Wild weather out West Tuesday offers a preview of things to come in Chicago--especially Thursday night when gusty thunderstorms capable of downpours arrive with a windy autumn storm. The storm system remains well west of the area Wednesday, and the day's clouds and light rain are products of an entirely different disturbance. But, the western storm will make a move on the area beginning Thursday when it is to produce gradually strengthening southeast winds likely to send temperatures into the 60s--possibly as high as 70 degrees in warmer areas away from the lake.
It's Thursday night when the storm's most noteworthy impact may be felt here. A marriage of strong low-level southerly winds and a powerful 140 m.p.h. jet stream above sets up what amounts to an atmospheric conveyor belt expected to import Gulf moisture into the area. Thunderstorms are likely to erupt in this environment with clouds which tower into the powerful wind field aloft. Computer models place 60-plus mph winds within 2,000 feet of the ground. Any thunderstorms may tap these winds and channel them down to the ground as powerful wind gusts. More than an inch of rain may fall before drier air takes over Friday with partly sunny skies. A second day of 60s is a good bet Friday before colder air wrapping around the system's back side sweeps over Chicago for the Halloween weekend.
The storm's impact in the West Tuesday was widespread and quite dramatic. Winds gusted as high as 75 mph from California to Arizona, producing dust storm conditions responsible for brownouts and blackouts in the San Fernando and San Gabriel mountains, and visibility reductions to as little as a quarter-mile in sections of the Phoenix area. Las Vegas and Palm Springs each recorded 40-plus mph gusts, and the California Highway Patrol issued high wind advisories for the bridges around San Francisco. In the storm's colder air, snowfall is predicted to reach 30 inches in the Colorado and Wyoming mountains.
Wet Octobers offer few clues on coming winter
With October on track to finish among the 10 wettest of the past 139 years here, concern over the coming winter grows. Yet, an in-house analysis of the winters which have followed Chicago's 16 wettest Octobers indicates that 12 of those winters (75 percent) produced less snow than the long-term average. Snowfall in those 16 winters averaged 31.6 inches--only 86 percent of the long-term average of 36.6 inches.
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