Avalanche on Newberry Crater. A firsthand account of a snowmobiler avalanche accident and the SUbsequent rescue-january 15,1998

Transcription

1 Avalanche on Newberry Crater A firsthand account of a snowmobiler avalanche accident and the SUbsequent rescue-january 15,1998 Brian Sali 1 and Art Keys ISSW Paper Summary prepared by Pam Hayes and Mark Moore from first person accounts and related newspaper articles Abstract Avalanche accident statistics for North America since 1990 indicate an alarming increase in avalanche incidents involving snowmobilers. This increase is probably due to a variety of factors, including more powerful machines, a limited amount of avalanche awareness by many of the victims, a lack of proper rescue equipment, and a feeling that "my machine will get me out of trouble. However, as most of us know or have experienced, even training or equipment are not an infallible safety net, especially if we do not utilize them all the time. This first person account of a snowmobiler avalanche accident, which thankfully had a positive outcome, illustrates many of the important concepts that avalanche courses emphasize, including route selection, terrain analysis, proper equipment, rescue techniques and a bit of luck. It further stresses the need "to buckle your seatbelf, even if it's only for a trip around the block In this event, which occurred along the east slopes of the central Oregon Cascades, the victim was totally buried after releasing and being caught by a 2-3 ft wind slab, which released on faceted snow developed early in the season. Fortunately, some friends were able to dig the victim out from under five feet of snow using tree branches and the windshield from one of their snow machines. Introduction In mid-january 1998 a significant avalanche cycle occurred across much of the mountain west that resulted in 7 snowmobile fatalities. Of three snowmobilers who survived an avalanche in the Paulina Peak area of central Oregon, one was completely buried and one partially buried. Their experience typifies both this particular avalanche cycle as well as the most likely scenario for many avalanche accidents involving snowmobilers. Cold temperatures and generally light amounts of snow in late November and early December resulted in the formation of a weak layer in the snowpack.. This layer consisted of a significant amount of weak faceted or recrystallized snow, that formed as a result of strong temperature gradients across a relatively shallow snowcover. The weak layer was especially prevalent along the east slopes of the Washington and Oregon Cascades, where overall colder temperatures and shallower snowpacks are common during much of the winter.. Following this period of snowpack weakening, a series of strong weather systems moved through the Pacific Northwest in January, with relatively warm temperatures and heavy snowfall combining to load the weak snow layers formed earlier that winter. Strong generally southwest winds during snowfall accentuated the loading and associated stress on north to east facing slopes. Continuing snowfall further stressed the very unstable snowpack structure that existed on the day of the Newberry Crater avalanche accident and continued through the following weekend when another snowmobiler accident resulted in an avalanche fatality further north in Washington.. The sequence of related weather events near the times of 1 Corresponding author address: Brian Sali, 5202 Cayuse Lane, Yakima, WA

2 these two accidents is illustrated by the weather and avalanche forecasts shown in the Appendix. Accident Narrative On January 1St!" Brian Sali, Mark Perry and Art Keys had been snowmobiling for about three hours in the Deschutes National Forest southeast of Bend Oregon. They'd been high-marking 2 on a treeless slope in the Newberry Crater near Paulina Peak. The most favored high-marking slopes are usually those slopes that are wind loaded with fairly soft surface snow, and this slope was no exception. On Brian Sali's second high-mark attempt, his machine failed to make the tum and he stepped off to tum his sled around at the top of his arc. Suddenly, a snow slab about the size of a football field released around him. "I just felt everything moving," he said. "The snow knocked my face mask down. My sled came over me. All I remember is it seemed like seconds of moving. I came to a standstill and I thought, 'This is OK I'll try to move.' I couldn't even move my finger inside my glove." Sali had been carried more than 100 yards and was buried under S feet of snow. He reported that "I could only move my stomach inward, not outward. I slowly went to sleep. There was no pain: Fortunately for Sali, the avalanche spared his friends from his predicament. Mark Perry was not involved in the slide, and Art Keys was buried to his waist on the edge of the avalanche. After digging himself out, Keys joined Mark Perry to look for SaiL They found one blade of Sali's snowmobile on the surface. The engine was still running, so they dug down to tum it off in hopes of hearing Sali's calls. They cut tree branches to use as probes to search for Sali, whom they located with the makeshift probes about 8 feet from his snowmobile. Without shovels handy, a snowmobile windshield was removed from one of their machines and used as a shovel to dig Sali out. When they cleared their friend's head, they found that he was 2 High-marking is when snowmobilers drive their sleds in as high an arc as possible up and across a steep snow-covered slope. unconscious, his face was discolored and his breathing was labored. Their digging was difficult, especially with the windshield-the snow was packed so tight that Keys and Perry had to dig out Sali's entire body to free him. When he was finally freed, Sali recounted,... "1 would go through stages of gasping for air. I can't remember any of that. All that I remember is standing with Art's arms around me, massaging my back." Doctors later said that Sali was probably seconds away from death when his head was uncovered, and it is probable that helmet and mask that covered Sali's face helped give him a little extra air space and with it, precious time. Finally, when he was completely dug out from the snow, Keys and Perry drove Sali to the Paulina Lodge, where they put him in a shower to await an expected helicopter. Sali was then transported from the lodge by helicopter to the St. Charles Medical Center in Bend, where he was treated and released later that day. Later, Sali remembered the rescue, "I definitely was awarded a gift. I'm grateful to have the helmet I had. It was one of the pieces of the puzzle that fit. The odds of Mark cutting the right length of tree. If they would've reached my foot, I would have died. But they got my shoulder. It sounds like a little fairy tale, but LIt's just stuck in my head. I just go over and over it. It's jusli can't explain it. You appreciate the sun and the things you took for granted. You sit and look at things more.ii Discussion Sali, Keys and Perry were lucky to survive this accident. After the avalanche, they were resourceful and, with the equipment they had, executed an efficient rescue. They did a number of things right. They stayed at the accident scene and searched the debris for clues; they fashioned probe poles from a tree, and a shovel from their snowmobile windshield. However, there are many other lessons that snowmobilers can and should learn from this accident. 96

