The Warming of Alaska

Many of us here in the lower 48 states are still dealing with the last whimpers of winter. In the past 24 hours measurable snow fell in the Rockies and northern Plains, across northwestern Iowa, and in the Great Lakes, and even in the southeast where snow was falling Tuesday in parts of North Carolina. In Alaska, however, the last few days have been spectacularly warm by Alaska standards. It was news that saw wide distribution in social media, but not much in terms of a "national" new story. How bad can it be when you high temperature in March is in the mid 30's, 30°F to 40°F above normal? Well, that would be like maximum temperatures here in the central Midwest being in the upper 80s to mid 90s, while records are generally in the low 80s this time of year.

Maximum temperature for March 30 in the northern half of Alaska (left) and the departure from normal (right). Credit:UAF/ACCAP/Rick Thoman, @AlaskaWx

A strong upper level high centered over the state was responsible for the record warmth.

The 500 mb chart for the morning of March 30 (left), the the departure from normal (right) with Alaska circled.

However, while the record warm daily temperatures the past week were newsworthy, the abnormally warm weather has been a persistent feature of the Alaskan climate for the past several years.

The chart below shows that monthly average temperatures have ranked in the top 50 percent in all but 10 months. More remarkably, monthly temperatures have ranked at the 90th percentile or higher 28 out of the 74 months.

Here are plots of the daily average temperatures for four Alaskan cities since January. Temperatures in Juneau are pretty well distributed between above and below normal. However, look at the chart for Barrow. Days below normal since the first of the year have been few and far between.

Plots of the departure from normal of the daily average temperature (°F) for four Alaskan cities since January 1.
Credit: Alaska Climate Research Center

A more detailed look at Barrow's daily temperatures shows how striking the warmth has been since September 1. The maximum temperature has been below normal on only three days since September 1. For the past eight days both the maximum and minimum temperatures have been higher than the normal maximum temperature.

Credit: Alaska Climate Research Center

The Juneau International Airport has set or tied a record high temperature each of the last eight days. Records go back to 1936 in Juneau. The low temperature in Fairbanks on both Monday and Tuesday was 34°F. The city’s lowest temperature has only been above 34°F in March on one other day in the last 114 years. In both Anchorage and Juneau there was no measurable snow during the entire month of March.

March 2019 was the warmest on record across most of the area north of the Alaska Range and on the west coast north of Bristol Bay. This follows a January that was the 26th warmest and February that was the ninth warmest on record.

Credit: Alaska Climate Research Center

Some locations recorded their earliest 70°F temperatures on record. Klawock, in southeastern Alaska, reached 70°F on March 19, the earliest any location in the state has reached 70°F.

The persistent warmth in Alaska is having serious consequences for a state the has adapted to living with extreme cold. Thawing of the permafrost is affecting the stability of the land that supports homes and roads. The softening land surface causes shifting foundations, cracked walls, and in some cases collapse of structures. Whole communities may need to be relocated. Roads crack and sink as the land supporting them shifts. Portions of the Iditarod race had to be shifted because of thin or no sea ice, or thin ice on rivers and streams normally used for travel. The breakup of ice on Alaska's rivers, a significant event marking the transition from winter to spring, is occurring earlier than normal, Ice breakup along with snowmelt can cause serious flooding. The extent and thickness of sea ice has been declining especially in the past 10 years. At the end of this March ice in the Bering Sea was at a record low extent.

Credit: Zachary Labe @Zlabe