Good afternoon, if you're looking at this as of 2:43 pm EDT, most of Northern Indiana is dry, with the exception of some light showers across west-central counties. The point of this blog is to go into a bit more detail, and explain what could happen in more layman's terms. First the breakdown of areas under the slight and marginal risks. Here are some of the cities that is under the slight risk for Monday...Indianapolis, Muncie, Anderson, Kokomo, Tipton, Lafayette, Frankfort, Logansport, Terre Haute, Carmel, Richmond, Westfield, Crawfordsville, Rensselaer to name a few. The following cities are under the marginal risk...Fort Wayne, South Bend, Gary, Warsaw, Plymouth, Michigan City, Elkhart, Goshen, Angola, Lagrange, Nappanee to name a few. As far as timing, the highest chance of severe weather will be from 1 am EDT to 7 am EDT Tuesday morning, though can not rule out an isolated strong or severe storm Monday afternoon and evening ahead of the main line.
In order to have severe weather, the Convective Setup needs to be there, if one of the items are lacking, it could reduce the overall severe threat. I know I put in my severe weather discussion is fairly technical, hopefully this breakdown will help you understand the reasoning behind the threat and what could also limit the threat. Before you can even have thunderstorms, you need a trigger mechanism, what will be the cause for thunderstorms, in this case it will first be a warm front that will move across the area tonight, then with the main line, it will be a cold front moving across the area. The next item to check off is instability, will we have enough juice for the thunderstorms. In this case, we will have plenty of juice. One of the many things I mention is the CAPE, or Convective Available Potential Energy. High CAPE however don't always mean thunderstorms will develop, but that's another blog for another day. In this case, the with CAPEs expected to be anywhere between 1000 and up to 4000 J/kg, thunderstorms will be able to develop quickly vertically. The CAPE is not the only way to measure instability. But back to Monday's/early Tuesday morning threat. The instability will be in place. We will also have plenty of shear in place, impressive by mid-August standards. There will also be not only low and mid level support, but upper level support, so all of those are checked off. We will also have plenty of moisture as dewpoints will increase into the 70s. The monsoonal moisture/flow from the southwest will also be tapped into, bringing dewpoints into the tropical category. With moisture in place, any rainfall will be heavy and lead to flash flooding. Now to the timing...
This is a look at how the radar could look like from 2 pm Monday afternoon through 8 am Tuesday morning. The radar could look very different and the timing is plus or minus 1 hour. At the start of this period, a secondary warm front could touch of showers and thunderstorms across portions of the area. These storms could gradually increase in intensity and it is not out of the question that any of the storms, especially if this verifies between 7 and 11 pm across far northern Indiana could reach severe limits. But it is the main event, the line of showers and thunderstorms that start to come into view by 11 pm. This line will quickly move southeast, and move into Indiana as early as 1 or 2 am. This line will continue to move across northern Indiana and will clear the region between 5 and 7 am. That line will end the severe weather threat, but additional showers and thunderstorms could redevelop Tuesday afternoon before everything clears out by Tuesday evening.
The following is an approximate timeline as to when the line will move through the area...again this is a forecast and subject to change due to timing and other factors.
Between 1 and 2 am, Gary and Lafayette
Between 2 and 3 am, Gary, Lafayette, Rensselaer, Royal City, and Logansport
Between 3 and 4 am, Lafayette, Kokomo, Plymouth, Logansport, Frankfort, Elwood, Tipton, Marion, Crawfordsville, Rockville, Terre Haute, Greencastle
Between 4 and 5 am, Muncie, Indianapolis, Anderson, Pendleton, Carmel, Westfield, Warsaw, Fort Wayne, Portland, Albany, Middletown, New Castle, Winchester
Between 5 and 6 am, Richmond, Hagerstown
The primary threat from this line will be damaging winds, the potential is there that this could be a widespread event. In addition, large hail, and a few tornadoes are possible. Just based on the dynamics, a strong tornado can not be ruled out, but the timing of the storms may help limit that potential. Also with plenty of moisture to work with and high PWAT values, heavy rainfall will be possible and that could lead to some minor flash flooding.
The bottom line, there are still timing differences between models and the aggressiveness. A lot can change between now and when the storms move through. A lot more will know once we get to the finer short term mesoscale features. That won't be known until tomorrow. The potential is also there for a portion of the slight risk area to be upgraded to an enhanced risk. Keep in mind that this will be an overnight event, be sure that you have a way to get warnings, the best way is to have one of many severe weather apps that will alert you if a warning is issued. We will also be here throughout the night and will also try and do some live updates as long as it doesn't wake up my boys. For additional updates, be sure to like the Equinox Weather Facebook page.
Thoughts on major weather events, severe weather events, and/or changes to the company.