Meteorologist Jim Woodmencey

Usually by now, I will hear some utterance to the effect, “Oh, it’s an El Nino year”, or, “I heard we are gonna have another La Nina”.

“El Nino” and “La Nina” have become buzzwords for ski towns like Jackson Hole El Nino has become synonymous with low-snowfall winters and La Nina with above normal snowfall winters.  No Nino doesn’t seem to have its own buzz, although if you looked at the No Nino winters we’ve had in Jackson Hole over the years, you might tag it as a buzz-killer.

First, let’s get some definition as to what El Nino, La Nina, and No Nino really mean. Collectively, these are known as the El Nino Southern Oscillation (ENSO), a phenomena that is happening down in the Equatorial Pacific. ENSO affects weather patterns around the globe, and these effects are more prevalent during Northern Hemisphere winters.

The ENSO phase we are in is determined by sea surface temperatures found across the Pacific, between the coast of South America and Indonesia.

El Nino is when sea surface temperatures are warmer than normal. La Nina is when temperatures are colder than normal. No Nino is when temperatures are normal, otherwise known as the neutral phase of ENSO.

Generally during El Nino winters, the Pacific Northwest and Northern Rockies experience warmer than normal temperatures and below normal precipitation, while the southern tier of the United States is usually cooler with above normal precipitation.

During La Nina winters, the opposite is true: the northern tier of the U.S. experiences a cooler and snowier winter, while the southern tier is usually warmer and drier.

This is why when we hear El Nino in Jackson, we think, “no snow”. And when we hear La Nina we think, “mo’ snow!” We came out of a weak La Nina last winter and have been stuck in neutral ever since.

Statistically here in Jackson Hole, El Nino winters are evenly split between above and below normal snowfall winters; 50/50. La Nina winters are snowier than normal more like 70-percent of the time. That’s why we get excited about them. But 30% of La Nina’s have had below normal snowfall.

You might surmise that No Nino winters (or Nada Nino) should then be “normal” or “average” winters. An average winter is difficult to define because our averages are created by our extremes. Almost every single winter is either above or below the average, some more than others. Besides, who is going to run around shouting, “Woody said we are going to have average winter!”

In Jackson Hole, winters that were spent in the No Nino phase more often than not produced below normal snowfall; about two-thirds of the 15 winters I analyzed in this category were drier than normal winters. That means that a third of the No Nino winters had above normal snowfall. Most notably was the winter of 1996-97, which was a very big snowfall year.

El Nino Southern Oscillation

Send in the Arctic Oscillation

ENSO isn’t the only thing that can disrupt weather patterns in the winter months. Another phenomenon that is closely monitored is the Arctic Oscillation, or AO.

AO is a measure of the difference in pressure between the Northern Polar Regions & the mid-Latitudes (where we live). This difference creates either a positive or a negative phase.

Positive AO occurs when there is lower pressure over the Arctic Circle and higher pressure over mid-Latitudes. This forces the jet stream and the storm track further north. The result is more ocean storms and wetter weather for Alaska, and warmer temperatures in the mid-latitudes.

Negative AO occurs when there is higher pressure over the Arctic Circle and lower pressure over the mid-latitudes. This forces the jet stream and storm track further south. The result is colder air and more storms in the mid-Latitudes, at the same time warmer air moves up into Alaska.

The problem is that the Arctic Oscillation fluctuates more regularly, from week to week, whereas ENSO fluctuations take longer to switch from one phase to another, on the order of months.

Given the current No Nino outlook for this winter, I will be turning my attention to the North Pole and looking for some “Negative AO” action to drive the storm track further south and right over Jackson Hole. Not sure that’s gonna have the same buzz as La Nina does.

Arctic Oscillation

The content of his week’s blog is excerpted from the Mountain Weather Column I wrote for the Jackson Hole News and Guide in October.
Graphics courtesy of NOAA.

Meteorologist Jim Woodmencey

Nice dump of snow for Jackson last night, with about 5 inches in a couple of hours at my house near Snow King Mountain.  At 7:00 pm there was no snow, by 9:00 pm I was shoveling the deck. As I write this at 5:00 a.m. on Tuesday morning, there is another 4 or 5 inches on the deck. Total of 8 to 10 inches in less than 12 hours. (It is still October, isn’t it?)