3 By definition and in most real-life instances, high-marking is done on avalanche prone slopes-these slopes provide an exciting challenge but also an associated risk. Nevertheless there are several common sense actions which can be taken to help minimize the danger and increase the chances of rescue if an avalanche should occur. First, snowmobilers should take specific precautions to recognize unstable snowpack structures that may produce avalanches when loaded. They should access danger information 3 from avalanche forecasting services, and try to update it in person en route to whatever destination they have chosen. Good information obtained here may lead to better route finding, rescheduling or re-routing of a trip, or at least avoidance of particularly susceptible avalanche terrain. Second, when high-marking, only the snowmobile actively high-marking should be on the slope or within the runout zone of a possible avalanche. This is so that if an avalanche does occur, presumably only one rider would be involved. The remaining individuals would have seen the avalanche, marked the last seen area and tried to analyze the victim's trajectory. They would therefore be better prepared to begin and carry out a successful rescue. Third, If traveling in avalanche terrain, all individuals in a party should be carrying appropriate rescue gear on every machine. They should be wearing avalanche transceivers and know how to use them. They should carry probes and a shovel. This avalanche accident ended with a successful rescue; however, if the above precautions had been taken and the suggested equipment carried, the party may not have needed to feel so "lucky" about the outcol1)e. 3 Although site specific avalanche forecasts for the Newberry Crater area of Central Oregon are not issued, avalanche warnings and a special statement had been issued for both the Washington and the northern Oregon Cascades for the previous day, and a high danger continued on the day of the accident. See the Appendix for forecasts and statements issued by the Northwest Weather and Avalanche Center for the preceding day and day of the accident 97

4 Appendix. Northwest Weather and Avalanche Forecasts and SJ;>ecial Statements for January 14 th, 15 th and 18, Forecast for Wednesday morning, January A._a_a_A_a_.a._. _._._..... *.A* NORTHWEST WEATHER AND AVALANCHE CENTER Program administered by USDA-Forest Service with cooperative funding and support from Washington Department of Transportation National Weather Service National Park Service Washington State Parks Pacific Northwest Ski Area Association and other private organizations A a._,._._. *_A_ MOUNTAIN WEATHER FORECAST This weather forecast is prepared expressly for federal, state and private snow safety programs in Washington and Northern Oregon. A ata_a A_*_ a._.a..._.._._.,. A_A_ 0830 AM PST WEDNESDAY January 14,1998 WEATHER SYNOPSIS The first of two strong weather systems-which has turned into a warm front overnight-spread increasingly heavy precipitation to the Northwest Tuesday night, along with rising freezing levels and increasing winds. However, lowering surface pressures to the west associated with a deepening offshore surface low also redeveloped the recently strong and cold easterly winds across the Cascade passes and east slopes. While this changed brief rain Tuesday afternoon to mostly snow in the passes Tuesday night, the warming aloft has still spread northward and gradually eroded the cold air dome. Light to moderate rain or mixed rain and snow is currently occurring near White Pass and the base of Crystal Mountain with areas of freezing rain spreading slowly northward along both sides of the Cascades. Currently the second strong frontal system is merging with the first along the coast. This should spread further increasing precipitation to most areas Wednesday morning and early afternoon along with continued rising freezing levels and strong winds. This warming aloft should continue to erode the cold easterly flow with rain or freezing rain spreading toward the Cascade passes later Wednesday morning and early afternoon, with a wind shift to westerly expected around mid-day to early afternoon in the south and mid-late afternoon in the north. FollOWing the front, lowering freezing levels and more showery precipitation are expected. However, strong westerly winds should combine with the upper trough and significant instability to produce moderate to heavy orographic snowfall to progressively lower elevations later Wednesday through early Thursday. A second strong upper trough should move over the Northwest later Thursday morning and this should enhance showers. Although weak upper ridging should move over the Northwest later Thursday morning and afternoon and this should result in generally decreasing showers, the next strong frontal system is expected to spread increasing precipitation to most areas overnight and Friday morning. This should also be accompanied by rising freezing levels and strong winds. Several waves developing along this front should then move over the region Friday afternoon and night. While this should help sptead heaviest precipitation southward into south-central Oregon and northern California, it should maintain at least moderate rain or snow at slowly rising freezing levels in most Northwest areas. Following the last frontal wave Friday night, moderate to heavy orographic snowfall is likely at lowering freezing levels through Saturday morning. Building upper ridging should produce rising freezing levels and decreasing showers later Saturday through early Sunday. However, a splitting upper trough should spread light to moderate rain or snow northward later Sunday, before most of it's energy drops southward into California. A_A A_AAa_Aa._. _. _.*A*. WEATHER FORECAST...WEDNESDAY AND THURSDAy... OLYMPiCS. Moderate to heavy rain or snow Wednesday morning, decreasing and becoming showery around mid-day. Light to moderate showers increasing later Wednesday afternoon and becoming moderate to heavy Wednesday night and early Thursday, especially west slopes. Showers decreasing later Thursday morning and 98

