Grand Teton Weather - Climbing Decision Support Page


National Weather Service  
 
Lower Saddle Forecast for 11,600ft
   
 
(summer only)
SOMETIMES HAS OPERATIONAL ISSUES
 
 
The National Weather Service's Lower Saddle Forecast is updated throughout the day. Its hourly forecast is our starting point before every climb. We also like to check their Forecast Discussion for Western WY. We have yet to find a better forecast for the Grand. We have seen them all. We favor it for analyzing unstable weather. Like any forecast, there is a lot of wiggle room when it comes to accuracy. BTW: Forecast wind speeds for the Lower Saddle are often off by a factor of 2 or more because the forecast doesn't take into account the topography of the saddle (wind speeds should be higher). You can compare a summer forecast with actual data from the Lower Saddle's weather station.


~ SUMMER ONLY  ~

 
 
Lower Saddle Wind Speeds


Keep an eye on rainfall totals in the hourly forecast. If the forecast shows a 60% chance of rain but only .01" of rain is expected, then you know that a big storm is probably not on the horizon. We often go climbing even though the odds are favoring a short shower. Sometimes, that short shower is miles away from the Grand. As we all know, a 70% chance of bad weather may never materialize while a 20% chance of bad weather does. This is especially true in the Tetons.

~~~~~~~~~~~

 
1-800-211-1448 
 
 
A Teton forecast is good for about 6 hours. An accurate forecast during periods of moderate instability is extremely difficult for anyone to nail down with certainty. You can have more faith in a forecast if a stable high pressure system sits over the Northern Rockies but it's still important to read the weather as you travel. A very modest instability in the atmosphere, like a highly localized mountain thunderstorm, might be omitted from a morning forecast. Keep in mind that all forecast temperatures are temperatures of the air in the shade. It can feel much hotter in direct sunlight. The wind chill may negate any feelings of additional warmth, however. 
 
The Lower Saddle's weather station is very useful during the summer. It allows you to keep tabs on weather conditions, and helps predict climbing conditions. It doesn't collect rainfall information. The weather station at the Jackson Hole Airport in Wyoming, and the one at the Driggs-Reed Memorial Airport in Idaho, report rainfall totals on their respective sides of the Tetons. Summer rain could mean icy conditions at upper elevations, or snowy conditions

We like to check recent rainfall totals prior to a climbing trip when traveling. Rainfall graphs are shown further below. Keep in mind that rainfall on the Grand can bypass the weather stations and vice-versa. If it rained at both airports then it's more likely to have rained on the Grand. And the Grand can get more precip (snow, hail, rain, etc) than lower elevations. Just depends.
 
If you are heading out during the winter, be sure to check the BTAC Avalanche Forecast, the GTNP avalanche discussions, the NWS's Snow Avalanche Guidance, and posts by the JLCR's. While not definitive on hazards (far from it), they can give you a good feel for when things might be really bad. The avalanche forecast is not for extreme terrain or elevations above 10,500 ft. The local Jackson Hole web portal Buckrail.com will often have a weather forecast for the mountains.


Many of the weather links are best viewed on a large screen, not a phone.
 

https://vimeo.com/douglasgautraud/thedeepness 
Usually, image is updated within last 15 min.
 Local Radar Pocatello, ID 
(best Teton Range coverage)
Local Radar Riverton, WY 
(so-so Teton coverage
(Expected Radar in 20 to 40 minutes
 
 
If you don't see our weather graphics, you might be using the Chrome browser on an Android device that has its Data Saver mode turned on. Additionally, you might need to clear your browser's cache to see newer data or refresh the page to see a newer image. Many images have a time stamp in Zulu or UTC time.  Check the CURRENT UTC/Z TIME to see how old the image is. Time.gov can tell you if your phone's time is correct and it will tell you the correct UTC/Z time.
 
 
 
   Check Time
Newest animation is here:
 
  
You might need to refresh the page, and maybe clear your browser's cache, to see a new satellite image. Most images are updated every 5 minutes but animation gif's are rarely that new. The image we pull up is usually within 15 min of being captured. The latest images can be found on the GOES website. This page does not refresh itself.
 
Here's a satellite image of cloud cover along the WY-ID Border as seen from the WEST. Teton County is in the center of the image. Jackson is near the bottom of Teton County. And a satellite image of cloud cover along the ID-WY border as seen from the EAST. APIs are available to build your own image from NASA and others like the Sentinel Open Access Hub.
 
 
 
Here is a nice interactive radar map
 
Keep in mind that it can be snowing or raining in JH and you may not see evidence of that on the radar image. And what you see on the radar image may just be 'noise'. You can read more about how to better examine a radar image at the NWS online school for weather. Here to: How to read radar images.
 
 
Updated every 15 min. or so. Check time

 
These images are good for checking on summer wildfire smoke. At night, the blue colors represent liquid water clouds such as fog and stratus, while gray to white indicate higher ice clouds. 
 

 
 Speed, Gust, Direction from.
^^WINTER Weather Station^^ ~

The Mt Glory Weather Station is mostly used for the Avalanche Forecast so it might be offline during the summer

