The NWS Climate Prediction Center released their updated outlook for June, 2015. The new June outlook shows northern Illinois, including the Chicago area, with an increased chance of warmer and drier than average conditions.
Much of central and southern Illinois has equal chances (EC) of above, below, and near-average temperature and precipitation. This is different from the previous outlook for June that was released mid-May. That one had central and southern Illinois with an increased chance of wetter than average conditions.
While these outlooks cover the entire month, most of the model forecast skill is in the first 10 days. So the features of warmer and drier conditions in northern Illinois may be more in line with what’s expected in the first week or two and less with the entire month. More useful information can be obtained from the NWS 6-10 and 8-14 day forecasts which are updated daily.
The statewide average temperature for February was 18.6 degrees. That is 12.3 degrees below the 1981-2010 average and the 7th coldest February on record. By comparison, February 2014 was 9th coldest at 19.5 degrees.
Here are some amazing statistics for Chicago. February was tied with 1875 for the coldest on record, according to the Chicago National Weather Service. The average temperature for February was 14.6 degrees, 13.1 degrees below average. In addition, it was the 10th coldest month overall on record. February snowfall in Chicago was the third largest on record with 26.8 inches, 17.7 inches above average.
Snowfall for February in Illinois was widespread and well above average. Amounts of 15 to 20 inches were common in western and northern Illinois and 10 to 15 across central Illinois and parts of far southern Illinois. This was 8 to 12 inches above average in many locations. See maps below. Click to enlarge.
Some other February snowfall totals from around the state:
Chicago Midway AP: 28.3 inches
Rockford: 14.7 inches
Peoria: 12.8 inches
Quincy Lock and Dam: 11.2 inches
Springfield: 22.6 inches
Champaign-Urbana: 12.4 inches
Bloomington-Normal: 13.0 inches
Carbondale: 6.0 inches
The statewide average precipitation (rain plus the water content of snow) for February was 1.5 inches, 0.5 inches below average. Most of the state received 1 to 2 inches of precipitation, except for far southern Illinois which got 2 to 3 inches. See the second batch of maps for precipitation and precipitation departures from average.
Snowfall across the central US has been slightly below average so far this winter and stands in stark contrast to last winter. However, the impact on soil moisture, rivers, and streams has been minimal.
Here is an example of snowfall differences. At Chicago O’Hare airport the snowfall total for this winter through January 14 is 13.7 inches. Last year through this date it was 35.0 inches and the 1981-2010 average is 14.2 inches.
In the first map are the snowfall departures for this winter. All the areas in tan or beige are up to 10 inches below average. That includes almost all of Illinois, Minnesota, Iowa, Missouri, Indiana, and Kentucky, as well as large portions of the Dakotas, Nebraska, Kansas, Wisconsin, Michigan, and Ohio. Areas in green are above average and include a small area in far southern Illinois and another around Moline. Snowfall is above average across upper Wisconsin and the Michigan UP. Continue reading “Quiet Winter for Snowfall across central US”
So far, November has been much colder and drier than average. The statewide average temperature is 34.6 degrees, which is 9 degrees below average.
The statewide average precipitation (rainfall + water content of snow) was only 0.6 inches, about a third of the average through this date.
There have been astounding snowfall totals in places like Buffalo, NY, and some significant snowfall in Minnesota and Wisconsin. However, Illinois and most of the surrounding states have had far less snowfall (first map) in November. Many sites in the state had 1 to 2 inches except for a stretch between Quincy and Chicago with less than an inch.
The modest snowfall totals in November so far are not that unusual. Average snowfall totals for the month are generally less than an inch south of I-80 and about 1 to 2 inches north of I-80 (second map).
Traces of snow were reported in Chicago and Rockford on October 4. A few years ago I did a post on the earliest and median dates for the first measurable snowfall of the season. Measurable means at least 0.1 inches or more. Snow flurries or traces of snow do not count since they have not been tracked closely in the historical weather records.
No real surprises for anyone who has experienced winter in Illinois. The earliest dates of measurable snow are in the late October, early November time frame. And the median dates range from late November in northern Illinois to the second half of December in southern Illinois. Even so, the dates can vary considerably between nearby sites since many of the early season snows are sporadic and not very widespread.
