Meteorologist Jim Woodmencey

After 6 days in a row of nearly perfect summer weather around Jackson Hole…..sunny skies and highs in the valley in the upper 80’s……from last Thursday (July 18) through Tuesday (July 23), we are finally going to see some changes over the next 6 days. Nothing radical, but we will go from absolutely no chance of thunderstorms to at least a possibility of some thunderstorm activity in the coming days.

We begin to make the switch from an extremely dry and stable airmass to one that is a little moister and more unstable. This new mass of air is a combo of some leftover disturbances that have been causing thunderstorms & heavy rainfall in parts of Arizona & Southern California (where they needed it!). And there may be a little remnant of the monsoon mixed in there also. That airmass has made it over Nevada and Utah will drift closer to us and provide the necessary ingredients to produce some thunderstorms.
(See Sat Photo and today’s weather map below).

This is not a true “monsoon” flow, which would be coming up more directly from the South. This moisture has basically drifting up around the periphery of a Ridge of High pressure that has been over the Southwest US this past week. That is now working itself into a very light Westerly flow aloft over Southern Idaho and Western Wyoming. That will bring an end to the extremely dry and cloudless conditions we have seen.

How Dry Was it?

The instrument at the Jackson Hole Airport bottomed out at 7% relative humidity on Monday. The Town of Jackson weather station showed 9 % RH. And I had a guy named Joe, who lives in a van down by the Hoback River (who happens to have a nice home weather station!) and he reported a Relative Humidity that registered as low as 0.04%.

Trust me, that is about as dry as you can get, even by desert standards. That extreme dryness was part of the cause of the haze we have had around here, in combination with dust and pollen in the air, and a bit of smoke mixed in from forest fires in Idaho that has drifted over us.

Infra-Red Satellite Wednesday morning, July 24, 2013

Surface Weather Map Wednesday, July 24, 2013

Meteorologist Jim Woodmencey

The weather we had this past Saturday morning caught me a little by surprise, with a line of thunderstorms moving over NW Wyoming and directly over the Grand Teton at around 8:30 a.m.

I was actually expecting that kind of weather Friday morning, not Saturday. When it didn’t materialize, I thought,  “oh well, it must have dissipated or not be as moist and unstable as I thought”.

The reality was, that moist and unstable air, what looked on Thursday to be an almost “monsoon-like” surge moving up from Arizona, didn’t make it to us until early Saturday morning. That is a lot of time to be “off” by.

This very small surge of  moisture that originated down in Arizona on Thursday, and was evident way down there on satellite and radar, and lightning maps, and then it crept its way north thru Utah with very little fanfare.

As with a normal surge from the monsoon, thunderstorms are possible anytime of day or night and they don’t need the afternoon heating to get them going. This case was eerily similar in nature. The only other indicator for the possibility of seeing earlier-in-the-day type thunderstorms was the presence of a stationary front in NE Idaho & NW Wyoming. I generally discounted that because it had been there the previous two days and did not seem to lend any additional boost to thunderstorm development on Thursday, or even on Friday. We had no thunderstorms here Thursday of last week, and only a few isolated strikes around the region Friday.

Re-Analysis

A series of maps (satellite, radar, & lightning maps) that I saved from this event illustrates how innocuous it looked and how quickly this developed. There were no lightning strikes evident over northern Utah or eastern Idaho prior to about 6:00 am, after that, things developed very fast that morning.

There was little to no indication on the computer models I looked at on Friday morning, after analyzing dozens of different products to give me an indication of moisture and instability. I had the thunderstorm potential at zero in the am Saturday, 60% in the pm for Saturday on my forecast that I issued on Friday morning.

I checked the NWS forecast at 8:00 am and it said “Slight Chance of Thunderstorms”. And once the lightning started, they issued a thunderstorm warning. So, apparently the NWS saw no early indicators either.

A bad forecast from my end, as I see it. And that’s why I re-analyzed that morning. My conclusion was, that it was one of those smaller features that would easily slip thru the cracks in the model resolution that was not picked up. Especially 24 hours ahead of time when I made my last forecast on Friday morning. But the rub is, there was little or no sign of developing activity overnight as that airmass moved up thru Utah, and then once it got over SE Idaho, and maybe got better orographics or closer to that stationary front, it really kicked in.

