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Weather in the upcoming weeks will play a pivotal role in the flooding potential during spring breakup

Several rivers in Alaska are expected to have above average flooding potential.
Ice and water near Bethel as breakup continues.
Ice and water near Bethel as breakup continues.(KTUU)
Published: Mar. 17, 2021 at 8:00 PM AKDT
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ANCHORAGE, Alaska (KTUU) - Winter got off to a rocky start in the Last Frontier, as the first half of the season was above average for practically the entire state.

Several locations either saw a top-five warmest January’s on record or placed just outside the top 10. Combine that with a new record low-pressure for Alaska, low sea ice, and the flooding and landslides that inundated the Southeast, this certainly has been an interesting winter.

Although the effects of La Niña were largely absent from the 49th state through December and January, a shift to a colder pattern emerged as the first month of the year came to a close.

Since then, numerous locations across the state have seen temperatures anywhere from 2 to 15 degrees below average, with the exception of near-record warmth for the Aleutians and the Alaska Peninsula.

This drastic shift in our weather has also led to one of the longest consecutive streaks of below-freezing temperatures we’ve seen since 2007. As of Wednesday, Anchorage is sitting at 52 straight days below freezing and the cold is sticking around.

While we have been far from record-breaking cold, the persistence of the cold has played a huge role in ice thickness. We’ve also seen an active line of storms during this time with a growing snow depth. Because of this, some rivers across the state can expect to see average to above average potential for flooding as breakup arrives.

One of the key components in our breakup will be the weather conditions in the weeks and months ahead.

In an outlook released by the National Weather Service Alaska Pacific River Forecast Center, they detail that ice thickness across the state is near average, with the Kuskokwim Delta, Gulf of Alaska region, and the northern inner channels of Southeast seeing a huge increase in snowpack compared to normal.

The only exception being the Yukon River near Galena, which is seeing below normal ice thickness. It’s the rivers where the ice thickness is average and snowpack is abundant where the flood potential remains the greatest, as the slow, yet upcoming spring warmth thaws the Last Frontier.

The outlook details the following rivers and their potential for flood risks this season.

Above Average Flooding PotentialAverage Flooding PotentialBelow Average Flooding Potential
Kuskokwim RiverTanana RiversNorth Slope Rivers
Rivers Along Turnagain ArmYukon RiversKoyukuk Rivers
Rivers Along Gulf of AlaskaCopper Rivers
Rivers of the Northern Southeast PanhandleOther Rivers in Alaska

While cooler weather looks to prevail through the latter half of March, the transition during April and May will determine the severity of the ice breakup.

The NWS says that typically cooler than normal Aprils followed by a sudden warm-up into May can exacerbate the flooding situation and lead to a higher threat for ice jams.

The trends ahead suggest we’ll continue to see cooler than normal weather as spring officially kicks into gear, with some warmth possible during the first week of April.

It’s the weather pattern that will follow, that will ultimately determine when breakup and potential flooding will commence.

The next outlook will be issued in the second week of April

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