Posted Tuesday, September 21, 2021
Scattered rain showers will cross the region today. More widespread showers and possible thunderstorms can be expected for Wednesday as a cold front approaches and crosses the region. Cooler temperatures and dry weather return to end the week.
The last day of summer 2021 won’t be sunny and bright. Scattered showers will be around today as a disturbance slowly crosses the region. Cloud cover will keep temperatures cooler than yesterday but it will be humid with dew points in the mid-60s this afternoon.
HEAVY RAIN AND THUNDER ARE POSSIBLE TONIGHT AND WEDNESDAY
The threat for heavy rainfall and thunderstorms will increase tonight as a potent cold front approaches and slides south through East-Central Ohio on Wednesday.
According to the latest guidance, rain is likely to come in two waves. The first wave late tonight and early Wednesday morning looks to bring periods of heavy rain. The second wave during Wednesday afternoon can contain another round of heavy rain and also some thunder.
The lack of sunshine and cooler temperatures will limit the amount of instability Wednesday afternoon. However, upper-level wind shear will be strong enough to overcome the lack of appreciable instability and bring a low-end risk for a strong gusty thunderstorm. With lots of shear high overhead (wind blowing in different directions at different heights), the risk of a quick spinup tornado can’t be ruled out. It’s a low risk – 2% according to the NWS Storm Prediction Center – but a 2-percent risk is twice higher than zero percent.
The NWS Storm Prediction Center has placed parts of central and eastern Ohio under a Marginal Risk (level 1 on a scale of 1-5) for severe weather.
How much rain can we expect? I’d have to say anywhere from an inch to two inches is likely today and Wednesday. A couple of the models indicate more than two inches and that’s certainly a possibility. Rain amounts will depend on how slow the front progresses through the area. But as of this morning, I think 1″ to 2″ is a pretty good bet.
The ground is pretty dry and should handle a couple of inches okay. The rain will fall over the course of today and tomorrow so it will be spread out over 24 to 36 hours. There may be some water issues in those areas where drainage is poor. If heavy rain occurs for a time there can be some street flooding. But generally speaking, widespread flooding is not expected in our area.
THURSDAY AND FRIDAY
The system should push off to the south and east of the region Thursday evening. Cooler and dryer air wraps in behind the system bringing an end to the rain by Thursday morning. This is going to bring much cooler temperatures to the Valley to end the workweek. If you’ve been waiting for cooler weather this will make your day.
Expect a more fall-like weekend. Gone will be the 80-plus degree heat and those high dew points. High pressure will supply mostly sunny and dry conditions. Saturday will be the coolest day with afternoon highs in the upper-60s. Sunday looks like a glorious day with sunshine and a high of around 72°.
Thanks for reading. Be safe out there.