I don’t like to miss stuff or be wrong about the weather, I take that personally, especially when it coincides with outdoor activities in Jackson Hole on a Saturday morning! However, that is also one of the things that I love about this game of weather forecasting, even with all the latest technology and sophisticated computer models, we still can’t see it all………and Mother Nature always gets to bat last!

 Post by Meteorologist Jim Woodmencey

Graphics From NWS & MeteoStar-LEADS On-line

Maps from around 6:00 – 7:30 AM Saturday

Satellite 7:00 am MST

Radar 7:30 am MST

Lightning Strike Map 6:15 am MST

Maps from around 8:00 – 8:30 AM Saturday

Satellite 8:00 am MST

Radar 8:20 am MST

 

Lightning Strike Map 8:30 am MST

Photos from Saturday Morning

Looking South from near Moose, WY  Photos by Rick Paul

Meteorologist Jim Woodmencey

For the past week I have been thinking about the tragedy that occurred during the wildfires in Arizona back on June 30th. Wildfires are perhaps one of the worst weather related disasters we can experience here in the Rocky Mountain West. They are no less violent, powerful, or unpredictable than the tornadoes of the Plains and Midwest.

Most wildfires are started by the weather with a lightning strike, from there the weather controls the fire’s behavior, wind & low humidity being the enemy. And it usually takes a change in the weather to get them under control.

My heart goes out to the families of the 19 firefighters lost in the Yarnell Fire in Arizona, and my praise and thanks goes out to all firefighters across the country. Thank you for what you do. We all appreciate it, especially here in the Western US.

 History Repeats

The Yarnell Fire tragedy is not the first of it kind in the Western US, and we should also remember those who were lost trying to fight other big fires in the past.

More recently was the South Canyon Fire on Storm King Mountain in Colorado, on July 6th, 1994 that fire blew u and made a rapid run up the mountain and killed 14 firefighters.

And back in August of 1949, there were 13 firefighters lost (some of this country’s first smokejumpers) in the Mann Gulch Fire in Montana. This incident was chronicled in Norman Maclean’s book Young Men and Fire, an excellent read.

You can keep up with the current wildfire situation locally and across the US by going to the the Jackson Hole Information Page and poking around the Fire Information section.

Meteorologist, Jim Woodmencey

Nearly record HOT in Jackson this weekend with the Town’s automated weather station reporting a high on Sunday of 90 degrees. Record high on June 30th in Jackson is 91 degrees set back in 1990.

FYI…Record high for July 1st is 92 degrees, also set in 1990.

Hot temps are courtesy of a big Ridge of High pressure that is sitting in place over the Western US. About as hot as it can be, for almost any summer month, but especially for late June in the Desert Southwest.

Looks like one or two more days of this before the Ridge breaks down a little and temps cool for the end of the week.

Some of the hottest high temperature records that were re-set this weekend are listed below.

Death Valley, CA…………..…….128 degrees on Saturday (ties highest June temp)*
Death Valley tentatively reached 129 degrees Sunday evening, and that breaks June record high. Which would tie for the hottest temp ever in the month of June in the US, set in Volcano, CA (not a town anymore!) back in June of 1902.

Las Vegas, NV …………117 degrees on Sunday  (ties all-time high temp record for Vegas)
Zion National Park, UT…….112 degrees (ties old record for the date in Zion)
Salt Lake City, UT………….103 degrees (ties old record for June 30th from 1979)

*Death Valley still has the distinction of being the hottest place on earth with their world record high temperature of 134 degrees, set 100 years ago, on July 10, 1913.

Weather Pattern Keeping it Hot

The Ridge of High pressure over the Western US is being held in place by two Troughs of Low pressure in the current blocking pattern that has established itself across North America. This Ridge is warm all the way up through the atmosphere. The air within the two troughs is much cooler.

This is a “blocking pattern”, which means it will be hard to change, kind of like a logjam in the river. The very cold trough off the West Coast will try and flatten this Ridge some towards the end of the week. And that will help cool temps, at least across the Pacific Northwest  & northern Rockies.

Upper Level (500mmb) Map showing large Ridge in Western US flanked by two Low pressure Troughs.

Meteorologist Jim Woodmencey

Might be a good time to gain some elevation to keep your cool, as we are looking at the has the potential to be the Hottest Day of the Year, so far…coming up this weekend.

