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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 15, 2022

SPC Jun 15, 2022 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0247 PM CDT Wed Jun 15 2022 Valid 152000Z - 161200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF WISCONSIN... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL AND SOUTHERN APPALACHIANS TO THE CENTRAL GULF COAST STATES... ...SUMMARY... Scattered severe thunderstorms are likely this afternoon into tonight across parts of the Upper Midwest and Upper Great Lakes. Several tornadoes, large to very large hail, and damaging winds all appear likely. Some of the tornadoes could be strong. ...Discussion... The current outlook continues to accurately reflect future expectations, as the anticipated severe weather event begins to unfold across the Upper Mississippi Valley/Upper Great Lakes region. Storms are expected to increase substantially in coverage and intensity over the next few hours, in and near the newly issued tornado watch across this area. Storms are also evolving now across the central and southern Appalachians, and southeastward across the Savannah River Valley area, with a ramp-up in severe potential over the next couple of hours expected in this region as well. Given current and anticipated convective trends, only minor tweaks to the outlook areas appears necessary in this update. ..Goss.. 06/15/2022 .PREV DISCUSSION... /ISSUED 1217 PM CDT Wed Jun 15 2022/ ...Upper Midwest including Wisconsin/Iowa/Upper Michigan... A regional outbreak of severe storms is expected this afternoon and evening, particularly across eastern Iowa/far southeast Minnesota into southern/central/eastern Wisconsin and Upper Michigan. Aside from large hail, this includes the potential for tornadoes, some of which may be strong, along with a focused corridor of appreciable damaging wind potential. Related to a decayed overnight MCS, morning surface analysis shows a precipitation-reinforced semi-stalled boundary extending from west/central Iowa into southwest/central Wisconsin, with some persistent precipitation and a few stronger storms/differential heating reinforcing this boundary. A notable upper trough over the northern Plains will influence the region particularly later today into tonight with increasing large-scale forcing for ascent and strengthening deep-layer southwesterly winds. Modest surface cyclogenesis is expected along the southwest/northeast-oriented boundary, with the gradually deepening wave expected to help maintain an easterly component to the near-surface winds. Surface dewpoints in the lower 70s F and steep mid-level lapse rates will yield MLCAPE values of 3000+ J/kg especially from eastern Iowa into much of central/southern Wisconsin. Strong deep-layer shear and large hodographs will promote supercells capable of very large hail and a few tornadoes during the first several hours of surface-based initiation. A few of the tornadoes could be strong (EF2+), although there are some mode-related uncertainties over time. Storms are likely to trend upscale across interior parts (central/southern) of Wisconsin with damaging wind potential appreciably increasing. Storms will move into Lower Michigan and northern Illinois after sunset, with a continued risk of locally damaging wind gusts persisting, potentially as far east as Lower Michigan and northern Indiana. ...Southeast/Mid-Atlantic/Northeast States... A hot and humid low-level air mass is in place today from the central/northern Appalachians and interior Carolinas southwestward into Mississippi/Alabama, with widespread temperatures in the 90s and dewpoints in the upper 60s and lower 70s. This will result in MLCAPE values over 3000 J/kg and steep low-level lapse rates throughout the region. The details of the timing and location of convective development remains uncertain even in the short-term, but multiple corridors of storms may unfold this afternoon into tonight on the periphery of the southern Appalachians-centered upper-level ridge. Sufficiently strong northeasterly flow aloft will aid in southwestward-propagating clusters capable of strong/damaging wind gusts. A conditional severe risk will exist as far north as west-central Pennsylvania and western New York today near the front. Several models also imply the potential for late-night MCS development centered across southern New York/west-central Pennsylvania into Maryland. Read more CHECK UPDATE ZOOM GRAPHIC