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.
Check out the the new U.S. Postal Service 2014 Earth Day postage stamp. It featured an ocean temp map off one of our key supercomputer climate models run by NOAA’ Geophysical Fluid Dynamics Laboratory–the research facility which has also produced hurricane forecast models which helped so in improving the accuracy of hurricane track forecasts.
Photo courtesy of NOAA (the National Oceanic and Atmospheric Administration)
Check the weather radar map above – triggered by a warm front, a wide band of showers – possibly including a few isolated thunderstorms will spread east into northeast Illinois, southeast Wisconsin and northwest Indiana this evening with rain continuing off and on across the Chicago area much of the overnight hours.
Late this afternoon the warm front was located over eastern Nebraska across northern Missouri into southern Illinois. That front will slowly move east across Iowa tonight – at the same time slowly lifting north – probably moving through the Chicago area Thursday morning. Clouds will gradually increase and lower this evening, while winds shift from northeast to east and finally southeast late tonight. Initially this evening dew-points will be in the 20s, and rain falling from the clouds into the dry air will evaporate, but eventually the air will moisten enough for the rain to reach the ground.
Scattered clusters and short lines of showers and a few thunderstorms will occur over northern and central Illinois into southeastern Wisconsin and northwestern Indiana this evening. By late afternoon the cold front was moving out of eastern Iowa into northwestern Illinois, accompanied and preceded by the shows and thunderstorms.
Locally brief heavy downpours will be likely in some of the stronger thunderstorms along with the possibility of isolated small hail, gusty winds and lightning. Severe storms are not expected to develop.
The cold front will make its way east, probably reaching our western suburbs by mid-evening – passing through Chicago before or around midnight. Showers and thunderstorms will gradually end as the front passes a given point. Generally lighter rains will occur to the north and heavier rainfall – perhaps as much as an inch at some locations in central and southern sections.
Snowfall in Chicago in mid-April is not that uncommon. Dsating back to 1885 at least a trace of snow has been reported in about two-thirds of the years from April 14th on and measurabgle snow (0.1″ or more) has occurred in a little less than a quarter of the years.
In 1961 the Chicago area was about to be hit with its largest late season snowfall when 6.8 inches of snow fell on April 15-17, the bulk of it 5.4 inches coming on April 16th. The city was hit by a 3.1 inch snowfall on April 23, 1967, just two days after the deadly Oak Lawn tornado. In 1982 the city received 1.2 inches of snow on April 16th.
Chicago has even received measurable snow in May in eight years, the biggest an official 2.2 inch snowfall on May 1-2, 1940, but many areas north and wet of the city received up to 5 inches of snow. The city’s all-time latest-in-the season measurable snowfall was 0.2 inches on May 11, 1966.
The city’s latest trace of snow occurred in June 2, 1910.
UPDATE 3:55AM: The Severe Thunderstorm Watch for Chicago’s northern suburbs was canceled at 3:47AM.
UPDATE 3:46AM: Small (non-severe) hail was reported in downtown Chicago.
At 3:27AM, a line of thunderstorms stretches from Gurnee south to New Lenox.
These storms are below severe limits at this time, and are being monitored closely here at the WGN Weather Center for any signs of intensification.
Brief heavy downpours, lightning and small hail are expected over Cook, Lake (IL) and Du Page counties between 3:30AM and 4:30AM. Several hours of quiet, storm-free weather are expected once this line moves east of Chicago and over Lake Michigan.
BELOW: Radar snapshot at 3:30 Sunday morning.
A Severe Thunderstorm Watch continues until 5AM for some of Chicago’s northern suburbs. Counties included in the watch are McHenry, Lake (IL), Boone, Kenosha and Walworth.
Large hail will be the main severe weather threat. Storms over the area will also produce gusty winds up to 50mph, lightning and brief heavy downpours.