Will it be a hot, dry summer, or not?

The latest long-range outlook for the summer season from NOAA is out, and it shows that the Jackson Hole area should have warmer and drier conditions for June, July and August.

At first glance, that might seem like ominous news, as far as drought conditions and fire danger are concerned. Although, when you dig a little deeper into the meaning of that forecast and how it was derived, it may not sound quite so bad.

Let’s take a closer look at how to interpret these long-range outlook maps from NOAA, then you can decide for yourself how good or bad this summer might be in Jackson Hole.

Warm and Dry, Maybe

This summer’s temperature outlook has most of the United States in the warmer than normal category. Jackson Hole falls under a 50 to 60 percent probability of temperatures being above normal, overall, for June, July and August 2022. Which means it is slightly more likely than not that we’ll end up warmer than a normal summer.

Precipitation-wise, the outlook is for below normal rainfall for June through August 2022, across the far northern Rockies and into the Plains States. In Jackson, the probability of it being drier than normal is somewhere around 40 percent, that is to say, the outlook is leaning towards a drier summer.

That is the official outlook from NOAA. What follows are the official instructions from NOAA on how these outlook maps are made.

How to Read the Outlook

“The contours on the map show the total probability (%) of three categories, above, indicated by the letter “A”, below, indicated by the letter “B”, and the middle category, indicated by the letter “N”. At any point on the map, the sum of the probabilities of these three categories is 100%.

For any particular location, and season, these three categories are defined from the 30 observations from 1981-2010. The coldest or driest 1/3 (10 years) define the B category, the warmest or wettest 1/3 (10 years) define the A category, and the remaining 10 years in between define the middle (N) category.

When the forecasters decide that one of the extreme categories, say above (A), is the most likely one, they assign probabilities which exceed 33.33% to that category, and label the map with an “A” in the center of the region of enhanced probabilities. To make it possible to display three categories on one map, we assume that, when either A, or B is the most likely category, the probability of the middle category remains at 33.33% for most situations. This means, for example, that when the probability of A (B) is 40%, the probability of N is 33.33%, and the probability of B (A) is 100% minus 40%+33.33%=26.67%.

When probability values of the favored category reaches 70%, or higher, the probability of the opposite category is fixed at 3.3%, and the probability of the middle category is adjusted to values (less than 33.33%) which cause the sum of the three probabilities to equal 100%.

When the middle category (N) is higher than 33.33%, the probabilities of the A and B categories decline by (equal) amounts required for the sum of the A, N, B probabilities to equal 100%.

In regions where the forecasters have no forecast tools which favor the chance of either A, or B, the chance of these two categories is defined to be 33.33% each, and the region is labeled “EC”, which stands for equal chances.

Shading is used to indicate different levels of probability above 33.33%.”

Say What?

You really need to read that explanation several times to understand the methodology used to arrive at these probabilities. I picture a team of meteorologists and statistics nerds sitting around, 5 days a week, 40 hours a week, tweaking numbers. After all that, they rarely ever commit to probabilities that exceed much more than 50 percent. Basically, a coin flip.

It might help to know that last summer’s outlook was also for warmer and drier than normal weather. The summer of 2021 ended up one-degree warmer than the long-term average, however, Jackson was wetter than normal by 0.81 inches.

My forecast for this summer is for warm and dry weather on the days I have outdoor plans and just enough rain to keep the dust down and hold the fire danger at bay. I’m giving that “wish-cast” a 50-50 chance of happening.

Jim is the chief meteorologist at mountainweather.com and has been forecasting the weather in Jackson Hole for over 30 years.


Note: This article originally appeared in the Jackson Hole News & Guide