Update posted at 2 p.m., Friday, March 31
Post-storm winds Friday howl above 50 m.p.h. in Chicago area, prompting wind advisory; new severe weather outbreak threatens Sunday
Chicago was spared severe thunderstorms Thursday night, but hasn't escaped howling winds in the storm's wake Friday. Late morning and early afternoon winds have gusted to 57 m.p.h. just off Chicago's shoreline out over Lake Michigan and have been clocked as high as 54 m.p.h. at Gary, Ind., 51 m.p.h. in Kankakee and 49 m.p.h. at Lewis Airport at Romeoville.
Area observers have witnessed some fascinating meteorological aspects of a classic spring storm system. Such storms exhibit a huge comma-shaped cloud configuration on satellite imagery. The cloud-free "notch" or indentation in the cloud mass responsible for this comma shape is referred to by meteorologists as a "dry wedge" or "dry slot." It's a region of strong subsidence, surging temperatures and high winds--all present in recent hours here. Skies cleared and the sun emerged for three hours as this feature arrived in the Chicago metro area.
The "dry slot" coincides with the jet stream's strongest winds and is the region of the storm within which winds line up vertically--blowing from the same direction through a deep layer of the atmosphere. It's little wonder such strong wind gusts have resulted with all that momentum. This morning's dry slot, only 120 miles in width, has shifted east as of this posting as the large spring storm reponsible for it continues to track northeastward. Rain showers will sweep the area Friday afternoon and night, and winds will remain strong. Look for temperatures to expeditiously fall back into the 50s as cooler air wrapped around the storm's backside swings into Illinois, Wisconsin, Indiana and Michigan.
The National Weather Service has issued a wind advisory through 6 p.m. Friday evening. Wind velocities will begin to ease--albeit slowly--during Friday night.
NEW SEVERE WEATHER OUTBREAK SHAPING UP SUNDAY
We are monitoring what appears likely to be another impressive severe weather outbreak across the nation's mid-section, including the Chicago metro area, Sunday afternoon and night. This will be a focus on our Nine O'Clock News program, here on our weather blog and on the Chicago Tribune's Saturday weather page. The large-scale pattern across North America is to remain an active one beyond the late weekend storm system as well with another important system slated into the Midwest later Thursday and Friday next week.
REMINDER: Our 25th Annual Fermilab/WGN-TV Tornado and Severe Weather Seminar takes place a week from Saturday on April 8. It's completely free of charge and seating is on a first come/first served basis, so we recommend getting there early to get a good seat. We repeat the program twice--the first at noon and the second starting at 6 p.m. We hope to see you at the beautiful Fermilab Ramsey Auditorium in Batavia, Ill., in the main building (the tallest structure on the Fermilab grounds visible in the surrounding area). Click the link on the wgntv.com web site for our speakers list and instructions on how to get to Fermilab. See you there!
Here are the area's peak wind gusts through 1 p.m. Friday:
Harrison-Dever Crib (3 miles off Chicago's lakeshore) 57 m.p.h.
Gary, Ind. 54 m.p.h.
Kankakee 51 m.p.h.
Lewis University Airport 49 m.p.h.
Valparaiso, Ind. 44 m.p.h.
Morris, IL 43 m.p.h.
DuPage Airport 41 m.p.h.
Waukegan 41 m.p.h.
Midway Airport 40 m.p.h.
O'Hare Airport 40 m.p.h.
Lansing 40 m.p.h.
DeKalb 39 m.p.h.
Joliet 39 m.p.h.
Sterling, Ill. 38 m.p.h.
Rockford, Ill. 33 m.p.h.
