Avalanche Forecasting and Control February 2015 I-90 Snoqualmie Pass and US 2 Stevens Pass

What passes are closed in the winter? How does WSDOT maintain state highway passes?

SR 410 Chinook Pass (5,430’) Chinook Pass is located on SR 410 WSDOT is committed to maintaining safe, efficient and reliable between the towns of Enumclaw and Naches. Chinook Pass closes from transportation systems. This commitment reaches beyond our highways Crews set explosives above an avalanche zone during a highway closure Weather stations help crews get vital Explosives hang from a tram above an Morse Creek (five miles east of the summit) to Cayuse Pass. When closed, to steep and often avalanche prone mountain slopes that threaten the conditions for active zones avalanche path the Crystal Mountain Ski Resort can be accessed from the west side, but highways and the traveling public. cannot be accessed from the east closure point on SR 410. WSDOT’s Avalanche and Forecasting Control team is a dedicated crew SR 123 Cayuse Pass (4,675’) Cayuse Pass connects to Chinook Pass of experienced professionals who monitor the weather and snow to and White Pass on the west side of Mount Rainier National Park. Crews determine when avalanches may occur. The crew is split into two close the gates in the north on SR 410 just south of Crystal Mountain regional teams with full-time employees and seasonal employees. The South Central Region North Central Region Boulevard and in the south on SR 123 at the Mount Rainier National Park Avalanche Control Supervisor for each team leads the crew throughout the year. Chinook Pass (SR 410), Stevens Pass (US 2), entrance. The closure affects eight miles of SR 410 and nearly 14 miles of Snoqualmie Pass (I-90) North Cascades Highway (SR 20) SR 123. When conditions indicate an avalanche is imminent, teams employ Contact Information various methods and tools to bring down unstable snow in a controlled SR 20 North Cascades Highway (4,855’) SR 20 is the northernmost route across the Cascade Mountains. The highway is closed to traffic from manner. The team works throughout the winter and spring along Stevens Pass/Washington Pass Washington’s mountain highways. Jeff Adamson milepost 124, the Diablo Gate, to milepost 171, the Silver Gate. 509-667-2815 What is avalanche forecasting? Snoqualmie Pass/White Pass/Chinook Pass 20 Washington Highway (closed in winter) Meagan Lott Summer Derrey Avalanche forecasting determines the potential risk along a particular 509-577-1618 509-577-1943 mountain slope. Avalanche forecasts are based on past, current and forecasted conditions. Some important factors used to determine the avalanche hazard include: Traffic Information 2 Stevens Pass (open all year) 1-800-695-ROAD • New snow or rain www.wsdot.wa.gov/traffic/passes/passinformation.aspx 90 Snoqualmie Pass (open all year) John Stimberis • Temperature Mike Stanford 410 Chinook Pass (closed in winter) Avalanche Control Supervisor Avalanche Control Supervisor • Wind speed and direction 123 Cayuse Pass (closed in winter) • Existing snow conditions 5 82 This information is combined with a mountain weather forecast to predict the chance an avalanche will occur on a particular mountain slope.

Americans with Disabilities Act (ADA) Information: Materials can be provided in alternative Title VI Notice to Public: WSDOT assures full compliance with Title VI of the Civil Rights Act formats: large print, Braille, cassette tape, or on computer disk for people with disabilities by of 1964 by prohibiting discrimination based on race, color, national origin and sex in the calling the Office of Equal Opportunity (OEO) at (360) 705-7097. Persons who are deaf or hard provision of benefits and services. For information on the Department’s Title VI Program, of hearing may contact OEO through the Washington Relay Service at 7-1-1. please contact the Title VI Coordinator at 360-705-7098.