This snowstorm was courtesy of a slow moving and very large Low pressure system that moved into the Western U.S. on Sunday. It basically parked itself over the Great Basin Monday and wrapped some cold air from Canada into itself.

For the most part, the flow aloft was out of the South overnight, a flow which favors Snow King Mountain and the Town of Jackson for orographic snowfall, that is, the extra lift the mountains provide to boost the snowfall. The jet stream was also in an optimal position to give an extra boost, as well.

Looking around at other mountain instruments, it seems that 6 to 8 inches overnight was the norm, even up at elevation in the Tetons. So a fairly even distribution from what we received in Town and what fell at 8 to 10,000-ft. in the Teton Range.

After a week of High pressure and sunny weather last week, we switched gears pretty quickly on Monday.

Even though technically I a supposed to be on my “Fall Break” right now, I couldn’t resist looking at this storm. Now our 5th snowstorm in the Tetons since late September.

I am off to Alaska this coming week to teach a weather course. Back to forecasting for JH on Nov. 11th.

Surface Map

700mb Map (around 10,000-ft. elevation)

Jet Stream Map (@ 30,000-ft.)

Post by Jim Woodmencey
Graphics from NOAA

Meteorologist Jim Woodmencey

Pretty good snowstorm for the western Wyoming mountains Thursday/Thursday night. But a really good snowstorm for the rest of Wyoming for Friday & Friday night. Winter Storm Warnings and Blizzard Warnings issued for much of the eastern half of Wyoming.

Some snow for the Colorado Rockies with this storm, but the Plains of Nebraska and South Dakota really get hammered by this weather system as it moves east Saturday.

From NWS Office Cheyenne Issued Friday morning Oct. 4

NWS Nationall Forecast Map for Friday Oct. 4

Snowdepths Getting Deep for Early October
Up in the Teton mountains there is now a foot or more of snow up around the 9,000 to 10,000-ft elevation being reported on the few instruments that are up and running. For instance, the Snotel sensor at Grand Targhee at an elevation of 9260-ft. is showing a 13 inch snow depth.

The Snotel sensor on Togwotee Pass at the 9850-ft. elevation is showing 16 inches of settled snow depth at 8:00 a.m. on Friday, October 4th. 

Over in the Wind River Range, which stands to get the most snow from this storm as it is now more of an “upslope” event for areas along and east of the Continental Divide (as the Low pressure center moves into Central/Eastern Wyoming), there dis even more snow on the ground now. Hobbs Park Snotel is at 10,100-ft., along the eastern side of the Winds, and it shows a 20 inch sow depth this morning.

Oh, and by the way, the temperature up at around the 10,000-ft. elevation this morning is 18 degrees. I guess we are skipping Fall and heading right into Winter.

RAP Snowfall forecast map of total snow accumulation Friday morning thru Friday Evening

WRF Total snow accumulation forecast for Friday morning thru Saturday morning.

Keep track of Jackson Hole & Wyoming Weather & Snowfall

If you want a quick way to check out all the local weather instruments, go to the “WAM” (Weather Access Map) for the Jackson Hole & Yellowstone area…..click here: WAM Tetons

There is also a “WAM” for the State of Wyoming……click here: WAM Wyoming

Both of thees maps will get you to the latest data and also the latest forecasts for those same locations.
(Note: Utah & Colorado WAM’s will be available soon, hopefully soon enough!)

Post by meteorologist Jim Woodmencey
Maps courtesy of the NWS

Meteorologist Jim Woodmencey

The big storm that brought rain and snow this week to the Northwest and the Northern Rockies will be moving across the central Rockies and the northern Plains the next 24-hours or so.

What it left behind was fairly impressive, with record September snowfall at Crater Lake National Park in Oregon of 8 inches in 24-hours Tuesday into Wednesday, above about the 6,000-ft. elevation.

At the Jackson Hole Mountain Resort there was also about 8 inches of snow reported up there at about the 9500-ft. elevation, which accumulated from just before midnight Tuesday through Thursday morning Sept. 26th. Togwotee Pass had about 10 inches at the same elevation. And the higher elevations in the Wind River Range had more than that, and appear to have the deepest snow accumulations from this storm.

