The Climate of Alaska for 2012
By Gerd Wendler, Blake Moore and Kevin Galloway of the Alaska Climate Research Center at the Geophysical Institute, UAF
This review of the climate of Alaska is predominantly based on the 20 first order climatological stations in Alaska, which are operated by NOAA’s National Weather Service. These stations are all of high quality, operated by professional meteorologists with identical or similar meteorological instrumentation and observational practices. However, this should not be taken as a sign that other stations, which might be operated by other agencies, industries or private individuals, are of poor quality. The normals used in this analysis are based on means of the 30-year time period from 1981-2010 and were calculated by NOAA’s National Climate Data Center. A convenient source for the NCDC normals of all stations for Alaska can be obtained at http://ggweather.com/normals/AK.html.
The mean average annual temperature in 2012 for the 20 stations was 30 degrees Fahrenheit, a substantial negative departure of 2.9 degrees from the 30-year normal of 32.9 degrees Fahrenheit. This is in stark contrast to the Lower 48 where record high temperatures were observed. There was only one station with a positive deviation. It was Barrow in northern Alaska with a deviation of plus 1.3 degrees Fahrenheit, continuing the trend of warming observed on the North Slope over the last decades (Wendler, Shulski and Moore 2010). All other stations were below normal, continuing the cooling trend of Alaska seen in the 21st century (Wendler, Chen and Moore 2012). The largest negative deviations were observed in the Bering Sea area, with both Bethel and King Salmon reporting a deviation of minus 5 degrees Fahrenheit, a very substantial value for mean of an entire year.
Figure 1 presents the temperature deviation data. It can be seen that solely northwestern Alaska was above normal, while all the rest of the state was too cold when compared to the normal. A new minimum in the sea ice extent in the Arctic Ocean was observed in September 2012. The lack of sea ice affected Barrow’s temperatures and in October the temperature deviation from the 30-year normal was a very substantial plus 10.3 degrees. The greatest negative deviations were found in the Bering Sea area. This is understandable after noting that sea ice extent for the Bering Sea recorded a new maximum in April for the time period since microwave satellite measurements became available. (Microwave instruments provide for observations of the sea ice through clouds and darkness.) This is, of course, in direct opposition to the above noted sea ice minimum observed in the Arctic Ocean.
The stations in southeastern Alaska reported deviations between minus 1 and minus 2 degrees Fahrenheit, rather typical for a maritime climate where deviations are less prominent. In summary, nearly all of Alaska was below normal for 2012. This was even more pronounced than what had been observed in 2011. Actual temperature deviations by station can be seen from Table A, with 19 of the 20 stations recording negative temperature deviation and an overall mean deviation of minus 2.9 degrees was calculated.
The mean deviation of temperatures by month is presented in Figure 2 for the 20 stations. The figure shows that only February and April were warmer than normal, with positive deviations of 2 degrees Fahrenheit. All other months were too cold when compared to the normal. Especially remarkable was January, with a mean deviation for all stations exceeding minus 14 degrees Fahrenheit. For one station it would be a very large deviation, however for the mean value of 20 stations fairly well distributed over such a large area as Alaska, it is astounding. Many new record low temperatures were observed. For example, Bettles, in the northern Interior, recorded temperatures at or below minus 60 degrees Fahrenheit for the last three days of the month. The monthly deviation exceeded minus 25 degrees Fahrenheit, making it the coldest January on record. In addition, January was also the coldest on record for Bethel, Homer and Nome and tied for the coldest at Cold Bay. It was the second coldest January for Kotzebue since 1929 and the third coldest January for Kodiak and St. Paul Island (with 99 years of data to draw upon). In general, Figure 2 shows that the winter months were much too cold across Alaska, while the summer deviations, though still negative, were much smaller in magnitude. This is also reflected in the record events reports, where new record lows outnumbered new highs by a ratio of about nine new lows to five new highs for the first order stations.
