textproduct: Cleveland

WHAT HAS CHANGED

Confidence continues to increase across the region for heavy rain and potential flash flooding today, and a Flood Watch has been issued for the entire forecast area. A limited strong to severe storm risk remains across the eastern half of the area today with strong to damaging wind gusts or a tornado possible.

KEY MESSAGES

1) Showers and storms will continue across the area today. Rain will bring efficient, heavy rainfall at times, posing a flash flooding threat to the entire area. Isolated strong to severe storms are possible this afternoon and evening, primarily across Northeast Ohio and Northwest Pennsylvania.

2) Monday and Tuesday have trended drier, but scattered shower and storm chances will return for Wednesday through the end of the week. Temperatures will be near normal.

DISCUSSION

KEY MESSAGE 1... A low pressure system over central Indiana will continue to slowly move east through the Ohio Valley today. Rain continues to move north across the forecast area on the northeast side of this system. Meanwhile, some persistent rain showers are present in southern Michigan and northern Indiana in a deformation zone with this low, immediately with the upper trough axis. This band of precipitation will be the first concern of the day as it pivots toward the Toledo metro area. Aloft, a coupled jet situation will develop with a left exit region of the southerly jet and the right entrance region of the northerly jet align over northern Ohio later today. This will enhance the lift across the region and allow for this band of rain to become heavier with more efficient precipitation rates. Portions of Northwest Ohio will get 1 to 2 inches of rainfall by this afternoon and some areas could receive higher amounts where rain persists. Elsewhere, a band of moderate to heavy rain continues moving northeast through northern Ohio early this morning. This band is progressing well and a dry slot is developing over central Ohio and moving into the forecast area. This will allow for some recovery before new showers and storms develop later this morning into the afternoon. Rainfall in NE OH and NW PA will be around an inch with locally higher amounts possible, especially in convective cores that develop this afternoon. With heavy rain potential for several portions of the forecast area, have gone ahead and issued a Flood Watch for the entire area. The Flood Watch for Northwest Ohio will start now and go through 5 PM this afternoon. For the rest of the area, the Flood Watch will start at 10 AM this morning and go through Midnight tonight.

The other forecast concern for today will be the potential for strong to severe thunderstorms. This will mainly be an issue for the eastern half of the forecast area, as the western half will likely continue to be worked over by heavy rain this morning. As the surface low moves across northern Ohio today and the coupled jet aloft provides ample lift, new showers and storms should develop during the late morning and early afternoon hours. A break in convective activity over the eastern half of the forecast area should allow for some instability to build, especially if we can get a couple breaks in the clouds and get temperatures in the lower 80s. The most likely severe weather threat would be strong to damaging wind gusts in some wet microbursts. However, given the shear in the region from the surface low and upper trough moving through and some slightly backed flow ahead of the low, there is a non-zero tornado threat this afternoon.

KEY MESSAGE 2... The upper trough from the system moving through the region today will amplify and form a cut off upper low. The trends in this upper low are much further south over the past couple of forecast cycles. This then depicts some upper ridging over the local area as surface high pressure enters the region from the north. The result is a drier forecast for the area on Monday and Tuesday with generally seasonable temperatures. On Wednesday, the upper low will get absorbed into an upper trough moving through the Great Lakes region. This will mean rain chances will return on Wednesday, especially areas south and east. The upper trough pattern will remain over the region through the end of the week and provide support for daily, scattered rain chances. Temperatures will remain near normal.

AVIATION /12Z Sunday THROUGH Thursday/

IFR to MVFR ceilings have begun to push into the area, primarily impacted terminals west of I71 this morning but these are expected to continue to expand east. Much of the area is seeing a break in precipitation this morning, however additional showers and thunderstorms are expected this afternoon into the evening. With this second round of precipitation, expect additional diminished visibilities less than 4SM. Very heavy and efficient rainfall is expected so in the most well developed storms, these visibilities could be reduced to IFR or even LIFR. Given some uncertainty in overall timing of showers throughout the day opted to handle much of the diminished conditions associated with showers and storms using TEMPO/PROB30. After sunset tonight, conditions should gradually begin to improve across the area with showers pushing east and ceilings slowly beginning to rise.

Winds ahead of the surface low will be from the south-southeast at 5-10 knots with winds behind the low from the northeast at 5-12 knots. Gusty winds up to 20 knots are possible behind the low, likely impacting the far western terminals through sunset.

Outlook...Isolated to scattered showers and thunderstorms with potential for non-VFR continue Monday through Wednesday, primarily during the afternoon hours.

MARINE

A low pressure system will continue to move east today across the Ohio Valley, staying just south of Lake Erie. The positioning of this system will keep northeast winds of 15-20 knots across the lake, gradually becoming more northerly by tonight. Winds in the latest forecast guidance have increased a bit which is support by current observations near Toledo. Due to this and the likelihood of waves building to 3-5 feet, a Small Craft Advisory and Beach Hazards Statement have been issued from now into this evening for the western basin. As those winds gain a more northerly component, expect waves to begin building across the central basin as well. Have opted to issued a Small Craft and Beach Hazards for the central basin as well beginning this afternoon and going into Monday morning. As high pressure builds in tomorrow, north-northeast winds will gradually weaken to 5-10 knots and waves will diminish to 2 feet or less. These conditions will persist through mid-week before another low pressure system looks to impact the area on Thursday into Friday.

CLE WATCHES/WARNINGS/ADVISORIES

OH...Beach Hazards Statement through late tonight for OHZ003-007. Flood Watch until 5 PM EDT this afternoon for OHZ003-006>009- 017>019-027-028. Beach Hazards Statement from 2 PM EDT this afternoon through Monday morning for OHZ009>012-089. Flood Watch through this evening for OHZ010>014-020>023- 029>033-036>038-047-089. PA...Flood Watch through this evening for PAZ001>003. MARINE...Small Craft Advisory until 2 AM EDT Monday for LEZ142-143. Small Craft Advisory from 2 PM this afternoon to 11 AM EDT Monday for LEZ144>148.