The National Weather Service has changed the criteria for extreme cold weather advisories.
NWS Alaska meteorologist Tim Markle said the warnings are designed to let community members know when the cold weather presents a risk to the community. However, the old system set wind chill warnings and advisories, which were statewide in scope, and only kicked in when there was a wind chill.
“The current threshold statewide for a wind chill advisory, our old product, is minus 40,” Markle said. “The last time that we saw criteria like that in Anchorage, 1989. So you're talking a once in a generation type advisory here, which we have realized is not an effective way of messaging.”
The new system updates advisories in two ways. The newly renamed extreme cold advisories and warnings no longer require a wind chill. And they’re regionally specific, instead of statewide. For example, Markle said an advisory in Anchorage would be at 25 below, and a warning would be 35 below.
“As we get closer to the coast, say along Prince William Sound the southern parts of the Kenai Peninsula, it's maybe minus 15, minus 25,” Markle said. “And going even farther into Southeast Alaska, you're getting closer to minus 10, zero to some places.”
Ideally, Markle said, an advisory would represent a level of extreme cold that a community sees once or twice a year, and a warning would mark temperatures a community sees maybe once every few years. He said since the new advisories and warnings were launched in the fall, they’ve been issued in Interior communities like Fairbanks and Ft. Yukon and Southeast communities like Haines.
NWS climate researcher Brian Brettschneider said keeping the advisories community-specific is important, since different cities are designed around different weather patterns.
“Cities are built for the climate that they're in," Brettschneider said. "And so our houses are built for it, our social services are built for it, our infrastructure is built for it. And so when you have, you know, an extreme level of cold, it's impactful to somebody in the community.”
He said he’s hopeful that the new advisories will send a clearer picture to communities, especially more vulnerable residents, about when they should worry about cold weather.
