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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.

Sunday, May 15, 2022

SPC May 15, 2022 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook AMEND 1 NWS Storm Prediction Center Norman OK 0435 PM CDT Sun May 15 2022 Valid 152130Z - 161200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM EASTERN OKLAHOMA INTO WESTERN ARKANSAS... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM OKLAHOMA TO INDIANA AND FROM NORTHEAST OREGON INTO IDAHO... AMENDED TO UPDATE LINES ...SUMMARY... Scattered to numerous severe storms with swaths of wind damage, very large hail, and a couple brief tornadoes remain possible through evening from easern Oklahoma into Arkansas. Other isolated severe storms will be possible later this afternoon across the interior Pacific Northwest. A primary cluster of storms continues to develop south across AR, with damaging winds and hail likely. Other cells with hail persist north of the outflow across southeast KS. Probabilities have been reduced in the wake of this activity across MO. Elsewhere, storms are forming along the front in IL, with a plume of instability to the east. Other cells may rejuvenate across southeast MO where outflow is enhanced. See mesoscale discussion 769. To the west, heating continues over OK, with a reservoir of strong instability across eastern OK. Midday soundings as well as objective analysis indicate MLCAPE in excess of 3000 J/kg with steep lapse rates aloft. This will clearly favor vigorous convection developing along the outflow boundary and ahead of the dryline now into central OK. It is unclear whether storms will affect the OKC area given the drying, but an unstable air mass remains with hot temperatures and a boundary approaching from the north. As such, will maintain a conditional Slight here. ..Jewell.. 05/15/2022 .PREV DISCUSSION... /ISSUED 1124 AM CDT Sun May 15 2022/ ...Ozark Plateau to the Lower OH/MS/Red River Valleys... Several clusters are ongoing across eastern KS and western MO, with the leading cluster in west-central to southwest MO having a reported history of sporadic wind and hail. With pronounced boundary-layer heating occurring downstream, further intensification is expected to the east-southeast as an MCV shifts towards the confluence of the MS/OH rivers. Damaging winds and a brief tornado or two will be the primary hazard in this regime. Farther south and southwest, low 70s surface dew points beneath the eastern plume of a stout elevated mixed layer over OK/TX, should yield a very unstable air mass with MLCAPE of 3000-4000 J/kg by mid-afternoon. Both warm-advection driven activity south of the MCV track, as well as regenerative development along and behind the trailing outflow will support supercells embedded within emerging south-southeast tracking clusters. Most guidance has become better aligned in suggesting multiple bowing segments within the broader northwest flow regime across eastern OK/western AR towards the Lower Red River Valley mainly during the late afternoon and early evening. Overall setup should support scattered swaths of golfball to baseball size hail in semi-discrete supercells, and 60-80 mph damaging winds within embedded bows. Some form of the MCSs should make it as far east as the Lower OH Valley and as far south as the Lower MS Valley and Ark-La-Tex, though the damaging wind threat will be diminishing later this evening. ...Interior Pacific Northwest/northern Rockies... A compact shortwave trough now off the OR/WA coast will move northeast into southern British Columbia by evening. Heating of boundary-layer dewpoints from the upper 40s to lower 50s and increasing ascent with the approaching shortwave trough/front will support scattered thunderstorm development this afternoon across northeast OR. Though buoyancy will be weak with MLCAPE of 500-750 J/kg, strengthening wind profiles/deep-layer shear will support the potential for organized convection, including a few supercells and/or short line segments with an attendant threat for large hail, damaging winds, and perhaps a tornado. Convection should eventually weaken in the ID Panhandle vicinity later this evening. ...Mid-Atlantic/Northeast... A diffuse surface trough should remain anchored from central NY southward in the lee of the Appalachians. This should help focus scattered thunderstorm development this afternoon, and a few of the storms could produce strong outflow winds and minor damage, along with marginally severe hail in an environment characterized by weak vertical shear and modest buoyancy with MLCAPE of 500-1500 J/kg. ...Eastern FL Peninsula... Downstream of a low-amplitude upper trough in the eastern Gulf, adequate vertical deep-layer shear will exist for a threat of marginally severe hail and localized damaging winds amid isolated to scattered thunderstorms this afternoon. Read more CHECK UPDATE ZOOM GRAPHIC