The entire state of Indiana and parts of other states (including Michigan and Ohio) have a slight risk of severe thunderstorms Wednesday, according to the “Day 3 Convective Outlook” that the National Weather Service Storm Prediction Center (SPC) issued at 3:20 a.m. EDT. The slight risk area includes all of the area covered by IMO SKYWARN.
The text of the outlook, however, indicates considerable uncertainty, in part because computerized numeric models of the atmosphere do not agree on how fast certain weather features will move. Storms along and ahead of a forecast cold front, however, will likely pose at least an “isolated/low-end risk” for severe straight-line wind and/or hail, according to the outlook.
Despite the uncertainty, SPC forecasters indicated that within the slight risk area (shaded in yellow on the map above), the probability of severe storms within 25 miles of any point is 15 percent. The normal probability in most of Indiana at this time of year is around two percent, according to climatology data from the National Severe Storms Laboratory, so that makes Wednesday’s probability about 7.5 times normal. Forecasters expect probabilities to change, however, in subsequent outlooks, as Wednesday draws near.
It would be wise for SKYWARN storm spotters in the area, as well as anyone who is concerned about severe weather, to monitor those outlooks.
The SPC’s next outlook for the period comes early tomorrow morning, when it issues the first of two day-two outlooks.