A large complex of thunderstorms are expected to fire to our west today and bring heavy rainfall and severe weather into Iowa on Tuesday evening and night. Nighttime precipitation is a very important part of Iowa's annual total. The featured map displays an IEM computed percentage of total precipitation during June, July, and August that falls during the twelve hours between 8 PM and 8 AM local time. All things being equal, we'd expect half (50%) of the precipitation to fall over a twelve hour period (50% of the day), but it does not work out that way for much of the country. A clear maximum appears over southwestern Kansas thanks to a phenomena known as the low level jet, which drives thunderstorms during the overnight hours and helps push them west through places like Iowa. Minimums appear over the deep south and desert southwest. These locations get summertime thunderstorms driven by peak heating from the sun driving instability.

Voting:
Good = 23
Bad = 8
Abstain = 2

Tags:   precip   jja   summer