No doubt today (September 22) will be announced as the “first day of fall” because of the fall or autumnal equinox. However, that concept refers to the date when we get equal amounts of daylight and dark. I don’t think it was ever intended that this astronomical event would be the start of fall. In fact, this equinox would be the start of spring in the southern hemisphere. So to be fair to everyone we should call it the September equinox and leave fall out of it. 😉
Climatologists and meteorologists prefer to use calendar months to define the four seasons in the US. For example, fall would start September 1 and end on November 30. Not only is this more convenient, because you can use monthly data, but it lines up better with the typical or average temperature pattern for Illinois. Unfortunately, the meteorologists would describe this three-month period as “meteorological fall”. However, I would argue it is “climatological fall” since we are looking at long-term average to determine the season.
Heavy rains fell across the Chicago metropolitan area again today (August 22, 2014). Here is the map of rainfall amounts from our volunteer CoCoRaHS network. You will get a slightly larger and more clear image if you click on the map below. Many sites in the orange have received the average August rainfall in just 1 day. The largest total so far is from an observer in Bloomingdale in DuPage County with 5.45 inches.
Here are the reports for the morning of August 22, 2014, ranked from high to low. Most observers report between 7 and 8 am.
As impressive as this cool summer has been in Illinois, the experience here and across the Midwest stands in stark contrast to the West Coast. Here is the temperature contrast from the last full month – July (map below – click to enlarge). While the Corn Belt was 3 to 6 degrees below average in July, the West Coast and parts of the Rockies have been running 3 to 6 degrees, or more, above average.
The contrast between Chicago and Portland (OR), two of my favorite cities, show how different things have been. For July, the average high in Chicago was 79.8 degrees and the average low was 60.9 degrees. The average monthly temperature of 70.4 degrees meant that Chicago was 3.6 degrees below average.
On the other hand, the average high for July in Portland was 83.8 degrees and the average low was 59.8 degrees. As a result, their average monthly temperature of 71.8 degrees meant that Portland was 2.6 degrees above average.
Furthermore, while Chicago barely reached 90 degrees on one day in July, Portland reached or exceeded 90 degrees 7 days in July, including a reading of 99 on July 1.
The long-term average temperature for July in Chicago is 74 degrees and in Portland is 69 degrees.
It is no surprise that the NWS forecasts indicate that the heat will remain in the West for the next two weeks. However, it looks like Illinois has a good chance of seeing above-average temperatures for a change in the August 16-24 period.
It is no surprise that June has turned into a wetter-than-average month. The statewide precipitation in Illinois is sitting at 6.1 inches, 1.9 inches above average. Several locations in central and northern Illinois have reported rainfall totals in the 8 to 10 inch range. Two of the highest so far are Dixon (IL-LE-17) with 10.15 inches and Galena (IL-JD-2) with 10.12 inches. We will have the final statistics on June next week.
As the map below shows, areas in green and blue are in the 5 to 12 inch range, and are common across central and northern Illinois, as well as northern Missouri, Iowa, Minnesota, southern Wisconsin, and parts of Indiana.
Of course, lots of rain means lots of runoff and flooding. Most of the rivers and streams in Illinois and the Midwest are having relatively high flows, shown by this USGS map. The green dots show flow in the normal range, blue dots indicate above normal flow, and black dots are record flows for this date.
Finally, the Chicago area has not only struggled with heavy rainfall events that have caused flooding in June, but they have had an unusually high number of days with fog. Here is the web page from the Chicago NWS office explaining what is going on with this fog.
Illinois State Water Survey scientist Dr. David Kristovich led a group of researcher examining lake breezes in Chicago and have released the following:
Lake breezes that bring some relief on a scorching summer afternoon are thought to move more slowly through Chicago than through the surrounding suburbs. Scientists at the Illinois State Water Survey have discovered that this is often not the case and have gained new insights into the mysteries of how cities affect winds off a lake.
Looking at 44 lake-breezes from Lake Michigan in the Chicago region from March to November 2005, Jason Keeler, a graduate student in the University of Illinois Department of Atmospheric Sciences, and David Kristovich, head of the Center for Atmospheric Sciences in the Illinois State Water Survey, found that in many instances, the lake breeze acted as if the city wasn’t there. Nearly 30 percent of the lake breezes moving through the city reached as far as 30 miles inland.