The National Weather Service Northern Indiana weather forecast office issued the infographic above at about 5:40 p.m. EDT. For those who have visual impairments, here’s what it indicates:
The threat for tornadoes is relatively low. The threat for damaging winds of greater than or equal to 58 mph is extremely high. The threat for extreme damaging winds of greater than or equal to 74 mph is fairly high. the threat for hail grater than or equal to one inch in diameter is fairly high. The threat for flash flooding is very high.

Tomorrow morning, we should see a round of showers and thunderstorms with a low threat of severe weather.

Tomorrow afternoon, isolated thunderstorms (possibly supercells) are expected to form, brining large hail, damaging winds and an isolated tornado. Storm coverage will increase by late afternoon.

Tomorrow evening into overnight, a line of storms with the risk of extreme damaging winds and an isolated tornado will move across the area.

WANE-TV Chief Meteorologist Jonathan Conder gives an excellent breakdown on his blog regarding when to expect what tomorrow and what factors might enhance or detract from the development of severe weather. Check it out.

The risk of severe weather in northern and central Indiana has increased from “slight” to “moderate,” according to the Day 2 Convective Outlook that the National Weather Service (NWS) Storm Prediction Center (SPC) issued at 1:32 p.m. EDT today. The outlook indicates a 45 percent probability of severe weather with 25 miles of any point in the moderate risk area, up from 30 percent in the outlook issued early this morning. In addition. there continues to be a 10 percent risk of significant severe weather in the area. For more, including the definition of “significant” and the importance of the probability figures, see my blog post from earlier today.

For IMO SKYWARN members, the new moderate risk area includes all of quadrants two and three, the Indiana portions of quadrant four and most of the Indiana and Ohio portions of quadrant one.

As a SKYWARN storm spotter, I’ve been looking at these convective outlooks for more than a decade. In my experience, the SPC indicates a moderate risk in northern Indiana only a couple of times per year. So, a moderate risk is not something to ignore.

The next look at tomorrow’s severe weather probabilities comes at around 2 a.m. tomorrow, when the SPC issues its first Day 1 Convective Outlook of the day.

The Northern Indiana National Weather Service weather forecast office plans to give citizens a behind-the-scenes look at what happens in the office before a severe weather event. The office will host a live Twitter chat in which meteorologists tweet about what they look at before such an event. They’ll also answer questions sent to them via Twitter.

The live Twitter chat is scheduled for 10 a.m. to 1 p.m. tomorrow, Wednesday, June 12.

If you have a Twitter account, simply follow @NWSIWX and you’ll see every tweet from the office. To ask a question, send a tweet that includes the @NWSIWX tag.

If you don’t have a Twitter account, you can’t ask questions but there are several ways you can monitor the chat.

Basic Web page

This Web page will show you every tweet that is either from @NWSIWX or mentions @NWSIWX. New tweets will not automatically appear but a click-able message will appear that indicates when new tweets have been posted. You can see them by clicking on that message.

Monitter.com

Monitter.com displays tweets that meet certain search criteria, as they appear. To use it, go to www.monitter.com. At the top of the page, in the space next to the words “Tweets containing,” replace the word, “monitter” with the string below:

from:nwsiwx OR @nwsiwx

Then, click the “add column” button and wait a few moments. The screen will eventually fill with the last 20 tweets that were either from @nwsiwx or mention @nwsiwx. New tweets that meet those criteria will appear automatically at the top, as they’re posted.

Probability of severe weather within 25 miles of a point. Hatched Area: 10% or greater probability of significant severe weather within 25 miles of a point. (More Info)

Update: The risk of severe weather in northern and central Indiana and northwestern Ohio tomorrow has increased from “slight” to “moderate.” Read more.

Update: National Weather Service to host live Twitter chat in advance of tomorrow’s severe weather. Read more.

