Temperature
In contrast to November, which had
been colder than normal for all first order stations in Alaska and brought new
record lows to the Interior; December brought lots of relief with mostly above
normal temperatures. Twelve of the 20 first order stations were seasonally
above normal, with some exhibiting very high positive deviations. In declining
order these are: Gulkana (11.1°F), Fairbanks (8.1°F), McGrath (6.9°F), Big
Delta (6.1°F) and Anchorage (4.4°F). The eight stations which were seasonally
below normal were much closer to their normals, with a maximal deviation of ‑3.0°F
observed for Nome. The mean monthly deviation of all stations is computed at 2.0°F
above the long-term climatic value.
Normally, the three mid winter
months of December, January and February are the coldest of the year, and this is
clearly demonstrated in the long-term averages. However, in 2011, 15 of the 20 first
stations analyzed were colder in November than in December, which is quite
unusual. In addition, one station (Kodiak) had the identical temperature of
28.4°F for both months. The greatest difference in temperature was found for
Gulkana (12.7°F) and Fairbanks (12.2°F), with December being substantially
warmer than November. Not only were the mean temperatures, but also the daily minima
were frequently lower in November than in December. For more details, see the
table below, which presents the mean values, the 30-year Normals (1991-2010),
and the deviations from these normals.
|
Station
|
Temperature
|
|
Observed
(°F)
|
Normal
(°F)
|
Delta
(°F)
|
|
Anchorage
|
23.0
|
18.6
|
4.4
|
|
Annette
|
36.9
|
37.1
|
-0.2
|
|
Barrow
|
-9.6
|
-7.8
|
-1.8
|
|
Bethel
|
12.4
|
10.4
|
2.0
|
|
Bettles
|
-1.8
|
-5.7
|
3.9
|
|
Big Delta
|
8.2
|
2.1
|
6.1
|
|
Cold Bay
|
29.2
|
31.1
|
-1.9
|
|
Fairbanks
|
4.0
|
-4.1
|
8.1
|
|
Gulkana
|
11.5
|
0.4
|
11.1
|
|
Homer
|
25.7
|
27.1
|
-1.4
|
|
Juneau
|
33.7
|
29.9
|
3.8
|
|
King Salmon
|
17.6
|
18.6
|
-1.0
|
|
Kodiak
|
28.4
|
31.2
|
-2.8
|
|
Kotzebue
|
2.8
|
2.3
|
0.5
|
|
McGrath
|
3.7
|
-3.2
|
6.9
|
|
Nome
|
6.5
|
9.5
|
-3.0
|
|
St. Paul Island
|
27.4
|
28.9
|
-1.5
|
|
Talkeetna
|
17.0
|
16.0
|
1.0
|
|
Valdez
|
28.5
|
26.0
|
2.5
|
|
Yakutat
|
32.6
|
29.6
|
3.0
|
In general, for the first
two-thirds of December, above normal temperatures were observed, but during the
last 10 days of the month the temperatures dropped sharply, with monthly minima
observed towards the end of the month. More details are given later in the text
when special events are discussed.

Daily temperature ranges and precipitation for Kodiak for December
2011. Note the warmer than normal first two-thirds of the month with two record
warm events, and colder than normals last one-third with three record cold
events.
Precipitation
Precipitation totals for December
were generally above the average; 18 stations measured values exceeding
expectation, while only two stations were below the norm, one of these just
slightly so (Annette -4%). The other (Kodiak) recorded a lower value of -32%.
The mean of the deviations expressed as percentages gave a value of +82%, a
substantial deviation for such a large area as Alaska, or otherwise stated,
Alaska was wet in December with, on average, nearly 80% additional precipitation.
