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StormsandAvalanchesofNovember1995,KhumbuHimal,Nepal RichardKattel mann1andTomomiYamada2 1 Sierra Nevada Aquatic Research Lab, Star Route 1, Box198, Mammoth Lakes, CA 93546 USA phone: 619/935-4903 fax: 619/935-4867 email: rick@icess.ucsb.edu 2 Institute of Low Temperature Science, Hokkaido University, Sapporo, 060 Japan

Key Words: severe storms, rare avalanches, Nepal HimalayaAbout75-80percent oftheannualprecipitation ofthe
Khumbu Himal (MountEverest region) of east Nepal oc-
ABSTRACT^{cursduringthesummermonsoonperiod(Inoue,1976).}
A severe storm struck the Nepal Himalaya on November 9^{Average annualprecipitationat valley stations is about one}
and 10,1995.This storm wasthe most intense event to^{meter at elevations of 3,400 to 3,900 m, and less than a half}
occur during the autumn in at least 50 years.The autumn^{meter at 4,400 m (Inoue, 1976).There are indications that}
season in the Himalaya tends to be quite dry, so this storm^{precipitationmaybeconsiderablygreaterontheupper}
seemed extraordinary.Precipitation gages at lower eleva-^{slopes than in the valleys in this area(Higuchi, etal. 1982).}
tions caught 50 to 200 mmof rain during the storm.Cold^{Although extraordinary amounts of rainfall (hundreds of}
temperatures ledto snowfall above 3,500 m in the Khumbu^{millimeters perday) can occur during the summerin the}
region of east Nepal,and snow depths increased rapidly^{Himalayan foothills,daily amounts exceeding 50 mm are}
with elevation.About 30-50 cm of snow fell at 3,800m;^{relatively rare in thehigh-elevation valleys of the Khumbu}
50-100 cm of snow was found at about 4,000 m;and 100-^{Himal.Inthepost-monsoonperiod,skiesaretypically}
200cmofsnowwasdepositedabove5,000m.Thein-^{cloud-free and precipitation is unusual (Yasunari,1976).}
tensesnowfallgenerated numerousavalanches through-^{During winter, westerly disturbances occasionally deposit}
out the region.A few had tragic consequences.The worst^{a few centimeters of snow.Total winter-season accumula-}
incident occurrednear the village of Pangkhain the Gokyo^{tion at two sites above 5,500 min the Langtang region of}
Valley where a crowded lodgewas destroyedbyan iso-^{central Nepal averagedabout 200 mm of water equivalence}
latedavalanche.Twenty-four peoplewerekilledthere.^{(Steinegger, et al., 1993).This region is believed to receive}
Sevenotherdeathsresultedfromanavalancheinthe^{considerablymoreprecipitationthantheKhumbuarea}
Kanchenjungaarea of far eastern Nepal.Many otherpeo-^{(Steinegger, et al., 1993).}
ple were involved in non-fatal avalanche accidents.Hun-^{Avalanches are not known to have been the subject of}
dredsofpeoplewerestrandedbythedeepsnowsand^{any systematic study in the Nepal Himalaya.Most of the}
approximately 550 people were flown out of thesnow zone^{scientificworkonHimalayanavalancheshas beencon-}
by helicopters.At least 100 animals were lost by burial in^{ducted at the Snow and Avalanche Study Establishment}
the deep snows.Village life in the higherareas was dis-^{in Manali, India(e.g., MohanRao, et al., 1987).Additional}
ruptedthroughmuchofthewinter.Theresidualdeep^{researchhasbeenconductedevenfartherwestinthe}
snowsresultedinanotheravalanche cycleinMarchas^{Karakorum (e.g.,de Scally and Gardner, 1990 and 1994).}
percolating melt water destabilized slopes.^{A brief descriptionof avalanchephenomenaintheKhumbu}
Himal was written by Andre Roch (1954) during the Swiss
INTRODUCTION^{reconnaissanceexpeditions to Mount Everest.Most of the}
ThesnowclimateandavalancheregimeoftheNepal^{observations of avalanches in the area have been made by}
Himalayaispoorlydocumentedinwesternliterature.^{climbers.Avalanches on the high peaks have killed a sur-}
Occasional scientific work has been conductedin associa-^{prisinglylarge fractionofclimbers,especially whenex-}
tionwithmountaineeringexpeditions (e.g.,Roch,1954;^{pressed in relation to successful ascents (McClung, 1981).}
Muller,1959),and some expedition reports contain anec-^{The avalanchehazard to Himalayan climbers ranges from}
dotal information that might be useful to compile.Much^{smallsluffsthatcause a climbertofalltogiantice ava-}
of ourcurrent knowledge has been developed during the^{lanches that descend thousands of meters and impact ex-}
Japanese Glaciological Expedition to Nepal (e.g., Higuchi,^{posed base camps (McClung, 1981).Countless mountain-}
1976and1993).Nepal'sDepartmentofHydrologyand^{eering articles describe avalanche releases from the steep}
Meteorologyhasexpandedroutinedatacollectioninto^{terrain after even a few centimeters of snowfall.}
higher elevation areas in recent years (Grabs and Pokhrel,
1993).If these stations can be continued,the systematic^{THESTORM OF NOVEMBER 1995}
record shouldeventuallyyieldacharacterization ofthe^{Although cyclonic storms routinely develop in the Bay of}
snow climate ofthe Nepal Himalaya.However,fornow,^{Bengal in the post-monsoon period, they typically remain}
we are left with sporadic snapshots of storm activity and^{at low latitudes and do not approach the Himalaya.The}
snow coverof thishigh mountain area.Thispaper pro-^{storm that began to develop on November7, 1995did not}
videsabriefdescriptionofthemostseveresnowstorm^{appear unusualat its onset.However, it soon took a trajec-}
and avalanche cycle known to have occurred in east Ne-^{tory almost due north, the only such event documented in}
pal.^{November between1891 and 1970 (more recentstorm track}
The climate of the Himalayan region isdominated by^{datawas notavailable)(Yamada, etal.,1996).Initially,}
the monsoon circulation that results in high precipitation^{thepathofthestormwasdirectedtowardwest-central}
from June through September, andrelatively little precipi-^{Nepal, but rapidlychangingcirculationmoved the air mass}
tationduringthe balanceoftheyear(e.g.,Mani,1981).^{into east Nepal on November 9.Orographiclifting resulted}
inheavypr ecipitationinthehigherHimalaya.

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