textproduct: Cleveland

WHAT HAS CHANGED

The risk for heavy rainfall that could produce flash flooding this evening into tonight has increased for portions of northern Ohio. A Flood Watch has been issued for these areas through 8 AM Sunday. The severe weather potential continues to decrease for today and tonight, focusing more on the heavy rain threat.

KEY MESSAGES

1) An active weather pattern is expected through the next 36 hours with several rounds of heavy rain and thunderstorms. Heavy rain may produce flash flooding through Sunday night. Thunderstorms could be strong to severe, primarily on Sunday, with the potential for gusty to damaging wind gusts or a tornado or two.

2) The next window for showers and storms will be on Wednesday with a strong cold front.

DISCUSSION

KEY MESSAGE 1... Some shower activity is moving across the forecast area this afternoon bringing just some light rain amounts across northern Ohio. The main show for this evening and tonight will be courtesy of an MCV moving through Indiana this afternoon. Activity ahead of this feature is waning across Ohio and Indiana and a dry slot with clearing has developed, stretching from Fort Wayne to just northwest of Indianapolis. This will allow for some instability to build and eventually this mesoscale feature to generate new convection with heavy rainfall and some thunder activity. The trajectory of this feature and any convection will be into the southwest portion of the forecast area. With precipitable water values over 2 inches, rain will be heavy and efficient. With recent rainfall across the area, there is more susceptibility to flooding. Therefore, there is flash flooding potential through tonight. Have gone ahead and issued a Flood Watch for the most concerning areas. In addition, some of this area is currently highlighted by a Moderate Risk for Excessive Rainfall by WPC. The severe risk for tonight continues to trend down with rain working over the region and limiting the overall instability. There remains a Marginal Risk for severe weather from SPC for the low end potential for a damaging wind gust.

For Sunday, another shortwave will move through the northwest flow aloft and support a cold front through the area. Ahead of this front, more shower and storm activity will be possible. There could be a brief break in convective activity during the morning hours as the MCV and associated convection leaves the region. This could allow for some instability to build and provide an environment more suitable for widespread shower and storm activity later in the day. The biggest concern will be the continued heavy rain threat that could have some flash flooding implications. The current Flood Watch may need to have some portions extended into Sunday. However, there will also be a slightly greater severe weather threat as more instability in a slightly better sheared environment could provide more fuel for storms and help provide more of a damaging wind threat or potentially a tornado or two. Most of the area is a Day 2 Marginal Risk for severe weather from SPC with a small south portion of the area in a Slight Risk.

Isolated to scattered rain showers may linger Sunday night into Monday morning across Northeast Ohio and Northwest Pennsylvania.

KEY MESSAGE 2... A cold front is expected to move through the forecast area on Wednesday, bringing showers and storms to the area. There will be less moisture and instability across the region compared to recent days and largely expect activity to remain generic and sub-severe. Behind the cold front, there will be a firm pattern change to more of a late summer/early fall air mass with high temperatures in the 70s, lows in the 50s, and low humidity.

AVIATION /00Z Sunday THROUGH Thursday/

The main message for aviation weather will be variable flight categories and conditions going into tonight through Sunday morning. Conditions are starting out VFR early this evening. A MCV will across the area tonight with scattered showers and convection. We have -SHRA spreading from west to east across the area tonight as well as 4 hour TEMPO groups highlighting 3sm -TSRA potential. Ceilings will lower to lower end MVFR to possible IFR later tonight into Sunday morning for most TAF sites. MVFR to VFR ceilings are expected for the most part on Sunday at all TAF sites. Winds will be start out southeasterly to southerly 5 to 8 knots this evening shifting around from the southwest to westerly 8 to 12 knots Sunday morning into the afternoon.

Outlook...Non-VFR possible with showers and thunderstorms through Sunday night. Non-VFR possible Wednesday with showers and thunderstorms.

MARINE

Winds across Lake Erie are fairly light at around 5 knots and variable. Showers and thunderstorms are possible across the lake this afternoon through Sunday evening and higher winds and waves are possible within these storms. Overnight, winds will increase to 10- 15 knots and be predominantly out of the east-southeast then shift to the south as a warm front lifts north across the region. Waves will be 2 feet or less during this time period. A cold front will pass over the lake Sunday night and winds will shift to be out of the north-northwest and 10-15 knots and waves will build to 1-3 feet. Winds will subside through the day on Monday down to 5-10 knots, then become light and variable Monday night into Tuesday. Winds will increase again Tuesday into Wednesday out of the southwest at 10-15 knots ahead of the low pressure system entering the Great Lakes region.

CLE WATCHES/WARNINGS/ADVISORIES

OH...Flood Watch through Sunday morning for OHZ017>019-027>032- 036>038-047. PA...None. MARINE...None.