11/17/21 Wednesday 1:40 pm

In a recent interview, I was asked “what makes forecast models so interesting when storms form and head our way? My response was that I found it interesting how many billions and billions of dollars are spent on developing and improving weather and climate models and how inaccurate they usually are.

The GFS operational model had this 24 hours ago for next week’s storm.

24 hours later it has this

That is why I said yesterday that I will stick with the ensemble models for a few more days.  Here are the ensemble precipitation forecast models for the Canadian, the GFS, and the Euro family of models.

Canadian liquid

GFS liquid

The Canadian model has the most run-to-run consistency at this point. The GFS and Euro both took a more southerly path with this “cut off low”. Cut-off lows are very hard to forecast because they move separately from the west to east current moving across North America. I did notice that the CPC (Climate Prediction Center) bumped our area up to the first percentile tier for above-normal chances of precipitation in the next 6 to 10 days. The first tier is categorized as “Leaning Above” and it means they think we have a 33% to 40% chance of above-normal precipitation in that time period.

I don’t like the probability scheme being used as a forecast because it is too confusing and it is not a forecast. That reminds me, I have not addressed a question I always get asked about, the NOAA Winter Outlook. They use the same type of probability scheme for their Winter Outlook that they do for the 6 to 10 and 8 to 14-day outlooks. The Winter outlook is always misinterpreted by the media because they think it is a forecast. I saw that a few weeks back. Here is NOAA’s Winter Outlook.

What they are actually saying is that they believe there is a 33% to 40% chance that we will have below-normal precipitation this winter. What usually gets reported is that NOAA is forecasting 33% to 40% less precipitation this winter. The two statements are very different.

Here is an actual winter forecast. Courtesy of WeatherBell Analytics.

I know which one I am rooting for…

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