Severe Weather Weekend – 2 Chances

Get ready for a wild weather weekend. Storm chasers are excited, meteorologists and emergency managers are a little bit on edge. The weather set-up for Sunday is looking worrisome for all types of severe storms. More on that in a second. We have to get through Saturday night’s storm chances first. Let’s take a look at the Storm Prediction Center’s forecast for Saturday night.

All of SE Wisconsin is included in the slight risk. This first round of storms will be kicked off as the warm front arrives during the night on Saturday night. The biggest risk from this first round would be large hail as the warm and moist air pour in over the cooler air at the surface. My biggest concern by this round of storms is where they will leave a boundary for the Sunday convection. What that means is that as storms die out they push out an area of cooler and more stable air. This boundary can actually lead to more storms later in the day as we heat back up. The boundary enhances wind shear. (The change of wind direction with height.) If this boundary lines up somewhere in southeastern Wisconsin I will have a greater concern of tornadoes. These boundaries can lead to discrete supercells. This means a thunderstorm that is all by itself, not in a line. These discrete supercells are often associated as tornado producers. If no boundary is formed or it stays to the north we are not out of the woods. We will still be warming dramatically on Sunday and as the powerful cold front arrives late on Sunday I expect a nasty line of storms to move in. The later it arrives, the lesser the chance of really nasty severe weather. If it is just a squall line, the biggest threat will be damaging winds. You can still have tornadoes in squall lines, but they are not usually as strong as discrete supercell tornadoes. With all of that being said, let’s see what the SPC has for their day three outlook. If you are wondering why it is called day three even though it is two days away, the SPC considers day one to be today. Day 2 is tomorrow. Day 3 is Sunday.

What stands out is the moderate risk over our western counties. For a day 3 forecast to see moderate risk, the SPC forecasters are pretty confident of a bigger outbreak of severe weather. I would not be surprised to see a high risk issued for parts of Wisconsin either tomorrow or Sunday. We don’t get that too often around here.

So, let’s check out the RPM model for the two rounds of storms. Let’s start with Sunday morning around 6-7 am.

Storms will fire along the warm front and depending on how far north it goes during Sunday night, the farther north the storms will be. The RPM does not have any convection popping up during Sunday afternoon, but does push part of the squall line through our area Sunday night. Here is the midnight Sunday forecast.

Keep in mind this is still 60 hours in advance of the storms. This will likely change over the next few days. Regardless of the severe threat, it will be very warm on Sunday. Temperatures will be close to 80 degrees and it will be humid. Truly a taste of summer. Here is the RPM temperature forecast.

There will be no lake breeze due to the strong southwest winds gusting over 30 miles per hour. Stay tuned to weather watch 12 all weekend for the latest forecast and our chances for severe weather.

Mark

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15 Responses

  1. WOW!! that is so scary:-((

    • Brandi,

      Not trying to scare, only trying to get everyone ready for the potential. Thanks.

      Mark

  2. What is an emergency manager?

    • Daniel G,

      Every county has an emergency manager. They coordinate disaster response in case of severe weather, etc.

      Mark

  3. I’m sorry if I missed it in the blog post, but do you have an estimation on when the storms will begin?

    I’m leaving the state Saturday evening, and coming back Sunday afternoon. Unfortunately, it seems like I’ll be hitting the storms in and out.

    • Chris,

      Storm timing looks to be late tonight and then more likely Sunday evening and night.

      Jeremy

    • “This first round of storms will be kicked off as the warm front arrives during the night on Saturday night.”

    • Jeremy, jinx. 🙂

  4. Moderate risk of severe weather sunday for wisconsin. noaa says that it could be updated to a high risk, which is very rare. I knew it was unusual for the spc to issue a moderate risk so early. It’s getting exciting.

  5. Good website talking about rarity of moderate severe weather forecast

  6. The thought of our area being in a high risk for severe weather and tornadoes worries me a bit. I love the thunderstorms, but when they start reaching tornado level, makes me worried. Should be an interesting weekend.

    • Nicole,

      As of now our area is under a moderate risk for severe weather on Sunday. No high risk in place yet. Certainly we will monitor the conditions and how the setup looks for Sunday over the next 24 hours. I always tell people not to worry, it takes just the right conditions for a tornado to form, and they are very isolated in nature, and most tend to be on the ground for a short period of time.

      Make sure keep up-to-date with the latest forecasts.

      Jeremy

  7. Only once has the spc issued a high risk forecast the day before an event. They usually issue it the day of because then there is a lot more certainty as to what may actually occur. We’ll have to see tomorrow as to what happens. Do you think parts of the midwest could be in a high risk for severe weather tomorrow?

    • Justin,

      High risk is possible. Our approach will be the same as any day, if severe weather occurs we will let you know on WISN 12 News, and if it is a tornado we will stay on until the threat clears the area. Lots of potential for Sunday, but will it be maximized.

      Jeremy

  8. Enjoy. We get a washed out dryline that passes dry. Sigh.

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