textproduct: Cleveland

WHAT HAS CHANGED

Expanded the Frost Advisory for tonight which now includes Ashtabula, Trumbull, and Mahoning Counties in Ohio and inland Erie and Crawford Counties in Pennsylvania. Confidence is increasing in the need for a wider spread frost and freeze headlines for Tuesday morning.

KEY MESSAGES

1) Below average temperatures are expected through Tuesday morning as cold high pressure builds into the region. There will be frost/freeze potential Monday and Tuesday mornings.

2) Unsettled weather returns Tuesday night as low pressure moves into the region bringing showers and possible thunderstorms. Moderate rainfall is expected as well on Wednesday.

DISCUSSION

KEY MESSAGE 1... Dewpoints in Northeast Ohio dropped into the upper 20s this afternoon. Winds are expected to decrease to near calm as the ridge expands this evening and we should see temperatures fall quickly through the first half of the night. While dewpoints are expected to creep back up overnight, lowered min temperatures, especially for inland North Central and Northeast Ohio. Some mixing may develop late as weak troughing develops over Lake Erie which could be a limiting factor for greater coverage of frost. However, added patchy frost to the forecast for most inland areas east of I-71 and expanded the Frost Advisory to inland Ashtabula, Trumbull, and Mahoning Counties where temperatures could reach the mid 30s.

Previous discussion... Temperatures will continue to be below seasonal averages over the next few days as colder high pressure builds into the region from the northwest. Overnight lows will drop down into the lower 40s for much of Ohio and down into the mid 30s for areas in northwestern Pennsylvania. Winds will become calmer overnight and with some clearing will allow for frost formation in Pennsylvania tonight into Monday morning. A Frost Advisory has been issued for that timeframe for inland Erie County and Crawford County, Pennsylvania. Tomorrow evening the surface high will build to be nearly overhead of the southern Great Lakes and will support efficient radiational cooling across the region. Winds will be calm with clear skies and temperatures will drop down into the mid to low 30s across northeastern Ohio and down into the low 30s in northwestern Pennsylvania. Additional Frost Advisory headlines will be needed for areas east of I-71 with Freeze warning possible for the eastern tier of Ohio counties and northwestern Pennsylvania. Temperatures will begin to moderate Tuesday as the high pressure builds off to the east and southwesterly flow moves across the region.

KEY MESSAGE 2... Low pressure will move into the upper Great Lakes Tuesday evening and bring precipitation back to the area late Tuesday night into Wednesday. The majority of the precipitation will enter the region around Tuesday night and exit to the east midday Wednesday. Given the timeframe the precipitation begins, generally expecting showers with isolated thunderstorms. Some moderate rain is expected overnight with the showers and will need to continue to monitor how this progresses and the extent of any impacts. There may be some lingering showers across eastern Ohio and western Pennsylvania Wednesday afternoon, but expected to be light. Rain showers will end across the region late Wednesday night as high pressure builds in from the west.

AVIATION /00Z Monday THROUGH Friday/

VFR conditions are expected to persist through the TAF period. Winds will drop off to 5 knots or less by 03Z and be calm at times overnight. A weak trough will develop over Lake Erie late tonight with light south to southwesterly winds developing towards dawn. On Monday the trough will push south of Lake Erie bringing broken clouds of 4-8K and a wind shift to the north/ northwest at 5-10 knots.

Outlook...Non-VFR expected in showers and thunderstorms late Tuesday through Wednesday. Non-VFR may linger across the eastern half of the area on Thursday in low ceilings and rain showers. Non-VFR may return in scattered rain showers and thunderstorms on Friday.

MARINE

Generally quiet marine conditions are expected through Tuesday with relatively light winds of less than 15 knots anticipated. Slightly stronger south to southwest flow of 15 to 20 knots will develop Tuesday night into Wednesday ahead of a cold front, with winds shifting towards the west to northwest behind the front Wednesday night, 15 to 20 knots. Will continue to monitor for Small Craft potential during this period. Northwest winds will gradually diminish to less than 15 knots by late Thursday as high pressure builds across the region.

CLE WATCHES/WARNINGS/ADVISORIES

OH...Frost Advisory from 11 PM this evening to 8 AM EDT Monday for OHZ014-023-033. PA...Frost Advisory from 11 PM this evening to 8 AM EDT Monday for PAZ002-003. MARINE...None.