Rain in the Town of Jackson was also significant, at the automated rain gauge in town 1.26 inches of rain fell in less than 24-hours. Significant because the average rainfall for the month is 1.29 inches.

See precip and snowfall coverage maps below from this storm.

One Day’s Precip on September 26th across the Western US

Zoom on Northwest US One-Day Precip Sept. 26

Zoomed into Wyoming One-Day Precip Totals Sept 26.

US Snow Depth Map on morning of Sept. 27th

Zoomed in Snow Depth Map for Western WY

Meteorologist Jim Woodmencey

Seasons are definitely changing this week, with word of a “big storm” heading our way, which began its hype on Monday. Sometimes the mere mention of the word “snow” in the forecast will set off a 4-alarm warning, among skiers especially, even in September!

This will actually be the second storm this September to bring snow to the Tetons. The first one was on September 18th, and most of that snow has melted off except for a skiff on north faces above 10,000-ft.

This incoming storm will bring even colder air with it and snow levels will get down near the valley floor, probably by Thursday the way it looks right now. It will be selective about where it deposits the bulk of the snow, as the whole weather system divides as it crosses the Rockies.

Best moisture comes over western Wyoming when snow levels are still fairly high during the day on Wednesday.

Certain areas in Western Wyoming will be favored as this large Low pressure Trof appears to split up as it moves across the Rockies, with the main center of that Low going north into Montana and eventually Southern Canada by the end of the week. And the southern part swinging across Nevada & Utah and eventually Colorado.

The higher elevations of Yellowstone Park (especially the SW corner of the Park) and the Wind River Range will potentially receive the most snowfall. As snow levels lower progressively Wednesday thru Thursday in western Wyoming, the lower elevations pick up some snow, as well. I also expect the Tetons will see a brief period of enhanced snowfall when that Low is over us and moving across Southwest Montana.

Who Gets It?

This is also a good looking set-up for Central Idaho’s Mountains, as they get into the colder air sooner, when the storm is still intact as it moves inland Tuesday night/Wednesday. And then another swath of snow will be likely across Southwest and Central Montana, initially with a SW flow as the Low approaches for west of the Divide, and then east of the Divide (central Montana) with decent upslope flow once the Low moves into eastern Montana.

A variety of different computer models depict the variability of the snowfall accumulation & distribution across the Northwestern US and NW Wyoming with this storm, and a few of those are shown below for comparison. Note that they each cover a different time period. So, which one is correct?

(Hint: A skier will pick the one that shows the greatest amount of snow where they like to go, every time!)

Don’t pull on your snow pants just yet, it will warm up over the weekend and melt a good portion of what accumulates in the mountains this week.

NAM 48-hour Total Snow Accumulation Tues. a.m thru Wed. p.m.

MFF Total Snow Accumulation Tues. a.m. thru Fri. a.m.

WRF Total Snow Accumulation Tues. a.m. thru Thursday evening.

Same Map as Above (WRF) zoomed in on Western Wyoming

Post by meteorologist Jim Woodmencey
Graphics courtesy of LEADS On-Line
and USDA-FS Fireweather

Meteorologist Jim Woodmencey

The First Day of the Fall Season doesn’t get here until Sunday, September 22nd,  but we will see a change in the weather pattern from what has been relatively warm to relatively cooler beginning Wednesday.

There will be a series of storm systems of different sizes and shapes working out of the Gulf of Alaska and moving across the Northwestern US over the course of the next 7 to 10 days, and each of these will be cold enough for some white stuff in the higher elevations, at least above 10,000-ft.

The first Low pressure system moves thru Tuesday night and early Wednesday. Then a break in the weather and warming Thursday & Friday. Next weather system looks weak but may bring some showers to the mountains later Saturday and on Sunday. Then another break between weather systems Monday & Tuesday of next week, with a larger and even colder looking Low pressure system moving into the Western US Thursday and Friday of next week, with snow levels may be down even lower.

Not to the valley floor, and not huge amounts of snow up high, but enough for a reminder that it ain’t summer anymore.

We also could see below freezing temps in the Jackson Hole valley this week, especially Friday morning with clearer skis overnight Thursday.