5 "':-'). afternoon. Light to moderate rain or snow increasing Thursday night. WEST SLOPES WASHINGTON CASCADES. Moderate to occasionally heavy snow north early Wednesday, with snow changing to rain or freezing rain south and spreading northward later Wednesday morning. Moderate to heavy snow, rain or freezing rain mid-<jay and early afternoon, decreasing and changing to mostly moderate rain or snow showers later Wednesday afternoon. Moderate to heavy showers Wednesday night and Thursday morning. Showers decreasing later Thursday morning and afternoon, but light to moderate rain or snow redeveloping later Thursday night. CASCADE PASSES STEVENS...SNOQUALMIE...WHITE PASS. Moderate to heavy snow from Snoqualmie Pass northward early Wednesday, with moderate to heavy rain or freezing rain south of Snoqualmie Pass. Rain or freezing rain lower elevations west approaches Stevens and Snoqualmie passes spreading toward the passes later Wednesday morning and early afternoon. Precipitation decreasing and becoming more showery mid-late afternoon. Moderate to heavy showers Wednesday night and Thursday morning, with locally heavy snow vicinity Stevens and Snoqualmie passes in convergence. Showers decreasing later Thursday morning and afternoon. Light to moderate snow redeveloping later Thursday night. MT HOOD AREA... Moderate to heavy rain or snow increasing Wednesday morning with some areas of freezing rain near Columbia River Gorge. Heavy rain or snow decreasing and becoming more showery early-mid afternoon. Moderate to heavy showers Wednesday night and Thursday morning, decreasing later Thursday morning and afternoon. Light to moderate rain or snow redeveloping later Thursday night. EAST SLOPES WASHINGTON CASCADES. Moderate snow north and central early Wednesday with moderate rain or freezing rain south slowly spreading northward Wednesday morning. Moderate snow becoming rain or freezing rain mid-<jay and early afternoon lower elevations north and central with precipitation decreasing and becoming more showery later Wednesday afternoon. Moderate to heavy showers Wednesday night and Thursday morning, mainly higher terrain near the crest vicinity central Cascades, with light to moderate showers and some partial clearing lower elevations. Further decreasing showers and partial clearing later Thursday morning and afternoon. Increasing clouds and light snow redeveloping late Thursday night or early Friday. A.a_ A.Ataa *t*. - SNOW levels-washington AND NORTHERN OREGON CASCADES 4000 ft N, 5500 ft S early Wednesday morning 4500 ft N, 6000 ft S late Wednesday morning and early afternoon 3000 ft N, 4000 ft S later Wednesday afternoon and evening 2500 ft N, 3000 ft S Wednesday night and Thursday morning 3000 ft N, 5000 ft S Thursday afternoon 3500 ft N, 5500 ft S Thursday night....except snow levels at the surface Cascade east slopes and passes from about Snoqualmie Pass northward Wednesday morning, rising to near free air levels early-mid Wednesday afternoon. Snow levels lowering to near the surface again Thursday night. SNOW LEVELS-OLYMPIC MTNS 5000 ft early Wednesday morning 5500 ft late Wednesday morning 4000 ft Wednesday afternoon 3000 ft Wednesday night and Thursday morning 4000 ft Thursday afternoon 5000 ft Thursday night taat_a.a _ _ AA*. -24 HOUR FORECAST OF PRECIPITATION IN INCHES OF WATER EQUIVAlENT ENDING AT 4AM THURS FRI HURRICANE RIDGE.75-1 MTBAKER 1 WASHINGTON PASS STEVENS PASS 1 SNOQUALMIE PASS 1 MISSION RIDGE.25 CRYSTAlMTN PARADISE

6 WHITE PASS MTHOOD [LT =LESS THAN NRO =NEAR 0] aaat, _.*.*. THE FOLLOWING WINDS ARE IN MILES PER HOUR (MPH) CASCADE PASS LEVEL WINDS E with higher gusts Wednesday morning E 5-15 with higher gusts early Wednesday afternoon W 5-15 later Wednesday afternoon W with higher gusts Wednesday night and Thursday morning W 5-15 early Thursday afternoon Variable 0-10 late Thursday afternoon E 5-15 Thursday night FREE WINDS AT 5000 FT S-SW Wednesday morning and early afternoon W-SW 3040 mid-late Wednesday afternoon W Wednesday night and Thursday morning SW Thursday afternoon SW Thursday night FREE WINDS AT 9000 FT S-SW 3D-50 Wednesday morning W-SW Wednesday afternoon W 3040 Wednesday night and Thursday morning SW 2040 Thursday afternoon EXTENDED WEATHER FORECAST... FRIDAY THROUGH SUNDAY... Moderate to occasionally heavy rain or snow Friday. Moderate to heavy showers Saturday, decreasing late Saturday. Scattered showers a.a _ _,.._ _., AAA. early Sunday. Increasing light to moderate rain or snow later Sunday. SNOW LEVELS ft N, ft S early Friday ft N, ft S later Friday ft N, ft S Saturday ft N, ft S late Saturday ft N, ft S Sunday...except snow levels at the surface Cascade passes and east slopes Friday, rising to near free air levels early Saturday, and lowering to near the surface Cascade east slopes and passes Sunday aaat _ _.*.a. At ".at AVALANCHE ADVISORY Advisories apply to back country avalanche terrain below 7000 feet. They do not apply to highways or operating ski areas. For the most current avalanche advisory... please call: (503) (Oregon) (206) (Washington) - aaat _ *_*. ZONE AVALANCHE FORECASTS.....WASHINGTON CASCADES NEAR AND WEST OF THE CREST...OLYMPICS......MT HOOD AREA......AVALANCHE WARNING. Extreme avalanche danger below 7000 feet Wednesday morning and early afternoon. Slightly decreasing avalanche danger late Wednesday afternoon, becoming high above 5000, considerable from 3 to 5000 feet and moderate below. Danger increasing Wednesday night and Thursday morning, becoming high above 4000 feet and considerable below. Danger gradually decreasing Thursday afternoon and evening, but increasing again later Thursday night. EAST SLOPES WASHINGTON CASCADES....AVALANCHE WARNING. High avalanche danger below 7000 feet Wednesday. Slightly decreasing avalanche danger late Wednesday afternoon and evening, becoming high above 6000 feet, considerable from 3 to 5000 feet and moderate below. Danger increasing later Wednesday night and Thursday morning, becoming high above 5 to 6000 feet and considerable below. Danger gradually decreasing Thursday afternoon and evening, but increasing again later Thursday night. PLEASE NOTE: Back country travel in avalanche terrain should be avoided Wednesday. SNOWPACK ANALySiS... Large accumulations of increasingly dense new snowfall continue to be deposited over previous 100

