SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0753 AM CDT Wed Jun 16 2021 Valid 161300Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS EVENING INTO TONIGHT FOR SOUTHERN MN INTO IA AND VICINITY... ...SUMMARY... A few thunderstorms with isolated large hail and damaging winds will be possible this evening into tonight from southern Minnesota into Iowa and vicinity. ...Western MN into IA this evening into tonight... A midlevel shortwave trough and associated cold front have begun to suppress the midlevel ridge over the northern High Plains, and this trend will continue through tonight as the shortwave trough/front progress generally eastward over the Dakotas/MN. Low-level moisture advection and strong surface heating in advance of the cold front will contribute to large buoyancy (MLCAPE up to 3000 J/kg), but a warm elevated mixed layer will act to cap the boundary layer. The more probable time for storm initiation will be this evening into tonight as warm advection increases on the nose of a 35 kt low-level jet in the vicinity of southwest MN/northwest IA. Storm coverage and subsequent storm evolution are still uncertain, though there is potential for a cluster of elevated storms to spread south-southeastward and produce large hail/damaging winds, given the large CAPE, steep midlevel lapse rates, and large DCAPE. If confidence in this scenario increases, an upgrade to Slight risk will be possible for parts of southern MN and IA for tonight. ...Elsewhere... A slow-moving front and local sea breeze boundaries will again focus thunderstorm development across the FL Panhandle and north FL today. However, a comparison of 12z soundings from JAX/TLH show a reduction in buoyancy over the past 24 hours, which suggests a lesser threat for downburst winds today. Likewise, some reduction in low-level moisture from the north/northeast and no clear inland boundaries suggest that storm coverage/intensity should be reduced this afternoon/evening across southeast TX compared to yesterday. Otherwise, high-based convection will again be possible with diurnal heating from CO into parts of AZ/NM. Very limited moisture suggests the storms will be weak and will produce little rainfall, though gusty outflow winds will be possible with deep inverted-v profiles. ..Thompson/Leitman.. 06/16/2021 Read more LIVE: spc.noaa.gov
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