Wednesday Sept. 18 Weather Map

Sunday Sept. 22 Weather Map

Freeze-free Days in Jackson

With high temperatures still reaching into the 70’s this week (78 in town on Monday!) and lows only in the 40’s most mornings, it may seem like we have had a long “frost-free” season this summer. But actually it was probably not as long as you might think.

According to the thermometers at the Jackson Climate Station the last day below freezing overnight low temps in the Spring was on June 23rd (28 degrees). And the next time it got below freezing was on September 1st ( 30 degrees). That’s 69 days, by my math, of “frost-free” or “freeze-free” days.

Although, there was one day in mid-August that it got down to 32 degrees for a morning low……if that qualifies as a “freezing” day, then our growing season was split in two!

Post by meteorologist Jim Woodmencey
Maps from NWS

Meteorologist Jim Woodmencey

Big Rain in parts of the Western US this week, with the Four-Corner’s States seeing the brunt of the precipitation all week long, in Arizona, Utah, New Mexico, and Colorado. Then the Front Range in Colorado was hit especially hard the last two days.

The large area of Low pressure that has been hanging over Nevada, Utah, & Colorado this week is responsible. And that Low has circulated a lot of moist and unstable air up from Mexico and the Gulf, deluging many areas with record rainfall, along with resultant mudslides and flooding.

One Day’s Rainfall Totals September 12, 2013

Colorado
In the 24 hour period from 6am Thursday Sept 12 to 6am Friday Sept 13 Burlington Colorado had 4.72 inches of rain. Centennial Airport had 2.44 inches, Colorado Springs 1.85 inches, and Denver Airport 1.30 inches.  That’s more than a whole summer’s worth of rainfall for some of these places! Map above shows precip totals from Sept. 12.

Wyoming
Southern Wyoming and into parts of Central Wyoming had between 3/4 and 1 inch of rainfall Thursday. Cheyenne 0.65 in. Lander 0.73 in. Laramie 0.91 inches.

Northwestern Wyoming and Jackson Hole meanwhile measured rainfall in hundredths of an inch. So, no whining about how wet it seems we have been lately, compared to Colorado anyway.

Jackson Hole Summer Rainfall
Total precipitation for June-July-August in the Town of Jackson was 1.65 inches. That is not even half of what our average summer precip would be, 3.85 inches.
However, September has been a little wetter, as of Thursday, Sept. 12th, we have received just over 1 inch of rainfall during September 2013. Starting to make up for the generally dry summer. And a huge difference in teh weather from this time last year whe we were warm & dry and had the Little Horsethief Fire raging.

Post by meteorologist Jim Woodmencey
Graphic from NOAA

Meteorologist Jim Woodmencey

This past week I have been caught using the “F-word”, a lot. I try to refrain, but I suppose it is inevitable, after all, “Fall” is just around the corner.

It is still August, and technically still the Summer Season for another 3 weeks. However, the last few days it is not the “F-word” that people are dropping as much as they are asking, “What kind of winter are we going to have?”

Seems way too early to be thinking about snow, but the main reason I get inundated the last week or so of August about the outlook for the coming winter is because around September 1st the price of a season pass at most ski areas goes up.

It’s simple psychological economics, if you hear it is going to be a “big” winter, then you are more likely to throw down now for the goods. Goods that haven’t even been manufactured yet. I suppose everyone is just looking for a little assurance that there will be plenty of snow this winter.

On the other hand, if you hear that is is supposed to be a “dry” winter where you ski, you might not be willing to make an investment in the product until it comes on the market and proves itself by out-performing the forecast.

You’re betting on the futures market. It’s commodity trading in the white stuff. I don’t do any trading, personally. I don’t even think I own any stocks, and my IRA has about $250 dollars in it (since 2008). Basically, my retirement plan is, I have to work until I am dead.

But I do follow the weather, and I do love to ski powder. So, I do follow the snow market, and for those of you who just gotta have the early forecast, the insider tips, I offer my analysis of how the snow futures market is looking ….before the price of a Season Pass goes up in the next few days.

If you want to skip all the analysis and get to the bottom-line, then just scroll to the bottom of this blog…..

