May 2012 Statewide Summary

Temperature

In contrast to April, a month that recorded above normal temperatures, May 2012 was seasonably too cold. 19 of the 20 first order meteorological stations in Alaska reported negative deviations. A mean deviation of all 20 stations from the long-term mean could be calculated as -2.7°F. Barrow, in Artic Alaska, was the only station with a positive deviation, but only slightly so with +0.5°F. Arctic Alaska has shown the greatest warming over the last decades; hence this trend appears to be continuing. The stations with the largest negative deviation were found in western Alaska; Kotzebue with -5.4°F and St. Paul Island with -5.2°F. This might be an effect of the lingering sea ice in the Bering Sea, which in March reached the greatest extent seen since 1979, the point when continuous satellite coverage in the microwave wavelength bands became available. Microwave instruments have the ability to look through clouds and darkness, necessary for collecting imagery in winter.

 

It is interesting to note that the monthly flip-flop in temperatures continued in May. November had temperatures far below the expected values, while December was much above normal, and for most stations substantially warmer than those of November. January was much colder and many new low temperature records were observed. Then in February the temperature for most of Alaska was above normal, with only the first and last days of the month being seasonably below normal. March was colder than normal again, and for most stations recording lower temperatures than in February. April was above normal, followed by a seasonable cold May. Further, May is the first month of this year when Anchorage's monthly temperature was lower than for Fairbanks. The more maritime climate of in the coastal areas has normally warmer temperatures in winter, but lower temperatures in summer when compared to the more continental climate of Interior Alaska.

 

Station

Temperature

Observed
(°F)

Normal
(°F)

Delta
(°F)

Anchorage

45.5

47.8

-2.3

Annette

47.0

50.2

-3.2

Barrow

21.6

21.1

0.5

Bethel

39.1

41.9

-2.8

Bettles

43.1

44.4

-1.3

Big Delta

45.0

47.6

-2.6

Cold Bay

36.5

40.3

-3.8

Fairbanks

47.9

49.2

-1.3

Gulkana

42.6

45.2

-2.6

Homer

41.4

44.5

-3.1

Juneau

44.7

48.6

-3.9

King Salmon

41.1

44.2

-3.1

Kodiak

42.5

44.3

-1.8

Kotzebue

26.5

31.9

-5.4

McGrath

46.2

46.7

-0.5

Nome

33.1

36.8

-3.7

St. Paul Island

31.0

36.2

-5.2

Talkeetna

45.4

47.8

-2.4

Valdez

43.5

47.0

-3.5

Yakutat

42.0

44.7

-2.7

 

Persistently cool daily maximum temperatures at the start of May allowed Juneau to set a new record cold month in terms of the average daily maximum temperature of just 48.9°F; 7.7°F below the previous record from 1955. Nevertheless, the extensive cloud cover meant the average daily low was near normal. The monthly mean temperature was 44.7°F, making this the 8th coldest May on record for Juneau for that statistic. On May 18th the temperature reached up to 63°F in Nome, a new daily record, topping the 1980 record of 62°F. All other daily extreme records for May were record low temperatures.

 

 

Temperature Records

Date

Station

Element

New
Record

Old
Record

Year of
old Record

05/03/12

Valdez

Low Temperature

32

32

2001

05/12/12

Cold Bay

Low Temperature

24

25

1971

05/13/12

Cold Bay

Low Temperature

18

25

1971

05/13/12

King Salmon

Low Temperature

22

22

1965

05/13/12

Kodiak

Low Temperature

29

29

1965

05/14/12

Cold Bay

Low Temperature

20

27

2009

05/14/12

Valdez

Low Temperature

33

34

2008

05/15/12

Valdez

Low Temperature

32

33

2011

05/18/12

Nome

High Temperature

63

62

1980

 

Daily temperature ranges and precipitation for Juneau for May 2012. Note the persistently cool daily maximum temperatures and consistent rainfall at the start of May.

