Alaska experienced record-setting warmth during the 2015-16 cold season (October-April). Statewide average temperatures exceeded the period-of-record mean by more than 4°C over the seven-month cold season and by more than 6°C over the four-month late-winter period, January-April. The record warmth raises two questions: (1) Why was Alaska so warm during the 2015-16 cold season? (2) At what point in the future might this warmth become typical if greenhouse warming continues? On the basis of circulation analogs computed from sea level pressure and 850 hPa geopotential height fields, the atmospheric circulation explains less than half of the anomalous warmth. The warming signal forced by greenhouse gases in climate models accounts for about 1°C of the of the anomalous warmth. A factor that is consistent with the seasonal and spatial patterns of the warmth is the anomalous surface state, which 454. The surface anomalies include (1) above-normal ocean surface temperatures and below-normal sea ice coverage in the surrounding seas from which air advects into Alaska and (2) the deficient snowpack over Alaska itself. The location of the maximum of anomalous warmth over Alaska and the late-winter/early-spring increase of the anomalous warmth unexplained by the atmospheric circulation implicates snow cover and its albedo effect, which is supported by observational measurements in the boreal forest and tundra biomes. Climate model simulations indicate that warmth of this magnitude will become the norm by the 2050s if greenhouse gas emissions follow their present scenario.
Available in-person in IARC/Akasofu 407 on the UAF Campus or online
Do you lie awake at nights wondering what the upcoming season will be like? Want to place bets with friends and family on next month's weather? If so, good news:
The tools and techniques for making monthly and season scale climate forecasts are rapidly changing, with the potential to provide useful forecasts at the month and longer range. Rick Thoman (Climate Science and Services Manager, Environmental and Scientific Services Division, National Weather Service Alaska Region) will review recent climate conditions around Alaska, review forecast tools and finish up with the Climate Prediction Center's forecast for the upcoming season.
Rick will also present a "Feature-of-the-Month" special addition in which each month he will highlight a topic relevant to the particular month.