There’s a fairly good chance of a widespread significant severe weather event across much of Indiana and nearby states tomorrow, Wednesday, June 12, according to various National Weather Service (NWS) sources, including the Day 2 Convective Outlook that the Storm Prediction Center (SPC) issued at 2:05 a.m. today. The area of risk is indicated on the map above, from this morning’s outlook. Notice especially the “hatched” area, which includes Fort Wayne and all 37 counties covered by the Northern Indiana NWS weather forecast office. That hatched area indicates a 10 percent or greater probability of significant severe weather within 25 miles of any point in the area.

The SPC defines “significant severe weather” as EF2 or stronger tornadoes, damaging winds with speeds greater than 75 mph, or large hail two inches or greater in diameter. So, the SPC is saying that the probability of at least oneof those things happening in our area tomorrow is 10 percent. While 10 percent might not seem very high, compare it to the probability of these things happening on any given day of the year. For example, if we get significant severe weather on average one day per year (and the actual average is probably lower than that), then the normal probability of significant severe weather is 1/365, or about three percent. So, if three percent is the normal probability, a 10 percent probability indicates that significant severe weather is more than three times more likely! That 10 percent looks a little more important now, doesn’t it?

Here are some details from the convective outlook:

After a round of thunderstorms late tonight and/or early tomorrow morning, few of which are forecast to be severe, new storms are forecast to develop by tomorrow afternoon. The initial afternoon storms will likely be supercells. Supercells often produce tornadoes, so a few tornadoes will be possible, along with large hail and damaging winds. The SPC expects the storms to eventually evolve into one or more bowing lines of storms, which will shift quickly east southeastward across the area. As this occurs, the threat for damaging straight-line winds is forecast to increase, along with large hail. The bowing band or bands of storms are forecast to reach the upper Ohio River Valley by late tomorrow evening, with ongoing and potentially widespread damaging winds.

I’ve noted in this blog in the past that sometimes information issued by the local weather forecast office seems to put less emphasis on severe weather risk than does the SPC convective outlook. For example, sometimes when the SPC calls for a slight risk of severe weather, the Hazardous Weather Outlook from the local office reads, “spotter activation is not anticipated.” That is not the casewith tomorrow!

The Hazardous Weather Outlook that the Northern Indiana weather forecast office issued at 5:14 a.m. today says the following about tomorrow: “There is a good chance for severe thunderstorms with large hail and damaging winds. An isolated tornado is possible as well.” In addition, it reads, “Spotter activation may be needed between late Tuesday night and late Wednesday night.” In addition, the Area Forecast Discussion that the local office issued at 4:05 a.m. today mentions a “potential high-impact event” Wednesday into Wednesday night.

So, if you’re a spotter, make sure you and your gear are ready. If you’re not a spotter, make sure you have fresh batteries in your weather alert radio and try to keep a television or radio playing during the day tomorrow, so you’ll know how the severe weather situation is progressing. As I have time, I’ll also post updates on this blog. The next time we’ll know more about tomorrow’s forecast will be around 1:30 p.m. EDT today, when the SPC issues an updated Day 2 Convective Outlook.

The Northern Indiana National Weather Service office published the above infographic on its Facebook page at 4:49 p.m. EDT today. With the infographic, the office included the following text:

The next storm system will arrive on Wednesday bringing severe weather and heavy rainfall to portions of the southern Great Lakes. The exact location and severity of the risk is conditional on the location of the frontal boundary and surface heating on Wednesday. We will monitor this situation closely and provide updates with the latest information on Facebook and Twitter, as well as on our webpage at www.weather.gov/iwx.

The northern three fourths of Indiana, as well as large parts of nearby states, have a slight risk of severe weather Wednesday, according to the Day 3 Convective Outlook that the National Weather Service Storm Prediction Center (SPC) issued at 3:30 a.m. EDT today. The outlook indicates a potential for a relatively broad zone of at least isolated hail and or damaging winds Wednesday afternoon. Also, computer models do not agree on how the weather system will move across the area, so forecasters say a more substantial wind threat might become evident tomorrow and/or Wednesday.

It would be a good idea to keep an eye on the SPC’s convective outlooks tomorrow and Wednesday. The SPC’s next outlook for the period will be its Day 2 Convective Outlook early tomorrow morning.