7 large accumulations of slightly stabilized lower density snowfall all over an old crust, with greatest recent accumulations received in the Washington Cascades near and west of the crest and in the Mt Hood area. In the Mt Hood area, increasingly dense new wind slab or wet heavy snow or rain has been deposited over about 4 feet of relatively light low density snow which was deposited over either a previous wind slab surface or platelike crust created early last week. Several buried weak layers exist in this new snow, both near the crust and closer to the surface from variations in wind speed and snowfall intensity during recent storms. Field reports continue to indicate that easy to very easy shears are occurring on a variety of weak layers, and wind transport is continuing to create some very large wind slabs on east through northeast exposures. Avalanche control on Monday produced slabs ranging up to 8 feet deep in Heather Canyon to the north of Mt Hood Meadows. In the Washington Cascades near and west of the crest, the most recent new snowfall amounts range from about 2 to 4 feet with generally denser and warmer wind transported or wet snow lying over weak layers of previously fluffy weak cold snow. At this time, from 3 to over 7 feet of new snow now lies over the early January crust and much of this remains susceptible to avalanching if loaded by heavy rain, surface avalanching or heavy wind transported snow. While some warming and light rain or wet snow Tuesday afternoon produced a slide cycle of surface snow below about 4000 to 4500 feet, substantial snowfall still remains above several buried weak layers. Hence, an increasingly unstable snowpack structure exists...and with current heavy precipitation, strong winds ~_. and rising freezing levels this is creating an ~ extreme avalanche danger in many areas. Along the Washington Cascade east slopes, less recent precipitation has been received. However, strong winds along with slow warming, especially at higher elevations, has produced a generally high avalanche danger here as well. WEDNESDAy... Further substantial warming, very strong winds, and increasingly heavy rain, snow or local freezing rain are expected Wednesday morning and early afternoon. Warm air aloft should slowly erode the cold easterly winds expected across the Cascade passes Tuesday night and Wednesday morning and mix downward toward the passes around mid-day and early afternoon-and this should spread rain, freezing rain or mixed rain and snow to higher elevations-about 4 to 5000 feet in the north and about 6000 feet in the south. This should increasingly load or weaken the existing snowpack structure, producing an extreme avalanche danger in many areas. Widespread natural or human triggered avalanches of the most recent snowfall are certain on a variety of exposures and slope angles. These slides or associated weather may also trigger more deeply buried weak layers reaching the early January crust, and large. destructive avalanches are possible. Back country travel should be avoided and travel confined to relatively flat terrain well away from avalanche path runouts. Although cooling and more showery precipitation expected later Wednesday afternoon should decrease the danger and lower it from extreme, moderate to heavy showers and strong winds should maintain generally high danger in most areas above 4 to 5000 feet Wednesday night. WEDNESDAY NIGHT AND THURSDAy... Moderate to heavy showers, lowering freezing levels and strong winds expected Wednesday night and Thursday morning should spread high avalanche danger to gradually lower elevations, with greatest danger on northeast through southeast facing slopes. Below about 3 to 4000 feet, refreezing and strengthening of previously wetsurface snow and a relatively good bond of new snow to the developing crust should help to limit the danger increase initially. however. areas of unstable snow should still develop Thursday morning. Decreasing showers and winds expected Thursday afternoon and evening should allow for generally decreasing avalanche danger. However, increasing winds, rising freezing levels and some light to moderate rain or snow expected late Thursday night should begin to slowly increase the danger. A,.. Backcountry travelers should be aware that elevation and geographic distinctions are approximate and a transition zone between dangers exists. Remember, there are avalanche safe areas in the mountains during all levels of avalanche danger. Contact local authorities in your area of interest for further information. 101

