaving all terminals in VFR conditions for much of the period. The exception to this will be KMFD, KCAK, and KYNG which may once again see a mix of fog/low stratus that impacts terminals between 09Z and sunrise. With moisture gradually diminishing, confidence is not as high as prior days so opted to handle the potential with a TEMPO. Light and variable winds are expected to continue through Thursday morning before increasing to 5-10 knots from the west-southwest by late morning.

Outlook...Non-VFR possible with scattered thunderstorms Thursday afternoon through Saturday afternoon.

MARINE

Quiet marine conditions are expected to persist across Lake Erie through the weekend. High pressure today and tomorrow will keep winds from the southwest at 5-10 knots and waves in the nearshore below 2 feet. Thursday night, a cold front will sag south of the lake marking a shift to west-northwest winds. There is a potential for scattered thunderstorms during the evening hours which may locally enhance winds and waves, but widespread conditions should remain calm. The cold front continues to push south on Friday as high pressure returns from the north over the lake. Winds will gradually shift to northeasterly at 10-15 knots on Saturday and Sunday afternoons with waves in the western basin building to 1-3 feet. Overnight winds will remain calm. There are no anticipated marine headlines at this time.

CLE WATCHES/WARNINGS/ADVISORIES

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