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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.

Friday, May 20, 2022

SPC May 20, 2022 0730 UTC Day 3 Severe Thunderstorm Outlook

SPC 0730Z Day 3 Outlook Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0220 AM CDT Fri May 20 2022 Valid 221200Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHEAST... ...SUMMARY... Isolated severe storms with wind damage and hail will be possible across parts of the Northeast on Sunday. A marginal severe threat may also develop in parts of the lower Mississippi Valley and central Gulf Coast states. ...Northeast/Mid-Atlantic... An upper-level trough will move east-northeastward across southeastern Canada on Sunday, as southwest mid-level flow remains over the Northeast. At the surface, a low will move northeastward across Quebec, as a front moves eastward into the central and northern Appalachians. Ahead of the front, surface dewpoints in the 60s F will result in a moderately unstable airmass by afternoon. Thunderstorms are forecast develop along the front around midday in western New York, and move eastward into eastern New York and western New England during the late afternoon. A few clusters or line segments are forecast to persist into the early evening. NAM forecast soundings late Sunday afternoon, along the instability axis, have MLCAPE peaking in the 2000 to 3000 J/kg range. 0-3 km lapse rates are forecast to approach 8.0 C/km. This thermodynamic environment will likely support a wind-damage threat with the more organized multicell line segments. Deep-layer shear is generally forecast to be at 35 knots or less, suggesting that the supercell threat will be minimal. Model forecasts indicate that most of the convection will form along or near the boundary, as it moves from west to east across the Northeast. A marginal wind-damage threat may also develop near or after peak heating southward along the instability axis from eastern Pennsylvania into northern Virginia. ...Lower Mississippi Valley/Central Gulf Coast States... Southwest flow at mid levels will be in place across much of the southern U.S. on Sunday. At the surface, a cold front is forecast to move southeastward into the lower Mississippi Valley and northern Gulf Coast states. Scattered thunderstorms should develop near and ahead of the front during the afternoon as temperatures warm and low-level convergence increases. The most likely area for thunderstorm development will be from north-central Louisiana northeastward into northwestern Alabama. Forecast soundings along this corridor at 21Z have 0-6 km shear mostly below 30 knots. But 0-3 km lapse rates near 7.5 C/km and MLCAPE around 3000 J/kg should be favorable for marginally severe wind gusts. Hail could occur with the stronger updrafts. ..Broyles.. 05/20/2022 Read more CHECK UPDATE ZOOM GRAPHIC