Thompson Pass
{{Infobox mountain pass
| name = Thompson Pass
| photo = Thompson Pass.jpg
| photo_caption = Thompson Pass, as seen in May 2009.
| elevation_ft = 2805
| elevation_ref =
| traversed = Richardson Highway, Trans-Alaska Pipeline System
| location = Valdez-Cordova Census Area, Alaska, United States
| range = Chugach Mountains
| coordinates = {{coord|61|07|43|N|145|43|47|W|type:pass|display=inline,title}}
| topo =
}}
Thompson Pass is a 2,600 foot-high (855 meter-high) gap in the Chugach Mountains northeast of Valdez, Alaska.Geographic Names Information Service. [http://geonames.usgs.gov/pls/gnispublic/f?p=gnispq:3:::NO::P3_FID:1410888 "Thompson Pass, Alaska"], U.S. Geological Survey. Accessed July 2, 2009. It is the snowiest weather station in Alaska, recording {{convert|500|in|m|sigfig=2|disp=or}} of snow per year on average.Desert Research Institute. [http://www.wrcc.dri.edu/htmlfiles/state.extremes.html "State Extremes: Alaska"], Western Regional Climate Center. Accessed July 2, 2009. In the winter of 1952–1953, {{convert|974.1|in|m|sigfig=2|disp=or}} of snow fell—the most ever recorded in one season at one location in Alaska.{{cite news |title= Alaska Snowfall and Snow Depth Extremes Table |work= National Climatic Data Center |publisher= National Oceanic and Atmospheric Administration |accessdate= February 9, 2013 |url= http://www.ncdc.noaa.gov/ussc/USSCAppController?action=extremes&state=50 }} It is not the most snow ever recorded in one season at one location anywhere in the fifty states as that record belongs to Mount Baker Ski Resort at {{convert|1140|inch|m|sigfig=2|disp=or}} in 1998–99.{{cite news |title= National Snowfall and Snow Depth Extremes Table |work= National Climatic Data Center|publisher= National Oceanic and Atmospheric Administration |accessdate= February 9, 2013 |url=http://www.ncdc.noaa.gov/ussc/USSCAppController?action=extremes&state=1100 }} The pass also holds the Alaska record for the most snow in a single day: {{convert|62|in|m|sigfig=2|disp=or}} fell on December 29, 1955.
The pass was named in 1899 by U.S. Army captain William Abercrombie "in compliment to Hon. Frank Thomson, of Pennsylvania", but he spelled the name "Thompson" on his sketched map, and that spelling stuck. The pass had been used by Alaska Native Ahtna people for generations prior to Abercrombie's arrival, but he marked and defined a trail through the pass for use by Klondike Gold Rush miners.Bleakley, Geoffrey. [http://www.nps.gov/wrst/historyculture/history-of-the-valdez-trail.htm "History of the Valdez Trail"], U.S. National Park Service. Accessed July 2, 2009. His route, which became the Valdez-Eagle Trail, later was used by the Washington-Alaska Military Cable and Telegraph System, which strung cables through Thompson Pass. The path through the pass continued to be improved, and automobiles first drove the entire length of the trail in 1913. By that point, it had become the Valdez-Fairbanks Trail, and it was renamed the Richardson Road in 1919.Wrangell-St. Elias National Park and Preserve. [http://www.nps.gov/wrst/historyculture/the-valdez-trail.htm "The Valdez Trail"], U.S. National Park Service. Accessed July 2, 2009.
Because of heavy snowfall in Thompson Pass, the Richardson Highway was used only in summer.{{Citation needed|date=July 2009}} Not until 1950, when a freight company foreman demonstrated that the pass could be kept open with snowplows, was the road drivable year-round.{{Citation needed|date=July 2009}} The trail through the pass remained gravel until 1955, when the Alaska Road Commission (part of the US Department of the Interior) paved it.Byron Johnson, PE
Pipeline construction
In the early 1970s, Thompson Pass was the scene of frantic activity as thousands of workers built a portion of the Trans-Alaska Pipeline System from a camp located nearby.{{Citation needed|date=July 2009}} Heavy snowfall in the pass slowed work in the winter, but the pipeline was completed by 1977, and oil today flows through the pass on an almost constant basis.{{Citation needed|date=July 2009}}
File:The Valdez bound Thompson Pass sign, as seen in May16..jpg
Because Valdez is the southern terminus of the pipeline and Thompson Pass provides the only overland transportation link to Valdez, the state of Alaska maintains a road service station in the pass to keep it plowed and ice-free year-round. This facility includes Thompson Pass Airport, a short landing strip used by state aircraft. The work of keeping the highway through the pass clear is extremely challenging due to weather conditions and was highlighted in the Discovery Channel television special Alaska: Most Extreme.