Out of the Univ. of Colorado, the University Corporation for Atmospheric Research manages the National Center for Atmospheric Research on behalf of the National Science Foundation. They provide a nice collection of Real-Time Radar, Models, Forecasts, etc. We sometimes use it for examining the Pocatello (KSFX) Radar's Base Velocity images which aren't always easy to find elsewhere.

 
Current Wind Obs Near 9800 ft (700mb)
 
 

Wind Barb Information
 
 
(outdated quickly in the Tetons)
  
 
The above graphic shows trends of unstable weather. It has an 'issued' time stamp and a very wide 'valid' weather window (24 hours). The fronts are valid at a specific time, however (see  above). The issued time is often 4.5 hours ahead of the valid times. This type of forecast graphic is very unreliable in the Tetons. Also, it doesn't tell you when forecast weather will arrive. 
 
The next forecast map has a set valid time and is issued closer to that time. Obviously, it is not as reliable as a forecast just updated by the National Weather Service. It will be of greater value if you see the following map just after it was issued. 
 
If the above map shows unstable weather but the one below suggests clear weather then you might want to check the forecast in more detail. Such a scenario might suggest high winds ahead of unstable weather at some point during the day or night.
 

 

For the most part, our checks on the weather are very limited during the summer. We know what to expect after reading a forecast. We also know how fast we move and we're usually alone. We will pay more attention to the weather when traveling with others. If we're alone and expecting a real possibility of unstable weather, or unstable conditions due to the weather, we will spend more time examining the forecast. Like any good alpinist, or forecaster, we accept that sometimes we'll get it wrong. Unlike many climbers, we can bail quickly. If you move slowly while climbing, you really need to think ahead about the weather and spend a little more time understanding it. All the more so if you are responsible for the safety of others.



Mt Glory above Teton Pass @ 10,059ft
~ WINTER ONLY ~ 
 
Precipitation Data @  Jackson Hole Airport
 
 
The JHA station is maintained by the FAA and not the NWS. According to our sources, the general feeling has been that the precipitation sensor at the airport vastly under-reported rain and snow in the past so maybe a new setup is in order. 
 
Runoff or Precip + Low Temps = SNOW/ICE 

The precipitation graph's BLUE LINE lags behind the current date if there hasn't been any recent rain.

 
14-day Temperatures Valley Floor 6450 ft
 

The JH Airport weather station reports several current values of atmospheric pressure and you can track the trends. Falling pressure is usually associated with the arrival of unstable weather during the summer. These pressure readings are near the ground.

Current Pressure at the JH Airport (inHg)

During the summer, most stable high-pressure systems over the northern Rockies provide excellent climbing weather. The calmest conditions and sunniest skies are found near the high pressure's center. If you're looking at weather graphics in the Northern Hemisphere, a high pressure system is a clockwise flow of sinking, dry air. It is often found behind a departing storm system. Areas where the jet stream bulges northward are also usually associated with high pressure. Additionally, wind will flow from an area of high pressure to low pressure. Just because a high pressure system is rolling over the Tetons doesn't mean it's associated with nice weather. A quick rise in pressure can indicate a short-lived high-pressure system with storms behind it.

High and low pressure systems don't have a set pressure value. They are relative to the pressure around them. Wind is produced in large part by differences in air pressure, and differences in pressure are caused by unequal heating of the Earth’s surface. Generally speaking, if you stand with your back to the wind in the Northern Hemisphere, the low pressure system is to your left.  



 
Mountain-valley breezes are often a localized wind pattern. These winds can be caused when mountain air cools quickly at night and flows down into valleys. In addition, valley air that gains heat during the day can rise upslope creating afternoon breezes (orographic lifting), and sometimes afternoon thunderstorms as the air cools and condenses. It's common for hail to fall just before thunderstorms, btw.
 
A quick look at the Pacific Jet Stream on a Wind Map, and on an Pacific Surface Analysis Map, will give you some insight toward understanding surface analysis maps
 
Low pressure systems tend to do the opposite of high pressure systems. In very hot weather, falling pressure might foretell thunderstorms. A sudden falling of the barometric pressure can denote high winds. See more here & See more here
 
 

  
Dornan's inside GTNP (currently offline 4-28-23)
 
Check the Time & Date. It may be an old image. An extensive list of area webcams is here: All Webcams
 
 
 Lower Saddle weather graphics may not be available outside of the summer season (you will see the message: "No data Available").
 
 
LOWER SADDLE WEATHER DATA
~ SUMMER ONLY  ~

 
 Last 7 days. 11,600'
~ SUMMER ONLY  ~

The accuracy of the temperature reading is unknown: +/- 1°F? The summit of the Grand Teton at 13,775ft can be 12°F colder but that is not always the case. The weather station is usually removed after the summer high season.


Last two months or so
~ SUMMER ONLY  ~


 Speeds, Gusts, and Direction (coming from)
Last 24 hrs
~ SUMMER ONLY  ~


http://mesowest.utah.edu/cgi-bin/droman/meso_base_dyn.cgi?stn=TETWY&unit=0&time=LOCAL&product=&year1=&month1=&day1=00&hour1=00&hours=24&graph=0&past=0&order=1
Speeds and Gusts over the last month or so
~ SUMMER ONLY  ~  
 
