September 2012 Statewide Summary

Temperature

Repeated early autumn storms pounded Southcentral Alaska in September, bringing high winds and rain to the region that resulted in wind damage and flooding. Some of the high winds and water levels managed to push into the Interior of Alaska. Most of the state reported below normal mean monthly temperatures for September. The stations with the largest negative deviations were located (as has been a common occurrence recently) in the Southwest and Bering Sea regions: St. Paul (-3.8°F), Bethel (-3.1°F), Nome (-3.1°F) and Cold Bay (-3.0°C). Stations with positive deviations were mostly from the Arctic and Interior with Big Delta on top at 3.5°F, then: Barrow (2.6°F), Gulkana (2.2°F), Homer (1.8°F) and Bettles (1.1°F). A mean deviation of all twenty stations from the long-term mean could be calculated at ‑0.6°F (same as for August 2012) and this is the fifth month in a row with a mean below normal. Fairbanks had its first hard frost on the 8th. See the table below for more details.

 

Station

Temperature

Observed
(°F)

Normal
(°F)

Delta
(°F)

Anchorage

47.9

48.6

-0.7

Annette

53.6

53.8

-0.2

Barrow

34.7

32.1

2.6

Bethel

42.5

45.6

-3.1

Bettles

41.7

40.6

1.1

Big Delta

47.4

43.9

3.5

Cold Bay

45.1

48.1

-3.0

Fairbanks

45.5

44.9

0.6

Gulkana

45.5

43.3

2.2

Homer

49.9

48.1

1.8

Juneau

49.6

50.0

-0.4

King Salmon

45.7

47.6

-1.9

Kodiak

48.3

49.4

-1.1

Kotzebue

40.8

42.3

-1.5

McGrath

43.1

44.6

-1.5

Nome

39.7

42.8

-3.1

St. Paul Island

41.5

45.3

-3.8

Talkeetna

45.5

47.5

-2.0

Valdez

46.6

47.3

-0.7

Yakutat

48.5

48.4

0.1

 

Temperature records were a mix of both high and low temperature events, scattered across the state. St. Paul set four new record lows during the second half of the month, while Cold Bay set three new lows in the first half of the month, along with a record high on the 2nd. Kodiak also set three new record lows, scattered throughout the month.

 

 

Temperature Records

Date

Station

Element

New
Record

Old
Record

Year of
old Record

09/02/12

Cold Bay

High Temperature

61

60

2005

09/06/12

Cold Bay

Low Temperature

32

35

1971

09/07/12

Kodiak

Low Temperature

35

36

2004

09/08/12

Cold Bay

Low Temperature

33

34

1975

09/09/12

Cold Bay

Low Temperature

30

37

1959

09/10/12

Galena

Low Temperature

24

26

1970

09/10/12

Kodiak

Low Temperature

34

34

1967

09/11/12

Big Delta

Low Temperature

25

25

1992

09/16/12

Northway

High Temperature

70

67

1951

09/16/12

Northway

Low Temperature

23

23

1992

09/17/12

St. Paul

Low Temperature

27

28

2006

09/19/12

Big Delta

High Temperature

66

66

1995

09/20/12

Northway

High Temperature

70

67

1951

09/20/12

St. Paul

Low Temperature

28

31

1991

09/21/12

St. Paul

Low Temperature

27

31

1993

09/22/12

Cordova

High Temperature

63

63

1981

09/27/16

McGrath

High Temperature

60

60

1979

09/29/12

Kodiak

Low Temperature

27

28

1996

09/30/16

St. Paul

Low Temperature

24

25

1968

 

Daily temperature ranges and precipitation for Anchorage for September 2012. Note the record precipitation event on the 19th from one of the storms that caused flooding across the Southcentral region during September.

 

 

Precipitation

Precipitation tended to the heavy side as ¾ of the stations reported above normal totals. The station with the highest deviation was Valdez at 172% above normal, reflecting the impact of the storms.  The stations that came in at greater than 100% above normal: Barrow (168%), Talkeetna, (148%) and Anchorage (117%), and McGrath (106%). With the exception of Barrow, all these high values demonstrate the effect of the storms on the Southcentral region. Stations reporting less the normal precipitation were Big Delta with just 12% of the expected value, then: Fairbanks (50%), Cold Bay (78%), Nome (84%), and Gulkana (85%). With the preponderance of stations reporting above average precipitation, it comes as no surprise the mean precipitation deviation for all stations is 46% above normal.

