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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.

Wednesday, June 22, 2022

SPC Jun 22, 2022 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0251 PM CDT Wed Jun 22 2022 Valid 222000Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS MIDDLE AND UPPER OHIO VALLEY AND MID-ATLANTIC STATES... ...SUMMARY... Scattered damaging winds are most probable across the middle and upper Ohio Valley and Mid-Atlantic States this afternoon through about dusk. ...Discussion... Only substantial change this outlook update is to include parts of northern KY and southwest OH in the 15-percent wind probability (categorical change from marginal to slight risk). A very unstable airmass will lead to pulse-like thunderstorms capable of strong to locally severe gusts (50-65 mph) and the potential for wind damage. ..Smith.. 06/22/2022 .PREV DISCUSSION... /ISSUED 1121 AM CDT Wed Jun 22 2022/ ...Upper OH Valley to the Mid-Atlantic... A closed low off the southern New England coast will retrograde westward, while a separate shortwave impulse in the westerlies moves across the Great Lakes. A northeast/southwest-oriented cold front will move southeast across the Lower Great Lakes and OH Valley, eventually merging with a north/south-oriented backdoor cold front drifting west in central PA to western NY. 12Z observed soundings were unimpressive in terms of mean-mixing ratios and mid-level lapse rates. While strong boundary-layer heating and evapotranspiration will yield a plume of moderate to large buoyancy, guidance such as the 12Z NAM appears far too moist with mean-mixing ratios peaking around 20 g/kg and extreme MLCAPE in excess of 5000 J/kg. MLCAPE of 2000-3000 J/kg will probably be more common between the two fronts across the Upper OH Valley to western PA. Northwesterly to northerly mid-level flow on the west side of the closed low will favor southeast to southward-moving clusters later this afternoon from central/western PA into northern WV and northwest VA, along and west of the stalled north-south front. A cooler marine layer to the east of this front will result in severe potential decreasing rapidly with eastern extent in eastern PA to the Chesapeake. Slightly longer hodographs will be present along the north-south front, where there will be some potential for a few transient supercell structures. However, multicell clusters should be the dominant storm mode, with a primary threat of scattered damaging winds from strong to localized severe gusts. This threat will gradually diminish during the evening as clusters spread southward into an environment with weaker buoyancy but residual steeper low-level lapse rates across southern VA into NC. Multicell storm clusters are also expected along the cold front farther southwest across the OH Valley by mid-late afternoon. Vertical shear will be weaker, but large CAPE/DCAPE will favor localized damaging outflow gusts with multicell clusters into early evening. ...Southern KS and far northern OK... A surface cold front has stalled near the OK/KS border. Isolated to scattered thunderstorms should develop towards early evening along and north of this boundary as strong surface heating and deep mixing impinges on the front. Despite some weak enhancement to the hodographs on the cool side of the boundary, vertical shear will largely remain weak, with multicell clusters the expected convective mode. A confined corridor of MLCAPE from 2000-2500 J/kg and DCAPE in excess of 1000 J/kg will support isolated strong/damaging outflow gusts, and marginally severe hail for a few hours this evening. ...Southern/central CA... A plume of richer moisture centered around 700-mb and ascent tied to a mid-level closed low just off the coast has yielded regenerative scattered thunderstorms across southern into central CA this morning. Pockets of stronger surface heating/mixing in cloud breaks to the south of this morning's activity will contribute to deepening inverted-v profiles. Weak surface-based buoyancy with MLCAPE of 250-750 J/kg should be sufficient to realize some downburst potential in an environment of steep low-level lapse rates and DCAPE greater than 1000 J/kg. Isolated damaging gusts will be possible, mainly during the late afternoon to early evening from the higher terrain of southern CA northward into the San Joaquin Valley. Read more CHECK UPDATE ZOOM GRAPHIC