~~~~~~~~~~~

 ↓MountainWeather.com
 
We have followed meteorologist Jim 'Woody' Woodmencey's forecasts since he started his website and see no advantage to using his forecast. It's just another tool in the box. We like his list of resources and the occasional blog posts about mountain weather. During the big Solar Eclipse in 2017, (The Great American Eclipse), Woody was unable to accurately forecast the weather (sunny & clear). He used to talk about massaging the weather data from the NWS to give us a better forecast but his forecast was just as unreliable, misleading, or useful as any other forecast. He no longer makes a personal forecast. His forecast is all automated with the NWS data as his source material. The NWS's hourly forecast for the Lower Saddle is more useful to us. And the local forecast from the Buckrail website sometimes has a climbing-specific upper-elevation forecast.


~~~~~~~~~~~~
 
Mountain-Forecast.com
We mention this website because it provides a forecast for the summit which, we think, no one else does. Accuracy is a coin flip. They are sometimes close to observed weather or wildly off the mark. While Mountain-Forecast will sometimes nail a summit forecast, we still prefer the NWS forecast for the Lower Saddle. We usually take a look at their forecast and compare it to what we observe later just out of curiosity.
 
A little history factoid: The NWS out of Riverton, WY, used to provide a custom recreational forecast for the Grand Teton's summit and the Lower Saddle starting back in 2011. We assume they stopped because it was inaccurate and could lead backcountry users into trouble. Had they taken into account the Lower Saddle's weather station data and adjusted their model, they might have had a more reliable forecast. Maybe they will try again. They do issue a zone forecast for the Gros Ventre & Teton mountains.
 
 
 ~~~~~~~~~~~
   
 
We are looking for evidence of future instability in the atmosphere when planning a trip up the Grand. Or future stability. As we have stated, the weather in the Tetons confuses the best meteorologists so you will need to plan for a little uncertainty. 

