Monday, May 4, 2015

Jackson Hole's Winter 2014-15 Reviewed

Meteorologist Jim Woodmencey

This winter began pretty much the same way it ended, with people thinking about mowing their lawns. Those thoughts were squashed at both ends with abrupt changes from warm and sunny to cold and snowy.

In this week’s column I will review the winter season and see how it stacked up against the historic records. In brief, I am sure everyone would agree it was warm and relatively dry. But here are all the details to put it in perspective, from beginning to bitter end.



Late Fall

Think back to the first week of November, when temperatures were in the lower 60’s in Jackson, and in the 50’s for the start of the second week of November. The grass was green, the birds were chirping, and no one was thinking of heading south.  Heck, it was 54-degrees on Sunday afternoon November 9th. Then it snowed the next day. Five inches in town, over a foot in the mountains, followed by record cold temperatures for early November. Overnight lows in Jackson got down to 22-below zero on November 16.

So much for mowing the lawn, everyone figured it was “game-on” at that point. Some headed south, others waxed skis.

November snowfall finished strong; with almost triple the normal monthly snowfall in town, 28 inches compared to an average of 10 inches. November was also more than three degrees colder than normal. And it would end up that November was the snowiest month of the season, and the only one with below normal temperatures.

December-January

December was about as close to normal as you can get for snowfall in town, with 19 inches in December 2014, compared to an average of 18 inches. In the mountains, at the bottom of Rendezvous Bowl at JHMR, there was 76 inches of snowfall, normal December snowfall is 79 inches.

December started the trend of warmer temperatures, ending up four degrees warmer than normal. January temps were only one degree above normal, when you compare monthly mean temperatures, that is, the average of the monthly average high and low temps.

February-March

February was the fourth warmest on record in Jackson, with the mean temperature for the month a full eight degrees above normal. Total snowfall in town was only four inches, well below the norm of 12 inches for the month.

February snowfall in the mountains was well below normal also, with 48 inches compared to the average of 67 inches in February.

March was cold for the first few days, then whimpered heavily as we hit a spell of warm and dry weather that lasted from March 6th through March 23rd. That spell peaked when we hit 60-degrees for the first time this year on March 16th. Hardly any snow fell in town, and the grand total for the month was just four inches, less than half the average of nine inches.

The mountains didn’t fair much better, with a total of just 23 inches at Rendezvous Bowl in March. Average March snowfall is 65 inches at that location. Not the grimmest March ever in the mountains, that distinction belongs to March of 1994 with just 16 inches. March of 2007 was another bleak one, with only 18 inches of total snowfall up there in March.

Winter Snow Totals

For the four-month period, December through March, the Town of Jackson had 40 inches of snow or 68-percent of normal, the average is 59 inches. However, if you were to include the snowfall we got in November, that would push the total snowfall to 68 inches. Normal snowfall for the five months is 69 inches. So, that would mean we had a pretty normal “snowfall season”, with 99-percent of our average snowfall for November through March. How about that for a stat!

Same thing was true with the water in that snow, December through March was 74-percent of normal for the four month period. Toss November’s water in there and we were 96-percent of normal precipitation for the five month period.

The mountains received 202 inches for December through March or 68-percent of normal, the average is 295 inches. If you pile November’s snow on top of that, it brings the entire season’s snowfall total up to about 81-percent of normal at JHMR. Once again, November carried us through an otherwise dry winter season.

  
Winter Temps

Temperature-wise this winter we ended up about 4-degrees warmer than normal in Jackson, when you look at the average mean temperature for the four-month period, December through March. The historic average mean winter temperature would be about 21-degrees, this winter we had an average mean temperature of 25-degrees.

That would make the Winter of 2014-15 the sixth warmest winter on record in town. The Winters of 2004-05, 2002-03, 1999-00, 1994-95, and 1952-53 were all warmer than this one, for the four-month period. That is still quite a feat to string together four winter months in a row with above normal mean monthly temperatures.