Recreation
The pass is a popular destination for tourists and adventurers. Heliskiing and snowboarding are popular recreational activities in the winter, and in the summer, hiking and backpacking is commonplace as well. Notable hikes in the summer include Little Odyssey and the Kaden Lake Trail.
File:A view of Kaden Lake with Little Odyssey in background-July 2024.jpg
Protected areas
File:Blueberry Lake campsite.jpg
Blueberry Lake State Recreation Site is a {{convert|192|acre}} park in Thompson Pass. It has a lake with Arctic grayling in it, a campground, and several picnic areas.[http://dnr.alaska.gov/parks/aspunits/kenai/blueberrylksrs.htm Blueberry Lake SRS] Alaska Department of Natural Resources It has been described as “one of Alaska’s most beautifully situated campgrounds”.The Milepost 2018 Edition, page 433, Morris Communications {{ISBN|9781892154378}}
Worthington Glacier State Recreation Site is a {{convert|113|acre}} site with picnic areas, interpretive displays, and trails enabling visitors to approach the glacier.[http://dnr.alaska.gov/parks/aspunits/kenai/worthglsrs.htm Worthington Glacier SRS] Alaska Department of Natural Resources
Climate
Thompson Pass has an alpine tundra climate (ET) with one of the highest snow totals in the world.{{Cite web|title=THOMPSON PASS, ALASKA - Climate Summary|url=https://wrcc.dri.edu/cgi-bin/cliMAIN.pl?akthom|access-date=2020-07-07|website=wrcc.dri.edu}}
The Upper Tsaina River SNOTEL weather station is located close to the summit of Thompson Pass at a height of 1750 feet (533 metres).
{{Weather box
|location = Upper Tsaina River, Alaska, 2004–2020 normals, 1991-2020 precipitation: 1750ft (533m)
|single line = Yes
|Jan record high F = 47
|Feb record high F = 45
|Mar record high F = 50
|Apr record high F = 61
|May record high F = 76
|Jun record high F = 88
|Jul record high F = 92
|Aug record high F = 85
|Sep record high F = 74
|Oct record high F = 60
|Nov record high F = 47
|Dec record high F = 50
|Jan avg record high F = 37
|Feb avg record high F = 39
|Mar avg record high F = 42
|Apr avg record high F = 52
|May avg record high F = 65
|Jun avg record high F = 77
|Jul avg record high F = 80
|Aug avg record high F = 76
|Sep avg record high F = 67
|Oct avg record high F = 52
|Nov avg record high F = 37
|Dec avg record high F = 38
|year avg record high F = 78
|Jan high F = 12.3
|Feb high F = 20.3
|Mar high F = 28.5
|Apr high F = 42.0
|May high F = 52.7
|Jun high F = 62.2
|Jul high F = 66.2
|Aug high F = 62.9
|Sep high F = 53.5
|Oct high F = 38.9
|Nov high F = 20.8
|Dec high F = 16.3
|year high F =
|Jan mean F = 4.4
|Feb mean F = 10.7
|Mar mean F = 17.5
|Apr mean F = 31.5
|May mean F = 42.8
|Jun mean F = 51.3
|Jul mean F = 55.7
|Aug mean F = 52.7
|Sep mean F = 44.6
|Oct mean F = 31.8
|Nov mean F = 13.9
|Dec mean F = 9.0
|year mean F =
|Jan low F = -3.7
|Feb low F = 1.1
|Mar low F = 6.4
|Apr low F = 21.0
|May low F = 32.9
|Jun low F = 40.4
|Jul low F = 45.2
|Aug low F = 42.5
|Sep low F = 35.5
|Oct low F = 24.7
|Nov low F = 7.0
|Dec low F = 1.7
|year low F =
|Jan avg record low F= -30
|Feb avg record low F= -23
|Mar avg record low F= -14
|Apr avg record low F = 2
|May avg record low F = 25
|Jun avg record low F = 32
|Jul avg record low F = 37
|Aug avg record low F = 32
|Sep avg record low F = 24
|Oct avg record low F = 6
|Nov avg record low F = -17
|Dec avg record low F = −23
|year avg record low F = −33
|Jan record low F = -39
|Feb record low F = -35
|Mar record low F = -25
|Apr record low F = -17
|May record low F = 16
|Jun record low F = 29
|Jul record low F = 34
|Aug record low F = 27
|Sep record low F = 12
|Oct record low F = -11
|Nov record low F = -29
|Dec record low F = -34
|precipitation colour = green
|Jan precipitation inch = 4.30