To find out about current climbing conditions, it's good to call the Jenny Lake Ranger Station, check out climbing forums, peruse social media, etc. At the trailhead, or in the backcountry, you can usually find returning climbers with beta during the summer.


JLCR's Conditions Reports

 
 
Lastly, we like to look at the night sky forecast, and sunrise & sunset times.
  

 ~~~~~~~~~~~
 
 ↓More Obs. & Forecasts

 
This is usually an older radar image. It gives us a snapshot of recent activity that we may have missed on the most current radar.
 

Animation

 
24 hour Precipitation Quantity Forecast. See 'valid' times. 


 
 Storm Prediction Center 
 
 
More Images
Station Plot Information, and Here
 
 
 
Surface Analysis - Check time
 
https://en.wikipedia.org/wiki/DBZ_(meteorology)
NOAA's dBZ color coding

 
dBZ values under 25 (blue & light green) are common to see on the radar image with no resulting precipitation as we alluded to above.
 
 
 
~~~~~~~~~~~~


Jet Stream, Pressure, & Winds
 
Forecast Jet Stream 300mbars (near 30,000 ft)
Again: FORECAST

  500mbars (near 18,000ft) Info
 FORECAST
 
 500mbars (near 18,000ft)
See Valid Time
 
 
Temperatures are shown in °C along the colored lines. Humidity in green. 500mbar heights—elevations where the pressure is 500mbars—are shown in decameters with grey values along the dark lines. High pressure systems rotate clockwise in the Northern Hemisphere. 500mbars is near the middle of the atmosphere (18,000 ft or so).

Many websites let you map the wind at various pressures/elevations. The Windy website is an impressive resource. The earth.nullschool.net website provides an animation of current winds at 500mbars over the Tetons (click on the word "earth" to see a menu for selecting different options). One other website that we will mention (there are many) is the University of Wyoming's: UW's Jet Stream Maps.

Current Surface Analysis at time shown
See more stuff  here from NCAR/UCAR
 
 
More Forecast Graphics
 
 
We can't say it enough: Nobody can accurately forecast the weather for a ten-mile radius around the Grand Teton during periods of moderate instability. You can learn to read the weather as it develops but it might be impossible to know how a developing threat will play out in the mountains. A forecast is only good for 6 hours past the time it was issued. Take all of these forecast maps with some healthy skepticism.
 
 
Issued near 5:30 a.m. each morning by the Riverton, WY, NWS office. 
 
 
Rain Outlook 48 hours
 (Will easily miss localized storms)

 
Today's forecast in Spanish
  
12-Hour Forecast - See 'valid' time (ex: 0000 UTC Monday is 6 p.m. Sunday)
 

 Tomorrow's  Forecast - General trends for Tetons but somewhat unreliable.


Tomorrow's Temps
 
 
  ~ Longer Outlook ~


http://www.cpc.ncep.noaa.gov/products/predictions/610day/interactive/index.php


http://www.cpc.ncep.noaa.gov/products/predictions/610day/interactive/index.php
 

Fire Outlook, Maps
 
One Month Fire Outlook



~ The Weather Forecast ~


A summer forecast can change dramatically in a few hours if there is any instability in the air which is why we say that a forecast that is 6 hours old may be stale.

Obviously, a forecast is no substitute for common sense. Most people wisely turn around if a threat is developing, or wait it out if they are back at camp. Again, it is possible to read the weather as it develops but it can be impossible to predict the how quickly the weather will go from passing to threatening, or if a real threat is imminent. Some storms come and go in 15 minutes leaving the rest of the day good for climbing. We factor in the chances of lightning, falling temperatures, and our location when the weather is expected to become an issue.