8 2. Special Avalanche Statement for the Northern Oregon Cascades issued on January ZCZC SEASABOR TIAAOO KSEA DDHHMM WAZ019-Q25-0RZ BACKCOUNTRY AVALANCHE FORECAST FOR THE MT HOOD AREA AND SOUTH WASHINGTON CASCADES FOREST SERVICE NORTHWEST WEATHER AND AVALANCHE CENTER ISSUED THRU NATIONAL WEATHER SERVICE PORTLAND, OREGON 0430 AM PST WEDNESDAY January 14,1998 SPECIAL FOREST SERVICE AVALANCHE STATEMENT FOR THE MT HOOD AREA AND SOUTHERN WASHINGTON CASCADES ISSUED WEDNESDAY, 14 JANUARY, 1998 FOR AVALANCHE TERRAIN BELOW 7000 FEET. THIS FORECAST DOES NOT APPLY TO OPERATING SKI AREAS OR HIGHWAYS.... EXTREME AVALANCHE DANGER TODAY IN THE MT HOOD AREA AND SOUTHERN WASHINGTON CASCADES NEAR AND WEST OF THE CASCADE CREST...AND GENERALLY HIGH AVALANCHE DANGER ELSEWHERE... Recent large new snow accumulations-with amounts ranging over 6 to 7 feet in some areas during the past 10 days-have been deposited during generally cold weather and low freezing :5- levels along with a variety of buried weak snow '. layers. Along with recently increasing winds, and gradually rising freezing levels Tuesday, this weather has created an increasingly unstable snowpack structure of heavier dense snow over lighter weaker snow. Field reports Tuesday indicated a very sensitive snowpack with many natural and controlled avalanches. Although most of these snow slides involved only the most recently deposited snow and ranged from 1 to 3 feet, some avalanche fracture lines reached 8 feet deep. With continued heavy loading, further rising freezing levels and strong winds expected Wednesday, an extreme avalanche danger should develop in many areas and widespread natural or human triggered avalanches are certain. Large destructive avalanches are also possible. Travel in avalanche terrain should be avoided, and travel confin~d to relatively flat terrain well away from avalanche path runouts. Less recent snow accumulations along the Cascade east slopes are producing a slightly lower avalanche danger in these areas, however a generally high danger and mostly unstable snowpack should develop here as well later Wednesday morning and afternoon. Lowering freezing levels and more showery precipitation expected later Wednesday should allow the danger to decrease from extreme. However, moderate to heavy orographic snowfall and strong winds should maintain a high danger in many areas, especially on northeast through southeast facing slopes in the Mt Hood area and southern Washington Cascades near and west of the Cascade crest. This statement will be updated as conditions warrant. AAaa _._ _ *.*_ A.A _. Backcountry travelers should be aware that elevation and geographic distinctions are approximate and a transition zone between dangers exists. Remember, there are avalanche safe areas in the mountains during all levels of avalanche danger. Contact local authorities in your area of interest for further information. For more detailed weather and snowpack information, please call , or visit our web site at MOORE/Forest Service Northwest Weather and Avalanche Center NNNN 102

9 3..Mountain Weather and Avalanche Forecast for Washington and Northern Oregon for Thursday. January *******************************************************A*_ NORTHWEST WEATHER AND AVALANCHE CENTER Program administered by USDA-Forest Service with cooperative funding and support from Washington Department of Transportation National Weather Service National Park Service Washington State Parks Pacific Northwest Ski Area Association and other private organizations a.a._a aa_._..... _ _. *A*_ MOUNTAIN WEATHER FORECAST This weather forecast is prepared expressly for federal, state and private snow safety programs in Washington and Northern Oregon. A.A A aaa.._.._.*_a. 9'A_A am PST THURSDAY a January._.._. 15,1998,_A_*_ WEATHER SYNOPSIS A strong westerly jet stream across the eastern north Pacific is directing a series of relatively fast moving and strong weather systems across the area. Following a frontal passage Wednesday, cool and unstable air along with moderate to strong westerly flow aloft are maintaining orographic precipitation along the west slopes early Thursday. The orographic precipitation is ~ expected to gradually decrease later Thursday as a short wave upper ridge moves over the area. The upper ridge is expected to cause further decreasing showers later Thursday and move east of the area Thursday night. The next frontal system is expected to bring increasing precipitation late Thursday night at rising freezing levels with lowering freezing levels Friday morning with continued moderate to heavy precipitation. While freezing levels are expected to peak near mid night Thursday, increasing easterly pass flow should help to maintain precipitation as snow over the lower passes overnight. Behind the front early Friday as cooling occurs a brief period of rain may occur over Snoqualmie Pass, with Stevens Pass maintaining snow. Strong west to southwesterly flow behind the front Friday should maintain moderate orographic precipitation through the day Friday before yet another frontal system approaches late Friday and Friday night to cause further increasing precipitation and winds. In the longer range Moderate to heavy precipitation and very strong winds are expected early Saturday. A building upper ridge later Saturday should cause decreasing showers and gradual drying. Another in the series of strong frontal passages is expected to pass across the area Sunday with significantly rising freezing levels and very strong winds. Following this strong front Sunday a cool upper trough passage should cause lowering freezing levels and gradually decreasing showers through Monday. A_A A a._. *_*. WEATHER FORECAST... THURSDAY AND FRIDAy... OLyMPICS. light to moderate snow showers early Thursday, especially west slopes. Snow showers decreasing later Thursday morning and afternoon becoming scattered. light to moderate rain or snow increasing Thursday night and early Friday. Rain or snow becoming moderate to heavy later Friday morning and early afternoon. Rain or snow briefly decreasing late Friday, but increasing again Friday night becoming moderate to heavy. WEST SLOPES WASHINGTON CASCADES. light to moderate snow showers early Thursday. Snow showers decreasing later Thursday morning and afternoon becoming light. light to moderate rain or snow increasing late Thursday night in the south and spreading northward early Friday. Rain or snow becoming moderate to heavy later Friday morning and early afternoon. Rain or snow briefly decreasing late Friday, but increasing again Friday night becoming moderate to heavy. CASCADE PASSES... STEVENS. SNOQUALMIE... WHITE PASS. Periods of light to moderate snow early Thursday. Snow showers decreasing later Thursday morning and afternoon becoming light. light to moderate snow increasing late Thursday night and early Friday. Snow or possibly rain at Snoqualmie and White Passes becoming 103

