SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0757 PM CDT Sun Oct 24 2021 Valid 250100Z - 251200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF CENTRAL AND SOUTHERN ILLINOIS INTO CENTRAL AND EASTERN MISSOURI AND NORTHERN ARKANSAS... ...SUMMARY... Scattered severe thunderstorms with damaging wind gusts, large hail and a couple of strong tornadoes are likely from parts of the Ozarks into the middle Mississippi Valley the remainder of this evening into tonight. Isolated damaging gusts and a tornado or two will also be possible along the Oregon/Washington coast. ...Synopsis... A well-defined mid-level trough is progressing eastward toward the central MS Valley, and is coupled with a surface low, centered over northeastern MO, which is poised to move into the OH Valley overnight. A cold front trails the surface low across central MO into eastern OK/north-central TX, while a warm front ahead of the low gradually lifts northeastward eastern MO into central IL/IN. Widespread 70-80F temperatures, coupled with 60-65 F dewpoints and overspread by 6+ C/km mid-level lapse rates are contributing to adequate buoyancy for continued scattered strong to severe storms across the MO Valley into the central MS Valley this evening into tonight. Along the Pacific Northwest Coast, a potent mid-level trough continues to amplify across the region. Strong kinematic flow fields are in place, with 30-50 kts of 925-850 mb flow overlapped by 70-100 kt flow at 500 mb. Though scant, buoyancy may become adequate enough to support a very isolated severe threat along the WA/OR coastline with any deep-moist convection that can become established. ...MO Valley into the Mid-MS Valley through tonight... Scattered strong to occasionally severe storms (some showing transient supercellular structures) are ongoing along and ahead of the cold front across central MO into eastern OK and northern TX, as well as with a secondary confluence band across eastern MO into northern AR. Around 1500 J/kg MLCAPE exists ahead of the cold front/south of the warm front, within the LLJ axis from southwest IL into AR, where 200-400 m2/s2 effective SRH is present. As such, any supercell or embedded rotating line segment that can become sustained may pose a tornado/damaging wind threat this evening through tonight. Strong to occasionally severe line segments have also been traversing the warm front across central/northern IL. Though these storms will cross the LLJ axis this evening into tonight, the more buoyant surface-based airmass has struggled to reach this convection thus far. Nonetheless, given the highly sheared, at least marginally buoyant environment, a couple damaging gusts and perhaps a tornado or two cannot be ruled out through tonight. ...OR/WA Coastline... While surface temperatures along the WA/OR coastline are barely reaching 60F (with dewpoints struggling to exceed the mid 40s F), 6-7 C/km mid-level lapse rates are overspreading the coastline, supporting patchy areas of marginal buoyancy. The aforementioned strong kinematic fields will support 50+ kts of effective bulk shear/200 m2/s2 effective SRH. As such, a damaging gust and or perhaps a brief tornado may accompany any sustained updraft that can develop tonight. ..Squitieri.. 10/25/2021 Read more LIVE: spc.noaa.gov
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