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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.

Friday, May 13, 2022

SPC May 13, 2022 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook CORR 2 NWS Storm Prediction Center Norman OK 0331 PM CDT Fri May 13 2022 Valid 132000Z - 141200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS CENTRAL OKLAHOMA TO FAR SOUTHERN KANSAS AND THE UPPER MISSISSIPPI RIVER VALLEY... CORRECTED FOR GENERAL THUNDER LINE ...SUMMARY... Isolated to scattered severe thunderstorms will be possible later this afternoon through this evening across a large portion of the central states. The most probable areas for large hail and damaging winds are across a portion of Oklahoma and southern Kansas, as well as from east-central Missouri to southwest Wisconsin. ...Discussion... The forecast generally remains on track with only minor adjustments required. Latest analyses and observations from central/southern OK show cool outflow from morning/ongoing convection lingers across the region with only modest recovery. Consequently, low-level lapse rates remain somewhat poor and may not recover sufficiently to support a widespread damaging wind threat. As a result, the 15% wind risk area is removed. However, thunderstorms developing this afternoon/evening will still pose a large hail risk with an attendant (albeit limited) damaging wind potential. Across the upper MS river valley, latest GOES visible imagery shows cumulus beginning to deepen along the surface cold front from northern IL into WI. Low-level lapse rates in the region continue to steepen to near 8 C/km, which will support a damaging wind threat as storms develop along the front around late afternoon. ..Moore/Mosier.. 05/13/2022 .PREV DISCUSSION... /ISSUED 1126 AM CDT Fri May 13 2022/ ...OK to southern KS... Below-average confidence exists in how convective evolution will play out late this afternoon and evening. A quasi-stationary thunderstorm cluster has been persistent in a portion of east-central to northeast OK. While most 12Z guidance suggest this activity should gradually drift east and weaken this afternoon, some CAMs indicate renewed storm development will occur along its southwest flank in the south-central OK vicinity later this afternoon when differential heating should be maximized. Other guidance suggests convection will also develop farther west-northwest along the weakly convergent surface front in south-central KS to west-central OK during the 00-02Z time frame. Given weak low-level winds and nebulous large-scale ascent, these various scenarios appear plausible. Within a belt of 25-30 kt 500-mb westerlies, a few slow-moving supercells and multicell clusters may develop with large hail and damaging winds as the primary hazards. ...WI to the Mid-MS Valley... An MCV near the MO/IA border should shift northeast into WI by this evening. A surface cold front will move east across WI and trail south-southwest into the Mid-MS Valley. Convergence along this boundary will be the primary forcing mechanism for a broken band of thunderstorms during the 23-02Z time frame. A relatively narrow plume of higher PW values evidenced in GOES imagery should be confined to along the surface boundary from the Mid-MO Valley south. Weak shear is expected in this region but should be compensated by larger buoyancy. The trailing influence of enhanced deep-layer shear attendant to the MCV should affect the WI/IA/IL border area north where MLCAPE will be subdued. Overall scenario suggests multicell clustering will dominate with a confined threat for isolated to scattered damaging winds and isolated severe hail. ...Lower MS Valley... Along a diffuse front aiding in low-level convergence, ongoing thunderstorms across western MS should expand in coverage from the AR/TN border south into southeast LA during the rest of the afternoon. Vertical shear will be weak, but a belt of 20-25-kt mid-level northerlies will support some multicell clustering. Localized damaging winds from wet microbursts will be the primary hazard, but isolated marginally severe hail will be possible as well. ...West TX... Hot temperatures to the west of the dryline will aid in scattered thunderstorms along the boundary during the late afternoon to early evening. Weak lower-level wind fields will minimize SRH, but sufficient deep-layer shear will exist for a few transient supercells and multicell clusters capable of isolated large hail and severe wind gusts. Read more CHECK UPDATE ZOOM GRAPHIC