10 moderate to heavy later Friday morning and early afternoon. Rain or snow briefly decreasing late Friday, but increasing again Friday night becoming moderate to heavy. MT HOOD AREA.... Light to moderate snow showers early Thursday. Snow showers decreasing later Thursday morning and afternoon becoming light. Light to moderate rain or snow increasing Thursday night. Rain or snow becoming moderate to heavy later Thursday night and early Friday morning. Rain or snow briefly decreasing late Friday, but increasing again Friday night becoming moderate to heavy. EAST SLOPES WASHINGTON CASCADES. Diminishing snow showers and partial clearing Thursday morning and afternoon. Increasing clouds and light snow redeveloping late Thursday night or early Friday. Snow changing to showers Friday afternoon and decreasing. Increasing rain or snow late Friday night. SNOW LEVELS-WASHINGTON AND NORTHERN OREGON CASCADES 2500 ft N, 3000 ft S Thursday morning 3000 ft N, SOOO ft S Thursday afternoon 3S00 ft N, 6000 ft S Thursday night 3500 ft N ft S Friday and Friday night...except snow levels at the surface Cascade east slopes and passes from about Snoqualmie Pass northward rising to near free air levels early Friday. SNOW LEVEL5-0LYMPIC MTNS 4 ' ft Thursday morning ~~ ft Thursday"afternoon 4500 ft Thursday night 3500 ft Friday and Friday night 24 HOUR FORECAST OF PRECIPITATION IN INCHES OF WATER EQUIVALENT ENDING AT 4AM FRI SAT HURRICANE RIDGE MTBAKER.75 1 WASHINGTON PASS.25- STEVENS PASS SNOQUALMIE PASS MISSION RIDGE CRYSTALMTN PARADISE WHITE PASS MTHOOD [LT =LESS THAN NRO =NEAR 0] a.aa_aaa_aa.a._.._._aka* THE FOLLOWING WINDS ARE IN MILES PER HOUR (MPH) CASCADE PASS LEVEL WIND W with higher gusts Thursday morning W 5-15 early Thursday afternoon Variable 0-10 late Thursday afternoon E Thursday night W Friday morn W 5-15 Fri aft E Fri night FREE WINDS AT 5000 FT W-SW Thursday morning SW Thursday afternoon S-SW Thursday night SW 30-SO Fri morn... strongest Mt Hood S-SW Fri aft S-SW Fri night... strongest Mt Hood FREE WINDS AT 9000 FT W-SW Thur mom W Thursday aft SW Thursday night and Fri morn W Fri aft S-SW Fri night EXTENDED WEATHER FORECAST...SATURDAY THROUGH MONDAY... Moderate to heavy snow early Saturday, decreasing late Saturday. Increasing moderate to heavy rain or snow again Sunday. Cooler Monday with light snow showers. SNOW LEVELS ft N, ft S Saturday ft N, ft S Sunday ft N, ft S Sunday...except snow levels at the surface Cascade passes and east slopes early Sunday, rising to near free air levels later Sunday. a_aa_aaaaaa_a_ _ _ _ _.,.,._._._.,. Aka_ a_a.*.*a*a AVALANCHE ADVISORY 104

11 Advisories apply to back country avalanche terrain below 7000 feet. They do not apply to highways or operating ski areas. For the most current avalanche advisory... please call: (503) (Oregon) (206) 52~77 (Washington) -A a._.a aaa_. _.- _ _ _.a**. ZONE AVALANCHE FORECASTS... WASHINGTON CASCADES NEAR AND WEST OF THE CREST FROM SNOQUALMIE PASS NORTHWARD... OLyMPiCS......AVALANCHE WARNING. High avalanche danger below 7000 feet Thursday. Danger slightly decreasing Thursday afternoon and evening, but increasing again later Thursday night and early Friday with natural avalanches likely. Danger remaining high below 7000 feet Friday and Friday night. WASHINGTON CASCADES NEAR AND WEST OF THE CREST SOUTH OF SNOQUALMIE PASS MT HOOD AREA. EAST SLOPES WASHINGTON CASCADES....AVALANCHE WARNING. High avalanche danger above 4 to 5000 feet Thursday and considerable below. Slightly decreasing avalanche danger late Thursday afternoon and evening, becoming high above 5 to 6000 feet and considerable below. Increasing danger Thursday night and early Friday becoming '.'>- high below 7000 feet with natural avalanches,-." likely. Danger gradually decreasing below about 4000 feet later Friday but remaining high above. Avalanche danger again increasing late Friday night becoming high below 7000 feet. SNOWPACK ANALySiS... Heavy amounts of new snow were received Wednesday through early Thursday at fluctuating temperatures and periods of very strong winds. New snow amounts ranged from about 8 to 16 inches. In total up to 8 feet or more of new snow has been deposited over the past 11 days. This recent snow overlies a strong rain crust from early January, with additional weaker crusts in many areas at lower elevations, below 4 to 5000 feet. Several buried weak layers exist in the recent snow, both near the crust and closer to the surface from variations in temperature, wind speed and snowfall intensity during recent storms. Field reports continue to indicate that easy to very easy shears are occurring on a variety of weak layers. Strong winds during much of the recent precipitation have built sensitive wind slabs and also large cornices along ridges. This has created an increasingly unstable snowpack structure and generally high avalanche danger. Along the Cascade east slopes, less recent precipitation has been received. However, strong winds and with slow warming, especially at higher elevations, have produced an increase in the avalanche danger here as well, with natural slides possible. THURSDAy... Moderate snow showers, lowering freezing levels and strong winds expected Thursday morning should spread high avalanche danger to gradually lower elevations, with greatest danger on northeast through southeast facing slopes. Decreasing showers and winds expected Thursday afternoon and evening should allow for generally decreasing avalanche danger. However, increasing winds, rising freezing levels and moderate rain or snow expected late Thursday night and early Friday should cause an increasing danger. FRIDAy... Moderate to heavy rain or snow and very strong winds should maintain a high danger at all elevations with the greatest danger developing on mainly north, northeast and east facing slopes at higher elevations. Backcountry travel is not recommended early Friday. Gradually decreasing winds and snow Friday afternoon should allow for a slowly settling snowpack, however, increasing rain and snow along with very strong winds expected later Friday night should again lead to an increasing danger. A_A aaaaaaaa_.._ _ _ *k*. *_***A*AA_ Backcountry travelers should be aware that elevation and geographic distinctions are approximate and a transition zone between dangers exists. Remember, there are avalanche safe areas in the mountains during all levels of avalanche danger. Contact local authorities in your area of interest for further information. 105