Farmers Almanacs

There are several different Farmer’s Almanacs out there to consult. These, in my opinion, are the least useful and least accurate indicators of long range weather. But I have to admit, I keep one within arm’s reach of my toilet every year.

There are three different Farmer’s Almanacs that you can consult:
1) Farmer’s Almanac, in print since 1818.
2) The Old Farmer’s Almanac, in print since 1792.
3) Harris’ Farmer’s Almanac, claims to have been around since 1692.

That means that Harris’ Almanac is actually 100 years older than the Old Farmer’s Almanac. Hmm……

To paraphrase that guy from the Dos Equis commercials, “I don’t often read a Farmer’s Almanac, but when I do, I prefer the Old Farmer’s Almanac“. Unfortunately, that one is not available yet (release date is Sept. 2nd). So, I’ll give you what info I could decipher from the other two almanacs.

Keep in mind, the wording they use is purposely vague, like many weather forecasts. What you have to realize is, a forecast is an expression of “uncertainty”. It is not exact. As I tell students in weather classes I have taught, use any forecast as guidance, not gospel. That said, here is what they said……

Farmer’s Almanac

Pacific Northwest: Cold & below normal snowfall.

Rockies: “Piercing Cold” & normal snowfall.

Sierras to Wasatch: Cool with normal snowfall.

Harris’ Almanac

Cascades & Sierras: Cold December & January with normal snowfall. Warm February & March with below normal snowfall.

Intermountain West & most of the Rockies: Cold December & February. Warmer January. And showing above normal snowfall December, January, & February. March was shown to have normal temps & snowfall.

In general the theme seems to be a colder than normal winter throughout the West, with relatively normal snowfall across the board, a little below in the Northwest perhaps, and a maybe little above normal in the Rockies. Overall nothing too remarkable….pick whichever one sounds better for where you ski, and run with it!

From the Farmer’s Almanac, not the Old Farmer’s Almanac

Climate Prediction Center (CPC) Forecasts

The CPC will give you trends for temps and precip broken down in 3-month increments, for the next year. They are very general in their depiction of the actual weather you might experience, but they do put long hours into dissecting the atmospheric trends and the work these guys do is as cutting-edge as you can get, and their maps are based on a lot of different models and exhaustive inputs, including the El Nino/La Nina situation, which I will address lastly in this blog.

When I flipped thru the maps and looked at the overall picture for the Western US from November thru March, it seems to carry a similar theme through the winter months, here’s my take on what the CPC is showing. (Refer to DEC-JAN-FEB maps shown below).

Temperatures: The Colorado Rockies  & Utah have a higher probability of experiencing warmer than normal temps. The Sierras, Nevada, and Wyoming had a little lower probability of warmer than normal temps, but were still “in the paint”, to steal a basketball phrase. The Pacific Northwest and Montana fell out of the paint, and had what they refer to as “EC”, Equal Chances of being warmer or colder than normal. Should we just call that “normal”? You make the call.

Precipitation: In general, the entire Western US fell under the category of “EC”, Equal Chances of having above or below normal precip the entire winter. For we simple-folk, that’s a coin flip, Bubb!

However, there was one exception to this overall outlook, and that was during the early part of the winter season. The Oct-Nov-Dec & the Nov-Dec-Jan map sets showed an area of Above Normal Precipitation over the Idaho panhandle, all of Montana, and across Northwest Wyoming. Why? I have no idea.

You can view all the maps on the Long-Range Outlook Page of mountainweather.com
then go to the CPC’s Seasonal Outlook Page.

3-Month Outlook Maps for December-January-February 2013-14
Temperatures	Precipitation

ENSO

The El Nino Southern Oscillation (ENSO) situation has been in a “Neutral” phase all summer, and the big boys who analyze all that ocean temperature stuff all agree, to a certain level of confidence, that these conditions will hold through the Winter of 2013-14. That means we will be in neither an El Nino nor a La Nina, but rather a “No Nino”, if you will.

The implications for that bear out in the long-range forecasts from the CPC that I just described above. “Equal Chances” for above or below normal snowfall almost everywhere in the Western US. It’s a coin flip, Bubb!

Summary

So far, the Farmer’s Almanacs and the CPC are not in agreement on temps in the Rocky Mountain Region, at least. One is saying colder and one is saying warmer. The farmer’s seem to have more of an opinion on the precip amounts. Maybe they too foretold “EC” in their prognosticating formulas and decided to flip a coin?

