SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1119 AM CDT Fri Jul 23 2021 Valid 231630Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE NORTHERN PLAINS TO WESTERN LAKE SUPERIOR... ...SUMMARY... Severe thunderstorms with damaging winds and large hail are possible later this afternoon into early tonight from parts of the northern Plains to western Lake Superior. ...ND... An expansive upper ridge is in place today over most of the southern and central U.S., with stronger mid-level flow relegated to the northern tier of states. A cold front extending from northwest ND into MT will move eastward this afternoon and provide focus for isolated-scattered thunderstorm development. Given the relatively weak large-scale forcing for ascent, 12z model guidance is quite diverse in the forecast coverage of storms. Have trimmed the SLGT considerably in this area, while maintaining areas of highest confidence for thunderstorms. Those cells that form will pose a risk of hail and damaging winds. ...MN... Slightly stronger forcing will be present along the front as it moves into northwest MN this afternoon and evening. This should result in one or more clusters of thunderstorms tracking across northern MN and eventually toward Lake Superior. The potential exists for bowing structures capable of damaging winds and hail. ...SD... Farther south, a subtle shortwave trough is moving across WY. This feature is expected to result in a few thunderstorms later today over parts of western/central SD. Very steep low-level lapse rates and moderate CAPE ahead of this cluster of storms, coupled with 20-30 knots of westerly mid-level flow, suggest the potential for locally damaging wind gusts in these storms. ...AZ/NM... Ample low and mid-level moisture across much of AZ/NM will result in rather widespread thunderstorm activity this afternoon and evening. Shear profiles are stronger than normal for this time of year, which may promote a few rotating cells. However, warm temperatures aloft, weak lapse rates, and limited surface heating opportunity will be mitigating factors to more vigorous updrafts. Gusty winds and hail will be possible with the stronger storms. ..Hart/Wendt.. 07/23/2021 Read more LIVE: spc.noaa.gov
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