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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.

Thursday, July 8, 2021

SPC Jul 8, 2021 1730 UTC Day 2 Convective Outlook

SPC 1730Z Day 2 Outlook Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1248 PM CDT Thu Jul 08 2021 Valid 091200Z - 101200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF THE MIDDLE MISSOURI VALLEY REGION... ...SUMMARY... Thunderstorms, some with potentially significant severe weather, are expected Friday afternoon into Friday night across parts of the central Plains and Mid Missouri Valley. A tornado or two associated with Tropical Storm Elsa also is possible in the vicinity of the New England coast through Friday afternoon. ...Synopsis... Compact, low-amplitude shortwave trough currently moving through northern MT will turn southeast and continue through the middle MO Valley region Friday. By early Friday, a warm front should extend from a surface low in NE southeast through MO. A cold front will stretch southwestward from the low through southwest NE into northeast CO and will likely stall during the day. ...Mid Missouri Valley... Thunderstorms will likely be in progress early Friday, primarily within the zone of isentropic ascent north of the warm front from southern MN through a portion of northern and eastern IA. The early activity should gradually shift southeast during the day, but will remain confined to the cool sector. Farther south in warm sector, dewpoints in the upper 60s to near 70 F will advect northward in wake of advancing warm front. This will contribute to moderate to strong instability with 2000-3000 J/kg possible as the boundary layer warms during the afternoon. The primary forcing for ascent associated with the southeast-advancing shortwave trough will probably remain confined to along and north of the warm front. However, additional storms may develop along this boundary by late afternoon and especially as the low-level jet strengthens by early evening. Strong effective shear from 45-50 kt will support some supercells, but storms may eventually evolve into lines and clusters as they spread southeast. All severe hazards are possible. ...Central Plains... Upslope flow regime is expected to evolve north of stalled front across the central plains maintaining a corridor of mid 50s to near 60 F dewpoints beneath steep lapse rates and contributing to moderate instability with up to 2000 J/kg MLCAPE as the boundary layer destabilizes. Storms are expected to develop within this regime and spread east through the high Plains. A belt of stronger flow aloft will contribute to 50+ kt effective bulk shear supportive of supercells early in the evolution. However, storms may eventually evolve into one or more MCSs. Large hail and damaging wind will be the main threats. ..Dial.. 07/08/2021 Read more LIVE: spc.noaa.gov