textproduct: Cleveland

WHAT HAS CHANGED

Minimal changes made 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 this afternoon into early Wednesday, bringing showers and thunderstorms into the area. A few storms may be strong to severe across Northwest Ohio.

DISCUSSION

KEY MESSAGE 1... Anomalously low pressure for mid-June will pass east across the Great Lakes late Wednesday and Thursday pushing across a warm front early Wednesday. Ample moisture will advect into the region ahead of a cold frontal passage Wednesday night into Thursday morning supporting showers and thunderstorms to expand east in coverage.

While the best instability and corresponding severe weather risk continues to correlate south and southwest of the forecast area due to more favorable diurnal timing, a robust wind field from a 60 to 70 knot low-level jet overhead will support organized convection and strong to severe thunderstorms overnight even with limited instability. Meso-scale features and parameters are just starting to shine a light to the evolution of the system and given its earlier stages, there will likely be organized convection with strong to severe thunderstorms Wednesday night into early Thursday morning. A Slight Risk (Level 2 of 5) for severe thunderstorms continues for locations generally along and west of I-77, and a Marginal Risk (Level 1 of 5) for the areas east of I-77 to roughly northeastern Ohio and northwest Pennsylvania state line. In addition to the severe thunderstorm potential, there is also the potential for heavy rain as PWAT values are expected to rise to around 2 inches with the potential for training storms if the mean flow becomes southwesterly. This being said, there is a Slight Risk for Excessive Rainfall for much of Ohio and a Marginal Risk along the far eastern and southeastern areas.

Outside of the thunderstorm potential, the wind field will be poignant for this time of the year, and therefor support gusty non-thunderstorm winds late Wednesday night through Thursday. Expect gusts of 30 to 40 mph area wide, with a period of 45mph gusts possible during peak diurnal mixing Thursday afternoon. This being said, 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 weak trough will pass east across northern Ohio and northwest Pennsylvania this afternoon and into early Wednesday, supporting some scattered showers and thunderstorms to pass across northwest Ohio this afternoon before spreading east across the remainder of the area through the evening hours. Shower/thunderstorm chances will decrease and taper off from west to east during the later half of tonight. Due to the timing of convection, the best areas for severe thunderstorms capable of producing, damaging winds will lie across far northwest Ohio mainly west of I-75 where a Marginal Risk (Level 1 of 5) for severe thunderstorms remains in place. As the activity progresses east, and with the loss of diurnal effect, strong to severe thunderstorms will lose their potency and pass in the form of showers with a few rumbles of thunder for the remainder of the area.

AVIATION /12Z Tuesday THROUGH Saturday/

Ridge axis of surface high pressure entering the Northeast will continue to support widespread VFR conditions this morning despite some cirrus advecting overhead of northern Ohio.

Winds will become southwest early this morning and be less than 10 knots. Southwest winds will increase to 10-15 knots later this morning with gusts 15-25 knots by this afternoon.

Showers and thunderstorms will pass from west to east across the area late this afternoon and through this evening. The western TAF sites (KTOL and KFDY) will have the potential to see the stronger of the storms, though thunderstorms can't be ruled out for the remainder of the TAF sites as the system passes east this evening. Even with the passage of thunderstorms, conditions will drop to low end VFR.

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

A light chop will continue into this morning before winds freshen to 15 to 20 knots as a warm front lifts north this evening. These conditions are expected to persist through much of Wednesday, however given the offshore flow waves should remain 1 to 3 feet across the near shore zones through Wednesday. Will continue to have to monitor trend in winds for the potential need of headlines, though at this time this potential appears marginal.

The most hazardous marine conditions are expected to impact Lake Erie late Wednesday evening and into the overnight hours as a deepening surface low centered over the region will support south-southwest winds of 20 to 30 knots across the entire basin and therefore result in increasing waves to over 6 feet and possible touching 10 feet at times in the open waters. These conditions should drastically improve throughout the day 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.