The most extreme values expressed as percentages above normal were found in
Barrow (329%), Bettles (251%), McGrath (162%), Kotzebue (146%), Anchorage
(138%) and Talkeetna (111%). For more details, see the table below:
|
Station
|
Precipitation
|
|
Observed
(in)
|
Normal
(in)
|
Delta
(in)
|
Delta
(%)
|
|
Anchorage
|
2.66
|
1.12
|
1.54
|
138%
|
|
Annette
|
10.28
|
10.72
|
-0.44
|
-4%
|
|
Barrow
|
0.60
|
0.14
|
0.46
|
329%
|
|
Bethel
|
1.22
|
1.12
|
0.10
|
9%
|
|
Bettles
|
3.23
|
0.92
|
2.31
|
251%
|
|
Big Delta
|
0.74
|
0.38
|
0.36
|
95%
|
|
Cold Bay
|
6.22
|
4.46
|
1.76
|
39%
|
|
Fairbanks
|
0.95
|
0.64
|
0.31
|
48%
|
|
Gulkana
|
0.91
|
0.78
|
0.13
|
17%
|
|
Homer
|
4.04
|
3.08
|
0.96
|
31%
|
|
Juneau
|
7.45
|
5.84
|
1.61
|
28%
|
|
King Salmon
|
1.64
|
1.23
|
0.41
|
33%
|
|
Kodiak
|
5.92
|
8.73
|
-2.81
|
-32%
|
|
Kotzebue
|
1.87
|
0.76
|
1.11
|
146%
|
|
McGrath
|
3.38
|
1.29
|
2.09
|
162%
|
|
Nome
|
2.15
|
1.08
|
1.07
|
99%
|
|
St. Paul Island
|
2.72
|
2.25
|
0.47
|
21%
|
|
Talkeetna
|
4.07
|
1.93
|
2.14
|
111%
|
|
Valdez
|
16.26
|
8.24
|
8.02
|
97%
|
|
Yakutat
|
18.95
|
16.28
|
2.67
|
16%
|
Looking of snowfall, also
expressed as percentage above or below normal, Barrow had the highest deviation
(+349%), followed by Kotzebue (+205%) and Valdez (+112%) above normal. On the
other side of the spectrum, Annette, in the southeast corner of Alaska,
reported a deviation of -64%. It should be noted that only 15 of the 20
stations supplied snowfall observations. The high snowfall experienced in
Kotzebue resulted in a mean snow depth of 42", 282% above normal.
Distinctive Events
At the beginning of the month, a
storm hit Alaska, bringing strong winds, warm air and precipitation. The 4th
saw temperatures soar to 51°F in Big Delta, a new record for this day, smashing
the old record of 40°F set in 1969. An increase in a record by 11°F is uncommon;
hence this was an extraordinary event. The cause was strong southerly flow
across the Alaska Range, called Chinook winds, which are gusty in nature. Chinook
winds are created when the air is cooled moist-adiabatical as it rises due to
precipitation on the south side of the Alaska Range, but descends
dry-adiabatical on the north side of the range. As the dry adiabatical rate is
higher than the moist-adiabatic rate, the air arrives warmer in Interior Alaska
than it started out with on the south side of the Range.
As there were a large number of
new daily records, we are not able to discuss all of these individually, but
make only some remarks on a few extra-ordinary occurrences, admittedly a
somewhat subjective assessment. However, all the records are listed in the
table below in which the temperatures are given in °F, snowfall and
precipitation in inches and atmospheric pressure in inches of mercury.
The storm that moved over Alaska
at the beginning of the month brought on the 3rd December at St.
Paul Island in the Southern Bering Sea a wind gust of 74 mph, and one day later
a gust of 118 mph was recorded at Glen Alps near Anchorage. On the 4th,
the maximum temperature of +47°F was recorded in Fairbanks - a balmy
temperature for Interior Alaska in winter. A mean temperature for the day was
37°F, a rare event, as mean daily temperatures above freezing are infrequent in
deep winter in Fairbanks. Also on the 4th, at Barrow in Northern
Alaska, average wind speeds were recorded at 30 mph, with gusts exceeding 50 mph.
These are high and uncommon values, however they do not represent new records.
More unique was the precipitation record of Barrow with 0.33"
(water-equivalent), beating the previous record for the 4th December
of 0.19 set in 1922. This was associated with a new snowfall record of 6.5",
surpassing the old record of 2.5" set also on this day in 1922. Both these
values are in fact new records for all
days of December. The previously highest precipitation amount for any day in
December had occurred on 13th December 1930 with 0.26", and the
highest amount of snowfall (5.0") had been observed on 29th
December 1922. Also Nome and Kotzebue reported new snowfall and precipitation
records during the first part of the month (see table). Further, in Valdez
2.80 of precipitation were recorded on the 4th, which more than
doubled the old record of 1.37 set in 1984. Interestingly, this was associated
with a record high in atmospheric pressure of 30.55. Normally, large
precipitation amounts are associated with low-pressure systems. The total
monthly amount of snowfall in Valdez was 144, a new record for the month,
surpassing the old record of 137 set in 1991.
