The Aleutians are already known for stormy weather. But this year, an unusually strong El Niño could increase the odds for an even stormier winter, in the archipelago and elsewhere in Alaska.
The National Oceanic and Atmospheric Administration announced in June that El Niño had developed in the tropical Pacific. That means the region’s water surface temperature had increased by half a degree Celsius above baseline for several months in a row.
Brian Brettschneider, a climate researcher at the National Weather Service, said that warming trend has continued over the summer.
“It's about 1.7 degrees Celsius warmer than normal, and that is very significant, especially for early August,” he said. “That's uncommonly warm.”
An El Niño is considered “strong” if the Central Pacific sea surface temperature is 1.5 degrees Celsius above normal, and “very strong” if it’s more than 2 degrees above normal. There have been only 10 strong or very strong El Niños recorded in the past 75 years, many of which increased winter temperatures across parts of Alaska.
This year’s El Nino is expected to be very strong, if not historic, according to NOAA.
However, Brettschneider said only about 30% to 40% of weather variability can be explained by an El Niño state.
“It kind of tips the hand and it puts a thumb on the scale, but all options are always on the table. Just some options may be a little bit more likely,” he said.
In Alaska, El Niño’s effects are most pronounced in the winter months. That often translates to more frequent strong storms and a shift in the location of storm activity.
Brettschneider said that in normal years, an area of semi-permanent low pressure sits over the Western Aleutians and causes storms. That area typically shifts eastward during El Niño winter.
“It gets centered maybe over the central Aleutians or even over the Alaska Peninsula, and that can drive storms and storminess over those areas more frequently,”Brettschneider said.
That would include areas like Dutch Harbor, Cold Bay, and Sand Point. But according to Brettschneider, the storm track has the potential to move even farther east with a stronger El Niño. But with only a handful of very strong El Niños on record, it remains to be seen what exactly this one will bring.
