Alaska Weather Summary for September 2012
Temperatures in August were colder than normal for five of the nine stations discussed in this summary. The greatest negative deviation was observed in Nome (minus 3.1 degrees Fahrenheit), followed by King Salmon (minus 1.9 degrees), and Kodiak (minus 1.1 degrees). Big Delta had the highest positive deviation at 3.5 degrees Fahrenheit above the mean. Barrow (2.6 degrees), Ketchikan (0.8 degrees) and Fairbanks (0.6 degrees) rounded out the stations with positive deviations. While the number of stations with below normal temperatures outnumbered the stations with above normal temperatures by one, the mean deviation for all stations was zero degrees Fahrenheit.
Precipitation was also mixed in September 2012, with just three stations reporting below normal totals, while the other six had precipitation excesses. Expressed as percentages, Barrow reported the greatest positive deviation, with 168 percent above normal, followed by Anchorage at 117 percent above the normal. Big Delta was the driest station with just 12 percent of the normal amount of precipitation. The mean deviation of all nine stations was 26 percent above normal.
In Fairbanks the average temperature for September was 45.5 degrees Fahrenheit, just 0.6 degrees above the long-term mean. The lowest temperature for the month was 26 degrees on the 13th and 30th, while the highest temperature was a balmy 67 degrees on the 22nd. Temperatures generally stayed within the expected trend, alternating from warm to cool to warm again. No new record events were recorded.
Like July and August, precipitation was below normal in September at 0.55 inches, just half of the expected value of 1.10 inches. Nearly half of the monthly precipitation was observed on the 21st, with 0.19 inches. The mean wind speed was 3.9 mph, with a maximum gust of 31 mph on the 23rd, blowing from a westerly direction.
In Big Delta the mean temperature for September (47.4 degrees Fahrenheit) was a substantial 3.5 degrees above the long-term normal of 43.9 degrees. The highest temperature (66 degrees) was observed on the 16th and 19th, while the lowest temperature dropped below freezing (25 degrees) and occurred on the 11th. Temperatures were mixed in regard to the expected trend, with cooler temperatures during the first half and warmer temperatures in the second half. Correlating to that trend were the daily temperature record events, with the low on the 11th of 25 degrees Fahrenheit tying the record from 1992. Then on the 19th, the record high of 66 degrees from 1995 was tied.
Precipitation was reported at a total of 0.12 inches, a meager 12 percent of the expected amount (1.03 inches).
The average temperature in Juneau for September was 49.6 degrees Fahrenheit, 0.4 degrees below the long-term mean. The maximum temperature of the month was 61 degrees, occurring on the 4th and 21st. The month’s minimum temperature was 38 degrees and occurred on the 19th and 30th. Temperatures stayed normal for most of the month, with little daily variation due to the high amount of cloudiness.
Trace amounts of precipitation, or greater, fell on twenty-nine days of the month. The total was higher than normal at 11.02 inches; this is 2.38 inches above the expected amount of 8.64 inches. While no new daily precipitation records were set, more than one inch fell on three days of the month and the total made this the tenth wettest September on record. The average wind speed was 8.8 mph. The maximum wind speed of 44 mph occurred on the 26th, blowing from a southeasterly direction.
Anchorage was slightly cooler than normal in September, with an average temperature of 47.9 degrees Fahrenheit, 0.7 degrees below the expected temperature. The maximum temperature (65 degrees) occurred on the 22nd. The month’s minimum temperature (29 degrees) occurred on the 30th. September temperatures started out normal, then alternated form cold to warm as storms impacted the region.
Precipitation was heavy at 6.49 inches, 117 percent above the normal of 2.99 inches. The first measureable snowfall occurred on the 29th, with 0.2 inches at the Ted Stevens Anchorage International Airport. Up to 7 inches was measured on the hillside. This was an early first snowfall, which normally does not occur until October 17th. The average wind speed was 8.5 mph, while the strongest gust of 58 mph was observed on the 4th. That gust blew from a southeasterly direction. High gusts were also record on the 5th at 55 mph and on the 22nd at 50 mph.
Barrow experienced the sixth month in a row with above normal temperatures this September. The mean value was 34.7 degrees Fahrenheit, a positive deviation of 2.6 degrees above the normal of 32.1 degrees. The highest temperature (45 degrees) occurred on the 23rd. The month’s the lowest temperature (27 degrees) was reported on the 16th, 29th, and 30th.
Precipitation in Barrow (1.93 inches) was heavy at 168 percent above the normal value of 0.72 inches, and helping this high total were two new daily record precipitation events. On the 5th a total of 0.34 inches fell, topping the 2002 record of 0.24 inches. On the 23rd, 0.36 inches fell, breaking the previous record of 0.25 inches from 2004. Trace amounts or more of precipitation was recorded on 29 days of the month. Snowfall (5.8 inches) was 32 percent above the normal value of 4.4 inches. The average wind speed was 11.7 mph, while the maximum gust (44 mph) occurred on the 16th. That gust blew from a northeasterly direction.
Ketchikan’s average temperature in September was 53.3 degrees Fahrenheit, 0.8 degrees above the long-term mean of 52.5 degrees. The maximum temperature for the month was 67 degrees, which occurred on the 7th. The month’s minimum temperature (41 degrees) was reported on the 16th.
Precipitation was near normal, totaling 14.43 inches or just 5 percent above the long-term mean of 13.79 inches.
In King Salmon, the average temperature for September was 45.7 degrees Fahrenheit, 1.9 degrees below the long-term mean. The maximum temperature (60 degrees) for the month was reported on the 4th, while the minimum temperature occurred on the 30th at 19 degrees.
King Salmon had a greater than normal amount of precipitation, with a total of 4.38 inches, 1.19 inches above the long-term mean. Twenty-six days of the month had at least trace amounts of precipitation. Trace amounts of snow were recorded on two days. The average wind speed was 9.6 mph. The highest gust of 64 mph occurred on the 16th, blowing from a southeasterly direction. A daily record for the highest sustained wind speed at 48 mph was also set on October 16; the previous record had been 36 mph set in 2002.
Kodiak was cooler than normal for September, having a mean temperature of 48.3 degrees Fahrenheit, 1.1 degree less than the expected mean of 49.4 degrees. The maximum temperature for the month (62 degrees) was observed on the 3rd. The month’s minimum temperature was 27 degrees reported on the 29th. The low temperature of 35 degrees on the 9th set a new daily record minimum temperature for that day. On October 10th, the minimum temperature of 34 degrees tied the old record set in 1967. Finally, the low of 27 degrees on the 29th broke the 1996 record of 28 degrees.
Precipitation was high at 31 percent above normal, with a total of 9.64 inches. Precipitation was 2.29 inches over the normal amount of 7.35 inches. The average wind speed was 9.4 mph. The highest wind gust occurred on the 26th. It was 58 mph, blowing from a northeasterly direction.
Nome had a mean temperature for September of 39.7 degrees Fahrenheit, a substantial 3.1 degrees below the normal value of 42.8 degrees. The maximum temperature was reported at 54 degrees on the 11th. The minimum temperature for the month was observed on the 28th at 27 degrees.
September had below normal rainfall with a total of 2.07 inches. This is 0.38 inches under the normal amount of 2.45 inches. The average monthly wind speed was 8.4 mph. The month’s maximum wind speed was 49 mph and occurred on the 26th. The gust blew from a northerly direction.
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 webmaster [at] akclimate [dot] org.