Powerful winds with the first of two autumn storms predicted to impact the region this week, whipped sections of the Chicago area with gusts topping 50 mph late Tuesday. A 63 mph blast was clocked at 9:05 p.m. three miles off Chicago’s shoreline at the Harrison-Dever Crib and other gusts included 54 mph at the Weather Bug wind sensor at Queen of Angels School in Chicago, 50 mph at Algonquin, and 48 mph at Glenview. The storm responsible produced modest amounts of rain here—only 0.03 inches at O’Hare and 0.27 at Rockford–but drenched the Upper Midwest with 1.74 inches at Tomahawk and 1.55 at Oconto–both in Wisconsin.
Tuesday’s stormy weather comes on the heels of the area’s coolest October open of the past 6 years. Temperatures over the month’s opening 6 days averaged 52.1-degrees— 7-degrees below the 138 year average and among the 7 coldest such periods since observations began in 1871. In 6 previous years with comparable cool October starts, the sub-normal temperature trend remained dominant the remainder of the month.
A powerful new early season cool surge—including a potential for the first daytime highs which fail to break above 50-degrees since April, continues a threat this weekend into early next week. The chill’s arrival in the U.S. is to ignite a new round of snowfall in the northern Rockies as it sweeps out of Canada. Winter weather advisories were issued in Montana for Wednesday.
A new storm threatens parts of the area with big rains Thursday
The week’s second storm may may bring parts of the Chicago area as much as 1 to 2 inches of rain—especially in southern sections Thursday into Friday morning.
What is the earliest occurrence of measurable snow in Chicago?
With the opening of October upon us it is time to start thinking about snow. Though the season’s first measurable snow doesn’t usually occur here until the middle of November, the city has experienced measurable snowfall on many occasions in October. The city’s earliest measurable snowfall on record took place here just three years ago on Oct. 12, 2006 when both Midway and O’Hare airports measured 0.3 inches of snow. The snow was more significant in the northwestern suburbs where 1.2 inches fell at Mundelein and one inch at both Algonquin and Crystal Lake. One reason the snow was able to accumulate that morning despite the still warm ground was the intense rate of fall, that reduced visibilities to near zero in some areas.
Runners will gather in Grant Park Sunday morning from all 50 states and nearly 100 countries to compete in the Chicago Marathon. Most studies indicate an ideal temperature between 50 and 55 degress for marathon runners. However, a recent study from the U.S. Army Research Institute of Environmental Medicine suggests colder temperatures might actually help produce better race times.
This Sunday morning will be a good test of that theory. The early forecast for the 7:30 AM start is partly cloudy with temperatures between 32 and 36 degrees. The winds should be out of the west about 5 to 10 mph. Dressing for a cold marathon can be summed up in one word – layers.
The chilliest spell of weather here in over five months moves into a
9th consecutive day Tuesday—but under cloudier skies than in recent
days. Rainfall with the first of this week’s two wet weather systems is
predicted to begin from the day’s rapidly lowering and thickening
overcast by mid-morning and continues in waves through much of the
afternoon. A suite of the 11 most recent computer projections places
the day’s potential rainfall from 0.10 inches to as much as 0.85—an
amount which comes on top of the 1.22 inches recorded here in the past
8 days—a period which has averaged nearly 5 degrees below normal.
Estimates based on temperatures since October’s open suggest the cool
spell has led to home furnace use nearly 60 percent more than the most
recent 30 year average.
Gusty west winds, likely to top 30
m.p.h. at times Tuesday night, deliver a reinforcing shot of chilly
air. But, the far more significant cold surge—potentially the coolest
in more than 5 months and likely to limit high temperatures to the 40s
for the first time since last April—looms this weekend.
Wet storm system later this week could produce up to 3 times Tuesday’s rainfall
frontal wave expected to sweep the area as the cold air approaches is
likely to produce a far wetter interlude than Tuesday’s—doubling or
tripling the amount of rain to fall today.
Has there even been a tornado produced by a snowstorm or when snow was on the ground?
Mike Callan Lemont
It is common for tornadoes to develop on the warm side of storms that deliver heavy snow, but it would be extremely rare for a twister to develop on the cold, snowy portion. Recently, on Feb. 5, 2008, 64 twisters battered the South while heavy snow swept the central Midwest. Though twisters usually form in a warm, moist surface environment, there are always exceptions. Dr. Harold Brooks of the National Severe Storms Laboratory in Norman, Okla. tells of a twister at Altus, Okla., on Feb. 22, 1975, with temperatures near freezing. The F2 storm killed two and injured 12 as it ripped through a trailer park. Twisters have also occurred during warm-ups when pre-existing snowpacks have not melted.