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Weather conditions on bar directly above are near Lakefront. Tabs under Moon Phases refer to O'Hare (official).

Archives for SPC Convective outlook are updated daily with a live map a the beginning of the article. Touch or click map to get possible update, and follow link at end of article for referral to NOAA/NWS Storm Prediction Center. Archives for Chicago's hourly weather data were updated 24-48 hours after end of each day prior to Dec. 2020.

Monday, May 9, 2022

SPC May 9, 2022 0100 UTC Day 1 Convective Outlook

SPC 0100Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0759 PM CDT Sun May 08 2022 Valid 090100Z - 091200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF CENTRAL AND EASTERN SOUTH DAKOTA INTO FAR WEST-CENTRAL MINNESOTA... ...SUMMARY... Isolated severe hail and/or wind gusts may occur this evening into tonight over portions of the north-central Plains. ...Synopsis... A broad cyclonic upper flow regime will persist across the western and central U.S., with an embedded mid-level impulse approaching the northern Plains from the intermountain West (per latest water vapor imagery). As this impulse begins to overspread the northern Plains, deep-layer ascent will increase, fueled both by divergence aloft, and low-level convergence at the terminus of a 40-60 kt 850 mb jet, which will also transport rich boundary layer moisture northward. Convective coverage and intensity is expected to increase through the night across portions of far northern Nebraska into the Dakotas, with enough shear and instability to promote strong to severe thunderstorm development. ...Northern Plains... The low-level jet is expected to intensify through the evening across the Plains states, transporting deep boundary layer moisture in advance of an approaching mid-level perturbation and ongoing showers/thunderstorms currently situated across the WY/NE border. Given boundary-layer decoupling, most of the northward-advecting buoyancy will be constrained above 850 mb, with some RAP forecast soundings depicting LFCs as high as around 700 mb. Still, deep moisture advection beneath 8 C/km 700-500 mb lapse rates will promote over 2000 J/kg MUCAPE. After 06Z, 80+ kt west-southwesterly 500 mb flow will overspread the 60 kt low-level jet, supporting well over 50 kts of effective bulk shear. Convergence at the nose of the low-level jet will support convective initiation across portions of central South Dakota. Given the steep mid-level lapse rates and associated MUCAPE, robust elevated convection could develop and propagate across the LLJ terminus with a severe hail threat, hence the introduction of a Category 2/Slight risk. Several of the latest HRRR runs and some of the earlier CAMs suggest that the greatest chance for robust, elevated convection would be in the 06-12Z period, from the NE/SD border into far west-central MN. ...Southeast North Dakota... Relatively strong updrafts, including a supercell in the Stutsman/Barnes County, ND vicinity are traversing a narrow but moist and buoyant low-level airmass, where a residual boundary is in place. Any storms that can favorably interact with this boundary may support a brief severe threat. However, this threat is expected to only last for a couple more hours. Please see MCD #0691 for more details. ...Central Texas... A couple of towering cumulus clouds have recently grown and have begun to precipitate, with MRMS mosaic radar data showing 30 dBZ echoes approaching 30 kft in the past hour. However, dynamic lift across the southern Plains remains quite weak, and the dryline has also begun to retreat to the west. As nocturnal cooling and associated boundary layer stabilization sets in, robust convective development becomes increasingly unlikely. ..Squitieri.. 05/09/2022 Read more CHECK UPDATE ZOOM GRAPHIC