We should count ourselves lucky, compared to many other areas around the Western United States this winter. Our snowfall was way ahead of everyone else, west of the Mississippi, and temperatures at elevation stayed cold enough to preserve the snow until the end. The Eastern United States was the complete opposite of the West this winter, much colder, and much, much snowier than normal.

Looks like I’ve run out of space, so I will have to save any discussion of “why” this winter was like it was for a future column. For now, get out and enjoy your last licks of the ski season.

(*Note: This blog post originally appeared in the JH News & Guide April 1 2015).
 

Jim is the chief meteorologist at mountainweather.com and has been forecasting the weather in Jackson Hole and the Teton Mountains for more than 20 years.

Monday, January 5, 2015

Big Snow & Blow in the Tetons

Meteorologist Jim Woodmencey
Lots of SNOW & wind for Jackson Hole, ski areas and weather instruments around the mountains reporting 20 to 26 inches of new snow from Friday night through Monday morning in the Teton Mountains. 

But, this is not technically a big "storm system". It is a STORM, and we are getting very stormy weather.....but it is not being generated from a typical low pressure system, or what we would call a storm system.

This is a strong Northwest Flow aloft that is carrying moisture over the top of a Ridge of High pressure that is parked over the Western U.S.


Yes, this is sometimes referred to as a "Dirty Ridge", when moisture rides over the northern periphery of the Ridge axis and causes some weather, rather than the clear skies we normally experience when directly underneath the Ridge itself (like California is right now).

There is no Trof of Low pressure in the upper atmosphere anywhere nearby. Just a weak surface Low pressure over Montana. 


But this is one of the best ways to produce snow in the Tetons, with a very moist and strong NW flow.

-- 700mb map and Satellite photo shows flow and moisture (RH) in that flow.
-- Surface Map shows the overall weather pattern with High pressure to south & west of Wyoming, and a stationary front east of the Continental Divide, with warm air to the west of that line and colder air to the east of that line.


-- Snowfall forecast map is for Monday morning thru Tuesday morning.
Good snow producer across the northern Rockies. Nothing going on to the south of Idaho or Wyoming with this current flow.

Infra-Red Satellite 0800 MST 05JAN15

700mb or @ 10,000-ft. 0500 MST 05JAN15


Surface Map 0500 MST 05JAN15

Snowfall forecast map 05 to 06 JAN 2015




Posted by meteorologist Jim Woodmencey
05JAN15

Friday, December 26, 2014

Understanding Winter Weather Warnings


Meteorologist Jim Woodmencey
This past year, I became what is known as a “Weather Ready Nation (WRN) Ambassador” The WRN program started in 2011 and it partners private meteorologists, like myself, with NOAA and National Weather Service forecasters, to help spread the word and educate people about how to be prepared for hazardous weather conditions.

In this day and age of the Internet, Facebooking, Tweeting, NIXLE alerts, etc. there is virtually no reason we should not all be getting the message when extreme or hazardous weather is on the way.

For instance, on my website mountainweather.com on the Jackson Hole Forecast page, whenever the NWS in Riverton issues any kind of weather alert, advisory, watch or warning for Teton County Wyoming, a red box appears above the forecast.

This box works great for the big stuff, but it becomes a bit annoying when there is an “Alert!” issued for things like: colder temperatures, valley fog, or slick driving conditions. These are things that would be extreme weather events in L.A., but this is Wyoming, and I think we can handle that sort of stuff on a daily basis.

What is more important than an “Alert”, is an “Advisory” or most importantly, a “Watch” or “Warning”, of more severe weather. Weather that might cause a true Wyomingite to take heed.

Here are some links to the "Ready Weather Nation" websites:

Advisories

The National Weather Service will issue Winter Weather “Advisories” to alert the public to weather situations that may present a hazard. “Advisories” are for weather that may cause significant inconvenience or difficulty to travelers.  Although, these weather situations should not be life threatening.

