All posts by Jim Woodmencey

The Updated Winter Outlook

Mountain Weather Blog

(This article originally appeared in the Jackson Hole News & Guide on Oct. 26, 2016)

At the very end of August, in this column, I gave you the early, early winter outlook for 2016-17. That was ridiculously early to be talking about winter. Now that we are deep into October, have some snow on the ground, and some among us have already been skiing, I thought it might be a good time to update what was said back in August.

Some predictions will not change, like the Farmer’s Almanacs, but an update from NOAA and the El Nino/La Nina situation might provide better insight, as we get closer to the actual winter months.

The Outlooks

As you may recall from that August column, the two most prominent Farmer’s Almanacs were basically at odds with each other, as to what sort of winter this part of the country would have. One painted a picture of “Mild and Dry” conditions across the State of Wyoming, the other depicted “Freezing Cold with Average Snowfall” for this part of the country. That was neither helpful nor definitive.

Back in August of this year, the Climate Prediction Center (CPC), which produces three-month outlooks of temperatures and precipitation, was telling a slightly different story than the Almanacs. The CPC had us right on the line for a 50/50 chance of being warmer than normal in December-January-February. For precipitation, Northwest Wyoming looked to have a slightly better than a 50-percent chance of having above normal precipitation this winter.

The latest predictions from the CPC, made at the end of last week, show that we now have a little better than a 50-percent chance of being warmer than normal, and are closer to a 55-percent chance of having above normal precipitation, in the December-January-February time period.

If you look at the next three-month prediction, for January-February-March of 2017, then we drop into the “Equal Chances” category for temperatures; that is, it could be above or below normal, temperature-wise, for these three months. For precipitation, Northwest Wyoming hangs closer to that 55-percent chance of above normal precipitation.

jfm-temps

 

jfm-precip

 

Trend-wise, I would say that might result in something closer to normal temperature-wise for Jackson Hole this winter, and our odds of having above normal snowfall this winter in Jackson Hole are solidly better than 50/50, through the winter months.

Now, let’s see how the projected La Nina situation is developing first.

El Nino/La Nina

To review: El Nino is one phase of what is known as the El Nino Southern Oscillation (ENSO), which is tied to the fluctuations in sea-surface temperatures in the Equatorial Pacific. During an El Nino, those water temperatures are warmer than normal. During a La Nina, they are cooler than normal.

El Nino winters generally bring warmer and drier conditions across the northern Rockies. Note: we had a strong El Nino last winter and yet we ended up with a winter that had average temperatures and just above normal snowfall.

La Nina winters typically bring and cooler and wetter weather to the Pacific Northwest and the northern tier of the United States. Like the strong La Nina winter we had in 2010-11.

At present, conditions in the Equatorial Pacific are near neutral or slightly cooler than normal. Therefore, water temps will have to start diving before they will call it a full-fledged La Nina. The prediction is that a weak La Nina will develop (70-percent chance) and may persist (55-percent chance) through the winter months.

For the latest updated info on La Nina, Click Here>>

If actually we end up with more of a “Neutral”, or No-Nino winter, then our odds of an above normal winter could drop. Part of what goes into those CPC forecasts depends on these ENSO predictions for the winter.

One last thing, which I personally like to look at, is what the water temperatures are doing in the northern Pacific. This is related to what is known as the Pacific Decadal Oscillation, or PDO. During the last two winters (2014-15 and 2015-16) the temperatures in that part of the Pacific have been warmer than normal, unusually warm at times.

Since June of 2016 those temps have been in a steady decline, and were almost back to normal by the end of September. My hypothesis is: whenever the PDO is near or cooler than normal, Jackson Hole has a bigger winter.

Let’s root for that northern Pacific Ocean to keep on cooling down over the next few months. That could make for a very “powder-full” winter here.

Jim is the chief meteorologist at mountainweather.com and has been forecasting the weather in Jackson Hole and the Teton Mountains for the last 25 years.

Summer in Jackson Hole 2016, in Review

Mountain Weather Blog
The Summer Forecast Was..

First though, let’s see how accurate the long-range predictions were for this summer. The National Weather Service’s Climate Prediction Center had forecasted back in April of 2016, that June-July-August over western Wyoming: a good probability of above normal temperatures, and a higher probability of having above normal precipitation.

Just for giggles, I also looked back at what the Old Farmer’s Almanac had predicted for our region, which was: a “Hot & Wet Summer”. That was in pretty good agreement with the Climate Prediction Center’s forecast.

Now, with the benefit of Bob Yaw’s hindsight forecasting, how would you describe this past summer? You might say that overall temperatures were “pretty warm”. But it certainly was not “wet”.

Let’s see what actually happened, by reviewing the data form the Jackson Climate Station, and comparing those numbers to the long-term historical averages.

This Summer Really Was…

June was the only month this summer with above average temperatures. And, it was much drier than normal. The total precipitation received was just 0.77 inches, which is less than half of the average precipitation amount for June of 1.63 inches.

July had much cooler than average high temperatures for the month, a solid four degrees cooler than the long-term average. Overnight low temperatures balanced that a little, they ended up two degrees warmer than normal.

Wait, I thought it was hot in July? Certainly, the last half of the month we heated up, with 13 out of 15 days registering high temperatures in the 80’s. However, the first half of the month took a toll on getting us anywhere near normal. Including a couple of exceptionally cold days around July 11th and 12th, with a high of 57-degrees followed by a low of 31-degrees. You might remember it also snowed down to near 8,000-feet in the Tetons.

August was also cooler than normal. The average high and low temperatures were each two degrees cooler than the long-term averages. You might find that surprising, as it sure seemed like it was hot in August, too. There were 12 days in August 2016 with highs in the 80’s, however, the remainder of the days had highs that were only in the 60’s or 70’s.

Overnight low temperatures in August also helped drag the overall average temperatures down. There were five days in August when temperatures dropped below the freezing mark, bottoming-out at 28-degreeson August 24th and again on August 27th, the coldest days of the summer.

Summer Summary

Each of the last three summers in Jackson has seen the overall average mean temperatures at or slightly cooler than normal. That should be encouraging to some, after a spate of warmer than normal summers earlier in the 2000’s.

This summer, the hottest temperature recorded in town was 88-degrees, on July 22nd and again on August 18th. Officially, it never made it to 90-degrees all summer. As a matter of fact, it has now been eight years since we have reached 90-degrees at the Jackson Climate Station. The last time it was “officially” 90-degrees in town was on August 1, 2008.

While the last three summers stayed cool, temperature-wise, this past summer was the only one of the last three that was drier than normal. Total precipitation in town this summer was a measly 1.90 inches, or around 50-percent of the long-term average. The two summers previous to this one were much wetter than normal, which helped keep hillsides green and fire danger relatively low.

Had it not been for wetter than normal conditions in April and May of 2016, we might have very well dried-up and blown away this year by September 1st.

Jim is the chief meteorologist at mountainweather.com and has been forecasting the weather in Jackson Hole and the Teton Mountains for almost 25 years.

Table:

Summer Weather Comparison
Town of Jackson
June-July-August
Summer
2016		 Normal Summer Summer
2015		 Summer
2014
Average High Temperature 77 °F 78 °F 75 °F 73 °F
Average Low Temperature 39 °F 39 °F 42 °F 41 °F
Mean Temperature 58 °F 58.5 °F 58.5 °F 57 °F
Precipitation 1.90 inches 3.77 inches 4.67 inches 4.40 inches
Data and Stats from Jackson Climate Station

 

Article re-printed from Mountain Weather column that appeared in the Jackson Hole News & Guide.