April 2015 Statewide Summary

Alaska Statewide Climate Summary

April 2015

Temperature

The warm temperatures that have existed throughout most of the winter continued into April 2015 with temperatures that were above normal for the first ten days followed by colder than normal temperatures for the next week. Thereafter, the last half of the month experienced above normal temperatures. Overall, it was a warmer than normal April with all 19 First Order Stations reporting positive deviations. Calculating the mean daily temperatures of the First Order Stations (see Figure), 24 days of the month were above the 30-year normal. The peak warm deviation, a high 9.2°F, occurred on the 7^th of the month, while the coldest deviation was -3.3°F on the 13^th. The monthly mean temperature of all First Order Stations was 33.4°F, 2.9°F above the normal of 30.5°F. This is 0.3°F above the April 2014 mean of 33.1°F. McGrath held the greatest positive deviation from normal at a significant 5.9°F above its long-term mean of 29.7°F. Stations following Homer with positive deviations exceeding 4°F were: Barrow (4.9°F), Homer (4.9°F), Bettles (4.5°F), Fairbanks (4.3°F), and Delta Junction (4.1°F).

The warmest temperature of the First Order Stations was 63°F reported at Annette on the 24^th and Fairbanks on the 27^th. Annette also reported the highest mean temperature for the month at 45.2°F. The coldest temperature was ‑14°F at Kotzebue on the 14^th. Barrow reported the lowest April mean temperature at 6.7°F.

Daily mean temperature deviation from the normal temperature for the mean of the first order stations for April 2015.

As has often been the case throughout this winter, the daily record temperature events for April were all high events, with no record low events reported. Most of these were reported during the warm period experienced during the first week of the month.

Precipitation

Like March 2015, April was wetter than normal, with the overall precipitation calculated as 28% above normal; this calculation was based on the mean of the deviations in percentage of the First Order Stations. Ten of the First Order Stations and 15 days of the month reported above normal values. This is relatively wetter than April in 2014 that had just 75% of the normal precipitation. The greatest daily deviation of 364% occurred on the 8^th, when a storm passed over the Southeastern portions of the state and set a number of records in that area. On a monthly basis, Homer had the greatest positive deviation from normal, with a total of 3.92", or 366% above the expected amount of 1.07". Other stations with precipitation greater than 200% of normal were: Barrow (288%), Juneau (244%), and King Salmon (225%). The leading station with a lower than normal precipitation amount was Kodiak with just 12% of normal. Other stations with less than 50% of their normal precipitation were: Gulkana (17%), and Bettles (28%).

Daily mean precipitation deviation from the normal for the first order stations for April 2015.

The maximum monthly precipitation total reported for a First Order Station was 14.17" at Yakutat and Yakutat also reported the highest daily total of 2.28" on the 18^th, a new daily record. The highest one-day snowfall occurred at Bethel on the 21^st with 4.6", a new daily record. Yakutat also reported the highest monthly snowfall of 12.1". Bettles reported the highest snow depth of 23" during the first three days of the month.

There were a quite a number of precipitation and snowfall record events that were set throughout the month and across the state from Annette to Barrow. This is the second wettest April on record for Homer, just 0.17" under the record set in 1988. It was also the second wettest April for Juneau, totaling just 0.30" below the 1999 record.

Snowfall was nearly normal in April, with seven of the 15 First Order Stations that measure snowfall reporting above normal amounts. Based on the mean of the deviations from all 15 stations, the overall deviation from normal was 5% above the expected amount. Annette and Juneau reported no snowfall. Mean snow depth was about 66% under the normal. King Salmon had the highest deviation at 310% of its expected amount with a total of 12.1". This is the 4^th snowiest April on record for King Salmon, and this was assisted by three record snow events in a row starting on the 7^th. Anchorage continues on track to have the least snowiest winter season on record with just 25.1" of snow.  The current record is 30.4" from 1957-58. The 2.2" snowfall in Anchorage on the 20^th tied January 22^nd for the third snowiest day of the season.

This water vapor satellite image from the National Weather Service shows clearly the weather pattern over the eastern Alaska Range that generated high wind warning on April 19^th.

Newsworthy Events

The blizzard and overflow problems at the Sagavanirktok River resulted in the closure of the Dalton Highway on the 1^st. The overflow water near mile 400 that started on March 13^th continued to be a problem during April, with limited traffic finally allowed on the 12^th. A disaster declaration was issued on the 8^th to allow the State to move quickly to procure needed assistance to deal with the problem.

A high wind watch was issued for the Anchorage and Turnagain Arm areas on the 5^th. The next day a fire weather watch with high winds was issued for the Matanuska Valley above 1500 feet. High wind warnings were also issued for the Eastern Alaskan Range and Denali areas on the 6^th; winds up to 70 mph were forecasted. Whittier reported a gust of 74 mph, and the Anchorage International Airport reported a high gust of 43 mph. In conjunction, areas of the eastern Brooks Range, eastern Beaufort Coast and Bering Strait had winter storm warnings broadcasted.

On the 10^th the annual Arctic Man competition was delayed due to poor visibility. The event, uncompleted, was canceled the following day due to the weather. A grass fire in Dillingham destroyed two structures while burning several acres on the 15^th. The next day, a power outage, which stretched from the Mat-Su to Interior areas, was caused by lightening strike on the transmission line. Wind advisories and warnings were again issued for the Denali and eastern Alaska Range on the 19^th. A wind gust of up to 47 mph was measured at the Fairbanks Airport, and the high winds caused power outages, some property damage and a few small fires from power lines. As a result of the nice weather and high winds the snowpack all but vanished in the Fairbanks area. The 19^th was also the first day since September 29^th, 2014 that the temperatures in Fairbanks did not dip below the freezing mark.

Winter weather advisories were issued for the northwestern coastal areas on the 19^th. Heavy rain was forecasted for the Juneau area for the same day, while snow was forecasted for the Anchorage and Mat-Su areas. The 19^th also saw the seasonal closing of the trails in the Chena River Recreation Area due to the spring thaw. The Division of Forestry also urged residents to stay off of logging roads throughout the break up season.

The Nenana Ice Classic annual guessing game came to an end on the 24^th when the tripod finally tipped fully over, the sixth earliest breakup since 1917. Also on the 24^th, red flag warnings due to low humidity and winds were issued for the Mat-Su area. A flood advisory was published for the Tanana River near Salcha on the 28^th, then canceled on the next day as the ice jam dissipated.

The very low snowfall and overall dry conditions over the Southwestern portions of the state resulted in fire risk warnings being disseminated, and preparations were begun for an early fire season. The low snowfall during the winter had a positive outcome; the Alaska Railroad tallied the lowest moose kill in a decade at a total of just 24. This is less than a tenth of the 292 moose struck during the record snowfall winter of 2011-2012.

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 907-474-7885 or visit the center web site at http://akclimate.org. Please report any errors to webmaster@akclimate.org. This summary is based on the 19 first order stations in Alaska operated by the National Weather Service. Extreme events of other stations are also mentioned.