| December 2009 - |
A warm southerly flow started off the month of December in Alaska, increasing temperatures by 4°F to as much as 12°F above the normal monthly mean. The flow off a Canadian high-pressure system gave an offshore flow to the southeast, bringing cold, dry air across the panhandle resulting in lower than normal temperatures and decreased precipitation. Mid-month a northwest flow developed and dropped temperatures across the Interior for a week. During the last part of December, the southerly flow had returned, bringing milder weather again to the mainland.
Decembers' temperature in Barrow was 7.2°F higher than normal, followed by King Salmon (6.7°F), Nome (6.6°F), Big Delta (5.8°F), Fairbanks (3.1°F) and Anchorage (3.0°F). Temperatures in the panhandle were lower than normal, Ketchikan at 3.9°F and Juneau at 0.8°F below the mean monthly temperature.
Precipitation in December was predominantly lower than normal, reflecting the high-pressure pattern. King Salmon came in at 25% of normal, followed by Fairbanks, 28%, Ketchikan, 40%, Anchorage, 54%, Big Delta 64%, Juneau, 73% and Nome 93%. However, the North Slope/Arctic Coast region saw increased precipitation, Barrow receiving 0.34”, well above the normal precipitation amount of 0.12”.
Snowfall for the month of December was also lower than normal across the state. Fairbanks reported 48%, Ketchikan 40%, King Salmon 16%, Juneau 43%, Nome 95% below normal for the month. Barrow, however, recorded 5.5”, 1.5 times their normal amount of snowfall.
Fairbanks experienced freezing rain at the beginning of the month, an unusual occurrence in the winter months. Temperature inversions and calm winds caused high particulate concentrations in Fairbanks, prompting air quality advisories.
Heavy snow fell in Valdez the 14th - 17th, and set a new daily snowfall record of 38.7” on the 15th of the month. The previous record for that day was 10.1”. On the 16th, Valdez WSO measured 21.4” breaking the previous record of 12.6”. Record breaking precipitation was recorded on December 1st of 1.82”, the previous record was 1.24”. Cold Bay had a record high temperature on the 5th of December with 46°F breaking the old record of 45°F. Kodiak set a new record low on the 18th of 7°F, the old record being 9°F. Two precipitation records were also broken, the first on the 20th of 1.56”, the second was 2.21” on the 21st, these amounts surpassed the previous records of 1.31” and 2.01” respectively. McGrath claimed two record high temperatures on the 5th and the 21st of 37°F and 43°F, the previous records being 35°F and 39°F. St. Paul recorded a record low temperature of 1°F on the 3rd and a record snowfall amount of 2.1” also on the 3rd. The previous records were 6°F and 2.0”. Kotzebue set records for snowfall and precipitation this month snowfall was 5” on the 1st, and precipitation equaled 0.27”, the previous records were 2.3” and 0.16” respectively. On the 21st, another record of 0.21” of precipitation was recorded, the old record was 0.12”. Nome had a record high temperature of 42°F on the 7th, breaking the old record of 40°F.
There were 9 road closures on the Dalton highway and Interior mountain summits this month. Only three earthquakes (magnitude 5.4 or less) were recorded, two in the Aleutians and one southwest of Homer. Mt. Redoubt also had a series of quakes.
A large storm moved through the Aleutians on the 4th and 5th, bringing gale force winds to the western Gulf of Alaska. A 125mph gust was recorded at Dutch Harbor on the 4th, knocking over a 110'crane. 80mph winds were measured on the western Alaska Range.
Sea ice was slightly below normal by the end of December, and sea surface temperatures were near normal.
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