The mean annual precipitation of the 20 stations was 35.86 inches, which is close to the long-term mean of 36.86 inches. As reported previously (Shulski and Wendler 2007), there is a very large variation in the precipitation totals when traversing from the southeast (Yakutat reported in 2012 a total of 107.94 inches) to the north (Barrow recorded an annual value of just 6.27 inches). It is even more remarkable that for 2012 Barrow reported 138 percent of normal precipitation, a value that is, when expressed as a percentage, not surpassed by any other first order station in Alaska for 2012. This large gradient in precipitation explains the fact that most glaciers are found in southern Alaska, with many calving in the ocean. In contrast, in the Brooks Range in northern Alaska where the temperatures are much colder, glaciers are less common and smaller in size. In Figure 3 the precipitation values are presented across Alaska, however isolines are not provided, as large variations can occur over short distances, especially in the summer due to localized shower activities. The figure shows that most of Interior Alaska had deficits in precipitation, while the coastal areas were somewhat above the expected values. However, altogether the deviations were small. More details can be seen in Table B, in which the actual deviation values by station are presented.
The precipitation deviations by month are presented in Figure 4 for the mean of the 20 stations. The figure displays that the first three months of the year observed above normal precipitation, while April was much too dry. The dry April was a bad start with respect to wildfires. However, the following three months reported above normal rainfall and it became a good year as far as acreage burned. Less than 300,000 acres were consumed by wildfires, less than one-third of the normal value. May 16th witnessed 0.84 inches of rain in Nome, a record of any day in May with data stretching back to 1907. August was a bit dry, while September was quite wet. In September, Valdez seta new daily record of 4.27 inches of precipitation, more than double the 1993 record of 2.01 inches. There was little snow in November and December, allowing for the frost to penetrate deeper into the ground than normal. The low precipitation in November was exemplified by Nome, with just 0.02 inches total precipitation equivalent, tying the record low for Nome for November.
Precipitation falls in summer as rain and as snow in winter. Winter is, of course, much longer in northern Alaska than in Southeast. In Figure 5, the annual snowfall for the stations is presented. It should be pointed out that four stations did not report snowfall amounts (Big Delta, Gulkana, Homer and Talkeetna) and one station (Bettles) was excluded for questionable data quality. It can be seen that two stations, Cold Bay and Yakutat, both coastal stations, measured more 80 percent above the expected amount of snowfall. Kodiak, King Salmon and Barrow, again all coastal stations, surpassed the expected snowfall by 60 percent. On the other extreme was Kotzebue, with only about half of the expected value of snowfall.
Anchorage hit the books in 2012 with a record winter snowfall. On April 7th the total reached 134.5 inches, topping the old record of 132.6 inches set in 1954-1955. This last bit of snow broke the record while ending the snowfall for the winter. The new winter record was built from numerous light snowfalls (with at least 36 days of more than an inch) and only two days of more than 7 inches. Only one daily snowfall record was set during the winter in Anchorage and that was 9.1 inches on February 3rd, which beat the 1970 record of 5.4 inches. Cold Bay also set a seasonal snowfall record of 83.6 inches, topping the 80.9 inches from 2008-2009. The frigid January saw a record monthly snowfall for Kodiak at 48.6 inches, breaking the 2004 monthly record of 40.4 inches. Valdez set a February snow depth record with 97 inches on the ground on the 27th, besting the 1990 record of 94 inches. Maximum snow on ground in Valdez occurred on March 3rd at 100 inches.
For more exhaustive monthly statewide summaries, as well as some select station summaries, including more detail on record events, please visit the ACRC website at http://akclimate.org. For seasonal reports, visit ACCAP’s website for the Alaska’s Climate Dispatch at http://ine.uaf.edu/accap/. In addition, the papers referenced below can be accessed from the ACRC's website.
Shulski, M., and Wendler, G. 2007. The Climate of Alaska. University of Alaska Press, 216pp
Wendler, G., M. Shulski and B. Moore 2010: Changes in the Climate of the Alaskan North Slope and the ice concentration of the adjacent Beaufort Sea. Theoretical and Applied Climatology. 99, 67-74
Wendler, G. and M. Shulski 2010. A Century of Climate Change for Fairbanks, Alaska. Arctic 62(3): 295-300
Wendler, G. L. Chen and B. Moore 2012. The first Decade of the New Century: A cooling trend for most of Alaska. The Open Atmospheric Science Journal 6, 111-116
This information consists of preliminary climatological data compiled by the Alaska Climate Research Center, Geophysical Institute, University of Alaska Fairbanks. For more information on weather and climatology, contact the center at 474-7885 or visit the center web site at http://akclimate.org. Please report any errors to firstname.lastname@example.org.