12 4.. Mountain Weather and Avalanche Forecast for Washington and Northern Oregon for Sundav, January 18, 1998 This forecast is shown because a similar avalanche danger along the Cascade east slopes extended into the following weekend, when another snowmobiler accident occurred. This avalanche accident resulted in a fatality near Blewett Pass, Washington, when once again the trigger was a high marking snowmobiler. A_A AAAA&AA&t_.._._AA*_ NORTHWEST WEATHER AND AVALANCHE CENTER Program administered by USDA-Forest Service with cooperative funding and support from Washington Department of Transportation National Weather Service National Park Service Washington State Parks Pacific Northwest Ski Area Association and other private organizations A.a a_a_aa_a_ _._ *t*_ MOUNTAIN WEATHER FORECAST This weather forecast is prepared expressly for federal, state and private snow safety programs in Washington and Northern Oregon. A_A._A._Aa_a._ _._....._._AA*_ 9 am PST Sunday 18 January a_a._a_aa a_._._.,_...._.._._.._._._._._. AtA_ WEATHER SYNOPSIS.~ A deep upper trough and an increasing moist south flow is slowly approaching the Northwest coast on Sunday. An initial short-wave and the strongest flow should move into California later Sunday. A front embedded in the south flow should also move most rapidly east into California, but should move much more slowly east into the Pacific Northwest on Sunday evening. This should bring gradually increasing precipitation on Sunday, which should initially be heaviest on the south volcanoes or other locations exposed to south flow. Yesterdays weather scoured out most of the cold surface air mass east of the Cascade crest except for some northern valleys. Therefore although east winds are expected most of Sunday in advance of the front, the warm south flow should cause rain the entire day Sunday at Snoqualmie Pass and after late Sunday morning after'some wet snow at Stevens and White Pass. The slow moving front should cross our area about Sunday midnight which should begin some gradual cooling and a temporary weak west flow at the passes. A second short-wave should help carry an upper trough and surface low over the area later Monday, which should bring a help make the flow aloft more southwesterly and bring some slightly increasing orographic precipitation near and west of the crest. The surface low may again reverse the winds to east in the passes on Monday afternoon. A slightly decreasing west to southwest flow should be seen Monday night after the short-wave and surface low move to the east, which should bring decreases in precipitation near and west of the Cascade crest. In the longer range...an trough should remain established over the north east Pacific Ocean and maintain a moderate, mild and moist southwest flow into the Pacific Northwest Tuesday through Thursday. A second frontal system should approach on TueSday, accompanied by some slight warming and gradually increasing light to moderate precipitation. This second front should cross the area on Wednesday, accompanied by more gradually warming, then cooling, and moderate to heavy precipitation. A third front carried by the southwest flow should approach the Northwest on Thursday, causing renewed gradual warming in increasing light to moderate and then moderate precipitation. Some heavy precipitation appears likely to accompany the third front over the area on Friday. A AaAaa._._ _..*_ WEATHER FORECAST OLYMPICS... Increasing light to moderate rain or snow Sunday and Sunday evening, occasional heavy south Olympics. Light rain or snow showers early Monday. Increasing light to moderate rain or snow Monday, heaviest west Olympics. Decreasing light to occasional moderate rain or snow Monday night WASHINGTON CASCADES NEAR AND WEST OF THE CREST... Increasing light to moderate rain or snow Sunday and Sunday evening, occasional heavy south 106

13 volcanoes. Light rain or snow showers early Monday. Increasing light to moderate rain or snow Monday. Decreasing light to occasional moderate rain or snow Monday night. STEVENS PASS... Increasing light wet snow Sunday morning, changing to light rain late Sunday morning, continuing into Sunday evening. Gusty east winds possible western approach Sunday. Light rain showers changing back to lightsnow showers early Monday. Increasing light to moderate snow Monday. Decreasing light to occasional moderate snow Monday night. SNOQUALMIE PASS... Increasing light to occasional moderate rain Sunday and Sunday evening. Gusty east winds possible western approach Sunday. Light rain showers early Monday. Increasing light to moderate rain Monday changing back to snow Monday afternoon. Decreasing light to occasional moderate snow Monday night. WHITE PASS... Increasing light wet snow changing to light to occasional moderate rain Sunday morning. Light to occasional moderate rain continuing Sunday and into Sunday evening. Light rain showers changing back to light snow showers early Monday. Increasing light to moderate snow Monday. Decreasing light to occasional moderate snow Monday night. WASHINGTON CASCADES EAST OF THE CREST... Increasing light rain or snow Sunday and Sunday evening, occasional moderate rain or snow south part. Light rain or snow showers early Monday mainly near the crest. Increasing light snow mainly near the crest Monday. Decreasing light snow mainly near the crest Monday night. MT HOOD AREA.. Increasing light rain or snow Sunday morning, becoming moderate to heavy Sunday afternoon and Sunday evening. Light rain or snow showers early Monday. Increasing light to moderate rain or snow Monday. Decreasing light rain or snow Monday night. A_a a.aaaaa&,., "",_",., _ _. AA*' SNOWLEVEL5-WASHINGTON AND NORTHERN OREGON CASCADES 4000 ft N 6000 ft S Sun morn 4500 ft N 5000 ft Slater S.un 3500 ft Nand S Mon morn 3000 ft Nand Slater Mon...except near the surface east slopes and higher passes Sunday morning, rising to near free air levels by Sunday afternoon, returning to near the surface east slopes and all passes later Monday. SNOW level5-0lympic MTNS 5S00 ft Sun morn 6000 ft later Sun 3500 ft Mon morn 3000 ft later Mon A_A.,_a a._. _._ _._.,._._._.._._ 24 HOUR FORECAST OF PRECIPITATION IN INCHES OF WATER EQUIVALENT ENDING AT 4AM HURRICANE RIDGE MTBAKER WASHINGTON PASS STEVENS PASS SNOQUALMIE PASS MISSION RIDGE CRYSTAlMTN PARADISE WHITE PASS MTHOOD MON It TUES It [LT A. a= LESS a._._. THAN._... NRO.,..._. = NEAR. 0]..,._._*.a_ THE FOLLOWING WINDS ARE IN MILES PER HOUR (MPH) CASCADE PASS LEVEL WINDS E Sun E 5-15 toward Sunday midnight W 0-10 early Mon E 0-10 later Mon FREE WINDS AT 5000 FT S Sun morn...strongest south and over the Olympics S Sun eve SW Mon morn SW later Mon FREE WINDS AT 9000 FT S-SW Sun morn...strongest south and over the Olympics S-SW 30-SO Sun eve SW Mon morn 107

