textproduct: Cleveland

WHAT HAS CHANGED

Only minor changes with this forecast update.

KEY MESSAGES

1) A strong low pressure system will develop and move east through the Great Lakes Wednesday night into Thursday. Some severe storms and gusty winds are possible.

2) A compact system will move east through the Central Great Lakes later Tuesday into early Wednesday, bringing showers and thunderstorms into the area. A few storms may be strong in Northwest Ohio.

DISCUSSION

KEY MESSAGE 1... A very anomalous low pressure system will move east across the Great Lakes later Wednesday into Thursday. Moisture will increase as the low lifts a warm front across the area on Wednesday and showers and thunderstorms will expand east across the area as the low's associated cold front approaches from the west Wednesday night into early Thursday.

At this point, the best instability/severe weather risk is to the south/southwest of the area owed to more favorable diurnal timing, but given the robust wind field (including a 60 to 70 knot LLJ), significant instability will not be needed for organized convection and strong to severe thunderstorms through the overnight. It continues to be a bit early to get too far into the weeds given uncertainty with mesoscale features/parameters, but there certainly may be organized convection/strong to severe thunderstorms Wednesday night into early Thursday morning. A Slight Risk (Level 2 of 5) of severe weather remains unchanged for locations generally along/west of I-77 for Wednesday night/early Thursday morning with a Marginal Risk (Level 1 of 5) continuing east to roughly the NE OH/NW PA border. Will also need to keep an eye on potential for heavy rainfall and possibly flooding, as PWATs are expect to increase to around 2 inches and there's potential for some training if mean flow becomes a bit more southwesterly. WPC now has much of Ohio in a Slight Risk for excessive rainfall, with a Marginal Risk confined to far eastern and southeastern areas.

The wind field will be quite impressive for this time of year and gusty non-thunderstorm winds are likely late Wednesday night through the daytime hours Thursday. Gusts to 30 to 40 mph are likely areawide, although there will likely be a period of gusts as high as 45 mph during peak mixing Thursday afternoon. Will need to continue to monitor forecast trends; a Wind Advisory can't be ruled out at some point for Thursday.

KEY MESSAGE 2... A relatively weak trough will move east across the area later Tuesday into early Wednesday. There may be some scattered showers and thunderstorms ahead of this feature beginning mid/late Tuesday afternoon across northwest Ohio then spreading east through the evening hours. The higher shower/storm chances will be in place through the early overnight, with shower chances then tapering off through the second half of Tuesday night. There's still uncertainty in shower/thunderstorm coverage and intensity as instability wanes as convection moves east into the area into the evening, but it's possible that a few storms along/west of the I-75 corridor could produce damaging wind gusts and hail. Overall, confidence in severe weather potential is low at this point, but there remains a Marginal Risk (Level 1 of 5) of severe weather along and west of I-75. The bulk of the better chances for stronger storms will likely be to the west of the local area.

AVIATION /18Z Monday THROUGH Friday/

High pressure will provide widespread VFR conditions through the 00Z TAF period with just mainly cirrus level clouds through 12z, before an increase in mid level clouds Tuesday.

Winds will become southwest tonight less than 10 knots. Southwest winds will increase to 10-15 knots later Tuesday morning with gusts 15-25 knots Tuesday afternoon.

Outlook...Periodic showers and thunderstorms with non-VFR are forecast Tuesday night through Friday.

Saturday...Mainly VFR. Mainly dry with a slight chance of showers/storms during the afternoon.

MARINE

Periods of hazardous marine conditions are possible this week as multiple frontal boundaries push east across the region. Mainly light chop will continue this afternoon as a surface high continues to push east, allowing for northwest winds of 10-15 knots to gradually become southwesterly 10-15 knots this evening. These conditions will persist into Tuesday before winds gradually increase to 15-20 knots as a warm front lift north Tuesday evening. These conditions are expected to persist through much of Wednesday, but given the offshore flow waves should remain 1-3 feet across the nearshore zones through Wednesday. Will have to monitor trends in winds for the potential need of headlines, but at this point that potential appears very marginal.

Late Wednesday evening into the overnight hours are when the most hazardous marine conditions are expected to impact Lake Erie. A deepening surface low centered over the region will bring south- southwest winds of 20-30 knots across the entire basin, increasing waves to over 6 feet, possibly touching 10 feet at times in the open waters. These conditions should gradually improve throughout the day on Thursday, but it is highly advised to remain off of Lake Erie late Wednesday through much of Thursday given the extremely dangerous conditions to small crafts and the increasing likelihood of strong rip currents. Will continue to monitor trends in this storm system to determine appropriate headlines.

CLE WATCHES/WARNINGS/ADVISORIES

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