The most common Advisories issued during the winter are:
1) Winter Weather Advisory:  Issued for snow events or when a combination of precipitation is expected, such as: snow, sleet, freezing rain, or blowing snow.

2) Snow Advisory: Issued when snowfall is expected to be between 3 and 6 inches in 24 hours in valley locations. For mountain locations the criteria is for 6 to 12 inches of accumulation within 24 hours.

3) Blowing Snow Advisory:  Issued when wind-driven snow intermittently reduces visibility to ¼ mile or less.


Watches and Warnings

“Watches” and “Warnings” are more serious business than advisories.

Winter Storm Watch means: Be Prepared! The NWS issues these when conditions are favorable for dangerous winter weather to occur. It does not mean it will occur, but you should start making preparations in case it does.

Watches are intended to provide enough lead-time so that people can adjust their schedules. They may be issued up to 48 hours in advance of the event and often will precede a “Warning”. 

Winter Storm Warning means: Take Action!  A warning is issued when a winter storm is imminent or occurring. If you hear a warning, immediately go home or seek shelter until it is safe to travel again. Blizzards, extreme cold and windchill can quickly become deadly outside.

Winter Storm Warnings are usually issued when heavy snow and/or strong wind are possible. Heavy snow means that snowfall is expected to exceed 6 inches per event in the valley. For mountain locations it is 12 inches or more per event.

Blizzard Warnings imply strong winds of 35 mph or greater, cold temperatures, and considerable falling and/or blowing snow that frequently drops visibility to ¼ mile or less. These conditions are expected to last for 3 hours or longer.

While a "Winter Storm Warning" may not necessarily translate into a “big dump” for skiers, it should at least prepare you to be cognizant of bad visibility, and some “western” driving conditions.

Unfortunately, there are times when I feel like we are being “over-warned”, and we run the risk of suffering from the “cry wolf syndrome”. That is, we stop paying attention to the warnings, because they come too often, in the form of alerts or advisories, that may seem like just everyday winter weather here in Jackson Hole. Hopefully this article helps to sort out the most important stuff, and explains some of the lesser weather events we may get alerted to during the winter.

 (This article was re-printed in part from the Mountain Weather Column in the Jackson Hole News & Guide)

Jim is the chief meteorologist at mountainweather.com and has been forecasting the weather in Jackson Hole and the Teton Mountains for over 20 years.

Wednesday, November 26, 2014

Winter Outlook 2014-15



Meteorologist Jim Woodmencey
(Note: This blog post was re-printed from the Mountain Weather column in the JH News & Guide, Nov. 12, 2014).

Even with the recent snowfall in mid-November, it is a rare day this time of year when someone doesn’t ask me, “What kind of winter are we going to have?”  I know what they are really thinking, they want to know how much powder will we get this winter? Will it be the epic winter to end all winters, or will it just be mediocre, or will it be a total bust?

In an attempt to answer these questions, and save me from having to repeat myself over and over for the next month or so, in this week’s column I will take a look at some of the long-range outlooks and predictions for this coming winter’s weather.

Farmer’s Almanac

One of the most oft-quoted sources of long-range weather prediction is the Farmer’s Almanac. I usually defer to the Old Farmer’s Almanac, the original, familiar, yellow-cover Robert B. Thomas Farmer’s Almanac that was founded in 1792.

Other Almanacs may claim to have been around longer, but this one is the one I have accumulating on my bookshelf from the past 20 years or so. I will tell you what info I plucked out of this year’s edition for this part of western Wyoming, but I will warn you, you may want to cover your eyes or skip this next paragraph, especially if you are prone to weather paranoia.

The Old Farmer’s Almanac 2015 has most of the western U.S. painted into the “mild & dry” category. Western Wyoming and Idaho are expected to have above normal temperatures and below normal snowfall, but above normal precipitation.

