SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Sat Jun 26 2021 Valid 262000Z - 271200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE MID-MISSISSIPPI VALLEY INTO LOWER MICHIGAN...AND OVER PARTS OF THE SOUTHERN PLAIN... ...SUMMARY... Scattered strong to severe thunderstorms remain possible this afternoon and evening from east-central Missouri to parts of Lower Michigan, and over parts of the southern Plains. Damaging winds and perhaps hail are possible in those areas, along with a tornado or two over the Illinois-Michigan corridor. ...20Z Update... The following primary changes have been made based on the latest observations and short-term model guidance: 1. The Slight Risk was expanded slightly southward across a larger portion of the Permian Basin in TX, based on latest short-term guidance regarding potential development of strong multicells, or perhaps a supercell or two, across the region. 2. 15% hail probabilities were removed from northeast IL/northern IN/southern lower MI, where midlevel lapse rates appear too weak (based on 18Z DTX sounding) to support more than an isolated marginal hail threat. 3. Other minor adjustments were made based on the location of surface boundaries and ongoing convection. Otherwise, the previous outlook reasoning remains valid. See the previous discussion below for more information. ..Dean.. 06/26/2021 .PREV DISCUSSION... /ISSUED 1121 AM CDT Sat Jun 26 2021/ ...MO to MI... A convectively aided baroclinic zone is shown on recent surface analysis from south-central MO into central IL - then northeastward into lower MI. Relatively strong heating is occurring along this boundary, and ample moisture is present to the south. This will aid in moderate MLCAPE values and the development of scattered thunderstorms along this entire corridor later today. Low and mid-level wind fields are southwesterly and relatively uni-directional, but are strong enough to pose a risk of some convective organization. Bowing structures as well as occasional supercell storms are expected. Damaging winds appear to be the main threat, but sufficient shear will be present to pose some risk of a tornado or two as well. The severe threat should diminish by mid-evening as nocturnal cooling ensues. ...NM/TX/OK... Strong daytime heating is occurring across portions of west TX/OK, where widespread upper 60s and lower 70s dewpoints are present. Forecast soundings suggest the air mass is not strongly capped. This will aid in the development of scattered clusters of thunderstorms this afternoon along pre-existing boundaries over west TX and southwest OK, and off the higher terrain of northeast NM. Low-level winds are relatively weak, but sufficient deep-layer shear and moderate CAPE may help a few storms to become severe with a risk of damaging wind gusts and hail. Read more LIVE: spc.noaa.gov
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