Don’t get too hung up on trying to hang your hat on one forecast or another. I’ll guarantee that wherever it is you ski in the West, there will be snow this winter.

How much, how many awesome powder days you will get, will always vary from year to year, season to season, month to month, week to week. Parts of the winter may see glorious dumps. Parts may see what seem like interminable stretches of drought. But you know you are going skiing, no matter what the weather does. My mantra is, “All skiing is good skiing, some skiing is better!” That’s a pretty good outlook, is it not?

The bottom-line is ….there are just two things you need to do right now, shut up & buy your season pass. While it’s cheap.

Post by meteorologist Jim Woodmencey
Graphics from NOAA

Meteorologist Jim Woodmencey

We have had an interesting cycle of thunderstorms over the past week, not always of the typical afternoon variety that we normally associate with summer. Some have developed early in the day, before noontime.

A good example was yesterday’s thunderstorms which perked up pretty rapidly just before noon and then hung over the Teton Range for a few hours. Nothing too extreme, but if you were up climbing in the Tetons (and about to summit) it would have been frightening, I am sure!

A photo of Monday’s thunderstorm when it was in its early stages of development is shown below. Followed by what it looked like within another two to three hours. I also included satellite & radar images to get a feel for the relative size of this little cell as it merged with other cells and reached its peak development.

Growth of this cell was aided by very light wind flow aloft (from West-SW), some orographic lifting from the Teton Range itself, and an unstable atmosphere on Monday.

SAFETY NOTE: Here is a link to a sheet you can print out about thunderstorm & lightning safety……… THUNDERSTORMS & LIGHTNING SAFETY

Taken before noontime Monday Aug. 12, 2013, from south of town, by John Patton

Webcam shot from Spring Creek at @ 1:20 pm

Visible Satellite Photo at 1:00 pm (cell over Tetons in red circle)

Pocatello Radar at 1:15 pm (Cell over Tetons in red circle)

Text by Jim Woodmencey
Photos from John Patton and Spring Creek Webcam

Meteorologist Jim Woodmencey

The “Dog Days” of Summer will be coming to an end soon (see definition at end of article), as we have now reached the midway point of the Summer Season in early August.  Much like Groundhog’s Day in early February marks the midway point of the Winter Season, we are currently sitting halfway between the Summer Solstice (June 21)  and the Autumnal Equinox (Sept. 22). And so far, the first half has been really dry, but maybe not quite as warm as you might have thought!

Sunny July day 2013, Photo by Doris Hargrave

Refer to the Summary table below for a quick rundown of June and July’s weather. Data is  from the newly relocated Jackson Climate Station instrumentation, formerly located at the USFS Office and currently located just a short distance north of the old location, at the Jackson-Greater Yellowstone Visitor Center.

Historic data for the “normals” comes from the newly updated, and more complete, climate record for Jackson, encompassing data from 1905 to 2012. However, beware that there is an awful lot of missing days, months, and years in this data set prior to about 1949. Our most complete and accurate climate data in Jackson, WY is from about 1950 to 2010.

June
Temps were about as normal as can be and the hottest day,officially, was 86 degrees, although many thermometers hit 90 in town at the end of the month.
Precip though was more than an inch below normal in June 2013.

July
Temps were again right about normal for July, with average highs for the month a degree cooler than normal, and average lows for the month a degree warmer. Hottest day was also 86 degrees in July. We also broke a record for a cold high temp on July 28, 2013 with a high of only 67 degrees in town. Previous record for that date was 68 degrees back in 1950. 
Precip came up short again, by about a half an inch.

Total precip for both June and July in town was 1.10 inches. “Normal” precip total for those two months would be 2.79 inches, which means we are behind by 1.69 inches.  My sense is that there were areas that receive more rainfall in July, depending on where the thunderstorms dispensed their rain.

(Note: The “Dog Days of Summer” are considered to be the hottest part of the summer between July 3 and August 11, the period of time that extends from 20 days before to 20 days after the conjunction of the dog star Sirius and the Sun.).

Post by meteorologist Jim Woodmencey
Photo by Doris Hargrave