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Archives for the SPC Convective Outlook are updated daily (approximately) with a live map at the beginning of each article. Follow the link at the end of the article to check for current updates on the NOAA/NWS Storm Prediction Center website. Also, see Archives for Chicago's hourly weather data on CARDINAL NEWS Magazine.

Sunday, June 12, 2022

SPC Jun 12, 2022 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 0348 PM CDT Sun Jun 12 2022 Valid 122000Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF THE NORTHERN HIGH PLAINS EAST TOWARD CENTRAL PARTS OF SOUTH DAKOTA AND NEBRASKA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MID MISSISSIPPI/LOWER OHIO VALLEYS...AND PORTIONS OF THE VIRGINIA/NORTH CAROLINA VICINITY... CORRECTED TO REMOVE SPURIOUS POINT IN TORNADO GRAPHIC ...SUMMARY... Scattered severe thunderstorms across the northern and central High Plains late this afternoon into tonight will be capable of producing large hail and damaging winds. Isolated severe storms also remain possible across the lower Ohio Valley and parts of the southern middle Atlantic. ...Discussion... Overall/prior forecast reasoning -- and associated risk areas -- continue to appear to adequately reflect severe-weather potential this afternoon and tonight. The primary change in this update is to expand the SLGT risk/15% wind area across the northern Plains area southeastward, to include the remainder of southeastern South Dakota, portions of northeastern Nebraska, northwestern Iowa, and the rest of southwestern Minnesota. Model guidance has become more consistent in suggesting that despite capping currently indicated across this area, that an evolving/southwesterly low-level jet nosing into the Mid-Missouri Valley will sustain convection across this region overnight. ..Goss.. 06/12/2022 .PREV DISCUSSION... /ISSUED 1215 PM CDT Sun Jun 12 2022/ ...Northern/central Plains to Upper Midwest... Regional upper-air analysis reflects an axis of moderate low-level moisture extending west/northwestward across the north-central High Plains this morning. This coincides with a belt of strong mid/high winds that precede an amplifying trough over the Pacific Northwest, with the aforementioned stronger winds extending over the northern Rockies east-northeastward into the Dakotas/Minnesota. Influenced by increasing larger-scale forcing for ascent and orographic lift in vicinity of mountains/higher terrain, increasing thunderstorm development is likely by mid-afternoon across northern Wyoming/southern Montana, and a bit later toward the Black Hills vicinity and southward along the lee trough/boundary into western Nebraska/northeast Colorado. Initial supercells capable of large hail can be expected, along with some tornado risk and a higher probability of very large hail particularly across northeast Wyoming/far southeast Montana into western South Dakota. Confidence has increased that a higher probability corridor of severe storms including upscale growth into one or more MCSs should evolve this evening across western/central South Dakota as well as western Nebraska. An Enhanced Risk has been added to these areas. ...Missouri/Kentucky and southern Illinois/Indiana... Complex short-term scenario across the region with multiple residual influences (MCV etc.) from last night's middle Missouri Valley MCS. A consequential reservoir of moisture exists across the region per 12z upper-air 850 mb analysis, extending from northern/eastern Kansas into Missouri and southern portions of Illinois/Indiana into northern Kentucky. This will contribute to a very unstable air mass with upwards of 4000-6000 J/kg MLCAPE. However, a major complicating factor, in terms of uncertainty, is expectations for steady mid-level warming via the eastward-advecting elevated mixed layer. 12z Topeka, KS observed sounding featured a 15.2 C 700 mb temperature, while Springfield, MO was 13.6 C. Short-term model guidance varies considerable in this modest forcing/prevalent mid-level warmth scenario. However, storm persistence/development through this afternoon will likely regionally favor the cooler side of this notable mid-level thermal gradient, with more probable storms across downstate portions of Illinois/Indiana into Kentucky. It is plausible that a severe risk, at least on an isolated basis, impacts at least parts of the region through the afternoon into evening, with potential late-night redevelopment on the eastern edge of the cap. Damaging winds and large hail will be possible in what could be a multi-round-related storm risk for parts of the region. ...Virginia/North Carolina... A cluster of strong/severe storms will continue to impact far southeast Virginia vicinity through early afternoon. Otherwise, a relatively moist and potentially unstable air mass is present to the west of these early day storms. Forecast soundings suggest sufficient deep-layer shear for convective organization and perhaps a supercell or two. Overall, locally damaging winds are the main threat through the early evening. Read more CHECK UPDATE ZOOM GRAPHIC