Breakup Progress

River ice breakup has been progressing across the state, and as expected it has been a relatively "dynamic" process with ice jams and flooding in a number of locations (notably McGrath and Manley Hot Springs).  However, it could have been even worse: temperatures have been below normal this month, significantly so at times, and there hasn't been the kind of dramatic warm-up that might have created a more violent collision between rushing meltwater and ice jams.

Here are temperature anomaly plots from (top) Fairbanks and (bottom) the UAF/ACCAP statewide temperature index (click to enlarge).  Every day so far this month has been cooler than normal by both measures.

The map below shows the latest breakup situation, with mostly open water now on the major interior rivers.  A major exception is part of the lower Yukon, where flood watches have been hoisted downstream of an ice jam just upriver from Grayling.  Apparently water is so backed up that flooding is occurring for 70 miles upstream of the jam, and when the jam releases there will be a rush of water and ice into communities downstream.

 

From the NWS river forecast center:

ALASKA SPRING BREAKUP SUMMARY
NWS ALASKA PACIFIC RIVER FORECAST CENTER
ANCHORAGE AK
500 PM AKDT WED MAY 18  2022

..RECENT NOTABLE EVENTS OR FORECAST CHANGES:

Current webcams show the breakup front on the Yukon is right at
Grayling, with ice shifting in the river across from town this
afternoon. Satellite imagery from yesterday showed a very large ice
jam in place 7 miles upstream from Grayling, extending to around 25
miles upstream from the toe of the jam.  This ice jam is causing
water levels to rise overbank and inundate low lying areas nearly 70
miles upstream. Sheet ice is still in place from Grayling down to
Russian Mission. Downriver communities can expect rapid rises in
water levels and heavy runs of ice when this jam releases. Additonal
ice jams could also form as the breakup front pushes into the
stronger sheet ice downstream, thus a flood watch has been issued
for Grayling to Russian Mission. Downstream from Mountain Village
the river was mostly open.

An ice jam released near Old Crow and water levels at the US-Canada
border crested Tuesday.  Rapid rises in water levels along with
heavy runs of ice are expected along the upper Porcupine River.



..SPRING BREAKUP STATUS FOR ALASKA...

Statewide, breakup this year has been largely dynamic with ice jams
observed at Manley Hot Springs, McGrath, Sleetmute, Red Devil,
Crooked Creek, Circle, and Galena so far.  While Manley Hot Springs
and McGrath suffered major flooding, the other ice jams created
minor to moderate flooding due to the cooler than normal
temperatures so far this May.

Breakup is complete on the Kuskowkwim, Koyukuk and Middle and Upper
Yukon Rivers.  The lower Yukon River still has some areas of weak in-
place ice and runs of ice with breakup still continuing on the lower
Yukon River.

The Kobuk, Buckland and rivers north of the Brooks Range are still
ice covered.