The 5.59 inches of rain reported at the Springfield Airport on Friday night fell in 6 hours. This represents the 100-year storm for that duration in central Illinois, according to Bulletin 70. The results were dramatic, as reported by the Springfield Journal Register.
The concept of the 100 year storm is commonly used by engineers for assessing the risk of heavy rainfall. The 100-year storm is more completely described as the storm expected to have a return period of once every 100 years on average. The phrase “on average” being key. It does not mean the storms are exactly 100 years apart. Instead it means that if you look at rainfall statistics long enough the average frequency of such a storm would be 100 years. Unfortunately, we don’t have hundreds of years of rainfall data. Instead we estimate the values based on fitting a statistical model to the observed data.
While the phrase “100-year storm” is eye catching, it does not do a good job conveying the risk of such an event. A better way of describing it would be the “1% chance storm”, Continue reading “100-Year Storm Strikes Illinois State Fair”
Heavy Rains on August 12-15
As forecasted by the National Weather Service, heavy rains have fallen across Illinois since Friday. Here are the totals by day and for the three days combined. More rain is expected today and tomorrow (last map). Friday’s rainfall is shown on the 24-hour totals for the morning of August 13, etc. We have had a stationary front parked over Illinois since Friday, which is usually a key ingredient for getting significant rainfall amount.
Here is the set of maps showing the rainfall totals for each day, using rain-gage calibrated rainfall totals. It provides a higher level of details with fairly good accuracy. The downside is that the color scale changes slightly from map to map.
Rainfall totals for the morning of August 13, 2016
Rainfall totals for the morning of August 14, 2016
Wet Weekend in Store for Illinois
One thing I love about the weather of Illinois it that it’s always changing. I was just getting ready to write a blog post about how dry it was getting in eastern Illinois. However, I soon realized that the dryness was the least of our worries right now. The NWS precipitation forecast for the next 5 days shows widespread, heavy rainfall across Illinois. The potential rainfall totals are smallest in the north and get progressively larger moving south. The potential totals are 1.5 to 3 inches in northern IL, 3 to 7 inches in central IL, and 7 to 10 inches in southern IL. The National Weather Service has issued Flash Flood Watches for northeast and southern Illinois.
Continue reading “Wet Weekend in Store for Illinois”
Deaths of Children in Hot Vehicles
Jan Null, certified meteorologist and professor at San Jose State University, CA, has been tracking child vehicular heatstroke deaths since 1998, creating a website on deaths of children in hot cars at noheatstroke.org
According to the website:
- 687 children have died since 1998
- 54% of the children were “forgotten” by the caregiver,
- 29% were playing unintended in a vehicle,
- 17% were intentionally left in vehicle by an adult,
- and 1% were unknown
- the inside of a car can heat up by 19 degrees in 10 minutes and 29 degrees by 20 minutes, cracking the window open had little effect on heating
And if you think that this tragedy only happens in the hotter climates of the US, think again. They have occurred in 46 out of the 50 states. Here is the distribution by state, including 16 in Illinois.
Continue reading “Deaths of Children in Hot Vehicles”