NWS defined terms: Rain: (Stratiform) Precipitation, in general, is relatively continuous and uniform in intensity. Sky condition usually changes little throughout the day. Showers: (Convective) Precipitation will be characterized by the suddenness in which it starts and stops as well as by rapid changes in intensity. The sky may rapidly change in appearance with peeks of blue and sun alternating with times of complete overcast.


https://www.google.com/search?q=Probability+of+precipitation+(POP)
Probability of precipitation (POP)


The word "isolated" in the NWS forecast refers to showers that are few and far between, only 10% to 20% of the forecast area will receive measurable precipitation. "Scattered" refers to the range of 30% to 50% coverage. Neither refers to intensity, amount, or time. The NWS does forecast a precipitation quantity in the hourly forecast graph; and, if you run your mouse over a graph you will see hourly percentages at the bottom of the graphics.


  ~ Thunderstorms ~


Sunny dry days are fairly common in the Tetons but so are afternoon thunderstorm which usually arrive between mid-afternoon and early evening (2 p.m. to 7 p.m.). If the forecast discussion mentions monsoonal moisture, low pressure, or a cold front then that should raise a red flag. Those conditions can produce very unstable and dangerous weather. If it starts to hail in the mountains, thunderstorms are about to bust loose. Speaking of hail... it hurts. It's another good reason for using a helmet.


The summit block is a lightning rod.


https://drive.google.com/file/d/0Bz64mkcmwTA4WjNDT1pIV1VHQ2M/view


Keep in mind that gullies can become the path of rushing water & tumbling rocks.


Storms can develop right at the edge of the Tetons. And develop quickly. Exum Mountain Guides had a group of high school students on the Grand Teton's summit ridgeline when a blast of white lightning shot through the air. They didn't see it coming and you may never see it coming.

In 2003, several climbers were struck by lightning while on the Exum Ridge and Erica Summers, a 25-year-old mother of two, was killed. In 2010, 17 people decided to climb this mountain in questionable weather. The result was the largest search & rescue operation in the park's history and the death of 21-year-old Brandon Oldenkamp. Learn from their mistakes.

There are no safe places if you are outside in a thunderstorm. Of course, you can make yourself safer. Don't group together during a storm. Ideally, stay 50-100' apart; at least 15'.  Remove all metal from your body - jewelry, biners, glasses, etc. Metal can increase the severity of burns. If you must rope up, you could try attaching the rope using something like an Alpine Girth-Hitch if that's even possible under the circumstances. Ropes will conduct electricity so there's a trade off between the fall-protection that the rope provides and the danger of it becoming a conductor that could easily kill you. The temptation to avoid hail and rain may drive you to caves or overhangs but they can increase your odds of getting zapped especially near openings and low overhanging rock.

Even though most people survive a lightning strike, over 70% have permanent disabilities. The forces are similar to an IED blast and peak temperatures can reach 50,000°F. With or without lightning, climbing in the rain is a bad idea. Besides being slick, that rain can turn to ice.


~ Historical Weather Patterns ~



The High Plains Regional Climate Center has nice tools for looking back in time at the weather. US Drought Monitor  &  Drought.gov


https://weatherspark.com/averages/30628/Jackson-Hole-Wyoming-United-States
Historical Weather 1958-2012 GTNP (not Jackson)


https://www.nps.gov/grte/planyourvisit/weather.htm
Moose, Wyoming from 1958 to 2016

As you can see from this data above, precip can vary wildly from year to year, month to month. The averages can be deceiving. WeatherSpark has a great weather page with graphics for all types of weather in Jackson Hole for a single month or all months of the year.

