SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1235 AM CDT Fri Sep 17 2021 Valid 171200Z - 181200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms appear unlikely across the contiguous United States today. However, a few strong storms are possible across parts of west Texas, and southern Arizona during the late afternoon. ...Great Lakes into the central Plains and into west TX... A fast-moving and deep upper trough will move from the northern Plains/Upper MS Valley across the Great Lakes through 00Z, lifting east/northeast into Quebec overnight. At the surface, a cold front will extend roughly from Lake Michigan into central KS and the TX Panhandle by 21Z, with 60s F dewpoints ahead of it. The strongest lift the upper trough will quickly depart the Upper MI/Lake Superior region, leaving behind weakening convergence along the boundary. Still, heating and sufficient moisture, as well as residual cool air aloft will likely yield regenerating storms along the front, from IL/WI southwestward into KS and western OK. Shear will be weak in these areas, with only short-lived updrafts likely. Other storms are expected to form during the peak heating hours from the TX Panhandle into the South Plains. Here, lapse rates will be steep below 500 mb, and could result in locally strong wind gusts. Most CAMs show storms initiating across the eastern TX Panhandle, propagating south/southwestward. ...Far southern AZ... Gulf moisture will begin to return to the border region of southern Arizona, possibly contributing to 500-1000 J/kg MLCAPE by late afternoon. Heating will result in inverted-V profiles, and a few storms may develop in this regime by late afternoon or early evening. Isolated, strong convective gusts cannot be ruled out, but being diurnally driven in a weak shear environment, any severe wind risk appears limited in magnitude, space and time. ..Jewell/Moore.. 09/17/2021 Read more LIVE: spc.noaa.gov
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