I take that to mean, we may see more rain down low, but it should translate to snow up at higher elevations.

Only the Desert Southwest, Arizona and New Mexico fell into the “cold & snowy” categorization. Well, the Midwestern U.S. and the Atlantic Coast, from New Jersey to Rhode Island, also fell into the “cold & snowy” regime, but who cares, there’s no good powder skiing there anyhow.

Now, before you get your Gore-Tex pants in a bunch, let’s look at what the Old Farmer’s Almanac said about last year. They said it would be “cold and snowy”, technically it wasn’t all that cold, and only February and March were snowy. But I’ll give it to them and say that was an accurate forecast of last winter.

But wait, how did they do forecasting the weather this past summer? Oops, they called for “hot & normal precipitation”. That couldn’t be further from correct, as we had a cooler and wetter than normal summer. Therefore, the Almanac’s accuracy rate just dropped to 50-percent.

Climate Prediction Center

Now let’s take a look at what the CPC (Climate Prediction Center) has to say about this coming winter. The CPC is the branch of the National Weather Service that is responsible for doing the long-range weather predicting for the United States.

The CPC has a team of meteorologists and climatologists who sit around all week trying to figure out what the weather is going to do months ahead of time. What they do after a 40-hour workweek of analysis is they assign a probability to whether temperatures or precipitation are going to be above or below normal, for a month or three-month time period. 

When their confidence is high, the probability percentage goes up. When they can’t make up their minds for a certain portion of the country, for instance, then they just say there will be “Equal Chances” (EC) of it being above normal, below normal, or near normal.

For this winter, the CPC is pretty confident that we will have above normal temperatures all winter long. However, after a 40-hour workweek, they apparently still have no opinion on how much precipitation we should expect, as we are in the EC category from December to April.  (See table).

Last year the CPC had us under above normal temperatures and above normal precipitation for November-December-January. Which was not the case. They then gave us “Equal Chances” for the second half of the winter, January-February-March. Seems like the safe bet, in this case they can be correct, no matter what happens.

Are you getting the feeling that maybe putting your faith in long-range forecasts is a waste of time? As I have always maintained, it is difficult enough trying to figure out what tomorrow’s weather will be, let alone the weather two or three months from now.

But here is my prediction for this winter anyway: We will have “Equal Chances” of the powder skiing being better than it has ever been, worse than last year, or just as good as it always is in Jackson Hole.


Climate Prediction Center
Winter Outlook 2014-15
3-Month Outlooks
Temperatures
Precipitation
Dec-Jan-Feb
Above (33%)
EC
Jan-Feb-Mar
Above (40%)
EC
Feb-Mar-Apr
Above (40%)
EC
Probability of above or below is given in a percent, higher percentage relates to high confidence. “EC” means that the CPC believes there are “Equal Chances” of being above, below, or normal.


Jim is the chief meteorologist at mountainweather.com and has been forecasting the weather in Jackson Hole and the Teton Mountains for over 20 years.

Thursday, September 4, 2014

Wet August in Jackson and Snow in Tetons

Meteorologist Jim Woodmencey
It was a much wetter than normal August here in Jackson, as well as in most of Idaho and Wyoming. The Southwestern US from Arizona to Utah was exceptionally wet also.
Early in August it was all about the monsoon, then it was about some cold Low pressure systems the last two weekends, that left behind some decent snowfall in the higher Tetons.

Read all about his past August's weather in the Mountain Weather column of this week's Jackson Hole News & Guide.

Some pics of the snow up high in the Tetons from these last two storms below:

These first three are from the first cold storm August 22 to 24, 2014

Black Rock Chimney between Lower & Upper Saddles-Grand Teton.
Photo courtesy of Mike Ruth (August 23)

Looking up Valhalla Canyon at west side of Grand Teton, from Cascade Canyon (August 24)
Photo Jim Woodmencey

Nearing the summit of the South Teton (August 25)
Photo Scott Pedersen

These last three photos are from the second cold storm August 30-31, 2014


On the fixed ropes below the Lower Saddle of the Grand on morning of August 31.
Thse photos all courtesy of David Bowers.



