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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.

Tuesday, May 31, 2022

SPC May 31, 2022 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Tue May 31 2022 Valid 312000Z - 011200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS LATE THIS AFTERNOON AND EVENING ACROSS THE SOUTHEASTERN TEXAS PANHANDLE VICINITY AND NORTHERN/WESTERN OKLAHOMA... ...SUMMARY... Scattered strong to severe thunderstorms are expected to develop in a narrow corridor extending from the southern Great Plains into the mid Mississippi Valley region later today through tonight. These may become most numerous across parts of northwestern Oklahoma into the southeastern Texas Panhandle vicinity, where large hail, a few strong downbursts and a couple of tornadoes are possible. ...20Z Update... No changes have been made to the Enhanced/Slight Risk areas across the southern Plains into the mid MS Valley, where scattered strong-to-severe storms are possible later this afternoon into this evening. The severe threat further east into parts of the Midwest and Great Lakes appears more uncertain, due an expansive cirrus impacting destabilization over parts of the region, and uncertainty regarding storm coverage through the most favorable part of the day. Part of eastern MI has been trimmed from the Slight, but no changes have been made from western MI into the Midwest, due to some potential for storms to increase early enough this evening to pose some organized severe threat. The Marginal Risk across New England has also been trimmed slightly from the east, based on the progress of the back-door cold front. ..Dean.. 05/31/2022 .PREV DISCUSSION... /ISSUED 1111 AM CDT Tue May 31 2022/ ...Synopsis... The center of a fairly broad and deep, but occluding, surface cyclone is now north of the Minnesota international border (near Lake of the Woods), and forecast to gradually weaken while migrating northward toward the southwestern shores of Hudson Bay by late tonight. This will accompany an associated remnant mid-level perturbation, which models continue to indicate will gradually consolidate with another short wave trough digging southeast of the Arctic latitudes, and contribute to a deepening, broader mid-level low to the southwest of an increasingly prominent mid-level high to the east of Hudson Bay. To the southeast of the mid-level high, an already deep mid-level low is in the process of slow shifting southward offshore of the northern New England coast and Canadian Maritimes. While a significant cold front associated with the eastern mid-level low advances south of southern New England coastal areas, its western flank is forecast to stall across the lower Great Lakes into areas southwest of James and Hudson Bays, where it gradually will be overtaken by the cold front associated with the weakening upstream cyclone. This latter cold front is also forecast to continue advancing southeastward across the interior U.S., through much of the upper Great Lakes, upper half of the Mississippi Valley and south central Great Plains by late tonight. This front is preceded by a convectively generated and/or enhanced boundary across the Upper Midwest into the lower Missouri Valley and Texas/Oklahoma Panhandle vicinity, with substantive ongoing lingering convection, associated precipitation and cloud cover across much of the lower Missouri Valley into the Upper Midwest. As the weakening deep-layer cyclone progresses away (north) of the international border, this lead boundary may tend to become displaced to the south of a seasonably strong west-southwesterly mid/upper jet. This jet trails to the south and southwest of the cyclone to another weaker, elongated low over the Great Basin, and may tend to shift northward on the crest of building short wave ridging across the central Great Plains, as the Great Basin perturbation is gradually forced east-northeastward. ...Southern Texas Panhandle into southeastern Kansas... While the lower/mid tropospheric flow tends to weaken through the day, along and south of the convective boundary and cold front, models continue to indicate that a seasonably moist boundary layer and steep lower/mid tropospheric lapse rates will contribute to a narrow corridor of large CAPE (2000-3000 J/kg) by late this afternoon. Mid/upper support for thunderstorm initiation remains a bit unclear, but models suggest that weakening inhibition with daytime heating may be enough. Even to the south of the stronger mid-level jet, deep-layer shear may still be marginally sufficient to support supercell structures capable of producing large hail, before convection becomes increasingly widespread. By this evening, a few strong downbursts may be possible, but activity likely will be generally slow moving and confined to a narrow corridor to the north of stronger mid-level capping, with a tendency to be undercut by conglomerating convective outflow. ...Lower Missouri Valley into Great Lakes... It is not clear that one, well-defined MCV will emerge from the weakening convection still ongoing across the lower Missouri Valley. However, the latest Rapid Refresh suggests that a belt of 30-40+ kt southwesterly flow in the 850-500 mb layer will nose northeastward toward lower Michigan today through tonight. Near the southern periphery of this jet, it is possible that deep-layer shear and boundary-layer destabilization could become conducive to one or two organizing thunderstorm clusters posing a risk for severe wind and hail. Read more CHECK UPDATE ZOOM GRAPHIC