‘Cooler By The Lake’ & Active Pattern Looms

***Watch WISN 12 News for the latest weather information!***

Thank you for stopping by the Weather Watch 12 blog!  A phrase many hate to hear this time of year will create a huge temperature spread on Friday – ‘cooler by the lake’.  Cooler readings are common this time of year for lakeshore counties, but with our cool spring, the chill has been a little tougher to take for those near the lake eagerly awaiting summer’s warm days.

The set-up for Friday will include southeast winds pushing the chilly air above the 42 degree lake waters over counties along Lake Michigan.  While this is occurring, inland areas will see southeast to south winds and much warmer temperatures.  Let’s start by looking at the surface forecast from the RPM computer model at 4pm Friday shown below. 

Surface winds along the entire lakeshore should be primarily southeast with a slight south component. 

RPM Friday June 3, 2011 4pm

If the southeasterly wind component plays out like I think it will, this will result in daytime highs around 10 degrees or even more below what inland locations will record.

Below are RPM forecast temperatures(not a high temperature forecast) at 4pm Friday.  If you are looking for highs in the 80s, you may want to travel west of Milwaukee and Ozaukee counties on Friday afternoon.

RPM Temperatures Friday June 3

By late Friday and into Saturday a few showers and thunderstorms will be possible across southeast Wisconsin as the warm front lifts north and the cold front begins to slide in.

This rain chance will signal what I believe to be roughly a 3 week stretch of active weather for southern Wisconsin.  The active pattern can be detected using a weather pattern theory called the LRC, which we have used right here in the blog with great success.  The weather pattern is still cycling on roughly every 50 days.

In looking back at April after the big warm-up occurred on thel 10th, a wet pattern took hold for the second half of April.  This wet pattern also occurred after the very warm end to 2010 as January had numerous snows that totaled almost 20″ in Milwaukee.

The upcoming active weather pattern for Wisconsin is beginning to show up on the 500mb charts on the long range GFS computer model.  Remember, 500mb is located in the middle of the atmosphere, and is a good location to track the longwaves the move across the U.S.

Below is the 500mb GFS forecast for June 10.  The key here is the southwest to west flow aloft on the north side of the ridge over the South.  And the little ‘X’s’ on the map are disturbances that will ride along the mid-level winds.  Since we are in June, these disturbances will likely be thunderstorm complexes.  So I think it could get pretty wet close to home once again.  

500mb GFS June 10, 2011


What I find amazing is that the GFS forecast map above which is a FORECAST map 180 HOURS out matches up very well with the 500mb map 50 days before June 10.  The April 21 map below has the same kind of west-southwest flow as the map above.  By comparing the map above and the one below, I conclude that the forecast from the GFS is likely close to reality, and another round of active weather looms!


500mb April 21, 2011


We will continue to watch the pattern and the possibility for showers and thunderstorms heading into next week.  In the meantime, make sure to watch WISN 12 News for the latest on the weekend forecast.

Keep in mind the blog is interactive, if you have a weather question or thought, please post it to the comments section of the blog.

Have a great day!

Jeremy Nelson




9 Responses

  1. Hi Jeremy,

    If I remember correctly both June and July of 2010 brought record rainfall amounts. Do you think we will be seeing record setting June and July rains again? I hope not. Thanks.


    • Lori,

      Always tough to predict record rains in advance. Much easier to tell when in the pattern storm systems are possible. Thunderstorms are generally localized events that can bring a wide range of rain totals to an area depending on how fast the storm is moving, moisture content, etc. While I think overall May-July will have an above average rainfall total, it’s tough to put an exact number on what lies ahead. Hopefully nothing like we saw last July 22!


  2. Thanks Jeremy.

  3. So is June 10th the start of wet weather or will be starting before that date ??
    And continue on for weeks ??

    • Rich,

      I think this Saturday lines up what was the start of the wetter part of the pattern this past April.


  4. Jeremy, what does the southwest/south flow mean in terms of temps? Average?

    • Usually means around or above average which is where every day has been (except for yesterday) since Memorial Day and what the NWS forecast calls for inland for the next 7 days at least.

      That map of April 21 has the southwest flow south of our area, but for us it was under a more west-northwest flow aloft and easterly flow at the surface which is why it was so darn cold during that period last time. The main front was running through central Illinois back then, but for the time being is hanging around closer to or even north of our area now.

  5. Hi, Jeremy!

    You remarked about the temp difference inland today. Don’t know what you’ve got where you are, but here in Reeseville, we’re sitting at 92 DEGREES–HOT–HUMID–AND VERY WINDY — as of 4 p.m. Whew!

    Since you predicted that ahead of time, I wisely was outside early to finish planting the garden. See how helpful you are to me???

    I have just a bit more planting to do on Saturday — or will I get rained out???

    Thanks for the help and the answers!


    • Don,

      Your temp looks pretty good…Watertown is 91 right now and Beaver Dam is 88. The inland areas are certainly hot today. Lakeshore was held back with the SE wind for much of the day. For tomorrow, best rain chance is in the morning where you live. Not everyone will see rain tonight or Saturday. Looks like some spotty to scattered stuff.


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