By Meteorologist Tom Skilling
Chicago finds itself in a windy air mass of Pacific origin Friday. Temperatures are headed for 70-degrees for the 5th time this year. That’s 4 more than had occurred by this date a year ago and surprisingly, in a year so dominated by temperature deficits, close to the long-term average number of 70-degree days by this date.
But enjoy the mild temperatures—a downturn looms once a front passes Friday night and shifts winds northeasterly. And, the development of a potent spring storm to our west is to set the stage for strengthening winds likely to gust over 30 mph as they ride into the city off chilly Lake Michigan.
The persistence of easterly winds into the first half of next week is likely to produce a wide spread in temperatures between lakeside and inland locations.
Large, slow-moving spring storm generating big computer model rainfall estimates
The huge spread in barometric pressures between a sprawling Canadian high pressure to the north and a deep storm expected to trek only slowly out of the central Rockies and into downstate Illinois and Indiana by the middle of next week is not only to produce gusty winds but also to encourage moisture-rich Gulf air to ride into the cooler air predicted here. It’s a process expected to give rise to waves of rainfall—some thundery and capable of downpours—which may really add up between Sunday and later next week.
Model forecasts suggest rains across that span of time could be as much as three times the 0.83” which typically falls over a 7 day period this time of the year—with totals potentially ending up in the 2 to 3″ range—possibly even higher in some locations.
Chicago spring rainfall of 3.04” the driest to date in 9 years and 20th driest on record
Rainfall of that magnitude would reverse the “drier than normal” precipitation trend which has dominated meteorological spring here.
At present, 3.04” is on the books—just 59% of the normal 5.16” to date. The tally is the lowest of any spring here in 9 years and 7.54” behind the season’s total rainfall by this date a year ago. The 3.04″ total to-date ranks 20th-driest of the past 143 springs.
The nation’s extreme temperatures Monday were both recorded in California at locations separated by only about 250 miles. What is the closest distance between extremes ever recorded?
–Thomas Rocheleau, Gurnee
Temperature observation stations at Truckee and Death Valley (the locations in question), both in California and separated by 254 miles, register same-day extremes a few days every year. That was the case Monday on April 21. We searched the lists of national daily temperature extremes back to 1997 and found that on Sept. 11, 2013, Medford and Silver Lake, both in Oregon, recorded the national temperature extremes on that day. Separated by only 135 miles, those cities might very well have be the shortest “as-the-crow-flies” distance.
Showers and a few embedded thunderstorms will precede and accompany a center of low pressure as it tracks east out of Missouri through central Illinois tonight on into Indiana early Friday. In the Chicago area, showers and possibly a few thunderstorms should spread into the area from the west late this afternoon/early evening and continue as the center of low pressure passes just to our south overnight.
Rainfall amounts should generally be a half-inch or less, although greater amounts under stronger thunderstorm downpours may occur. Strong southeast winds gusting over 30 miles per hour will continue in our area this evening – then swing more east to eventually northeast as the center of low pressure tracks east through central Illinois tonight.
By sunrise Friday, rain should be over in the Chicago area with the center of low pressure in central Indiana pulling away to the east. Winds Friday morning will be northwest 15 to 25 miles per hour here – gradually becoming more westerly as the day progresses.
By Meteorologist Tom Skilling
It was SO nippy Wednesday that the day’s chilly northeast flow off Lake Michigan could only muster a March-level high of 51-degrees.
The flow produced quite a range ion temperatures across the greater Chicago area Wednesday. While inland readings hit 60 degrees toward Pontiac, lakeside temperatures made it no higher than 42 degrees at a number of locations.
Temps are to surge most strongly away from the lake Thursday; highs likely to beat Wednesday’s by almost 20-degrees inland.
Readings will rebound Thursday and Friday reaching the mid-60s inland Thursday and close to 70 degrees over much of the area Friday—-a near 20-degree increase compared to Wednesday’s highs.
Powerful spring storm’s southerly front side winds are to help pump temperatures up during this period. But model forecasts take readings down dramatically this weekend as rain chances edge higher Sunday—and even more so Sunday night and Monday.