Wet June So Far in Illinois – More on the Way

Rainfall across Illinois and the central US has been substantial for June so far. This map represents the June rainfall through this morning. Large portions of the Missouri and Upper Mississippi River Basins have seen between 2 to 5 inches (yellows and oranges), while some spots in Illinois, Missouri, Nebraska, and Kansas have received 5 or more inches (red).

map1
Click to enlarge.

Zooming in on Illinois, the map below shows how far above average the wet areas have become. The areas in blue are 2 to 4 inches above average while the areas in green are 0.5 to 2 inches above average. Only small areas northwest of Chicago and south of Carbondale are below-average on rainfall.

map2
Click to enlarge.

Forecast

The potential rainfall amounts over the next week are significant. The 7-day precipitation forecast from the National Weather Service shows that central Illinois could see between 4 and 6 inches of rain, while the northern third of the state could see 2 to 4 inches. The southern third of Illinois could see 1 to 3 inches. Since much of this rain will come from thunderstorms, local amounts could be much higher or lower.

The reason for this rain is that a somewhat stationary front is sitting over Illinois and will remain so over the next week. Rain will continue to develop along and south of that front as warm, moist air flows northward.

p168i
Click to enlarge.

Heaviest Reported 24-Hour Rainfall in Illinois – A Look Back at Records

map1
Reported rainfall amounts from the July 1996 storm in northern Illinois. This storm caused widespread damage across the region. See the report for details. Click to enlarge.

The current record for the heaviest 24-hour rainfall total in Illinois is 16.94 inches at the NWS cooperative observer gauge in Aurora on July 17-18, 1996. An entire Water Survey report was written on the storm that produced this record.

The previous record 24-hour rainfall was 16.54 inches set on June 14-15, 1957, near Millstadt in St. Clair County (near East St. Louis), according to a Water Survey report. While the 1996 event occurred over 24 hours, the 1957 storm lasted only 12 hours – essentially producing the same amount of rain in less than half the time.

But here is the next interesting fact. Before the 1957 storm, the previous record 24-hour rainfall was 10.48 inches on October 1, 1954 set at Aurora, IL.

So Aurora held the statewide record 24-hour rainfall for about three years until it lost out in 1957 only to regained the crown in 1996, where the record remains to this day. I’m not sure if they deserve the golden rain gauge or the golden sump pump award for this honor.

Two Tornadoes and other Severe Weather in Illinois over the Weekend

Severe weather, including tornadoes, heavy rains, high winds, hail, and flooding occurred across parts of Illinois yesterday and last night.

Here is the radar estimated precipitation with areas in green indicating 1 to 2.5 inches an areas in yellow and orange indicating 2.5 to 4 inches.

june8-radar

Below are reports of storm damage across the US for the 24 hours ending on the morning of June 8, 2015. The two tornadoes in Illinois occurred near Petersburg and Seymour. Neither one cause much damage and no injuries. There were a few reports of 1-inch hail and many reports of wind damage in Illinois from these storms. Data obtained from the NOAA Storm Prediction Center storm damage page. Continue reading “Two Tornadoes and other Severe Weather in Illinois over the Weekend”

New Weather Outlook for June

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.

off15_temp
Temperature forecast for June. Click to enlarge.
off15_prcp
Precipitation forecast for June. Click to enlarge.