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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, March 1, 2023

SPC Mar 1, 2023 0600 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1153 PM CST Tue Feb 28 2023 Valid 011200Z - 021200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST TEXAS TO THE TENNESSEE VALLEY... ...SUMMARY... Severe thunderstorms will be possible on Wednesday from northeast Texas through the Mid-South and into Middle Tennessee, with a threat of hail, damaging wind, and a couple of tornadoes. Additional strong to isolated severe thunderstorms capable of wind damage will be possible across the Ohio Valley vicinity. ...Synopsis... A potent large-scale mid/upper trough will dig south and east across the western U.S. today. Ahead of the trough, fast southwesterly mid/upper flow will overspread TX to the Mid-South/Ohio Valley and eventually the Mid-Atlantic. A subtle shortwave impulse ejecting ahead of the western trough is expected to migrate through this fast southwesterly deep-layer flow from the Arklatex through the TN/OH Valley vicinity. Ahead of the ejecting shortwave impulse, southerly low-level flow will transport boundary-layer moisture northward across the TN/OH Valleys, and strong to severe thunderstorm development is expected this afternoon into the evening. ...TX to the TN Valley vicinity... A stalled front is forecast to reside from eastern OK into central TX early this morning. Weak ascent associated with the lead shortwave trough and convergence along the stalled front may be sufficient for isolated, elevated thunderstorms this morning across a narrow corridor from central TX into north TX. These initial cells could produce hail. Limited storm coverage and somewhat conditional threat will preclude higher severe probabilities across this portion of TX. By afternoon, stronger heating and moistening, coupled with increasing forcing for ascent from the Arklatex into the Mid-South will result in erosion of the midlevel cap. Isolated supercells are expected by mid/late afternoon along a front extending from northwest AR into the Ohio Valley. Elongated forecast hodographs amid effective shear values greater than 45 kt suggest splitting supercells will be possible. Large hail, some greater than 2 inches in diameter, will be possible with these initial supercells from far northeast TX through southern AR and into northwest MS. With time, a modestly increasing low-level jet and forcing along the front will support convection organizing into a line shifting east across the Mid-South/TN Valley this evening into tonight, with an attendant increase in damaging gust potential. Low-level shear is forecast to be modest, but sufficient, and some curvature to low-level hodographs suggest a couple of tornadoes also will be possible within the line and amid any preceding cells. Separate from initial convection further west, some guidance suggests isolated supercells could develop from northeast MS into northern AL and arcing southeast toward east-central AL/west-central GA during the afternoon if sufficient heating occurs to overcome capping. While this threat is a bit conditional, should storms develop, a threat for damaging gusts and a couple of tornadoes would exist. ...OH Valley Vicinity... The Ohio Valley portion of the cold front is expected to advance more quickly east/southeast this evening. Boundary-layer moisture will be more modest, from the mid/upper 50s to near 60 F. However, steep lapse rates and strong heating ahead of the front will contribute to MLCAPE around 500-1000 J/kg. Strong storms are expected to develop along the surging front by early evening and track southeast across the region, producing strong to locally damaging gusts. ..Leitman/Flournoy.. 03/01/2023 Read more CHECK UPDATE ZOOM GRAPHIC
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CHICAGO UTC-6 during CST (Central Standard Time, e.g., winter)
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