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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.

Tuesday, May 25, 2021

SPC May 25, 2021 0730 UTC Day 3 Severe Thunderstorm Outlook

SPC 0730Z Day 3 Outlook Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0244 AM CDT Tue May 25 2021 Valid 271200Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR MUCH OF OKLAHOMA...SOUTHEAST KANSAS...AND A LARGE PART OF MISSOURI... ...SUMMARY... Scattered severe thunderstorms are likely on Thursday and Thursday evening from parts of the southern Great Plains into the Ozarks and middle Mississippi Valley. Very large hail, significant severe gusts, and several tornadoes are possible. ...Lower MO Valley eastward into the OH Valley... Uncertainty remains regarding details on the evolution of an early day MCS over the lower MO Valley per recent model guidance. However, models indicate an MCV over the lower MO Valley may aid in storms persisting during the morning or possibly developing on the outflow and moving east across central MO into the mid MS Valley during the day. Strong potential instability and mid-level flow will favor organized storms. Severe gusts and a few tornadoes may be the primary threats with this activity as it eventually moves into lower OH Valley late. ...KS/OK/eastern TX Panhandle into the Ozarks... To the south of morning showers/storms over the lower MO Valley, a very moist boundary layer (15-17 g/kg lowest 100 mb mean mixing ratios) is forecast to become very to extremely unstable (2500-4500 J/kg MLCAPE) by mid afternoon south of an outflow boundary and cool front. Strong heating near the front and outflow boundary will likely be preferable locations for thunderstorm development by mid-late afternoon. Forecast soundings show ample deep-layer shear favoring organized storms (e.g., supercells) with very large CAPE in the -10 to -30 deg C layer. Large to giant hail is possible with the early discrete supercell activity. Although low-level shear is modest, a tornado risk may focus near a potential outflow boundary or perhaps where SRH may be maximized (per stronger 850-700 mb flow) during the early evening over northeast OK into southeast KS and southwest MO. While it is too early in the outlook cycle to have much confidence in the potential for a significant tornado, some environmental ingredients may overlap. By early evening, additional explosive thunderstorm development is probable near the front as storms congeal and grow upscale within the moist/instability reservoir centered over OK. A severe-wind producing MCS is possible during the evening and perhaps persisting into the overnight across OK into the western Ozark Plateau. ...TX dryline... Strong heating over west and southwest TX will contribute to very steep low-level lapse rates beneath an elevated mixed layer. Models show a mid-level disturbance initially over AZ will quickly move east into central/eastern NM by late afternoon with an associated speed max. Although most of this region will remain capped, weakening convective inhibition and appreciable boundary-layer moisture will result in a very unstable airmass (2500-3500 J/kg MLCAPE) with 50-kt west-southwesterly 250 mb flow. A couple of widely spaced supercells posing a risk for large to very large hail and severe gusts are possible during the late afternoon through early evening. ..Smith.. 05/25/2021 Read more LIVE: