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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 4, 2023

SPC Jul 4, 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 0755 AM CDT Tue Jul 04 2023 Valid 041300Z - 051200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF NORTHERN KANSAS AND SOUTHERN NEBRASKA... ...SUMMARY... Severe thunderstorms are most likely today from the central Great Plains into the western Great Lakes from late afternoon into tonight. Severe thunderstorm gusts, possibly significant, will be the primary hazard, with instances of large to very large hail also possible. ...Central Plains to upper Midwest... Thunderstorms associated with a decaying MCS will continue to move east across eastern SD/southwest MN this morning. Although cloud cover may delay diurnal heating in some areas early, eventual destabilization is expected by this afternoon across the upper Midwest/western Great Lakes region. As a positively-tilted mid-level trough moves east over the central/northern Plains today, a cold front will move east/southeast from the upper Midwest southwest into the central High Plains. Strong insolation of a moist air mass south of the front and seasonably steep mid-level lapse rates over the plains portion of the risk area will result in moderate-strong surface-based instability this afternoon in advance of the front. Isolated thunderstorms are expected to develop mid/late afternoon initially over the higher terrain of northern CO/southeast WY, with additional development along the front from eastern SD/southwest MN where more substantial large-scale ascent with the upper trough will be present. With time, thunderstorm coverage should increase along the front aided by frontal convergence and a reduction in CINH. Initial development will consist of both supercell and multicell storm structures as 30-40 kts of deep-layer shear will be present over much of the risk area. A significant hail area has been introduced over central NE where steep mid-level lapse rates and potential for initially more isolated storm development appears greatest. South of the front, a well-mixed boundary layer/very steep low-level lapse rates should result in storms evolving into clusters/line segments with damaging winds as the primary severe hazard. Modestly increasing warm advection tonight with strengthening low-level jets across northern WI/Lake Superior and also across western KS should allow the severe risk to continue into the early overnight hours. ...Mid-Atlantic and southeast... Pockets of moderate/strong MLCAPE are expected by afternoon along a diffuse surface boundary from the coastal mid-Atlantic region west to northeast TX, with scattered thunderstorms developing within a moist (PW in excess of 1.75 to 2 inches) and weakly sheared air mass. Isolated stronger updrafts or storm clusters may have the potential for strong/locally damaging gusts. ..Bunting/Gleason.. 07/04/2023 Read more CHECK UPDATE ZOOM GRAPHIC
SUNRISE AND SUNSET TIMES IN UTC (if you're not logged in to Google)
CHICAGO UTC-6 during CST (Central Standard Time, e.g., winter)
CHICAGO UTC-5 during CDT (Daylight Savings Time, e.g., summer)