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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.


Friday, May 20, 2022

SPC May 20, 2022 Day 4-8 Severe Weather Outlook

Day 4-8 Outlook Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0357 AM CDT Fri May 20 2022 Valid 231200Z - 281200Z ...DISCUSSION... ...Monday/Day 4 to Wednesday/Day 6... On Monday, an upper-level trough is forecast to move across the southern and central Rockies. Ahead of the trough, low-level moisture return is forecast over the southern Plains, where pockets of moderate instability may develop during the afternoon. Thunderstorm development will be likely over parts of the southern Plains along pre-existing boundaries and near thermal gradients. However, the stronger mid-level flow is forecast to stay further north. This will keep the potential for organized thunderstorms relatively low. A marginal severe threat will be possible in areas where the strongest instability develops. On Tuesday, the models are in relatively good agreement that an upper-level trough will move into the southern and central Plains. Ahead of the trough, low-level moisture advection is forecast over the lower to mid Mississippi Valley. A large area will have potential for thunderstorms from Texas northeastward into the Ohio Valley. The strongest instability is forecast over the southern half of Texas. Organized thunderstorms could occur along the northern edge of the stronger instability from the Texas Hill Country east-northeastward into the Arklatex. But mesoscale aspects of the forecast make predictability low, an outflow boundaries and local convergence zones will be key to where the greatest convective potential is realized Tuesday afternoon. On Wednesday, the models continue to move an upper-level trough slowly eastward across the southern Plains. A cold front is forecast to move into the southern Plains, Arklatex and mid Mississippi Valley. Thunderstorm development will again be possible across a broad area from the southern Plains northeastward into the Ohio and Tennessee Valleys. There is a lot of uncertainty on Wednesday's forecast. The models vary on where the front will be, and have large differences in the distribution of instability. It appears that an MCS could develop across parts of central and east Texas, but this will depend upon a number of factors that are more mesoscale in nature. Further northeast on Wednesday, thunderstorm development will also be likely in parts of the mid Mississippi and Ohio Valleys. Instability could be sufficient in some areas for a severe threat Wednesday afternoon. However, the models have yet to show a concentrated area with increased severe potential. Concerning the early to mid week time-frame, a severe threat area could be added in later outlooks as model forecasts become more conclusive concerning key elements for severe potential. ...Thursday/Day 7 and Friday/Day 8... From Thursday into Friday, an upper-level low is forecast to continue moving slowly eastward from the Mississippi Valley into the eastern U.S. Ahead of the associated trough, a cold front is forecast to advance east-southeastward across the southern third of the nation. Thunderstorm development will be likely along and ahead of the front each day. An isolated severe threat could develop in areas that destabilize the most during the afternoon and evening on both Thursday and Friday. It would seem that the greatest severe threat would be over the southern Appalachians Thursday afternoon, where low-level flow is forecast be maximized. However, much uncertainty exists from Thursday into Friday, mainly due to large differences in the model solutions. Read more CHECK UPDATE ZOOM GRAPHIC
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