A large and very hot Ridge of High pressure building northward from the Four-Corners Region of the country the next few days will bring afternoon highs up around 90 degrees in the Jackson Hole Valley this weekend.

We made it to 84 degrees a couple weekends ago in Town, and we will easily top that this week.

• Record high temp in Jackson for this time of the month (June 28 to 30) is 91 degrees, set back in 1990.

• Hottest June day ever in Jackson was 95 degrees set back on June 26, 1988.

Photo below taken from Lower Saddle looking at Grand Teton last Saturday. Very cool up there at 11,600-ft. last weekend….in the 40’s. This weekend it will be in the 60’s to near 70 up there! Daytime freezing levels (where it is 32 degrees) will be up above 16,000-ft. and overnight the freezing levels probably won’t even get down to the elevation of the summit of the Grand (13,770-ft.).

Post & Photos by Jim Woodmencey

Meteorologist Jim Woodmencey

Summer will officially begin tonight, June 20th at 11:04 pm MDT (Mountain Daylight Time). That is the exact time of the Summer Solstice, the exact moment that the sun is directly overhead at the Tropic of Cancer, 23.5 degrees North latitude.

That means Friday, June 21st will be the first full-day of Summer 2013.

This is the time of year when our days are the longest, with almost 16 hours of daylight in Jackson Hole, not including twilight! Compare that to only about 9 hours of daylight around the Winter Solstice in December.

Green Down Low, White Up High

While elevations below about the 9000-ft. elevation are green and wildflowers are abundant, there is still a considerable amount of snow above at least 9500-ft. in the Tetons. Higher elevation passes are going to take awhile to melt out. To give you an idea of how much snow remains, I have posted a few shots from a trip up into Paintbrush Canyon and from the top of Mt. Woodring (11,503-ft.) in Grand Teton National Park over the Father’s Day Weekend.

From the Summit of Mt. Woodring. Photo by Greg Winston.

That little lake before Holly Lake (still frozen), Elevation 9200-ft. Paintbrush Canyon

Upper Paintbrush Canyon…note the small slab avalanche.. …zoomed below

A not-too-old Slab Avalanche

North & Northeast aspects of the main Teton Range as seen from Mt. Woodring

A Green Valley. Looking over Leigh & Jackson Lakes to the Northeast

Post by Jim Woodmencey, meteorologist
Photos by Greg Winston & Jim Woodmencey

Meteorologist Jim Woodmencey

I received a number of very cool photos from the severe thunderstorm that passed through Jackson Hole on Wednesday afternoon June 12th. Below is a collection of some of those photos. There was also another strong thunderstorm the following evening, Thursday June 13th that produced strong wind gusts and some rain, while there were no reports of hail, there was apparently some damage done by falling trees.

Both of these thunderstorms were related to a Low pressure system that was moving across the Pacific Northwest and northern Rockies mid-week. (See maps, etc. from previous blog post). A cold front associated with that Low was in the vicinity of the Idaho/Wyoming border, pretty much was a stationary front on Wednesday and then that front passed across the Tetons on Thursday evening. Most of the more intense thunderstorm activity was occurring near this front.

Thanks to all who contributed to this collection!

Thunderstorm Photos from June 12 & 13, 2013
Photo by John Hanlon	Photo by Ian Raben
Photo of Mammatus Clouds by Jim Springer from Near Jenny Lake	Zoomed in Photo by Jim Springer
Looking Southwest from Rec Center in Jackson. Photo by Darrell Miller.	From Victor Idaho on THURSDAY June 13, 2013. Photo by Susan Lykes
Hail stones down the drain! Photo by Mary Gridley	Hail Stone
Taken from the Top of Snow King Mountain

Meteorologist Jim Woodmencey

As much as I hate to sensationalize the weather, this afternoon’s thunderstorms were pretty cool to observe. Between 3:30 and 4:00 pm  a series of thunderstorms moved through the Jackson Hole area that produced hail 3/4 of an inch to one inch in diameter, measured in the Town of Jackson.

While we did not receive a lot of rain (we actually had less than 0.10 inches in Town, even with this morning’s rain), it was the size of the hail that qualified this as a “Severe” storm, by the National Weather Service definition:

“Severe Thunderstorms produce large hail, at least one inch in diameter, and/or damaging winds, at least 58 mph (50 knots).”