 

Barrow was the first order station to register the most snowfall in September with a total of 5.8", 32% higher than the normal amount. Fairbanks had its first trace snowfall on the 29th. Anchorage had its first trace of snow on the 28th, followed by measurable snowfall in the 29th ranging from 0.2" at the airport to up to 7" on the hillside. This is much earlier than the normal first snowfall for Anchorage, which is around October 17th. As with the temperature, the precipitation deviations for the twenty 20 first order stations are given in the table below:

 

Station

Precipitation

Observed
(in)

Normal
(in)

Delta
(in)

(%)

Delta
(%)

Anchorage

6.49

2.99

3.50

217%

117%

Annette

12.27

9.79

2.48

125%

25%

Barrow

1.93

0.72

1.21

268%

168%

Bethel

3.68

2.75

0.93

134%

34%

Bettles

3.55

1.91

1.64

186%

86%

Big Delta

0.12

1.03

-0.91

12%

-88%

Cold Bay

3.67

4.73

-1.06

78%

-22%

Fairbanks

0.55

1.10

-0.55

50%

-50%

Gulkana

1.35

1.58

-0.23

85%

-15%

Homer

5.26

3.31

1.95

159%

59%

Juneau

11.02

8.64

2.38

128%

28%

King Salmon

4.38

3.19

1.19

137%

37%

Kodiak

9.64

7.35

2.29

131%

31%

Kotzebue

2.04

1.58

0.46

129%

29%

McGrath

5.14

2.49

2.65

206%

106%

Nome

2.07

2.45

-0.38

84%

-16%

St. Paul Island

4.73

2.99

1.74

158%

58%

Talkeetna

10.72

4.32

6.40

248%

148%

Valdez

26.15

9.61

16.54

272%

172%

Yakutat

21.51

21.11

0.40

102%

2%

 

 

There were a fair number precipitation records for September, backing up the heavy rainfall experienced for most stations. The month started off three events in the Southwest/Bering Sea area, followed by several events in the Southeast on the 12th and 13th. Starting on the 16th the events centered in the Southcentral as a result of the storms impacting the area. Valdez set new records on the 16th, and 19th, but as the rain continued, on the 20th Valdez more than doubled its 1993 record of 2.01" with a new total of 4.27". Valdez finished the month with a final new record of 2.12" on the 28th, breaking the previous record of 1.61" also from 1993.

 

 

Precipitation Records

Date

Station

Element

New
Record

Old
Record

Year of
old Record

09/02/12

Bethel

Precipitation

0.82

0.72

2005

09/02/12

St. Paul

Precipitation

0.81

0.39

1965

09/04/12

Cold Bay

Precipitation

0.97

0.90

1997

09/06/16

Barrow

Precipitation

0.34

0.24

2002

09/12/12

Annette

Precipitation

2.71

2.16

1978

09/12/12

Sitka

Precipitation

2.32

1.83

1979

09/13/12

Skagway Airport

Precipitation

1.03

0.83

2001

09/16/12

Valdez

Precipitation

3.86

2.47

1993

09/19/12

McGrath

Precipitation

0.82

0.71

1977

09/19/12

Valdez

Precipitation

2.59

2.46

1982

09/19/12

Cordova

Precipitation

3.70

3.10

1998

09/19/12

Anchorage

Precipitation

1.41

0.94

1985

09/20/12

Valdez

Precipitation

4.27

2.01

1993

09/23/12

Barrow

Precipitation

0.36

0.25

2004

09/24/12

St. Paul

Precipitation

0.62

0.55

1955

09/28/12

Valdez

Precipitation

2.12

1.61

1993

 

September's main weather events were the four storms to hit the Southcentral area. Starting on the 4th, high winds up to hurricane strength struck the region. The highest measured was 88 mph at McHugh Creek. However that station stopped reporting during the storm, and there were likely peak winds stronger that went unreported. See the table below for the recorded max wind speeds. High winds closed the Anchorage airport, and seven flights were diverted to Fairbanks. Schools and state offices were closed due to power outages and difficulty getting around because of all the trees downed. Power was out for parts of the city up to five days. The high winds pushed into the Interior and warnings were put out for the eastern Interior on the 5th

 

Location                       

Max Wind Speed

 

Anchorage

 

Mchugh Creek (Turnagain Arm)

88 Mph*

 

Paradise Valley (Potter Marsh)

75 Mph

 

Upper Hillside (1400 Ft)

70 Mph

 

Anchorage Port

63 Mph

 

Merrill Field

58 Mph

 

Hillside Rd At Upper Huffman

57 Mph

 

Lake Hood Seaplane Base

55 Mph

 