|Feb precipitation inch = 3.74
|Mar precipitation inch = 2.55
|Apr precipitation inch = 1.03
|May precipitation inch = 1.33
|Jun precipitation inch = 0.94
|Jul precipitation inch = 1.77
|Aug precipitation inch = 3.81
|Sep precipitation inch = 6.94
|Oct precipitation inch = 5.24
|Nov precipitation inch = 4.51
|Dec precipitation inch = 5.39
|year precipitation inch =
{{cite web
|url = https://xmacis.rcc-acis.org/
|publisher = National Oceanic and Atmospheric Administration
|title = xmACIS2
|access-date = November 7, 2023
}}
|source 2 = NOAA (Precipitation)
{{cite web
|url = https://www.ncei.noaa.gov/access/services/data/v1?dataset=normals-monthly-1991-2020&startDate=0001-01-01&endDate=9996-12-31&stations=USS0045M07S&format=pdf
|title= Upper Tsaina River, Alaska 1991-2020 Monthly Normals
|access-date = November 7, 2023
}}
}}
{{Weather box
|location = Thompson Pass, AK
|single line = Yes
|Jan record high F = 43
|Feb record high F = 42
|Mar record high F = 50
|Apr record high F = 56
|May record high F = 62
|Jun record high F = 69
|Jul record high F = 73
|Aug record high F = 70
|Sep record high F = 60
|Oct record high F = 61
|Nov record high F = 44
|Dec record high F = 42
|year record high F = 74
|Jan high F = 10.3
|Feb high F = 18.7
|Mar high F = 24.8
|Apr high F = 36.7
|May high F = 40.7
|Jun high F = 54.1
|Jul high F = 57.7
|Aug high F = 54.6
|Sep high F = 46.8
|Oct high F = 33.7
|Nov high F = 21.5
|Dec high F = 14.1
|year high F= 34.5
|Jan mean F = 4.8
|Feb mean F = 13.4
|Mar mean F = 18.8
|Apr mean F = 29.7
|May mean F = 33.4
|Jun mean F = 45.2
|Jul mean F = 49.2
|Aug mean F = 48.1
|Sep mean F = 40.1
|Oct mean F = 29.1
|Nov mean F = 16.8
|Dec mean F = 8.7
|year mean F =
|Jan low F = -0.7
|Feb low F = 8.9
|Mar low F = 12.8
|Apr low F = 22.5
|May low F = 26.1
|Jun low F = 36.2
|Jul low F = 40.7
|Aug low F = 41.6
|Sep low F = 33.4
|Oct low F = 24.4
|Nov low F = 12.0
|Dec low F = 3.8
|year low F= 21.8
|Jan record low F = -33
|Feb record low F = -28
|Mar record low F = -29
|Apr record low F = -10
|May record low F = 0
|Jun record low F = 29
|Jul record low F = 31
|Aug record low F = 20
|Sep record low F = -3
|Oct record low F = -23
|Nov record low F = -39
|Dec record low F = -40
|year record low F = -40
|precipitation colour = green
|Jan precipitation inch = 6.18
|Feb precipitation inch = 8.41
|Mar precipitation inch = 7.11
|Apr precipitation inch = 6.29
|May precipitation inch = 1.92
|Jun precipitation inch = 1.32
|Jul precipitation inch = 4.66
|Aug precipitation inch = 4.62
|Sep precipitation inch = 5.93
|Oct precipitation inch = 10.82
|Nov precipitation inch = 10.09
|Dec precipitation inch = 9.89
|year precipitation inch= 77.25
|Jan snow inch = 61.9
|Feb snow inch = 92.1
|Mar snow inch = 65.9
|Apr snow inch = 56.6
|May snow inch = 23.1
|Jun snow inch = 0.0
|Jul snow inch = 0.0
|Aug snow inch = 0.0
|Sep snow inch = 8.7
|Oct snow inch = 65.3
|Nov snow inch = 83.1
|Dec snow inch = 94.7
|year snow inch = 551.5
|source 1 = The Western Regional Climate Center
{{cite web
|url = http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?akthom
|publisher = Western Regional Climate Center
|title = THOMPSON PASS, ALASKA (509146)
|access-date = May 14, 2016
}}
{{cite web
|url = https://www.weatherbase.com/weather/weather-summary.php3?s=641905&cityname=Thompson+Pass,+Alaska,+United+States+of+America
|publisher = Weather Base
|title = Thompson Pass Alaska - Climate Summary
|access-date = July 6, 2023
}}
}}
See also
[[File:Color post card. "Winter Trail over Thompson Pass, Alaska." Dog Sled Teams. - NARA - 297822.jpg|thumb|right|280 px|Horse-drawn sleds crossing Thompson Pass in the early years of the 20th Century
]]
- Mount Billy Mitchell (Chugach Mountains)
- Keystone Canyon, which is the route connecting the Pass to Valdez