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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.

Saturday, November 27, 2021

SPC Nov 27, 2021 0700 UTC Day 2 Convective Outlook

SPC 0700Z Day 2 Outlook Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1100 PM CST Fri Nov 26 2021 Valid 281200Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk of thunderstorms appears negligible across most of the U.S. Sunday through Sunday night. However, some lightning may accompany stronger lake-effect snow showers and bands expected to develop near and southeast of Lake Erie during the late afternoon and evening. ...Discussion... Models indicate that amplification within the main belt of westerlies emanating from the mid-latitude Pacific will translate from ridging, inland of the Pacific coast into the Great Plains, into downstream troughing, east of the Mississippi Valley into western Atlantic. Within this regime, the most prominent short wave trough is forecast to dig sharply southeast of the upper Great lakes, through the northern/mid Atlantic Seaboard vicinity by late Sunday night. As it does, associated forcing for ascent appears likely to contribute to renewed surface cyclogenesis offshore, accompanied by a reinforcing cold intrusion across much of the East. At the same time, the remnants of a cut-off low appear likely to continue to weaken while becoming absorbed within a confluent regime across the Gulf Coast states, through the base of the large-scale mid-level troughing, across and offshore of the south Atlantic coast by Sunday evening. While this may be accompanied by mid/upper-level moisture return and weak high-based convection across the Gulf coast vicinity and Florida Peninsula, generally dry and stable near-surface conditions appear likely to persist across this region, as an initial low/mid-level moisture return to Texas on Saturday becomes suppressed southward across the northwestern into central Gulf of Mexico. ...Lake Erie vicinity... A corridor of strong mid-level cooling (including temps of -20 to -30 C in the 700-500 mb layer) due to lift and cold advection is forecast to nose southeastward, across and southeast of the Lake Erie vicinity late Sunday afternoon and evening. This will contribute to steepening low-level lapse rates and weak CAPE, particularly near the relatively warm lake waters. The latest NAM forecast soundings, supported by the Rapid Refresh, suggest that thermodynamic profiles might become conducive to convection capable of producing lightning, primarily after 28/21Z into the 29/03-04Z time frame. ..Kerr.. 11/27/2021 Read more LIVE: spc.noaa.gov