The best thing about today’s thunderstorms, is that they were well forecasted. My own MountainWeather Forecast for Jackson Hole had the probability of thunderstorms at 90% (rarely do I peg it at 100%!) with “Moderate” amounts of lightning, meaning several ground strikes would be likely with thunderstorms.

AND….. the National Weather Service was also right-on with this one, with the National Storm Prediction Center forecast map for the day, and the Riverton NWS Office issuing a a Special Weather Alert very early this morning warning of strong thunderstorms and dangerous  lightning, and telling people to get out of the hills and seek shelter early this afternoon. Good Work NWS!

National Forecast Map from This Morning

More Images

A selection of weather maps is cataloged below, capturing the satellite, radar, and lightning that was occurring just prior to and during this weather event. Days like this make it fun to be a weather nerd! Shouldn’t be outside anyway, so might as well look at the weather on the computer, eh?

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National Lightning Strike Map at 2:45 pm Wednesday, less than 1 hour prior to Jackson storm. Graphic courtesy of MeteoStar LEADS On-Line

Infra-Red Satellite Photo at 2:30 pm

Visible Satellite Photo at 3:00 pm

Pocatello Radar Image at 3:15 pm (Note the severe thunderstorm & tornado boxes just Southwest of Jackson)

Image from the MountainWeather Lightning Detector on Top of Snow King Mountain at around 3:30 pm

Image from lightning detector about the time hail was falling in town and thunderstorm was right overhead

Hailstone

Jim Woodmencey, meteorologist

Temperatures will be warming up pretty significantly around the Western US the rest of this week and into early next week (June 5 to 11) not just at the lower elevations but also up at higher elevations, were there is still significant snow to melt above about the 9,000-ft. elevation.

At around 10,000-ft. this week in the Tetons, for example, temps will get into then 60’s during the day and not re-freeze overnight, only dropping into the 40’s for overnight lows. This will lead to melting occurring 24-hours a day for several days in a row.

Settled Snowdepths on Wednesday June 5, 2013
Rendezvous Bowl (Elevation 9580-ft.) = 44 inches
Targhee  Snotel (Elevation 9260-ft.) = 61 inches

Snowpacks should be shrinking pretty significantly as we go into next week. And expect rising creeks and rivers from the runoff, the peak of that should be seen about the third day into the meltdown.

Snow Depth Map	Snow Water Map	River & Reservoir Levels

This is a big change from the last couple of weeks of relatively cool temps, below freezing at 10,000-ft. most nights and highs generally in the 40’s most days. And there were even a few days when we had snow accumulating above 9,000-ft. in the mountains.

Post by Jim Woodmencey, meteorologist
Graphics from NOAA & BOR

Jim Woodmencey, meteorologist

Powder skiing in late May? Well, that might seem like a bit of a stretch, but we are actually accumulating a little snow this week at the higher elevations in the Teton Mountains, above about 9500-ft. the last 24-hours. Snow levels will probably get down closer to 8,000-ft. as overnight temps get down into the 20’s at 10,000-ft. the next two nights. Total new snow at 10,000-ft. or higher in the Teton Range could be between 3 & 6 inches by Friday.

This is due to a complicated weather pattern that includes a couple of cold Low pressure systems extending across the Pacific Northwest and northern Rockies.

Powder this late in the year may not excite you, at all, especially if you were dreaming of maybe one last weekend of spring corn-skiing up high. And for those who would just love to see it all melt and get on with summer, there is some promise of that next week and the week after.

Summer Weather Ahead

We do flip a switch on Saturday June 1st, with at least more spring-like weather over the weekend, plenty of sunshine and temps warming up pretty quickly. High temps at 10,000-ft. get back up into the 50’s by Sunday afternoon. Which would turn powder to slush pretty quickly. In the valley, we should see temps returning closer to normal for this time of year, with highs in the upper 60’s to around 70.

Beyond that, we should stay close to or slightly warmer than normal for the first week of June. And it looks even more promising for warmer & drier weather in the western US as we go into the second week of June. (See maps below for expected conditions).

14-Day Outlook Maps for June 5 to 11, 2013
Temperatures	Precipitation