Lower Saddle Exum Hut August 31

Looking North towards the Upper Saddle from Lower Saddle Hut

Post by meteorologist Jim Woodmencey


Friday, August 8, 2014

July Not as Hot as it used to be....

Meteorologist Jim Woodmencey

(Reposted from the Mountain Weather column in Aug. 6 Jackson Hole News & Guide).

I heard some complaining in late July that it was “too hot”, which sparked some memories of Julys not so long ago, which truly were “hot”. This July was not.

That also prompted me to dig back through the records to see which Julys were the hottest here in Jackson.  What I found may surprise you, or at least it should cause you to apologize for any whining you may have done about the heat this July.

 To no one’s surprise, July is normally the hottest month of the year here in Jackson. Our average high temperature in July is 82 degrees (actually 81.8) over the last 80-some years of climatological record.

July of 2014 had an average high temperature of 80-degrees, two degrees below normal. There was one day this July (the 23rd) that some thermometers in town hit 90-degrees. However, the highest temperature recorded “officially” at the Town of Jackson Climate Station was 87-degrees. Close, but no 90-degree readings this July.

As a matter of fact, upon further investigation I discovered that we have not seen a temperature reading of 90-degrees at the Jackson Climate Station since August 1, 2008. Prior to that, there were quite a few.



Official Hottest

Probably the best way to gauge a “hot” July is to look at the average high temperature for the month. Another way is to count how many days we hit 90-degrees or above, which usually coincides with those average high temperatures.

Prior to the early 2000’s, July of 1988 was the hottest July on record. That was the famous summer of the Yellowstone Fires, and the average high in Jackson was 88-degrees (actually 87.6). We had eight days with high temperatures of 90-degrees or warmer that July. I should also mention there were four days that weather readings were not recorded in July 1988, which might have pushed that average even higher.

Then along came July 2003, which set the new record with an average high of 90-degrees (actually 90.2). There was a whopping 17 days that July with high temperatures of 90-degrees or warmer, more than twice as many as in July 1988. There were no missing days of weather readings that month. 

Other Julys of note were: July 2007, with an average high of 88-degrees and 13 days that went into the 90’s. And also July 2000, which had an average high of 87-degrees and 11 days in the 90’s.

From Jackson, WY Climate Station records. Note, there were no records for 2012.
Unofficial Hottest

In order to be included in the monthly average temperature record, there cannot be too many missing weather readings. Months that have five or more missing days are not considered when calculating our averages.

There is a July in our official climate record that was likely even hotter than 2003. Unfortunately, there were too many missing days in the record, but I thought it interesting enough to give it an honorable mention. That was way back in July of 1934.

The climate station at that time was located somewhere in the valley to the south and west of town. The observer was Albert Butler, and I would love to know if anyone related is still living in Jackson.

Perhaps Mr. Butler was too busy haying his fields that July and he missed his daily weather readings 11 out of 31 days. Yet, of the remaining 20 days, he did record 14 days with high temperatures of 90-degrees or hotter. His average high temperature in July 1934 was 92-degrees (92.5 actually).

But here is the real kicker, he recorded two days that month, on July 17 and 20, with a high temperature of 101-degrees. And that is the highest temperature we have, for any month, in the official weather records for Jackson.

Cooling Trend

I did not have time to go back through and look at the entire temperature history for July in Jackson to see all the ups and downs between 1934 and 2014. However, there is an obvious trend that you may have noticed if you have lived here for at least the last 15 years.

Looking at the average high temperatures in July from 2000 to 2014, we were on the uphill climb with some very warm Julys from 2000 to 2007. Since then, we have seen a cooling trend, from 2008 through 2014. (See graph).

