What an intense storm. Well done making it through the last few days of weather data. Curious about what happened in 2012? Watch the following video.
The synopsis of the WYDOT mission from the Wyoming DOT forecaster reads: Western Wyoming was hit hard with this moisture with 4 feet of snow and 5.4” of snow water equivalent recorded at the milepost 12 study plot in 5 days. The new snow was deposited on slick sun crusts and weak faceted snow from the December and January dry spell. The new snow was initially very dry with a 6% density in the first 8-10”. The density then increased to 12% and finally to 14% making for extremely upside down conditions. Winds were also strong with some 100+mph gusts recorded during the 5 day period.
***And just as an aside, Don talked about wind slab and persistent/deep slab avalanches, but in reality Rocky Gulch and Beaver Slides were probably best described as Storm Slabs. So Storm Slabs were another avalanche problem during this storm.***
The storm continues…and so does your job. Take the time to develop a plan for the next 12 hour block. Will you close the road again? Will you mitigate any avalanche paths? Which ones? How? When? Are you seeing any storm trends that are remarkable? Develop your plan and answer the questions on the quiz.
It has been an intense 24 hours. Nice job coming up with a plan. Now let’s see how closely your plan lines up with what happened in January 2012.
Armed with these results, it’s time to plan for the next 12 hours. Same assignment….review the weather forecast and then download the weather data for the next 12 hours. When you have developed your plan for the highway for these 12 hours, take the quiz and answer in detail.
Now that you’ve uploaded your plan through 6 pm on January 19, take the time to build a plan for January 19 at 6 pm through January 20 at 6 am. Will you close the road again? Will you shoot? What trends are you observing in the storm. Take the time to build your plan. When it’s built, take the quiz and answer the questions in detail.
It’s your show. Are you going to close the road during this 12 hour period? Are you going to mitigate any slide paths? Which ones? How?
You can download the document below and add your notes. This weather data can be found on the quiz on the next page, as well, so you don’t need to download this and record your responses. Once you have your plan built, take the quiz and answer all of the questions in as much detail as you can. This is a graded portion of your exercise.
In the following video, Don Sharaf will walk you through January 17 and January 18 weather data, as well as his observations and his mitigation plan. This is a model of what we expect from you in 12 hour time periods from January 19 – 20. You will be asked to upload a notated PDF of when you will close the road, notes on weather trends, and any other pertinent observations.
Once you have done this, you will be able to watch a video that gives actual results from the storm that hit Teton Pass in late January 2012.
As a forecaster, there are multiple avalanche paths on Teton Pass that you need to pay attention to. The following video is an introduction to those paths.
We recommend spending some time studying the avalanche paths on Teton Pass. Below you will find the path descriptions from the Teton Pass Avalanche Atlas and a link to a CalTopo map where the avalanche paths are marked. If you want to put these markers on a google map, you can export the KML file and it should open in google earth. If you choose to use google earth and you know how to use the history slider, 1/2005 shows the terrain snow covered, otherwise 6/2017 shows the best images and is the default.
You can find a CalTopo Map with the paths marked here.
Now that you have all of the information for your assignment, it is important to understand what we expect of you as you forecast for the pass. As the Teton Pass Avalanche Forecaster, you need to understand the tools that are available to you, including artillery, the gazex, the avalanche guard, and hand charges.
You also need to understand timing for closures, as well as how you communicate with the public. The document below describes tools available to you, as well as communication expectations.
It has been a dry season in the Tetons thus far. It’s quite the shock, as last year was non-stop snow. The snowpack has virtually flat-lined in January. The last “storm” you got was 6” and there was a 3-car wait for the tram. Folks are thinking their luck may change soon. There are rumors that the flow is “going zonal” and that the Tetons may finally get a big storm. As a WYDOT worker, you’re looking forward to the prospect of doing something besides studying the weather models and fixing all of your electronics, like you’ve done all winter.
Weather Obs: On January 17, skies started out cloudy and there was 1” of snow overnight. Snow, temperature, and sky cover data is available from the mid-mountain study plot at 9360’ and wind data is available from the top of the tram at 10450’. Conditions at 0500 are:
HS = 42”
HN24 = 1” HNW24 = .08” r = 8%
Wind avg = 19 mph Wind DIR = W Wind Gust =45 mph
Temp = -3° C
Ski Pen = 4”
Boot Pen = 16”
Sky = OVC
Avalanche Hazard Forecast:
Avalanche Obs: Yesterday, the Grand Targhee Ski Patrol triggered two slides on a north facing slope at an elevation of 9,000 feet. HS-AE-D2-O – 24” deep. 100-200’ crowns.
Expect light snow showers to continue ahead of approaching Pacific moisture. Temperature Forecast for 8,000´-9,000´: Rising into the positive single digits. Ridge Top Wind Forecast for 10,000´: Increasing to 25 to 35 miles per hour out the west to southwest. Snowfall Expected Next 24 Hours: 3 to 6″
Based on the information above, as well as the season history you have reviewed, it is time to complete a PM Form. Take your time completing this form. You can only submit the PM Form once. Once it is approved by AAI admin, you will be allowed to move on with this forecasting exercise.
Now that you are beginning to build a picture of what the 2011/12 early season looked like, graph out a hypothetical snowpack if you haven’t already. Translating a season history into a hypothetical snowpack is a skill that has to be practiced. Try it now for an easterly aspect at 9000 feet. The goal is to have an opinion. This doesn’t have to be turned in.
Now let’s talk about snow pits dug around Teton Pass during the winter of 2011/12. Here is an introductory video.
Now that you have your sample snow profile, compare it with the snow profiles from the range. Do they line up? If not, what looks different? Do you have an idea about why they vary? Remember, one of the most important skills as a forecaster is to HAVE AN OPINION. You don’t have to be right, but if you don’t have an opinion, you don’t get the opportunity to learn when conditions didn’t match your forecast/opinion.
This forecasting exercise takes some time. It is an involved, educational exercise that we expect you to do over a couple sessions.
In this section, you are going to be forecasting for Teton Pass. It is January of a lean snow year. The storm cycle that you are forecasting for actually happened, so this exercise is a great learning opportunity. Take your time in completing the exercise. You will be graded on your quiz answers. You will also receive data about what actually happened during this storm cycle.
There are quite a few resources to review before we dive into the exercise. Here is a quick introduction to the weather spreadsheet of the season history up to the date of the storm.
Take the time to study the season history. Consider whether you have the potential for basal facets or depth hoar forming within the snowpack. Look for times when there were dry spells and surface hoar and near surface facets were formed. Look for periods of high winds. Look for storm cycles. It can be useful to develop a hypothetical snowpack based on season history. You will have snow pits to compare your hypothetical snowpack to.
Another resource that you have for this forecasting exercise is the radial plot of avalanche activity. Below is a video introducing the radial plot. We like this tool as it can paint a picture of where avalanche activity is concentrated. It’s important to recognize factors that might bias the data reported including concentration of skiers in terrain (ie. there are a lot more skiers in the Tetons on east, northeast, and north facing terrain than on west facing terrain), skiable terrain, etc..
Take the time to study the avalanche activity that has occurred up to mid-January 2012. What aspects and elevations have seen the most avalanche activity? Have those avalanches been to the ground or have they been shallow soft slabs? This can help you better understand the structure of the snowpack in mid-January.