El Nino has transitioned to below normal sea surface temperatures in the mid latitude Pacific. If that persists, the condition known as La Nina, typically results in a colder than normal winter for Alaska, but National Weather Service climate science and services manager Rick Thoman said low sea ice and remaining warm water around Alaska, will be primary drivers of the state’s autumn weather.
“The Gulf of Alaska, the Bering Sea on up into the Chukchi Sea… much warmer than normal,” Thoman said. “That heat will take a while to dissipate.Sea surface temperatures don’t typically reach their maximum until the end of August or even early September so that’s kinda locked in.”
Thoman said warmer seas provide more, potentially rain and snow yielding, moisture to the air.
“That’s one part of the equation,” Thoman said. “The other part of the equation is we had to have the atmospheric conditions. We need storms to be able to turn that moisture into precipitation. Typically in the autumn, that’s not so hard to do.”
Thoman stressed that ocean temperatures and moisture most directly impact coastal weather.
“Once we move inland a little bit, then it becomes more complicated. For instance, across the Interior, if our dominant flow during the fall is out of, say the East or the Northeast from Canada, well… it won’t matter very much that the oceans around us are warm, cause that’s not where our air’s coming from. So it can have a potential effect, but away from the coast, there’s other factors involved.”
Thoman cautions that while the overall fall outlook for Alaska is for warmer than normal, there can still be below normal days, weeks or even a month.
Dan Bross is a reporter at KUAC in Fairbanks.
