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.
Chicago quiet severe season took off with a rousing bang this morning as severe thunderstorms raced across the north and northwest suburbs
12:20PM: Here are a few hail reports
1.75″ Crystal Lake
1.50″ Buffalo Grove
1.00″ Lake Zurich
1.00″ Hoffman Estates
0.75″ Arlington Heights
0.75″ Vernon Hills
In addition, wind damage was reported in the Marengo area about 10:25 am.
Damage in Marengo included: shingles peeled off roofs, large grain augers ripped from bins, irrigation systems blown over, barns blown down, branch embedded in side of a house.
12:00PM: A compact line of thunderstorms that produced penny to egg sized hail over some of Chicago’s northern suburbs has moved out over Lake Michigan. All warnings have been cancelled or expired. A few thunderstorms could re-develop later this afternoon, once again over the northern suburbs.
11:00AM: Severe Thunderstorm Warning for some of Chicago’s northern suburbs until Noon. The warning includes McHenry, Lake, northern Kane and far northern Cook County. Large and damaging hail is the main threat with this storm. This storm is also producing a tremendous amount of lightning.
10:02AM: One inch, or quarter sized hail was reported at the Rockford Airport at 9:58. There is a report of some broken glass from hail just south of Rockford. If you live in McHenry, Lake or far northern Cook County, it’s time to put the car in the garage (if that’s an option).
9:40AM: Thunderstorms developing along a warm front are expected to impact some of Chicago’s northern suburbs late this morning. A few of the stronger cells will be capable of producing 1″ hail and wind gusts of 50 to 60mph.
The best chance of rain between 10AM and 1PM will be over McHenry, Lake (IL), northern DeKalb, northern Kane, and far northwest Cook County . Areas from the city southward should stay dry.
BELOW: Snapshot of radar imagery and lightning detection earlier this morning (9:40AM)
Strong southwesterly low-level flow will pull warm moist unstable air into Illinois and southern Wisconsin today. There is a threat of severe thunderstorm development later this afternoon over the Chicago area with the best chance this evening into the overnight hours. Large hail and strong damaging winds will accompany heavy downpours in the stronger storms.
Low pressure will move northeast through Iowa today into central Wisconsin tonight. The associated cold front will move out of eastern Iowa into northwest Illinois in that same time frame, triggering showers and thunderstorm development in the warm moist air mass over northern Illinois and southern Wisconsin.
The National Storm Prediction Center outlook for severe thunderstorms Saturday and Saturday night is depicted in the yellow-shaded area on the map below.
Strong southwesterly low-level flow will pull warm moist air from the Gulf of Mexico north up the Mississippi River Valley into Illinois Saturday. As temperatures rise into the 70s here Saturday afternoon, dew points will jump into the 50s. With a cold front approaching from the west and an upper–air disturbance aloft, atmospheric conditions will be ripe for strong thunderstorm development across northern Illinois and southern Wisconsin Saturday night.
Sunday we could be on the northern edge of potentially severe storms later in the afternoon and at night. If the warmth can persist into the evening hours Sunday, the moisture-laden air would be primed for a second round of severe storms that might include central and northern Illinois. The preliminary map below show the severe storm potential just reaching into southwest Illinois Sunday.
The maps below issued by the National Storm Prediction Center outline the preliminary outlook area included under a slight chance of severe storms in yellow for Saturday (top map) and Sunday (bottom map).
Slight chnce of severe weather Saturday…
Slight chance of severe storms Sunday…
There is little doubt among computer models that an El Niño is coming later this summer but the question is how bad will it be? El Niño is a build up of unusually warm sea surface temperatures in the eastern portion of the Equatorial Pacific. The graphic below shows the various computer model solutions for SST or sea surface temperature anomalies through the end of the year and into January of 2015. The further above the line the model solution, the warmer the predicted El Niño.
Dr. Cliff Mass from the University of Washington cautions these early predictions can sometimes be unreliable. The skill level is much lower this early in the year for forecasting such events for the upcoming winter. After July 1st the “spring forecast barrier” is no longer in place and the forecast can improve substantially.
The signal does appear strong enough though that there is confidence an El Niño is coming but it is too early to say just how big a deal it will be. It’s possible a moderate to strong El Niño could warm global temperatures by almost a quarter of a degree Celcius like the 1997-1998 El Niño did. That kind of warming could help make 2014 the hottest year on record. A strong El Niño spilling into next year could make 2015 even warmer.
Update 8:15AM CDT…
The occluded front is through the Chicago area (note north-south oriented arcing cloud/precipitation band shown on weather radar picture above). The low pressure center is moving out of southeast Wisconsin headed over Lake Michigan – pulling away from our area. Visibility is on the rise and winds are picking up out of the southwest.
The winds will continue to increase and become more westerly and then west-northwesterly with time today – gusting over 40 miles per hour at their peak this afternoon. Winds will gradually diminish tonight.
Update 7:15AM CDT...…
At 7AM CDT the center of low pressure is just along the Illinois-Wisconsin line north of Rockford continuing an eastward movement. The associated occluded front will be swinging through the Chicago area from the west during the next hour. As the front passes a given point, visibility will slowly improve and winds will shift to the southwest. As the morning progresses, winds will become more westerly and pick up in speed. This afternoon west to northwest winds will be gusting at times over 40 miles per hour.
Map of 7AM CDT Chicago area visibility
The slow-moving center of low pressure and associated occluded front will slowly drifts east through northern Illinois this morning. Light rain and drizzle along with foggy cool conditions will prevail across the Chicago area. Visibility will be lower than a quarter mile in spots as easterly winds will eventually shift to a strengthening west wind this morning. Once winds shift, visibility will pick up along with the wind speed and rain/drizzle will diminish. The day’s high temperatures will probably not be much more than the low 40s experienced this morning.
Below is a map of visibility as of 4AM.