Bomb’s Away

Well, it sure looks like the October 26th storm is about to make a return visit this weekend. Before we get to that, we first have to get through the cold. The coldest air since February 12th when it was 11 degrees. This morning, it was 13 degrees and I think we will likely be a few degrees colder than that on Tuesday morning. It all depends on cloud cover, but I think the clouds will break up during the night.

Our first shot of snow comes with a little clipper on Thursday. This does not look impressive at this point.

You can see on the latest GFS forecast, just a light swath of snow is expected late in the day on Thursday. Accumulations, if any, look to be minor.

Now, let’s chat about the weekend storm. I wrote about this in yesterday’s blog about how I thought this might be the return of our powerful wind storm from October 26th. Yesterday, the GFS model’s 12z run had very little inkling that a storm was about to form. 24 hours later and what a difference. The GFS is now showing a very strong low undergoing intense cyclogenesis. At this point, the GFS is not intensifying the storm until after it has moved to our east. I believe that the storm will actually undergo quite a bit of intensification before it moves past SE Wisconsin, but there are still many questions to be answered.

1) The eventual path of the low. (This will make a huge difference on who gets the heaviest snow/rain.)

2) The strength of the low. ( This will make a difference on how much moisture will be dragged into the system and speed of the wind.)

3) Timing. (Too early to try to pinpoint when the storm will start and end.)

I want to share a comparison of 3 models, the similarities and differences on the upcoming storm. Here are the GFS, European, and Canadian models side-by-side.

To get a closer look, click on the image. I had to use the 120 hour forecast, which equates to Saturday morning. The Canadian model was not available after 120 hours. You probably immediately notice one model called operational, the other ensemble. Operational computer models are strictly the model run from the initiation time. Ensemble forecasts, add a couple more variables. These can include adding climatological events of the past to the model, adding other data to the initialization of the model, or by including additional model data from another source to the model. You will notice, the ensemble forecasts are kind of the “watered down” version. It allows for more of a “fudge factor” in forecasting.

 Note how all three models have the low pressure center in different locations. The Canadian model has the low farthest north which would actually bring a chance of rain mixing in. The ECMWF or European model is the farthest south. The GFS is in the middle. It’s now time to show some patience and use a wait and see approach.

While I am confident in that there will be a major winter storm this weekend, it is way too early to put any kind of numbers out there. Stay tuned.

Thanks for reading.



11 Responses

  1. Nice entry Mark. I will definately continue to follow this storm all week. I love snow so hopefully it makes Milwaukee the target. Too bad it’s on the weekend, no snow day. I did have a question—which model is usually the most reliable?

    • Thanks, Bryan,

      The key is to figure out which model is working best for every new event. I have a lot of confidence in our RPM model when precip is 24 hours out. It outperforms anything I have seen. All models have their biases that you have to be able to recognize. GFS is almost always overblowing amount of precip after 72 hours. Keep watching for the weekend!

  2. Glad it’s on the weekend because I don’t get a snow day no matter what and then the following day is absolutely brutal. Anyways, I’ve followed the models for winter storms the last couple of years and found the ECMWF to be the most reliable this far out. GFS usually has difficulties to say the least… just look at how much it changed in one day. Who knows what it will do next?

    • Daniel,

      Well said. I get more comfortable with GFS within three days.


  3. Glad I booked a room for our company’s Christmas Party this Saturday. Would hate to drive 50+miles in the snow. I hope it waits until after 5pm.

    • Karen,

      I think you will be happy with that decision. Drive safely.


  4. Bombs away indeed. 😉

  5. 0600 GFS model has the storm staying well south and not strengthening until then. Mark or Jeremy where could I see the European model, the main ones that NWS has are the NAM and GFS.

    • Bryan,

      Still a long way away. European has us in bulls-eye. Many places for ECMWF. Just google ECMWF.

  6. Great post Mark. I have followed your blog regularly, very intently during the winter months. The LRC model is very intriguing, keep up the great work. I would not go anywhere else for my weather forecast, as you seem to forecast the winter storms with great accuracy each year!

    • Thanks, Scott. LRC is indeed intriguing. Have fun watching weekend storm come together.


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