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The two largest observed totals come from Anna, with 11.64 inches,
and Carbondale, with 8.05 inches. Radar-estimated precipitation
indicates a similar range in totals in the region.
Generally, rainfall totals of more than 8.8 inches in 48 hours
have exceeded the 100-year design storm for southern Illinois. The
measured amount of 11.64 inches in two days at Anna exceeded the
threshold, and radar estimates suggest that some other areas around
Anna and Mount Vernon may have exceeded it as well.
"What this means is that these events are exceptionally rare,
with less than a 1 percent chance of occurring at a specific
location in any given year," Angel said.
Rainfall totals in other parts of the southern third of Illinois
ranged from 3 to 7 inches. As a result, the National Weather Service
has issued a flood warning throughout the area.
"Our two largest measured precipitation totals, one at Anna and
the other at Carbondale, came from our new volunteer-driven
Community Collaborative Rain, Hail and Snow network. You cannot have
enough rainfall observations during events like this. These
volunteers, using standard equipment and standard observing
practices, are a valuable addition to our existing observation
networks. We are always looking for new observers," Angel said.
To find out more about this program and to look at rainfall maps
and tables, visit
http://www.cocorahs.org/.
[Text from file received from Illinois
State Water Survey] |