Seward Highway At Huffman Rd

55 Mph

 

Ted Stevens Airport

53 Mph

 

Elmendorf Air Force Base

53 Mph

 

Glen Alps

48 Mph*

 

Campbell Creek Science Center

40 Mph

 

Ktuu (Midtown)

39 Mph

 

Eagle River

38 Mph

 

Rest Of Southcentral Alaska

 

Portage

64 Mph

 

Palmer Airport

53 Mph

 

Homer Spit

51 Mph

 

Gulkana

46 Mph

 

Homer Airport

43 Mph

 

Nikiski

38 Mph

 

Wasilla Airport

33 Mph

 

Seward Airport

32 Mph

 

* Equipment stopped reporting during thee event. Peek winds likely higher than reported.

 
 

 

The second storm hit on the 15th, and while it lacked the extreme high winds of the first storm, heavy rain was experienced across the Southcentral region. Flood watches were issued. High winds did make it into the Interior, and wind damage was reported from Healy to Tok, with the community of Tanacross reporting the worst damage with unofficial speeds of up to 114 mph recorded. One unexpected effect of the high winds was the revival of the Dry Creek fire, and the resulting smoke was pushed into the Fairbanks area on the 16th. This is very late in the fire season to have heavy smoke in the Fairbanks area.

The third storm came ashore on the 19th, with somewhat lighter winds and more rain. The heavy rain resulted in flooding from Talkeetna to Seward to Anchor Point. All residents of Talkeetna were urged to evacuate on the 21st, and the levee was breached. Other areas had evacuations as needed. The airport in Seward was closed with water on the runway. Both the Richardson and Denali highways had to be closed at times, as well as many local roads in affected areas as well. Damage to the Parks highway by the Nenana River reduced it to one lane in the canyon. The Nenana River hit a record of 14.9 feet, topping the old record of 14.1 feet from 1990. The main line of the Alaska Railroad was washed out near Gold Creek and nearby bridge damage, halting train traffic through that area until the 25th. The Kenai River was closed to all boat traffic for most of its length, and flood warnings were issued for many areas along the river. The Kalifornsky Beach road was washed out on the 20th, and not reopened until the end of the month. The fourth storm hit on the 26th and thankfully lacked the punch of the earlier storms, but did manage to keep streams and river high with more precipitation. The tables below are for the storm of the 19th.

 

 

Location                       

Rainfall

 

Kenai Peninsula

 

Seward

5.87 As Of 9Pm

 

Whittier

5.13 As Of 9Pm

 

Girdwood

1.80 As Of 9Pm

 

Homer 8Nw

2.13 As Of 6Pm

 

Anchorage:

 

Nws Office

1.41 As Of 10Pm

 

Anchorage Intl Airport

1.27 As Of 9Pm

 

Upper Hillside

2.08 As Of 9Pm

 

North Potter Heights

1.51 As Of 9Pm

 

Mat-Su Valley:

 

Mat-Su Valley:

 

 

Willow

2.19 As Of 9Pm

 

Wasilla

0.89 As Of 9Pm

 

Skwentna

3.26 As Of 9Pm

 

Talkeetna

2.23 As Of 9Pm

 

Bentalit Lodge

2.42 As Of 6Pm

 

Amber Lake

2.73 As Of 8Pm

 

24 hour rainfall (in inches) for select areas as of 10pm AKDT Wednesday the 19th

 
 

 

 

Location                       

Max Wind Speed

 

Anchorage

 

Arctic Valley

79 Mph

 

North Potter Heights

86 Mph

 

Upper Hillside

68 Mph

 

Upper Dearmoun

84 Mph

 

Eagle River

76 Mph

 

Port Of Anchorage

56 Mph

 

Kenai Peninsula

 

Seward Highway At Huffman Rd

55 Mph

 

Harding Icefield

91 Mph

 

Whittier

57 Mph

 

Portage Glacier

82 Mph

 

Seward

51 Mph

 

Girdwood

50 Mph

 

Mat-Su Valley

 

Palmer Airport

54 Mph

 

Palmer Midtown

44 Mph

 

Glenn Hwy At Knik River Bridge

59 Mph

 

Unofficial peak wind gusts from across the region.
These values are from public sensors, NWS and other agency equipment.

 
 

 

The Denali Park Road was closed two days due to snow, once on the 6th and again on the 9th, even though the park was still open to tourists. Rare, late September thunder and lighting were reported in the Interior on the 24th and then was followed by snowflakes the next morning at the University's West Ridge.

 

 

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.