If you complained in the early 2000’s about the July heat, it was warranted. If you have complained about the heat in recent July’s, it has been unjustified, because July in Jackson is not as hot as it used to be.

Summary of July High Temperatures in Jackson WY
(*From Jackson Hole Climate Station historical data).
  • The historic average high temperature in Jackson in July is 82-degrees.
  • Average high temperature for July 2014 was 80-degrees.
  • No days in July 2014 that were "officially" 90-degrees or warmer.
  • Hottest July ever was in 2003, with an average high of 90-degrees.
  • July 2003 had 17 days of 90-degrees or warmer.
  • The last time we hit 90-degrees in Jackson (officially at the Climate Station) was back on August 1, 2008.

Jim is the chief meteorologist at mountainweather.com and has been forecasting the weather in Jackson Hole and the Teton Mountains for over 20 years.





Posted by meteorologist Jim Woodmencey
jim@mountainweather.com

Wednesday, August 6, 2014

The Monsoon Explained

Meteorologist Jim Woodmencey
A couple of summers ago I posted an explanation of the "Monsoon" on this blog, seemed appropriate to re-visit that this week.

We were getting some good surges of moisture from the Desert Southwest Monsoon this week, with rain and thunderstorms plaguing us, and some heavy downpors with late day thunderstorms the last two days (August 5 & 6, 2014).
 
If you happen to read my forecast discussions on the JH Forecast page of www.mountainweather.com or perhaps you listen to my forecast rap in the mornings on the radio (iMix 92.3 FM) you will frequently hear me mention “monsoon moisture”, during the summer months.

The term “monsoon” comes from the Arabic word mausim, which means “a season”. It refers to the large-scale wind flow that lasts for a whole season near the Indian Ocean and the Arabian Sea.
A "monsoon", therefore, is simply a seasonal wind flow pattern. The Desert Southwest Monsoon that occurs in the United States is similar to the Asian Monsoon that affects India and the Himalayas during this same time of year, from July to early September.

The North American version of the monsoon kind of originates over the interior of Mexico, where very moist (i.e. humid), tropical air is converging over the land from the Pacific Ocean to the west and from the Gulf of Mexico to the east. That moisture is then drawn northward by southerly winds over the hot, dry deserts of the Southwest. This causes frequent strong thunderstorms over New Mexico and Arizona.

Often in July and August the monsoon will surge up into Utah and Colorado, causing thunderstorms over the deserts of southern Utah and western Colorado. Some of these thunderstorms create flash flooding situations in the canyon country of the Southwest.
A few times a summer that monsoon moisture will reach as far north as Northwest Wyoming and Southwest Montana, causing thunderstorms here, which are often some of the strongest of the summer season.
The typical weather pattern that sets up in July and August that will transport the monsoon moisture this far north is when a thermal Low pressure (dry low pressure caused by heating) develops over southeast California and western Arizona, at the same time High pressure develops over eastern Texas. Then when a Low pressure system or upper level Trof of Low pressure moves into the Northwest U.S., that helps draw that monsoon moisture northward. (See today's weather map, which kind of shows that pattern, but not as well defined as some years).

Surface weather map Wed. August 6, 2014



Monsoon Surge early August 2014
This round of monsoon moisture has been particularly WET, with flooding, landsldides, mudslides, etc. from California to Nevada, and Utah. 

The downpours we had this afternoon (Wednesday August 6, 2014 ) in Jackson were aided by an upper level Trof of Low pressure that is moving over the Great Basin and making things even more unstable. Thunderstorms produced 0.40 inches of rain at my rain gauge in less than an hour! That's more than we got the previous 24-hours.

Here are some weather maps from today.......Wednesday August 6, 2014.

Satellite showing extent of monsoon moisture from California to Wyoming

Pocatello Radar @ 5pm Wednesday

Snow King Lightning Detector screen shot @ 5pm Wed.





Post by meteorologist Jim Woodmencey

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