textproduct: Cleveland

WHAT HAS CHANGED

Confidence is increasing for a line of showers and thunderstorms to develop and move east across the area late this morning and early afternoon. If storms become severe, damaging wind gusts are the most likely hazard. Concern is also increasing for a few rotating storms to develop later this afternoon and evening across NE OH/NW PA.

KEY MESSAGES

1) Showers and storms will develop and move east across the area late this morning and early afternoon. The most likely window for severe weather is between 11 AM and 2 PM along and east of the I-71 corridor with damaging wind gusts being the primary hazard.

2) Anomalously-cool air mass arrives on Wednesday with lake- enhanced showers possible.

3) Temperatures return near or slightly above normal by the end of the week and weekend. Shower and thunderstorm chances increase by early next week.

DISCUSSION

KEY MESSAGE 1... The latest water vapor imagery (~3 AM ET) depicts a potent shortwave across southern Wisconsin/Lake Michigan early this morning, with scattered showers and storms beginning to develop across northern Illinois. This area of showers and storms will be the main area to watch this morning and early afternoon as the shortwave continues to quickly move east through the Lower Great Lakes, providing plenty in the way of environmental shear to support organized convection. There remains some uncertainty on the amount of destabilization ahead of the line, mainly west of the I-71 corridor, where probabilities of >1000 J/kg of CAPE are lower. Further east, along and east of the I-71 corridor, severe weather chances appear to be increasing with a longer period of daytime heating ahead of the line. Given the anticipated line storm mode, damaging wind gusts up to 70 mph are the primary concern with a most likely time window between 11 AM and 2 PM, particularly along and east of the I-71 corridor.

Attention then turns to later this afternoon and evening across portions of Northeast Ohio and Northwest Pennsylvania where a second area of pre-frontal showers and thunderstorms may develop. Concern is increasing for a few rotating storms with this round as the low-level hodograph profile becomes more favorable, potentially resulting in a localized tornado risk, evident by the slight westward expansion of the 5% tornado probabilities in the latest SPC SWODY1 outlook. These storms appear to be driven by mesoscale processes mainly below 700 mb, evident by an abundance of dry air aloft, and thus, anticipating this second round of convection to be fairly shallow, similar to the type of storms seen across Wisconsin yesterday (7/20). Confidence on this second round remains on the lower side, especially with regards to intensity and coverage.

KEY MESSAGE 2... A strong cold front will move across the area tonight, ushering in a chilly air mass into the region, characterized by 850 mb temperatures falling as low as 6C on Wednesday. Lake-enhanced rain showers will be possible throughout Wednesday across portions of Northeast Ohio and Northwest Pennsylvania in addition to ample cloud cover, especially Wednesday morning and early afternoon. As a result, high temperatures may struggle to get out of the 60s in some spots.

KEY MESSAGE 3... A large upper-level ridge across the Western and Central CONUS will gradually expand further east into the Great Lakes by Friday into the weekend, resulting in temperatures to return near or slightly above normal in the 80s. However, a series of upper-level troughs across Hudson Bay appear poised to block the eastward progression of the ridge. This pattern would appear to favor increasing shower and thunderstorm chances across the area by early next week if trends continue.

AVIATION /12Z Tuesday THROUGH Saturday/

First round of showers and thunderstorms is moving east into the western part of the area early this morning. This round of storms will continue to move east across the area this morning with additional redevelopment likely on the western edge of storms as better forcing moves into the region. Amendments will likely be needed as confidence in convection coverage into this afternoon increases. Regardless, any storms will be capable of producing non-VFR conditions and erratic wind gusts to at least 35 knots. Locally higher thunderstorm gusts to 50 knots are possible primarily at southeastern terminals late this morning into this afternoon. Another round of showers/storms is possible ahead of a cold front this evening, but would like to see how the atmosphere recovers this afternoon before getting too aggressive with shower/thunderstorms. Lake effect showers/clouds will likely develop behind the cold front tonight which could produce MVFR ceilings and perhaps some light showers at KERI/KYNG/KCLE in the later part of the TAF period.

Southwest winds will increase to 10 to 15 knots with gusts to 20 to 25 knots this morning. As mentioned above, wind gusts will likely be stronger in thunderstorms. Winds will shift to the northwest and diminish to about 10 knots with periodic gusts to 20 knots behind a cold front tonight.

Outlook...Residual non-VFR possible on Wednesday in lake effect rain showers and clouds across the eastern half of the area.

MARINE

Southwest winds will increase to 15 to 25 knots this morning, resulting in waves of 3 to 5 feet in the nearshore zones from roughly Vermilion to Ripley NY. Winds may briefly diminish as a cold front crosses the area this afternoon/evening, but strong cold air advection will cause winds to shift to the northwest and increase to about 20 knots overnight, which will produce continued elevated waves into Wednesday. The Small Craft Advisory from Maumee Bay to the Islands has been adjusted to start early this morning and end at 4 AM Wednesday morning to account for the enhanced northwest flow behind the cold front. Meanwhile, the Small Craft Advisory remains in effect from the Islands to Ripley NY from 8 AM this morning until 10 PM Wednesday evening. Thunderstorms are likely this morning and afternoon which will result in higher winds/waves.

Winds will diminish below 10 knots by early Thursday morning and expect light (10 knots or less) and variable flow through at least the first half of the weekend.

CLE WATCHES/WARNINGS/ADVISORIES

OH...Beach Hazards Statement through Wednesday evening for OHZ010>012-089. PA...Beach Hazards Statement through Wednesday evening for PAZ001. MARINE...Small Craft Advisory until 4 AM EDT Wednesday for LEZ142-143. Small Craft Advisory until 10 PM EDT Wednesday for LEZ144>149.