Severe Weather Likely This Afternoon through Tonight

Good afternoon, it is a hot and humid across portions of the state.  Temperatures as of 1:05 pm range from the upper 70s generally where rain has fell this morning to the lower 90s in southwest Indiana.  Also cloud cover and a few showers on radar, some heavy from Monticello to Royal Center and Logansport.  This shower is moving a bit south of due east.


On the surface, a stationary warm front that stretches from northeast Nebraska all the way to eastern Indiana, with an area of low pressure to the west of Fort Wayne, this puts nearly all of Indiana under this unstable, humid atmosphere that will later set the stage for the potential for severe storms later.

Jul 21 2017 1320

There is currently a decent cap in place for east-central Indiana that will help keep thunderstorms at bay initially, but this cap will eventually erode and will help aid in thunderstorms later on in the day.

As far as the Convective Outlook is concerned, if you saw on the Equinox Weather Facebook page from 1 pm, an enhanced risk of severe storms for northwest Indiana, with a slight risk for the rest of northern and a portion of central Indiana. Marginal risk of severe storms for the rest of Indiana with the exception of southwest Indiana.  Primary threat will be damaging winds, but can not rule out large hail, or even isolated tornadoes, especially areas to the northwest of Kokomo.

Now as far as the timing is concerned, both of the model runs I’m going to post I’m not totally in agreement with, there will be isolated showers and thunderstorms that will try and develop through the afternoon and early evening, but with the cap in place in the mid levels, it will in essence limit the intensity of the storms until additional storms develop back west in Iowa and Illinois and move southeast through the evening hours and could arrive in northwest Indiana sometime after midnight and continue across the state.  Now the HRRR model want to weaken the storms as they move across the state, which at this point, while I think they will weaken some, I do believe that they will maintain near or over severe limits.  Widespread damaging winds is possible, and within the line, some isolated tornadoes will be possible, again especially areas to the northwest of Kokomo.  The second model, the NAM 3km not only suggest that the storms weaken, but limit the storms to the northern part of the state, could prove to be wrong as storm motion will be between the east-southeast and southeast moving around an upper level high.  Both of these model sets are courtesy of Pivotal Weather…



HRRR Model simulated radar from Noon Friday to 6 am Saturday
NAM 3km Model simulated radar from 5 pm Friday to 8 am Saturday

To sum things up, yes severe weather is expected, but the best and highest chances will likely be after midnight, isolated storms are certainly possible before then and even then.  The areas that will most likely see severe storms will be northwest of Kokomo, however anyone in the marginal or slight risk and especially in the slight risk can see severe storms.  Damaging winds will be primary threat with severe storms, but large hail and isolated tornadoes will also be possible.  Last thing that I haven’t discussed, with this tropical airmass still in place, any thunderstorm will be capable of producing very heavy rainfall that could lead to flash flooding.  So be weather aware, have a couple of ways to get watch and warning information tonight, and updates will also be available on the Equinox Weather Facebook page.