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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, May 17, 2023

SPC May 17, 2023 0600 UTC Day 2 Convective Outlook

LIVE MAP (ABOVE) ... SPC 0600Z Day 2 Outlook Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Wed May 17 2023 Valid 181200Z - 191200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM OKLAHOMA SOUTH-SOUTHWESTWARD INTO THE TRANSPECOS REGION OF WESTERN TEXAS... ...SUMMARY... A few severe thunderstorms may occur over portions of the southern Plains region Thursday. ...Synopsis... An upper low initially over southern portions of the Canadian Prairie will shift southeastward with time, crossing the north-central U.S. through Friday morning. As this occurs, a surface cold front is forecast to advance southeastward across the Upper Mississippi Valley into the Upper Great Lakes region, and southward across the Plains states. Elsewhere, northern-stream ridging aloft will prevail over the West. ...Oklahoma southwestward to the Transpecos region of Texas... As a cold front advances southward across the central Plains and a weak low evolves over the Texas South Plains region along a southern High Plains lee trough, daytime heating of the moist boundary layer will result in mixed-layer CAPE values in the 1000 to 2000 J/kg range to develop from parts of western Oklahoma south-southwestward to areas near the Texas Big Bend. During the afternoon, isolated convective development is expected to occur near the lee trough, and later should increase in coverage across the Oklahoma vicinity as the front advances southward, and eventually a 50 kt southerly low-level jet develops. Initial/more isolated convective development near peak heating may pose a local risk for gusty winds and hail, though somewhat modest shear should limit overall storm intensity. During the evening, as the low-level jet develops, increasing low-level flow will contribute to stronger low-level and deep-layer shear, sufficient to otherwise support rotating storms. However, with instability diminishing later in the evening, this should somewhat offset the more favorable shear which is expected to develop. Additionally, storms would likely grow upscale rather rapidly into a cluster/MCS, which also may mitigate a more robust supercell severe risk. At this time, will maintain only MRGL risk, as the degree of potential for any one severe hazard does not appear particularly notable at this time. Still, upgrade to SLGT may be required in later outlooks, as cumulative threat may eventually appear sufficient to warrant slightly higher probabilities. ...Wisconsin southwestward to northwestern Kansas... As the cold front advances southward/southeastward through the day, weak destabilization is forecast to occur near the boundary, where daytime heating combined with modest (generally upper 50s dewpoints) boundary-layer moisture allows roughly 500 J/kg mixed-layer CAPE to evolve. This instability will likely be sufficient to allow a broken band of storms to develop during the afternoon, but likely insufficient enough to limit storm intensity overall -- particularly given only modestly sufficient shear for organized updrafts. As such, it appears that any severe potential should remain limited enough so as to not warrant inclusion of a MRGL risk area at this time. ..Goss.. 05/17/2023 Read more CHECK UPDATE ZOOM GRAPHIC
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