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ALASKA and NORTHWESTERN CANADA 

Weather and Climate Highlights and Impacts, Sept.-Nov. 2018; Climate Outlook Jan.– Mar. 2019
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Temperature & Precipitation, September-November 2018

Source: NOAA and ECCC 

Source: NOAA and ECCC 

Between September and November 2018, Alaska, the majority of the Yukon Territory, and a small

portion of northwestern Northwest Territories (NT) experienced warmer than average conditions.

Small pockets of below average temperatures were recorded in northern BC and southeastern

NT. In contrast, below average temperatures were observed over the eastern NT over that same

period (not shown on the map). Total precipitation between September and November 2018 was

below average over a small area in northwestern Alaska, and across a band spanning southern

Alaska, southern Yukon, and southern NT. On the other hand, above normal precipitation was

observed along the coast of the Beaufort Sea extending inland along the Alaska/Yukon border,

and over northern eastern British Columbia.

A persistent high pressure system brought warmer and drier than average conditions in Alaska.

The photo above shows the resulting lack of sea ice along the shore of the Beaufort and Chukchi

Seas, as well as the large extent of bare ground in Northern Alaska on October 4, 2018, where

snow was limited to mountainous areas. Photo courtesy of GINA/UAF, Rick Thoman, 2018.

Unlike the majority of the Beaufort Sea area, the

ocean edge in the Tuktoyaktuk area started

freezing in October, and water stayed open until the

end of November. This is much later than usual for

the community, which typically sees freeze up by

late September. This was partly due to warmer than

average ocean temperatures.

The photo on the left shows a young boy throwing a

rock into the ocean from a beach in Tuktoyaktuk,

NT in late October 2018. Photo credit: Janet Elias.
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Warm sea surface temperatures in the Bering and Chukchi Seas

Exceptionally mild sea surface temperatures continued across the Bering and Chukchi Seas

through most of the autumn, as seen by the red areas in the above figure. The October average

sea surface temperatures were 3oC above normal (red areas) everywhere north of St. Matthew

Island. These are exceptionally large departures for sea surface ocean temperatures for this time

of year in this region. This follows the summer when temperatures were very mild and which saw

dramatic changes in fish stocks in the northern Bering Sea as Alaska Pollock swarmed north and

Arctic Cod were hardly to be found.

The Gulf of Alaska was also very warm relative to normal. However, these warmer conditions are

part of the warmth that covers most of the Pacific Ocean north of Hawai’i, which is quite different

in origin and extent from the very warm northeast Pacific that made headlines in 2014 and 2015.

A few boats remain in the still ice-free harbor at Nome, Alaska

on November 1, 2018. Photo by R. Thoman.

The influence of key climate indicators on the region 

The figure shows the typical El Niño

winter pattern, with warmer than

average air temperature over

western North America, and wetter

and cooler than average conditions

in southern United States. Figure

courtesy NWS/NCEP Climate

Prediction Center.

The climate of Alaska and northwestern Canada can be influenced by different climate indices, which

vary on a yearly basis. The main climate indicators of the region are El Niño, the Arctic Oscillation (AO),

the Pacific North American Pattern (PNA) and the Pacific Decadal Oscillation (PDO). As El Niño is

developing this winter, its intensity is forecast to be weak to moderate at most. As a result, El Niño will

only have some minor effects on weather in Alaska and northwestern Canada. This winter, the region will

likely experience a winter similar to last year, where most of the region experienced warmer and wetter

than average conditions, as illustrated in the above figure. Compounding climate effects from the AO,

PNA, and PDO will likely have variable combined effects on winter conditions. Together, the key climate

influences (El Nino, AO, PNA & PDO) will likely lead to a near normal winter, with air temperatures

forecast to be somewhat above normal while precipitation will be highly variable throughout the region.

Snow and sea ice cover, on the other hand, are likely to be lower than normal.

Drought conditions in southeast Alaska

The figure to the left shows the

anomalously low water levels in

Green Lake Dam near Sitka, Alaska.

Typical water levels at this site are

about half way up the dam from the

level in this photo, where a white

water level mark can be seen. Photo

courtesy KCAW Radio.

Can a location that averages 150 inches (3,800 mm) of precipitation annually, and whose driest year saw

85 inches (2,100 mm) ever have a drought? The answer is unequivocally "yes" if you are in Ketchikan,

Alaska. Over the last year, Ketchikan is over 30" (750 mm) below normal for precipitation. Fall 2018 saw

a precipitation deficit of over 16" (400 mm)! The resultant drop in area lakes caused the hydroelectric

generator at Swan Lake to be shut off in mid-October for several weeks. This meant that diesel was

burned to generate electricity – a substantial cost to the community and environment.
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Sea Ice Conditions at the end of November 2018 in the Beaufort and Chukchi Seas

Sea ice north of Alaska continued to melt back during September and did

not reach the lowest extent of the season until the first week of October.

Thereafter, sea ice increased in the Chukchi Sea but there was no

appreciable ice anywhere in the Bering Sea until the first days of

November. Although sea ice growth was faster in Chukchi Sea during

November 2018 than in November 2017, sea ice extent remained far

below historical normal. The Bering Sea remained at or near record low

ice extent due to the combination of a significantly warmer than average

ocean surface temperatures and a change weather pattern that did not

allow ice to set up and thicken.

By the end of November, freeze-up was complete in the Beaufort Sea. In

addition, the region is experiencing overall greater than normal old ice

which makes up 55% of the overall ice coverage in the region. Indeed, the

old ice edge was located further south than normal and was about 30 to

50 nautical miles north of Hershel Island, Prudhoe Bay and Point Barrow

by the end of November. The only exception is the northwestern part of

the Beaufort Sea, which had less than normal old ice at that same time.

Temperature Outlook: Jan.-Mar. 2019 Precipitation Outlook: Jan.-Mar. 2019

A combined Canada-USA climate forecast model is used to provide

temperature and precipitation outlook for January-March 2019.

The temperature outlook for January through March 2019 shows that

Alaska and northwest Canada have a 40-90% chance of above average

temperature (warm colors). None of the area is forecast for having

chances of below average temperatures for that period.

The precipitation outlook for January through March 2019 shows that

most of eastern Alaska, the Yukon, the western part of the NWT, and

northern British Columbia have a 40-60% chance of above normal

precipitation (green areas). The majority of western Alaska, a portion of

northern Alaska along the coast of the Beaufort Sea, as well as the Great

Slave Lake area, Banks Island, and the portion of Victoria Island showing

on the map in the NWT have a 40-50% likelihood of below normal

precipitation (brown areas).

Content and graphics prepared in partnership with the Alaska Center for Climate Assessment and Policy and Environment and 

Climate Change Canada. 

ALASKA REGION PARTNERS: Alaska Climate Research Center, Alaska Climate Science Center, National Snow and Ice Data Center 

(NSIDC), NOAA / NWS Weather Forecast Offices, NOAA National Weather Service Alaska Region, NOAA / NESDIS / NCEI, 

Scenarios Network for Alaska + Arctic Planning. 

ALASKA CENTER FOR CLIMATE 

ASSESSMENT AND POLICY CONTACTS: 

RICK THOMAN rthoman@alaska.edu 

BRIAN BRETTSCHNEIDER: 

brbrettschneider@alaska.edu

ENVIRONMENT AND CLIMATE CHANGE 

CANADA WESTERN CONTACTS: 

GABRIELLE GASCON 

gabrielle.gascon@canada.ca