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Archives for the SPC Convective Outlook are updated daily (approximately) with a live map at the beginning of each article. Follow the link at the end of the article to check for current updates on the NOAA/NWS Storm Prediction Center website. Also, see Archives for Chicago's hourly weather data on CARDINAL NEWS Magazine.


Sunday, August 8, 2021

SPC Aug 8, 2021 0730 UTC Day 3 Severe Thunderstorm Outlook

SPC 0730Z Day 3 Outlook Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0217 AM CDT Sun Aug 08 2021 Valid 101200Z - 111200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE UPPER MISSISSIPPI VALLEY AND GREAT LAKES... ...SUMMARY... Severe storms producing damaging winds are expected from the upper Mississippi Valley eastward across the Great Lakes on Tuesday. Potentially significant wind gusts may develop. ...Upper MS Valley and Great Lakes... A shortwave trough will move across the northern Plains and upper MS Valley, with a 60+ kt midlevel speed max into northern MN. Height falls will occur from the eastern Dakotas across MN and WI during the day with a cold front affecting MN and WI. Southern portions of this front will trail southwestward into the central Plains. A warm front will lift rapidly north across WI and MI during the day. Dewpoints in the upper 60s F and lower 70s F will exist ahead of the cold front, with MUCAPE over 3000 J/kg developing near and east of the MS River during the afternoon. Very strong instability will extend southward into the mid MS Valley and central Plains as well. MUCAPE over 2000 J/kg may spread east toward Lake Erie by 00Z. Although the strongest winds aloft will move across northern MN toward Lake Superior, 500 mb speeds to around 30 kt are expected over the remainder of WI and Lower MI. In addition, 850 mb wind speeds are forecast to exceed 30 kt out of the west, which will aid moisture advection. Storms are likely to develop near the primary cold front, with wind and hail threat, and sufficient SRH may exist for supercells. Focus for other storms away from the front is more uncertain, but heating will likely lead to clusters of storms from WI into Lower MI during the afternoon. Extreme instability, including steep midlevel lapse rates, suggest significant wind potential. Parts of this region may be upgraded further in later outlooks as predictability increases. Elsewhere...additional strong to severe storms are possible along the front into the central Plains. Flow aloft will be much weaker, but strong instability and heating should result in at least isolated areas of severe wind. ..Jewell.. 08/08/2021 Read more LIVE:
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