12AM Day 1 Convective Outlook for Wednesday, October 22. NO SEVERE THUNDERSTORM AREAS FORECAST
SUMMARY
Severe threat is negligible today.
Discussion
Dominant upper trough over the northeastern part of the CONUS will influence much of the country east of the Rockies during the day1 period. Surface anticyclone is expected to settle into lower latitudes which will force a front deep into the Gulf basin. As a result, continental air mass will limit buoyancy across much of the region.
Even so, lightning is expected with convection across portions much of New England prior to a strong frontal passage, and over the warmer waters of the lower Great Lakes. Another region where lightning is expected is across portions of the southwest. A notable upper low is approaching southern CA and this feature will advance inland as a 500mb speed max translates across the lower CO River Valley into AZ late in the period. PW values are not forecast to be that high so instability will be limited ahead of the trough. Despite the weak buoyancy, lightning is expected with the deeper convective updrafts, initially across central CA by mid day, then spreading east toward the Four Corners by early evening.