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2012 Year in Review - Fairbanks
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Persistently colder than normal temperatures along with near normal precipitation and snowfall for Fairbanks for 2012 |
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The mean temperature for Fairbanks in 2012 was
24.1°F, 3.5°F below the long-term average of 27.6°F. This makes 2012 the
coldest year of the new century, and continues the cooling trend observed over
the last decade. More information on the recent cooling trend in Alaska can be
read in this
paper from the ACRC. Looking further back in time, 2012 was the second
coldest year in the last forty for Fairbanks. Only 1999, with a mean of 23.4°F,
was colder. The mean temperature for 2012 was more reminiscent of what
Fairbank's routinely experienced earlier in the 20th century. 2012
was also notably colder than 2011, which had a mean temperature of 28.0°F. The highest temperature of 86°F was observed on the
23rd of June, close to the summer equinox with over 21½ hours
of sunlight. June 23rd was also the day with the highest mean daily
temperature of 71.0°F. There were only five days with temperatures at or above
80°F, less than half the long-term normal of twelve days. The lowest
temperature of the year was -51°F, occurring on the 29th of January,
while the 28th of January was the coldest day in terms of the daily
mean temperature at -46.0°F. There were a total of 26 days with lows at or below
-40°F, more than twice the long term normal of eleven days. The only
temperature record for 2012 was a new daily high set on April 16th
with 61°F, topping the 1993 record of 59°F. Month Temperature Observed Normal Delta January -26.9 -7.9 -19.0 February 5.9 -1.3 7.2 March 4.5 11.4 -6.9 April 36.9 32.5 4.4 May 47.9 49.4 -1.5 June 61.6 60.4 1.2 July 60.8 62.5 -1.7 August 56.3 56.1 0.2 September 45.5 44.9 0.6 October 22.5 24.2 -1.7 November -8.8 2.6 -11.4 December -17.3 -4.1 -13.2 Looking at the temperature data by month, it can
clearly be seen that the colder than normals temperatures were not evenly
distributed throughout the year. Below average temperatures were more prominent
during the winter months, while summer experienced more normal temperatures.
January had the greatest deviation of -19.0°F. The actual mean temperature for
the month was a frigid -26.9°F, the coldest January in more than 40 years.
Large negative deviations were also observed in December (-13.2°F), November
(-11.4°F) and March (-6.9°F), while February was above normal with a positive
deviation of 7.2°F. The rest of the year had no other remarkable deviations
from the long-term mean. The temperatures of Alaska are strongly affected by
the Pacific Decadal Oscillation, which is an index derived from the surface
temperature of the waters of the North Pacific Ocean. Warm temperatures in
Alaska are related to positive PDO values, while negative values indicate below
normal temperatures. Before 1975 this index was predominantly negative, and the
temperatures up to that time tended to be cool. After 1976 the PDO values switched
to predominantly positive and warmer temperatures were observed. With the start
of the new century, the PDO values trended to the negative again, and a cooling
started. With colder surface waters, the semi-permanent Aleutian Low weakens,
and less warm air is advected into Alaska. While this is of minor importance in
summer, as days are long, in winter the solar elevations are low, the days are
short, and this transport of warmer air from the south greatly influences the
Alaskan temperatures. For more details of the annual course of temperature for
Fairbanks, see the figure below. For 2012 the Precipitation total was 10.62",
very close to the expected value of 10.81". Highest daily total was
0.82" and occurred on August 26th. Five months of the year had
precipitation deficits, while six had excesses. February hit its normal value
of 0.42". The annual course over the year also followed fairly closely the
long-term mean value, as can be seen from the third figure. 2012 was wetter
than 2011, which saw a total of only 9.52". As might be expected from the near
normal precipitation, the snowfall of the year was close to normal with a total
of 61.7", only 3.3" below the normal of 65.0". Interestingly,
this is the same snowfall total as for 2011. Despite the near normal annual precipitation and
snowfall, there were a number of records set in 2012. March 6th saw
a snowfall of 2.6", tying the previous record set way back in 1932. The
precipitation equivalent was 0.17", and this was a new daily record,
breaking the old record of 0.15" set in 1967. The storm continued on into
the next day, and 6.9" more snow fell, smashing the 1943 record of
3.5". The precipitation equivalent came to 0.28", a new record too,
topping the old 1985 record of 0.24". Then on May 25th a total
of 0.52" of rain tumbled down, just outdoing the 1973 record of
0.50". Two events occurred at the beginning of October. First, 0.21"
of rain fell on the 6th, tying the 1989 record. This was followed on
the 7th with 0.55", eclipsing the 1974 record of 0.28". A
final snowstorm in December dropped 9.5" of snow on the 12th,
which broke the 1972 record of 5.7". On the same day, the precipitation
equivalent was 0.72", shattering the 1972 record of 0.17". The last day of seasonal snow cover was April 22nd,
and the last frost of the winter came on May 14th. Green up day
occurred on the 10th of May, which is about normal. Growing
degree-days totaled 1003 and the growing season was 117 days long, about average.
The first frost hit on September 10th, and the snowpack was
re-established on October 15th. As might be expected, heating
degree-days was 1297 above the normal of 13666. Correspondingly, cooling
degree-days totaled just 34, 27 less than expected. Mean annual wind speed was
3.3 mph, with lower values in winter, when the semi-permanent inversion
decouples the surface conditions from the upper circulation. Less than 300,000 acres burned due to forest fires,
a relatively low value, as the mean over the last 50 years is about 1 million
acres. This is understandable, as there were fewer hot days in 2012. Hotter
days cause both a higher number of lightning strikes (starting new fires) and allow
existing fires to expand. The most vexing fire for the Fairbanks area was the
Dry Creek fire. It started on June 23rd about eighteen miles south
of North Pole, and continued to occasionally send smoke into the unban area
until after the middle of September. |
2012 Statistics
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Click on the images for a larger view.
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Questions or comments? Please contact the Alaska Climate Research Center. Preliminary climatological data are used for this summary. Please report any errors found to the Climate Center Posted: 16 February, 2013 |
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