Monday Night Weather Update: Timing and location of overnight storms

We’ve been looking over forecast data and trends from radars across the Midwest.  We’ve got more confidence in where overnight storms are going to track.

A line of thunderstorms has fired up in central Indiana this evening.  Earlier we thought they would develop over northwestern Illinois/eastern Iowa.  Turns out that wasn’t the case.

The storms are firing up along a boundary we noticed earlier this evening on satellite imagery.  Upon closer inspection, they are developing along the leading edge of a warm front.  South of the warm front dew point temperatures have climbed in to the low 80°s.  That is extremely humid air!

The line of storms has been moving methodically due east for the last hour.  At some point the storms will start to turn to the southeast.  The question is how sharply do they turn.  Do they track southeast or do they turn more southerly?

Latest computer model data suggests they storms turn more southeasterly over the next couple of hours.  The data suggests the line will be along the I-70 corridor from the west side of Indianapolis to Effingham, IL.

Computer model projection of radar/satellite imagery.

By 4 a.m. the line of storms is nearing the Ohio River.

Computer model projection of radar/satellite imagery.

For those in the Indianapolis metropolitan area, I’m not sure everyone is going to have thunderstorms.  The best chance will be west and southwest of downtown Indianapolis.

The Storm Prediction Center has issued a Tornado Watch for parts of central Indiana.  The watch is in effect until 4 a.m. Tuesday.


While a Tornado Watch means that a tornado is possible, the main threat from storms will be damaging winds and wind gusts, perhaps up to 75 mph.

With high winds possible power outages remain a possibility for mainly the southwestern half of the CBS4 viewing area.

The second threat will be the potential for heavy rain falling.  New data tonight is suggesting some areas could pick up in excess of 3″ of rain by Tuesday morning.  This would cause flash flooding for areas picking up anything more than 2″ in a three hour period.

The previous update can be found here.

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