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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.


Tuesday, July 11, 2023

SPC Jul 11, 2023 1300 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0714 AM CDT Tue Jul 11 2023 Valid 111300Z - 121200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING EXTENDING FROM EASTERN MONTANA INTO PARTS OF THE NORTHERN AND CENTRAL PLAINS.... ...SUMMARY... The greatest risk for severe storms on Tuesday will be centered over portions of the northern and central Great Plains. Damaging winds and large hail are the primary risks. ...Eastern MT into SD/NE... Morning water vapor imagery shows a large upper ridge over the southwest states, with rather strong northwest flow aloft extending from the northern/Canadian Rockies across much of the northern Plains and Midwest states. Relatively strong heating will occur this afternoon over eastern MT, where temperatures in the mid 80s and dewpoints in the 50s to lower 60s will combine with steep mid level lapse rates to yield MLCAPE values of 1500-2500 J/kg. An upper trough currently over northwest MT will emerge into the high plains by mid-afternoon, promoting scattered thunderstorm development. Forecast soundings across this region show favorable deep-layer shear for discrete supercell storms capable of large/very large hail and damaging wind gusts. Activity will move/develop eastward into southwest ND and western SD during the evening, and eventually into parts of NE with a continued severe threat. ...Eastern SD/NE into IA... Scattered showers and thunderstorms are affecting the western Dakotas this morning, in association with a subtle mid-level shortwave trough. Model guidance varies considerably regarding the evolution of this activity today, but at least some guidance suggests that storms will intensify by mid-afternoon as daytime heating becomes established. Forecast soundings appear favorable for strong to severe storms, with sufficient vertical shear and steep mid-level lapse rates to promote a conditional risk of large hail and damaging wind gusts. ...Northeast TX into southern MS/AL... A large nocturnal MCS is tracking southeastward across OK this morning. This system and its associated MCV will progress into a very moist and unstable airmass extending from northeast TX into the central Gulf Coast region. Winds aloft are rather weak, and model guidance is inconsistent on the evolution of the MCS. But it appears likely that scattered strong storms will develop this afternoon ahead of the MCV, with a risk of locally damaging wind gusts in the stronger cells. ..Hart/Leitman.. 07/11/2023 Read more CHECK UPDATE ZOOM GRAPHIC
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CHICAGO UTC-5 during CDT (Daylight Savings Time, e.g., summer)