Again, just averages.


https://www.weather.gov/help-past-weather
Historical Weather 1981-2010 GTNP (not Jackson)
 
Past National Weather


https://www.wunderground.com/history/airport/KJAC/2017/1/1/CustomHistory.html?dayend=12&monthend=9&yearend=2017&req_city=&req_state=&req_statename=&reqdb.zip=&reqdb.magic=&reqdb.wmo=
2017 Seasonal Rainfall at the Valley Floor


http://mesowest.utah.edu/cgi-bin/droman/past_dyn.cgi?stn=TETWY&hour1=9&day1=6&month1=11&year1=2015&product=&time=LOCAL&unit=0&order=1
 Lower Saddle Temperatures Summer 2015 -11,600'


http://www.mountainweather.com/jackson-hole/jackson-hole-weather-observations/
 Lower Saddle Temperatures Summer 2016 - 11,600'


 Lower Saddle Temperatures Summer 2017 - 11,600'


The hottest day of the year is, on average, July 16, with a high of 79°F and a low of 48°F at the valley floor.


https://vimeo.com/267406224
 Lower Saddle Temperatures 2018 - 11,600'


  Lower Saddle Temperatures 2019 - 11,6009


Climbers have been killed by wind gusts while on the Grand Teton. It's could be a threat for soloing climbers on places like the Friction Pitch. Usually, however, the wind-chill temperatures cause the biggest problems for climbers.


http://mesowest.utah.edu/cgi-bin/droman/past_dyn.cgi?stn=TETWY&hour1=9&day1=6&month1=11&year1=2015&product=&time=LOCAL&unit=0&order=1
Lower Saddle Wind Speeds Summer 2015 - 11,600'


http://www.mountainweather.com/jackson-hole/jackson-hole-weather-observations/
 Lower Saddle Wind Speeds Summer 2016 - 11,600'


  Lower Saddle Wind Speeds Summer 2017 - 11,600'


https://vimeo.com/69045994
   Lower Saddle Wind Speeds 2018 - 11,600'


 Lower Saddle Wind Speeds 2019 - 11,600'


Unlike much of Wyoming, Jackson Hole's valley floor is not know for high wind speeds.

The Lower Saddle's wind speeds usually die down to a more manageable level once you get a little ways above the saddle. Higher wind speeds can reappear at the Upper Saddle but it is unlikely that you will find the same rocket-ship wind speeds that one finds at the Lower Saddle unless it's just one of the days.


Weather during the summer of 2019


We can have dry summers or nasty wet ones but they are usually a mix favoring more sun than rain in Jackson Hole. A typical summer provides many exceptional days for climbing. If it does rain, it's usually in the afternoon. Most climbers try to summit before noon, and reach the Main Rappel to the Upper Saddle by noon if the afternoon weather has any instability. Plenty of climbers make later summits including us. Our summit times vary with the weather outlook, mountain conditions, and our preferences for warmth, solitude, sleep, etc.

Between June and September, summit temperatures can swing from the single digits to the 60's. Temperatures in the 20's and 30's are possible when people are climbing in the early morning. During the hottest part of the summer, you will find shaded morning temperatures in the 40's. Those temperatures can change very quickly as a cold front, bad weather, or darkness moves over the area.  Be cognizant of the direction that temperatures are moving under wet conditions. Moisture can quickly freeze to rock and make it impossible to safely navigate the mountain if you are soloing under falling temperatures.


~ Weather Contacts ~


GTNP Weather Line: 307.739.3611
National Weather Service - Riverton
Western and Central Wyoming
nws.riverton@noaa.gov (weather)
1-800-211-1448
12744 West U.S. Hwy 26
Riverton, WY 82501
307-857-3898


~ Typical Temperature Differences ~


https://en.wikipedia.org/wiki/Lapse_rate


The above graphic illustrating the lapse rate is used to estimate the worst-case scenario for falling temperatures while climbing. The atmosphere can include both dry and moist adiabatic conditions at the same time. For example, moist clouds can sit above hot dry air. And the moist lapse rate (3.3 °F/1,000 ft) can vary while the dry lapse rate is pretty constant (5.4 °F per 1,000 ft). There are obvious exceptions to our lapse rate calculations. Inversions are one example. They happen when heavy dense cold air gets trapped under the less dense hot air. Temperature inversions can have a 40°F spread between the valley floor and 10,000' during the winter. Summer inversions are typically limited to overnight or early-morning hours and they rarely have large temperature spreads.

