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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.


Wednesday, July 26, 2023

SPC Jul 26, 2023 2000 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0302 PM CDT Wed Jul 26 2023 Valid 262000Z - 271200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PORTIONS OF THE SOUTHERN GREAT LAKES REGION... ...SUMMARY... Severe thunderstorm gusts remain possible this afternoon and evening for parts of the southern Great Lakes, along with occasional large hail. Severe gusts also are possible over parts of the central High Plains this afternoon. ...20Z Update... The primary changes to the ongoing forecast were to reduce wind probabilities in the wake of convection, trim severe probabilities behind the shortwave trough in the Upper Midwest along with minor changes to the general thunderstorm area. The remainder of forecast remains on track with additional thunderstorm development possible in the southern Great Lakes region as the low-level jet intensifies later today/tonight. ..Wendt.. 07/26/2023 .PREV DISCUSSION... /ISSUED 1109 AM CDT Wed Jul 26 2023/ ...Lower MI and Vicinity... Multiple strong/severe MCSs are ongoing this morning over western Lower MI, Lake MI, and southern WI. Two lead bowing clusters of convection over western Lower MI will likely continue to track quickly eastward today into a progressively more unstable air mass. Dewpoints in the mid/upper 60s and relatively strong heating will yield afternoon MLCAPE values over 2000 J/kg. Mid-level lapse rates are not particularly steep, but rather strong winds aloft and mesoscale organization of these clusters will help to pose a risk of damaging winds across much of central/eastern Lower MI through the afternoon. The potential also exists for a few supercells to form ahead of the main bowing structures, posing a risk of hail and a few tornadoes as well. Behind the lead convection, another bowing MCS is moving across southwest WI. These storms are closer to the mid-level vorticity center and even stronger winds aloft. It is unclear how much destabilization can occur in the wake of the lead storms, but it seems plausible that this cluster will also pose a severe risk through much of the afternoon and evening, traversing a similar track as the southern lead bowing structure. ...UT to CO/KS/NE... A corridor of sufficient mid-level moisture is expected to result in scattered high-based showers and thunderstorms from parts of UT into northern CO and southern WY today. As the storms over the CO mountains spread eastward into the plains, they will encounter an increasingly moist and unstable air mass. A few of these storms may become severe by late afternoon/evening with damaging winds being the main concern. ...Southern AZ... Several 12z HREF members show a cluster of thunderstorms developing over the higher terrain of southern AZ and spreading northwestward during the evening. If this scenario unfolds, strong wind gusts could affect the region. Read more CHECK UPDATE ZOOM GRAPHIC
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