Purgatory Opening Day

Purg’s planned opening day is 11/23/19, a week from Saturday. The Euro operational model run has a 10 day (240 hours) lead time for forecasts, the Canadian model is the same, the GFS model has a longer window 16 days (384 hours).

The biggest mistake new weather enthusiasts (who have weather model access) make, is seeing one particular long term (10-16 day) model run and getting too excited about what they see. As I have preached over and over, you have to look for model agreement with itself (consistency) and model agreement among other weather models. You then need to take into consideration model bias. The GFS bias is nearly exactly opposite what the Euro bias is. The GFS likes to move storms from west to east too quickly, this can cause an issue with timing and intensity. The Euro has its own issues with timing and intensity, its bias is to place storms further west and hold them deeper in the west for too long before tracking them east across the country. These biases show more prominently in the early stages and slowly correct, at times having a final correction in the last 24 hours before arrival.

Take a look at the GFS for next Wednesday 11/20/19


The important thing to look at is the position of the closed low-pressure system in SW Utah (look for 1001).

Now look at the Euro for the exact same time


The low position is still off the California coast (the L with 1006)

Fast forward to hour 240 GFS



The GFS has already moved the storm well into the midwest.


Here is the Euro at 240 hours


The main low is still spinning offshore circulating deep moisture all of the way into our area, btw if you are concerned about all of the green versus blue, don’t be too concerned, on this particular model run the snow level is 8,000 feet.

So 10 days out there is roughly an 1800 mile difference between the location of the storm centers.

Of course, it is right at the very end of the model run that things start to get good on the Euro (240 hours). Looking at the GFS it has had some very impressive snow totals for this storm over the last several runs.  In fact, the GFS has shown storm totals between 10-30 inches. Since the GFS runs are 6 days longer than the Euro, of course, I had to look and it showed another decent storm around Thanksgiving.

At this point, I am cautiously optimistic that we will see a pattern change and I am pleased that I have something to talk about, I also find it interesting that we had snow at the same time last year.

I will do another update on Thursday it will be interesting to compare the same models for the same times next week.

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