We now consider 12 to 14°F to be the worst-case temperature difference under clear skies between the Lower Saddle and the summit (about a 2175ft difference in elevation). We don't know how accurate the Saddle's temperature readings are, nor a exact lapse rate, so we give ourselves some wiggle room on the worst-case scenario. An average of 8°F was the difference used by the National Weather Service back when they provided a forecast for both. 

 
https://vimeo.com/267618536
 Inversion Temperatures: Saddle (11,600ft) vs. Airport (6450ft)


As the graphic above clearly illustrates, the time of day can influence the temperature difference between two different elevations. And temperature swings at the Lower Saddle are fairly minor compared to those at the valley floor during the summer.
 
It should now be obvious that the temperature difference between two different elevations depends upon several factors besides the amount of moisture in the air. Also, inversions can happen in highly localized and unexpected ways. We have found new ice at the Lower Saddle when overnight temperatures seemed too warm for new ice to develop, or stick around. On a clear and calm night, the temperatures close to the ground can easily be 3 to 5 degrees cooler (or more) than just 2 meters above (typical weather station height is 2m). At night on the Saddle, dense cold air is sometimes sitting right under lighter warmer air by the weather station's temperature gauge. Also, sometimes rocky surfaces stay cool as the air warms, or cool more rapidly due to radiational cooling. That cold rock can keep ice from melting, or assist in ice/frost formation. 
 
Snow or hail can form 1000' ft above the mountain, then fall and accumulate on the ground even though temps on the mountain are above freezing. Lastly, just as adding salt to water can lower its freezing point, the opposite can happen by adding a tiny amount of insoluble particulates to water. That can actually help water freeze at a higher temperature.


http://wyomingwhiskey.blogspot.com/p/owen-spalding-route-august-9th-2015.html
The Catwalk - Mid-afternoon August 9th, 2015.


In July of 1993, 6 feet of snow fell at the Lower Saddle (11,600') and it was the coldest & wettest summer on record in Jackson, WY. In 2015, it was hard to find a summer raindrop — except for that snow storm shown above. We have found new ice above the Lower Saddle when overnight temperatures seemed too warm for new ice to develop. The accuracy of the temperature reading at the Lower Saddle's weather station is not known. 

Keep in mind that the days get colder and shorter as we roll through summer. You'll have about 16 hours of daylight during the 2nd-to-last week in June when the summer solstice arrives in GTNP.

You'll find more snow at the lower elevations in the month of June compared to September; however, the June days are longer and warmer. June usually gets more thunderstorms but September's storms typically bring snow and ice that sticks around. These two months are considered part of the shoulder season for climbing in GTNP.

Occasionally, on the hottest days, shaded temperatures on the summit hit 60°F and overnight temperatures ping 45°F. The highest temperature at the 11,600' Lower Saddle in 2016 was 63°F on July 21st, so that would put the 13,775' summit near 55°F in the shade under worst-case lapse rate predictions. Most high temperatures don't arrive until after 3:00 pm. We have seen climbers turn around in July & August simply because they didn't have gloves, or jackets, when the temperatures took a morning dip.


~ Atmospheric Pressure & Altitude ~
 
 
The atmospheric pressure atop the Grand has slightly more than half the atmospheric pressure found at sea level: 0.58 atm (at 40°F) vs 1.0 atm found at sea level. It is common to find 600hPa of pressure near the elevation of the Grand. That is about .59atm, 8.7psi, and 17.7inHg. A jet stream map close to 500hPa (500mb) is usually associated with atmospheric pressure near 18,000 ft. A higher jet stream near 300hPa (30K ft) can have a very different movement. You can see this play out on animated wind maps if you change the target atmospheric pressure, or change the forecast model used (more here, and here too).
 
