textproduct: Cleveland

WHAT HAS CHANGED

Increased pops for this afternoon and tonight. Also adjusted high temperatures down near Lake Erie on Saturday.

KEY MESSAGES

1) Scattered thunderstorms this afternoon will give way to widespread showers overnight. A few of the stronger thunderstorms in NW Ohio this afternoon could produce wind gusts to 50 or 60 mph.

2) Cooler air arrives behind a cold front for the weekend. Locations closer to Lake Erie will be below normal.

3) The next chance of precipitation will accompany a front Monday night into Tuesday.

DISCUSSION

KEY MESSAGE 1...

Scattered thunderstorms developed this afternoon in Northwest Ohio and have continued northeast towards Sandusky and Central Lake Erie. This area is focused along an area of low level theta-e advection and is not expected to be severe, with brief heavy rain and lightning the main concerns. We will be monitoring the evolution of thunderstorms moving out of Indiana this evening for slightly more organized convective threat. Mid- level shortwave energy is expected to move from northern Illinois towards Central Lower Michigan and provide some increase in lift while a cold front wraps in from the west this evening. Instability is expected to be marginal with 500 J/kg of CAPE. While shear will be on the uptick in NW Ohio, effective shear will remain at 25 knots or less and the severe weather threat is expected to remain isolated with a few wind gusts of 50-60 knots possible in NW Ohio. The main time frame for any stronger thunderstorms will be in the 4-8 PM time frame.

Beyond that, a swath of rain is expected to move across the area overnight with generally a quarter to a half inch of rain and a chance of thunderstorms. Rain will tend to taper off from west to east between about 4 AM in the west to 11 AM in NW Pennsylvania.

KEY MESSAGE 2...

High temperatures for Saturday will occur early in the morning for some locations with temperatures falling into the 50s behind the front. Temperatures at 850mb will tend to be about 7 C cooler than today. Northern areas will be influenced by breezy flow off Lake Erie and remain in the 50s through the day with mostly cloudy skies. Temperatures for inland areas will do a little better with some locations climbing back into the 60s in the afternoon. Skies will tend to clear for Sunday with seasonable temperatures.

KEY MESSAGE 3...

A warm front lifts back north on Monday as the upper level ridge axis shifts towards New England. A trough will lift out of the Rocky Mountains towards the Upper Midwest Monday night into Tuesday. Strong low pressure will track northeast across Lake Superior with showers and a chance of thunderstorms moving east across the area Monday night into Tuesday ahead of a cold front. Another quarter to a half inch of rain is expected with this system but the late night/morning timing will be less favorable for strong thunderstorms.

AVIATION /00Z Saturday THROUGH Wednesday/

Low pressure centered over southeast Michigan will move east- southeast across the area late tonight, bringing a cold front across the area. Several hours of rain showers are expected with and behind the cold front, with a slight chance for thunderstorms before the cold front swings through (mainly west of I-77). Ceilings quickly deteriorate behind the cold front, with areawide IFR expected and pockets of LIFR especially closer to Lake Erie in Northeast Ohio and Northwest Pennsylvania. Conditions improve to mostly MVFR during the day Saturday, with pockets of IFR persisting in some areas. Light winds tonight become 10-14 knots out of the north during the day Saturday.

Outlook...Non-VFR possible with showers and thunderstorms late Monday night into Tuesday. Isolated rain showers may persist into Wednesday.

MARINE

East to northeast winds have increased to 10 to 15 knots with gusts up to 25 knots this afternoon. Also, Walnut Creek waves have increased up to 4 feet this afternoon. A cold front will push east this evening into the overnight hour, shifting winds northerly with speeds of 5-10 knots. An associated surface inverted trough will park over western Pennsylvania and create a relatively tight pressure gradient on Saturday. As a result, northerly winds will increase across the central and eastern basin Saturday and Saturday night with winds between 15 to 20 knots and waves approaching 5 feet. We will monitor and may need a Small Craft Advisory Saturday night. Winds are expected to subside on Sunday. A strong low pressure system that moves through the western Great Lakes region for the start of next week. Winds look to increase to 15-20 knots for a period of time late Monday into Tuesday, which may need a Small Craft Advisory.

CLE WATCHES/WARNINGS/ADVISORIES

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