December Records
|
Date
|
Station
|
Element
|
New
Record
|
Old
Record
|
Year of
old Record
|
|
12/02/11
|
Kodiak
|
High Temperature
|
47
|
46
|
1992
|
|
12/03/11
|
King Salmon
|
High Temperature
|
51
|
48
|
2002
|
|
12/03/11
|
Kotzebue
|
Snowfall
|
5
|
4.9
|
2010
|
|
12/03/11
|
Nome
|
Snowfall
|
6.5
|
6.2
|
1979
|
|
12/03/11
|
Big Delta
|
High Temperature
|
46
|
42
|
1963
|
|
12/03/11
|
UAF West Ridge
|
High Temperature
|
45
|
44
|
1948
|
|
12/03/11
|
North Pole
|
High Temperature
|
49
|
47
|
1968
|
|
12/04/11
|
Barrow
|
Precipitation
|
0.33
|
0.19
|
1922
|
|
12/04/11
|
Barrow
|
Snowfall
|
6.5
|
2.5
|
1922
|
|
12/04/11
|
King Salmon
|
High Temperature
|
46
|
45
|
2008
|
|
12/04/11
|
Valdez
|
Precipitation
|
2.8
|
1.37
|
1984
|
|
12/04/11
|
Valdez
|
Pressure
|
30.55
|
30.41
|
2000
|
|
12/04/11
|
Kotzebue
|
Snowfall
|
3
|
2.1
|
1978
|
|
12/04/11
|
Big Delta
|
High Temperature
|
51
|
40
|
1969
|
|
12/06/11
|
Valdez
|
Pressure
|
30.57
|
30.41
|
2000
|
|
12/06/11
|
Kotzebue
|
Snowfall
|
2.6
|
2
|
1997
|
|
12/06/11
|
Nome
|
Snowfall
|
4.1
|
3.9
|
1993
|
|
12/07/11
|
Kotzebue
|
Precipitation
|
0.32
|
0.27
|
2002
|
|
12/07/11
|
Kotzebue
|
Snowfall
|
6.5
|
3
|
2002
|
|
12/07/11
|
Nome
|
Snowfall
|
5.6
|
4.4
|
1981
|
|
12/08/11
|
Kotzebue
|
Precipitation
|
0.34
|
0.2
|
1981
|
|
12/08/11
|
Kotzebue
|
Snowfall
|
6
|
2.4
|
1987
|
|
12/08/11
|
Valdez
|
Snowfall
|
12
|
11.9
|
1985
|
|
12/10/11
|
Nome
|
Snowfall
|
4.5
|
4.1
|
2007
|
|
12/10/11
|
Kotzebue
|
Snowfall
|
5.7
|
2.1
|
1978
|
|
12/10/11
|
Kotzebue
|
Precipitation
|
0.29
|
0.14
|
2007
|
|
12/11/11
|
Valdez
|
Snow Depth
|
20.3
|
14.9
|
2001
|
|
12/11/11
|
Valdez
|
High Temperature
|
40
|
40
|
2002
|
|
12/11/11
|
King Salmon
|
Snowfall
|
10
|
3
|
1963
|
|
12/11/11
|
Kotzebue
|
Precipitation
|
0.16
|
0.12
|
1950
|
|
12/11/11
|
Valdez
|
High Temperature
|
40
|
40
|
2002
|
|
12/11/11
|
Valdez
|
Snowfall
|
20.3
|
14.9
|
2001
|
|
12/13/11
|
Bettles
|
Snowfall
|
4
|
4
|
1955
|
|
12/17/11
|
Valdez
|
Snowfall
|
20
|
18.6
|
1978
|
|
12/18/11
|
Kodiak
|
High Temperature
|
44
|
44
|
1985
|
|
12/27/11
|
Kodiak
|
Low Temperature
|
4
|
4
|
1951
|
|
12/28/11
|
Cold Bay
|
Low Temperature
|
3
|
3
|
|
|
12/30/11
|
King Salmon
|
Low Temperature
|
-29
|
-25
|
1997
|
|
12/30/11
|
Kodiak
|
Low Temperature
|
3
|
5
|
2006
|
|
12/31/11
|
Kodiak
|
Low Temperature
|
-3
|
2
|
1974
|
This information consists of preliminary climatological data compiled
by the Alaska Climate Research Center, Geophysical Institute, University of
Alaska Fairbanks. This summary is based on the 20 first order stations in
Alaska operated by the National Weather Service. Extreme events of other
stations are also mentioned. It should be noted that the new climate normals for the time period of 1981-2010 are applied for
the calculations of the deviations, and they can be slightly different from the
old normals (1971-2000), which were in use up until
end of July 2011.