 

 
Atmospheric pressure changes with the weather so these are estimates based upon a set of parameters much like the simplified Ideal Gas Law from high school chemistry which relates pressure and temperature, etc.


~ Hypothermia ~


Climbers can experience hypothermia & frostbite during the summer. Wet clothes lose much of their insulating properties and a breeze can greatly increase the rate of heat loss so hypothermia can happen in air temperatures up to 50°F. Mild hypothermia can increase the odds of an accident due to the loss of dexterity, mental focus, and other factors. Forget hypothermia, just being cold is uncomfortable and can result in a loss of focus and dexterity.

The cold can be deadly. Hypothermia took the lives of several Grand Teton climbers in 1985 after a snowstorm trapped five climbers on the Exum Ridge, and hypothermia ultimately took the life of Gary Miller in 2013. Hypothermia took the toes of Aaron Gams who wrote the guidebook, Teton Rock Climbs, after he got stuck on the Middle Teton during a shoulder-season climbing trip.


https://en.wikipedia.org/wiki/Wind_chill


If you're unprepared for a cold windy day on the Grand Teton, you're likely to turn around after a whole lot of effort & time on the approach.
 
 
~ Winter Snow Averages ~
 
 
Around 9600 feet at the JHMR Ski Area. Any one year can be vastly different
 

Valley-Wide Snowfall Averages Oct- April

Togwotee Pass usually sees its snowiest month in April (avg 46") due to its location. The Grand - just east of Targhee - can get far more snow than anywhere else but it tends to shed off aspects. The Surprise Meadow weather station (winter only) is just to the east of the Grand and it collects snow depth information near 9600'. Snow will still fall at higher elevations outside of the Oct-April months. Buckrail has a nice overview of winter weather patterns.
 
 

~ The Sky ~


http://suncalc.net/#/51.508,-0.125,2/2018.04.04/19:35
Typical Equinox & Summer Solstice sun positions


The sun sets far in the northwest during June's summer solstice and burns the Owen-Spalding route clean, or tries to. It also reaches its maximum height in the sky during the solstice. Near the fall & spring equinox, the sun sets almost directly in the west and the route burns off slowly. During the winter the Owen-Spalding route gets very little direct sunshine. And the floor of Garnet Canyon doesn't see too much sun during the winter because the sun is low in the southern sky for most of the day which means it's behind Nez Perce, etc. The winter sun also sets in the southwest. The Upper Exum rises above 12,000' and faces south so it gets the winter sun's warmth.


http://www.athropolis.com/sunrise/def-sol2.htm
Position of the Sun in the sky at 43° N

~ Grand Teton Webcams ~


If an image is dark, the webcam may be having issues or it may be nighttime. Sometimes the live stream is working but the still image is not being captured.


 
AAC's Grand Teton Climbers' Ranch webcam inside GTNP.



Jackson Hole Golf & Tennis
South of the Airport in GTNP.
Check the Time & Date - It may be an old image




Teton Pass Summit
 
Jackson Hole Airport inside GTNP at its southern end
 
 
Other Forecasts, Obs, etc↓
 
NWS
 

 
The USDA Interactive Map has a snow depth feature. Choose that "Snow Depth" option from linked page. You will be taken to the online map. The Map Controls dialog box should show that "Snow Depth" has been selected. Click on a station shown on the map. The interactive map will return a popup box with the value for the snow depth. You can click on the Data Reports icon to see more info.
 
 
Weather Underground's Calendar View shows past precip during the current month (most likely at the airport). The NWS Jackson Hole Airport weather station has rainfall totals for the last 3 days.
 
 
MesoWest Observations↓ 
 
 
About 15 miles W of GT @ 6,227'
 About 10 miles S-SE of GT @ 6,450'
 
MesoWest Stations At Upper Elevations 
 (some are only available during the winter or summer)
(summer only)
(winter only)
(winter only)
 
 

 
 
Enjoy Safe Climbing

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