Up to 2 more inches of rain could fall in the Alaskan peninsula through Tuesday as an atmospheric river continues to bring heavy rain and the potential for floods to The Last Frontier.

Why It Matters

Atmospheric rivers are a “long, narrow region in the atmosphere—like rivers in the sky—that transport most of the water vapor outside of the tropics,” according to the National Oceanic and Atmospheric Administration (NOAA). They commonly impact the Pacific Northwest during the winter months.

In Southwest Alaska, such storms typically begin in early to mid-August. One such storm has brought rounds of heavy rainfall to the region since last week.

What To Know

On Sunday night, the National Weather Service (NWS) office in Anchorage posted an update on X about the ongoing atmospheric river.

“An atmospheric river will cause rain to continue across the Alaska Peninsula and northern Bristol Bay coastal areas through Tuesday morning. Up to another 1-2″ can be expected through Tuesday morning,” the post read.

So far, northern Bristol Bay has seen the most rainfall since the storms began last week at 1.22 inches. NWS meteorologist Michael Brown told Newsweek that rain is still falling, although it’s becoming lighter.

“That’s going to generally be the trend for the day, but they’re still going to get a little additional rainfall through the afternoon,” he said.

“This is the time of year we see them the most,” Brown said about atmospheric rivers.

He also urged people along the rivers to be careful as rivers are running high.

Meanwhile, a heat advisory is in place for southeastern Alaska, with a flood watch in place for northwestern Alaska. Myriad other alerts, including a gale warning, small craft advisory, and high surf advisory, are in place along the western coast.

What People Are Saying

NWS Anchorage in a post on X on Monday afternoon: “A Flood Advisory has been issued for the Northern Susitna Valley in the Petersburg area until 9:15 AM Thursday. The heaviest rain is expected to occur across the headwaters of Peters Creek and Cache Creek.”

NOAA in a webpage about atmospheric rivers: “Atmospheric rivers usually begin over tropical regions. Warm temperatures there cause ocean water to evaporate and rise into the atmosphere. Strong winds help to carry the water vapor through the atmosphere. As atmospheric rivers move over land, the water vapor rises up farther into the atmosphere. It then cools into water droplets, which fall as precipitation.”

What Happens Next?

The atmospheric river is expected to diminish later in the day on Monday. Looking further out, the NWS Climate Prediction Center anticipates above-average precipitation for much of Alaska between September 8 and 14.