Good afternoon, a fantastic Sunday afternoon across Indiana right now, with lots of sunshine and temperatures ranging from the mid 70s in Marion to the mid 80s in Evansville.
For late tonight, there is a slight risk for severe storms for extreme northwest Indiana, with a marginal risk for the rest of northern Indiana, as far south as the Kokomo area. Damaging winds will be the primary threat, but a few large hail reports will also be possible.
Before the severe threat increases, short term models continue to show a few popup storms developing between 3 pm and shortly after sunset, so can’t rule out an isolated storm in a few locations. For any storms that develop this afternoon, severe storms are not expected, but could produce brief heavy rainfall.
Then our attention turns to the northwest as we see storms ongoing in southeast Minnesota and Wisconsin. These storms will merge into one nasty storm complex and move to the southeast, eventually reaching extreme northwest Indiana by the early morning hours of Monday. The short term models also indicating new storm development could occur in central Indiana as early as 1:00 am, so this is also something that will need to be monitored.
Now what I’m about to show is another model of a different version of what the radar could look like from 8 pm this evening through 8 am Tuesday morning. The following is courtesy of Pivotal Weather. In this version, it does show some isolated storm development during the late afternoon and dying off after sunset. Then you see the storms developing in Minnesota and Wisconsin moving to the southeast. The difference is that the storms will move into northwest Indiana around 3 or 4 am, weakening as the storms continue southeast into the state. Then there will be new storm development Monday afternoon, with these storms possible turning severe and moving southeast into what will be a very moist and unstable environment. The risk for Monday will be damaging winds and large hail. This model shows the line weakening somewhat, but then picking up more steam as the complex moves towards southern Indiana by Tuesday morning. Below this model, shows the Convective Outlook for Monday that shows the slight risk of severe storms for portions of northern and central Indiana, with a marginal risk to the north and south of the slight risk.
Before I end this blog, two more items that I will show, the first one is the dewpoint temperatures, which air must be cooled to become saturated with water vapor, the higher the dewpoint, the more moisture is in the atmosphere. You will see dewpoint temperatures by Monday afternoon shoot well into the 70s, suggesting the there will be plenty of moisture available, so heavy rainfall will be possible with these thunderstorms. Again this is from 8 pm this evening to 8 am Tuesday morning and provided by Pivotal Weather.
Finally something I don’t post very often and normally look at in the background, is the CAPE or convective available potential energy basically is one way we meteorologist can measure the amount of instability in the atmosphere and is measured in joules per kilogram(J/km). The higher the CAPE, the higher the instability. For this model, we are using surfaced-based CAPE (SBCAPE). By Monday afternoon, you can see that CAPEs in northwest Indiana is nearing 5000 J/kg, strong to extreme instability, a driving force in severe storm potential. This like the last two, shows the timeframe from 8 pm this evening through 8 am Tuesday morning.
We will continue to have updates on the severe weather potential for late tonight and Monday through the rest of today and into the day on Monday. Be weather aware and have a way to get watches and warnings if any are issued. Have a great rest of your Sunday!