456001\Communications\Projects\10 12Dec Avalanche Folio_updated Log #11-02-0452 Why does WSDOT perform Avalanche Forecasting and Control? Rayrock Merritt Lake

The WSDOT Avalanche Forecasting and Control team was established to reduce the danger of avalanches N School House reaching the highway. Numerous avalanche paths along state highways have the potential to impact the safety Gaynor East Camp of the traveling public and the reliability of our transportation system. Lake Vahalla

West Camp 78 Rayrock Where does Avalanche Control happen? 77 79 69 Merritt 68 75 76 Stevens Pass and Snoqualmie Pass are both maintained throughout the winter and avalanche control work is Berne Snowcamp 74 University 80 performed to keep the highway safe for the traveling public. WSDOT typically closes Chinook Pass, Cayuse Pass 67 73 70 East Portal and the North Cascades Highway each winter due to avalanche danger. Avalanche specialists perform avalanche 72 to Leavenworth (18 miles) control work in the spring so these passes can reopen in time for busy summer travel. 71

66 Arrowhead Mountain Avalanche control may be necessary anytime between November and June depending on the amount of snowfall Arrowhead (6209 ft.) and conditions. WSDOT avalanche crews try to plan avalanche control during times when the traffic volumes are Wellington Avalanche Shoulder STEVENS PASS low. This is not always possible as safety takes priority over convenience. Crews reopen Chinook, Cayuse and 63 Jim Hill Mountain (6765 ft.) the North Cascades Highway in the spring, but depending on conditions, more avalanche control work needs to 65 64 be done. Stevens Pass Ski Area 62 Alpental How does WSDOT conduct avalanche control work? Ski Area Denny 9 and 10 WSDOT avalanche crews deploy explosives and trigger avalanches in a controlled manner. Explosives are Denny Mountain delivered to an avalanche slope using aerial trams, artillery or by hand. When conditions warrant avalanche 52 control measures, the avalanche crew will ask for traffic to be stopped in a safe area outside the avalanche zone. 61 60 Snoqualmie Pass Airplane (3,022 ft) to Seattle (93 miles) Granite Mountain South Curve Granite Mountain Summit West 51 Ski Area What happened to the snowshed on Snoqualmie Pass? Bandera Mountain GS-0 West Shed GS-1 53 In spring 2014, WSDOT and the contractor removed the 64-year-old snowshed to start construction on two new 1 2 3 GS-2 GS-3 Lodge Creek avalanche bridges. This work is part of the I-90 Snoqualmie Pass East Project that builds a wider, more reliable East Rock to Seattle (42 miles) stretch of I-90 from Hyak to Keechelus Dam. Without a snowshed, clearing snow from I-90 after avalanche Rock Summit Central 50 Ski Area control work will take longer. However, the traffic pains are temporary. By winter 2016, both directions of traffic 54 are schedule to be traveling on the first of two new bridges. A second bridge will open to traffic in 2018. Until 44 Gully then, drivers are encouraged to plan for added travel time over the next two winters. Never Slides 90 90 45 47 46 49 48 HYAK 55 How is WSDOT performing avalanche control work without the snowshed? Rampart Ridge Summit East Ski Area Crews shifted the lanes away from the hillside to provide room to store snow. Avalanche specialists will continue to monitor snow and weather conditions east of Snoqualmie Pass until WSDOT and contractor crews finish 56 building the new avalanche bridges. SNOQUALMIE PASS

Keechelus Lake How does WSDOT utilize new technology for avalanche forecasting and control? 57

WSDOT avalanche crews test new technologies that could be incorporated into the avalanche control program. WSDOT avalanche personnel continue to test, evaluate and research new and/or improved methods of avalanche NOTE: US 2 and I-90 are shown out of scale and not East Shed forecasting and control. proportional to allow view of both highways. 58 All Avalanche Zones have the potential to fall on the highway. Snowshed WSDOT will control all Avalanche Zones as needed. What do recreationalists accessing backcountry areas need to know? LEGEND Slide Curve 59 Skiers and snowboarders accessing backcountry areas could potentially trigger avalanches that will impact the US 2 and I-90 Avalanche Path highway. On Stevens Pass, signs mark the area between mileposts 60.15 to 66.24 as a designated No Parking, Bridge Denny Creek Viaduct No Hitchhiking or No Pedestrian Zone from November 1 through April 15. On Snoqualmie Pass, signs are posted Occasional 60 warning skiers and snowboarders about avalanche control zones. Hitchhiking and non-emergency stops are Avalanche Hazard to Ellensburg (49 miles) prohibited along Snoqualmie Pass.