Severe Weather Chances – Friday

***Watch WISN 12 News at 5, 6, & 10 p.m. for the latest on thunderstorm chances!***

Thank you for stopping by the Weather Watch 12 blog!  Hard to believe, but with dry weather in the forecast for today(Thursday), this will mark the first time in June that Milwaukee has seen consecutive dry days!

The dry weather will not last long, so enjoy the sunshine and highs around 80.  The focus quickly shifts to our next chance of thunderstorms for Friday.  So far our viewing area has seen very little severe weather this Spring, but Friday may represent our best chance so far this year for strong or severe storms to develop.

Let’s go over the setup for Friday, and also look at what areas may see an elevated risk of severe weather.  With a warm front pushing into the region early Friday, one round of morning thunderstorms will be possible across southeast Wisconsin.  Below is the forecast surface map for 7 a.m. Friday.  Notice the warm front near our area, with the cold front over LaCrosse.  Click on any of the maps below to enlarge.

At this moment I don’t expect the morning t-storms to produce much if any severe weather.  However, heavy downpours, gusty winds, and small hail can’t be ruled out.  The morning round of t-storms should move out by 7-9 a.m., and not everyone will see rain.

Once the clouds break from the morning round of showers/t-storms and winds shift to a more south-southwest direction, temperatures and dew points will begin to climb quickly.  Remember, the dew point is a measure of moisture near the surface.  Last Friday dew points climbed into the low 70s during the afternoon, making it feel very uncomfortable.

I think that same scenario may play out on Friday.  Below is the forecast dew point map from the 12Z NAM.  This is valid for 1 p.m. Friday.  This computer model is forecasting sticky dew points in the low 70s!  Get the A/C and fans ready!

By Friday afternoon, it looks like abundant moisture will be in place, and a cold front(see surface map above, cold front is blue line near LaCrosse) will begin pushing into southwest Wisconsin.  The last ingredient needed for potentially severe weather would be instability.  Assuming the sun breaks through for several hours on Friday, the instability would increase with daytime heating.  This would mean the potential for strong to severe thunderstorms could exist across the western Great Lakes.

Below is the severe weather outlook from the Storm Prediction Center(SPC) for Friday.  All of southeast Wisconsin has been outlined in the area that has a slight risk of seeing severe weather.

Now what exactly does a slight risk mean.  The SPC breaks down the slight risk into percentages.  Notice our viewing area is in the 15-30% regions on the map below.  This means there is a 15-30% chance of severe weather within 25 miles of a point

That is still a fairly low chance of seeing severe weather where you live.  Remember, severe weather is often very isolated.  The main threats with the storms on Friday would be heavy rain, hail, and strong winds.  While an isolated tornado somewhere in the slight risk area cannot be ruled out, the threat of hail and strong winds is higher.

Make sure to stay tuned to WISN 12 News for the latest updates today and on Friday.  You can also follow our updates here:

  • Facebook: WeatherWatch 12
  • Twitter: WISN12News
  • iPhone App: WISN
  • WISN.com  (Interactive Radar & Futurecast)

Feel free to ask any questions you may have, just post them to the comments section of the blog. 

Have a great day!

Jeremy Nelson

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3 Responses

  1. I was wondering why the dew points out west are always so low. Wouldn’t a flow coming from the Pacific Ocean have the same effect as when the flow brings up muggy air from the Gulf of Mexico?

    • The air that flows over the Rockies loses moisture as it decends into the Plains. In a way this is how dry lines form. The Gulf air does not have any mountains to cross, just a straight shot north.

      Jeremy

  2. Hey Jeremy, I was wondering if you could tell me what a QLCS is? I’ve seen it in the SPC forecasts, and I was wondering what it is.

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