Published: August 21,2017
Severe thunderstorms with damaging winds and large hail are possible early this week from the Plains and Midwest into the Northeast.
(MORE: Tornado Central)
Current Radar, Watches and Warnings
By Tuesday, the jet stream maximum will shift toward the Ohio Valley and interior Northeast, where thunderstorms should flare up during the afternoon and evening hours ahead of the potent cold front. Hot and humid conditions will also be in place in those regions, which will increase the risk for severe weather due to extra moisture in the atmosphere.
Below is our latest forecast thinking on the timing and magnitude of the severe threats early this week.
Severe Weather ForecastInto Monday Evening
- Forecast: Scattered severe thunderstorms are forecast to impact parts of the mid-Missouri Valley east-northeastward into the mid- and upper Mississippi Valley into the evening.
- Threats: Damaging wind gusts and large hail are the main threats, but an isolated tornado cannot be ruled out. Flash flooding is also possible, especially where storms stall or move slowly over the same areas for a period of an hour or more.
- Cities: Madison, Wisconsin | Des Moines, Iowa | Omaha, Nebraska
Thunderstorm Forecast into Monday Evening
- Forecast: Severe thunderstorms are possible across much of upstate New York and Vermont southwestward into central and western Pennsylvania and the Ohio Valley, as well as parts of the mid-Mississippi Valley, during the afternoon and evening. Showers and storms could reach parts of the heavily-populated Interstate 95 Northeast corridor later Tuesday evening or overnight, but the risk for severe weather will be minimal as the storms weaken after sunset.
- Threats: Damaging wind gusts are the primary threat, though large hail and an isolated tornado can't be ruled out. Flash flooding is also possible, especially where storms stall or move slowly over the same areas for a period of an hour or more.
- Cities: Buffalo, New York | Pittsburgh | Cleveland | Cincinnati | Indianapolis
Tuesday's Thunderstorm Forecast
Highs will generally be 5 to 10 degrees below average for late August, as the muggy 80s and lower 90s are replaced by temperatures in the 70s and lower 80s.
(MAPS: 10-Day Forecast High/Low Temperatures)
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