textproduct: Cleveland

WHAT HAS CHANGED

Slightly lowered dew points for this afternoon. Otherwise, no significant changes to the previous forecast.

KEY MESSAGES

1) Isolated to scattered showers and thunderstorms will develop Monday afternoon and evening along a surface trough. A few storms could become strong to severe.

2) Widespread showers and embedded thunderstorms will arrive across the region Tuesday into Wednesday. Some nuisance and/or minor river flooding is possible.

3) A chilly air mass will return across the region towards the end of the week with another round of Frost conditions possible.

DISCUSSION

KEY MESSAGE 1...

A weak mid-level shortwave will move northeast across the Ohio Valley ahead of a stronger upper-level trough near the Upper Great Lakes on Monday. A narrow corridor of higher dew points in the 50s and mid-level lapse rates of 6.5 to 7 C/km will accompany this feature, potentially yielding MLCAPE values in excess of 1000 J/kg by Monday afternoon and evening. The latest SPC SWODY2 marginal risk encompassing portions of North-Central and Northwest Ohio appears reasonable at this time given modest westerly bulk shear of around 30 to 35 knots. The main hazards with any stronger storms that form would be isolated damaging wind gusts and large hail.

KEY MESSAGE 2...

A secondary area of low pressure will develop along a slow- moving cold front as it approaches the Lower Great Lakes region on Tuesday. Widespread showers and embedded thunderstorms are expected with the front, especially late Tuesday into Wednesday, with high probabilities for much of the area to receive at least one inch of rainfall. Although not particularly impressive amounts, the recent wet pattern coupled with a widespread rain could lead to some nuisance road and/or minor river flooding and will be something to watch in future forecast iterations.

KEY MESSAGE 3...

Another anomalously-cold air mass will enter the region towards the end of the week, with 850 mb temperatures falling to around 0C. Though not as cold as the current air mass over the region, there does exist some potential for another round of Frost conditions, especially Thursday night into early Friday morning.

AVIATION /12Z Sunday THROUGH Thursday/

Skies are starting off mostly clear this morning with high pressure located over the Ohio Valley. The high shifts south today which will allow winds to increase with gust of 20-28 knots developing after 15Z. Wind gusts will drop off towards 00Z for inland locations in eastern Ohio and possibly closer to 06Z in other NW Ohio locations. If wind gusts drop off then low level wind sheer is likely as speeds increase to 40-45 knots near 2K feet overnight.

Otherwise some cumulus cloud around 5-7K feet is expected this afternoon with coverage of VFR clouds increasing after 22Z. A shortwave will pass overhead tonight with a few light showers passing near or over Lake Erie tonight. Included vicinity shower at ERI where confidence was highest but but otherwise expecting coverage to be too low for many impacts.

Outlook...Non-VFR possible in scattered showers and thunderstorms Monday afternoon/night followed by increasing coverage of precipitation Tuesday afternoon and night and again on Thursday.

MARINE

High pressure over the Ohio Valley will shift south today as a trough crosses the Upper Great Lakes this afternoon and evening. Winds will increase ahead of the trough, with speeds of 15-25 knots, peaking on the western basin this evening with 20-30 knots as a low level jet passes overhead. A Small Craft Advisory has been issued for areas west of Avon from Noon-4 AM. Higher waves of 4 to 7 feet will be focused over the open waters given the offshore flow. The eastern nearshore water are expected to remain just below Small Craft criteria but will need to be monitored.

A warm front lifts north of Lake Erie for Monday and the stable marine layer should limit winds to 10-20 knots during the day but may exceed 20 knots Monday night. May need to monitor for another window of Small Craft conditions. Winds make an abrupt shift to the north behind a cold front on Tuesday but timing is somewhat uncertain. Conditions improve Wednesday as high pressure builds over the lake.

CLE WATCHES/WARNINGS/ADVISORIES

OH...Frost Advisory until 9 AM EDT this morning for OHZ003-006>009- 011-012-017-018-027-036-089. Freeze Warning until 9 AM EDT this morning for OHZ010-013-014- 019>023-028>033-037-038-047. PA...Frost Advisory until 9 AM EDT this morning for PAZ001. Freeze Warning until 9 AM EDT this morning for PAZ002-003. MARINE...Small Craft Advisory from noon today to 4 AM EDT Monday for LEZ142>145.