 

 

Precipitation

Precipitation was above normal for eleven of the 20 stations. The greatest positive deviations above normal were found for Barrow (178%), Annette (83%), Gulkana (82%) and Juneau (77%). On the other side of the spectrum were Talkeetna, with only 23% of the expected value, or 0.38" of the normal of 1.62" and Bethel with 42% or 0.48 0f the normal of 1.14". As the positive deviations were larger in magnitude, the mean of the 20 stations ended up positive with 15%, or differently expressed, about 1/7 more precipitation fell in Alaska in May than normal. As with the temperature, the precipitation deviations for the different station are given in the table below:

 

Station

Precipitation

Observed
(in)

Normal
(in)

Delta
(in)

(%)

Delta
(%)

Anchorage

0.43

0.72

-0.29

60%

-40%

Annette

10.20

5.56

4.64

183%

83%

Barrow

0.50

0.18

0.32

278%

178%

Bethel

0.48

1.14

-0.66

42%

-58%

Bettles

0.70

0.88

-0.18

80%

-20%

Big Delta

1.30

0.90

0.40

144%

44%

Cold Bay

1.51

2.60

-1.09

58%

-42%

Fairbanks

0.73

0.60

0.13

122%

22%

Gulkana

1.18

0.65

0.53

182%

82%

Homer

0.81

0.82

-0.01

99%

-1%

Juneau

5.73

3.24

2.49

177%

77%

King Salmon

1.62

1.25

0.37

130%

30%

Kodiak

5.93

5.62

0.31

106%

6%

Kotzebue

0.37

0.41

-0.04

90%

-10%

McGrath

0.75

1.09

-0.34

69%

-31%

Nome

0.88

0.86

0.02

102%

2%

St. Paul Island

0.49

1.13

-0.64

43%

-57%

Talkeetna

0.38

1.62

-1.24

23%

-77%

Valdez

4.42

2.88

1.54

153%

53%

Yakutat

13.23

8.21

5.02

161%

61%

 

On May 16th 0.84" of rain fell in Nome, more than double the 1990 record of 0.40" for this day. This was nearly the entire amount rain for the whole month of May that reported a total of 0.88". In addition, it was the wettest day ever record in May; the historical record is long dating back to 1907. The previous record was 0.76" from 1996.

 

 

Precipitation Records

Date

Station

Element

New
Record

Old
Record

Year of
old Record

05/02/12

St. Paul

Snowfall

0.8

0.8

1975

05/04/12

King Salmon

Snowfall

1.8

1

1971

05/06/12

Ketchikan

Precipitation

4.73

2.4

1959

05/07/12

Ketchikan

Precipitation

4.26

2.6

1973

05/10/12

Cold Bay

Snowfall

1

0.8

1994

05/10/12

King Salmon

Precipitation

0.33

0.32

1991

05/10/12

Kotzebue

Snowfall

1

0.3

1967

05/12/12

Cold Bay

Snowfall

0.7

0.3

1976

05/12/12

Kodiak

Snowfall

0.8

0.7

1971

05/12/12

Petersburg

Precipitation

1.52

1.42

1952

05/13/12

Kodiak

Snowfall

2.4

0.2

1971

05/14/12

Juneau

Snowfall

T

0

1985

05/15/12

Juneau

Snowfall

T

0

 

05/15/12

Petersburg

Snowfall

T

0

 

05/16/12

Nome

Precipitation

0.84

0.4

1990

05/25/12

Fairbanks

Precipitation

0.52

0.5

1973

 

 

According to the National Weather Service, "Greenup' day for Fairbanks was May 10th. The average day is about May 8th.  Low precipitation for the Interior for the first third of the month resulted in low humidity, and combined with high winds on the 11th resulted in red flag warnings being issued. A number of small wild fires erupted around Fairbanks and Delta Junction, but were generally contained quickly.

 

The 25th recorded a new precipitation record in Fairbanks at 0.52", just above the 1973 record of 0.50". This record rain combined with last season snowmelt generated rapidly rising river levels in the Interior and flood advisories were issued for Chena, Salcha and Goodpaster rivers. This heavy precipitation terminated the wild fire concerns from earlier in the month. A late winter storm with strong winds and drifting snow on May 27th resulted in a travel advisory being issued for the Chandalar region of the Dalton Highway.

 

It was an extreme winter for sea ice in the Bering Sea. As noted before a record extent was observed in March. On May 3rd, St. Paul Island was engulfed in ice, and had been for 103 days at that point and the ice had yet to retreat north of the island. The previous record was 100 days reached in 2010. St. George Island also set a record of 79 days, topping the old record of 60 days, also from 2010.

 

 

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.