14 ,,,,".' W-SW 2540 later Mon A.A._.._' ' " ' ' ' "_*'*' EXTENDED WEATHER FORECAST...Tuesday through Thursday... Increasing light to moderate rain or snow and some warming Tuesday. Moderate to heavy rain or snow and warmer Wednesday, followed by some cooling. Light rain or snow Thursday becoming light to moderate Thursday night with renewed warming. SNOW LEVELS ft N ft S Tue ft N ft S early Wed ft Nand S later Wed ft N ft S Thu... snow level probably near the surface Cascade east slopes and passes late Tuesday and early Wednesday, and again late Thursday in advance of the frontal systems. A'A a.aaaa'a. '.'. ',,,.,_..,_,_A'a' ** a... AVALANCHE ADVISORY Advisories apply to back country avalanche terrain below 7000 feet. They do not apply to highways or operating ski areas. For the most current avalanche advisory... please call: (503) (Oregon) (206) (Washington) A_A._.a k_. '._..'.'.._._'._.,ta_ - ZONE AVALANCHE FORECASTS... WASHINGTON CASCADES NORTH OF MT RAINIER... Considerable avalanche danger Sunday above 4000 feet and moderate below. Danger decreasing on Monday becoming considerable above 5000 feet and moderate below. WASHINGTON CASCADES RAINIER SOUTH...OLYMPICS... Considerable avalanche danger Sunday above 5000 feet and moderate below. Danger decreasing on Monday becoming considerable above feet and moderate below. MT HOOD AREA... Considerable avalanche danger above 5000 feet Sunday and moderate below. Danger decreasing on Monday becoming considerable above 6000 feet and moderate below. SNOWPACK ANALySiS... About a half and inch to an inch of water equivalent was seen at most locations near and west of the Cascade crest on Saturday, which fell as damp snow at higher elevations and as rain at lower elevations, with the snow level at about 3500 feet in the north and about 5000 feet in the south. Mt Baker and Stevens Pass reported 11 and 6 inches of new snow respectively. At most locations there has been up to several inches of settling of the 4 to 8 feet of snow received the past few days near and west of the crest, and the 2-3 feet seen east of the crest. We have reports from snow pits on Sunday morning that weak layers and easy shears seen Saturday have settled and strengthened. However, mainly at higher elevations where extremely strong winds were seen much of Saturday there is still certainly the possibility of weak layers and local unstable wind slab persisting, mainly on northeast to south east aspects. Therefore, caution and good routefinding should still be used at higher elevations where deep avalanches are still possible. We also have more reports of the buried, mid November recrystallized snow east of the Cascade crest. Loading by new snow east of the crest is apparently becoming great enough that smaller triggers are required to release these layers which are near ground level. Although natural avalanches are not expected in this area, groups of persons or snowmobilers should use caution since triggered avalanches or large loading could cause deeper releases. Persons traveling on or near steeper slopes east of the Cascade crest should travel with a safe amount of space between them to avoid loading these types of slopes. Sunday... Gradually increasing south winds and rain or snow at rising snow levels should develop on Sunday. Rain or snow should be heaviest on the south volcanoes or locations exposed to south flow. East winds may help temporarily maintain lower snow levels in the higher Cascade passes Sunday morning, but snow levels should rise to near free air levels at feet by Sunday afternoon. Although significant settling has recently occurred, the wet snow or rain should add some loads to any unstable wind slab which 108

15 should be mainly on northeast to southeast facing slopes at higher elevations. Some local new wind slab is possible on north slopes above feet. Monday... Gradual cooling, moderate west flow and light to occasional moderate snow should be seen Monday, which should decrease Monday night. New snow should generally bond fairly well to previous surfaces due to the cooling, and new lower density snow should help create more favorable density profiles near the surface. This should lead to slightly less avalanche danger. However, the westerly flow may create some new isolated shallow wind slab on more easterly aspects at higher elevations. Due to the possible new shallow wind slab or previous wind slab, unstable snow should remain possible on steep terrain and back-country travelers should continue to use caution near avalanche terrain. ***************************************************** *************** Backcountry travelers should be aware that elevation and geographic distinctions are approximate and a transition zone between dangers exists. Remember, there are avalanche safe areas in the mountains during all levels ofavalanche danger. Contact local authorities in your area ofinterest for further information. 109