They covered less ground than either of the two rounds of storms which preceded them this week. But Thursday evening’s storms were formidable and, like their predecessors, created problems in the areas they swept.
Their development followed Chicago’s first official 90-degree temperatures of June and the second such reading of the year at O’Hare the city’s official airport weather observation site and the season’s third at Midway Airport.
Sparser surrounding cloud coverage Thursday meant the upward surging cumulonimbus clouds —those vast, cottony-appearing mounds of cloudiness from which Thursday’s storms emanated — bubbled to heights of ten miles into the atmosphere. The open skies around them meant the mammoth cloud towers were visible at great distances. Weather watchers and photographers as far as 90 miles from Chicago had spectacular views of the tree-downing storms as they raced across the area.
Gusts to 77 mph downed trees; downpours drenched hardest hit locations with 1”+ rains in an hour or less
With powerful jet stream winds aloft, Thursday afternoon and evening’s thunderstorms had no problem transferring wind energy to the surface in the form of damaging gusts.
Wind speeds hit 77 mph at Gary, Ind., 70 mph Oak Park, 65 mph Berwyn, 60 mph Cicero and Merrillville, 55 mph Itasca, 53 mph Midway Airport and East Chicago, 52 mph Glenview, 50 mph Arlington Heights and Hoffman Estates and 48 mph at O’Hare.
The thunderstorm’s unique ability to channel rainfall into intense downpours led to some eye-catching precipitation tallies. 1.15” of rain fell in under an hour at Algonquin while 1.30” fell in less than an hour at Hoffman Estates where power was knocked out for a time.
Other impressive totals included 1.15” in Schaumburg (that amount fell in just 40 minutes), 1.06” in just 40 minutes five miles northeast of Addison and a total of 0.73″ drenched Lake of the Hills in just 20 minutes.
Scattered gusty afternoon storms expected to “bubble up” again Friday afternoon after the day’s sun-filled open
Sunshine, as Friday gets underway, will contribute to daytime heating expected to de-stabilize the atmosphere, allowing a re-eruption of possibly gusty showers and thunderstorms in the afternoon.
The best indications we have at the moment suggest storm formation is to take place beyond the Blackhawks outdoor rally, occurring Friday afternoon and evening instead.
Chicago headed for cool June close and July open; 4 days of north/northeast winds get underway Saturday
The warm spell, which has been in place more than a week here, has yielded eight consecutive 80-degree or higher daytime highs. A ninth is likely Friday.
But North America’s weather pattern is undergoing impressive changes which involve the westward drift of a blisteringly hot air mass which is predicted to produce near record temps across the Southwest. That pattern realignment will prove a game-changer for Chicago.
The jet stream which runs around the hot air mass’ periphery is to buckle farther north then dive into the United States from Canada. It’s a set-up expected to allow cooler Canadian air to sink southward into the Lower 48. As that happens, late May-level temperatures are replace recent 80s in each of the next 4 days beginning Saturday. The cool-down is to coincide with the closing days of June and July 2013′s open on Monday.
Phoenix and Las Vegas headed for brutally hot temps which may flirt with all time highs ; Death Valley highs predicted within striking distance of 130-degrees by Sunday
The new pattern is to envelop the West in a mass of dangerously hot air. Highs in Phoenix are to reach 119-degrees Friday with a 114-degree high forecast in Las Vegas and 129 degrees headed for Death Valley over the weekend. These highs come within a few degrees of each of those site’s warmest temps on record!