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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.


Saturday, October 23, 2021

SPC Oct 23, 2021 1730 UTC Day 2 Convective Outlook

SPC 1730Z Day 2 Outlook Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1233 PM CDT Sat Oct 23 2021 Valid 241200Z - 251200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDDLE MISSISSIPPI VALLEY REGION... ...SUMMARY... Scattered severe thunderstorms associated with damaging wind gusts, isolated large hail and some tornadoes will be likely from parts of the Ozarks into the mid Mississippi Valley. A more isolated severe threat is expected in parts off the Arklatex, western Tennessee Valley, Ohio Valley and southern to central Plains. ...Ozarks to Middle Mississippi Valley region... Consensus among the models is that a low-amplitude shortwave trough now moving into northern CA will continue into the central Plains Sunday and the middle MS Valley Sunday evening before reaching the OH Valley overnight. Attendant surface low will move from northeast KS through northern MO and eventually NW IN by the end of period. Cold front will sweep eastward through the middle MS Valley, while a warm front extending eastward from the low through northern MO into central IL and IN will struggle to move north. A strengthening southwesterly low-level jet will tap into reservoir of richer low-level moisture now present across TX, with mid 60s F dewpoints likely advecting northward through the warm sector beneath modest mid-level lapse rates. This process will result in moderate instability with 1500-2000 J/kg MLCAPE likely. Some low clouds may accompany the moisture return which may delay boundary layer destabilization in some areas. Initial storms are expected to initiate within zone of stronger forcing along the cold front across far northeast KS southward into eastern OK. Other storms will be possible farther east along the warm conveyor belt. Activity will subsequently spread east through the middle MS Valley region during the afternoon and into the evening. Mixed storm modes will be likely along the front with more discrete activity possible in warm sector. Both supercells and bowing segments capable of all hazards will be supported by 40-50 kt effective bulk shear. Low-level hodographs with 200-300 m2/s2 storm relative helicity will also support a threat of tornadoes, a few of which could be strong, especially in ENH risk area. With time, the dominant storm mode should transition to lines with damaging wind becoming the main threat. An upgrade to MDT might be warranted in later updates once mesoscale details become more apparent. ...Oregon Coast... Scattered low-topped convection will develop within an environment characterized by very strong shear and weak instability but steep lapse rates. These storms may become capable of producing a few damaging gusts and possibly a couple of tornadoes later Sunday afternoon and evening. ..Dial.. 10/23/2021 Read more LIVE:
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