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ESFAK 



Hydrologic Outlook 

NWS Alaska Pacific River Forecast Center Anchorage AK 

320 PM AKDT FRI MAR 29 2024





...UPDATED BREAKUP OUTLOOK ISSUED USING AN EXPERIMENTAL GRAPHICAL 

FORMAT...





The Alaska-Pacific River Forecast Center is updating the format of 

its breakup outlook and summary products. The new experimental 

format proposes to move to a more graphical presentation, away from 

the historically text-based product below.  



The experimental graphical format Alaska Spring Breakup Outlook 

products are posted to the Alaska-Pacific River Forecast Center 

website at: www.weather.gov/aprfc/breakupProducts





A direct link to the latest graphical product is: 

www.weather.gov/media/aprfc/BreakupProducts/ESFAK_ACR_20240329.pdf 







...SPRING BREAKUP OUTLOOK FOR ALASKA... 





...Updates to the previous Spring Breakup Outlook... 



Recent river ice observations confirm jumbled ice, and suggests 

normal to above normal thicknesses in reaches on the Middle and 

Upper Yukon River. Kuskokwim River ice thickness is reported as 

normal to slightly below normal between Aniak and Bethel.





...Statewide Flood Potential Overview... 



The outlook for Alaska spring ice breakup and snowmelt flood 

potential is currently rated as normal for the majority of the state.



The spring breakup flood potential for major rivers in Alaska:



..Yukon River: Normal

..Koyukuk River: Normal

..Kuskokwim River: Above Normal

..Tanana and Chena Rivers: Normal

..Copper Basin Rivers: Above Normal

..Susitna River: Normal

..North Slope Rivers:  Normal



This outlook is based on observed snowpack, ice thickness reports, 

and seasonal temperature outlooks. The term ‘normal’ is defined as 

being at or near the climatological value, which is typically 

defined over a 30-year period of record.





...River Ice Observations...



River ice observations are available for a limited number of 

observing sites in Alaska. Late February and early March 

measurements indicate that ice thickness is near-to-below normal 

across the state. Observations from the Interior range from 65%-95% 

of normal, with observations along the mid-Yukon River approximately 

85% normal. However, dense jumble ice has been observed on the Yukon 

River between Rampart and Tanana. Recent UAF Fresh Eyes On Ice team 

(FEOI) reconnaissance confirmed that ice this year (2024) along the 

middle Yukon and Tanana River was on average thicker than last year 

(2023). Yukon River ice thickness at Eagle appears to be thicker 

than the past two winters (2022-2023). Observers on the Kuskokwim 

River have reported normal to slightly below normal ice thicknesses 

between Aniak and Bethel, with recent reports indicating that river 

ice has begun to deteriorate, and/or soften in some locations. No 

freeze-up jams or mid-winter breakups were reported across the Yukon 

and Kuskokwim River basins.





...Freezing Degree Days...



Cumulative freezing degree days (FDD), which can serve as a proxy 

for river ice thickness, are near normal across most of Alaska due 

to fairly mild winter air temperatures. Colder conditions were 

observed across coastal sites along the Gulf of Alaska (Homer to 

Sitka), where FDD was reported to be 139% to 200% of normal. Near 

normal FDD conditions have been observed across Southcentral and 

Copper River Valley, averaging approximately 98% of normal. The West 

Coast, Interior, and North Slope observed near normal FDD, ranging 

from 85% to 100% of normal. 





...Snowpack... 



Analysis of the March 1st snowpack by the Natural Resources 

Conservation Service (NRCS) indicates a variable snowpack; but 

generally the statewide snowpack is above normal for the majority of 

the state.  Since March 1st, there has been a 10-25% increase in 

snowpack for Eastern AK along the ALCAN Border. 



The snowpack for the Upper Yukon (largely in Canada) is reporting 

near normal. A handful of sites in the perimeter of the basin are 

100-125% of normal, but the vast majority are 60-90% of normal, 

bringing the basin total to 92% of normal.  The Central Yukon Basin, 

which includes Eagle, Circle, and Ft Yukon is above normal, at 133%. 

 The Porcupine and the Fortymile Rivers are reporting well above 

normal, with 157 and 137% or normal respectively.  The Tanana Basin, 

which includes Fairbanks and Delta Junction, is near normal at 109% 

of normal.  The Koyukuk Basin has a variable snowpack; along the 

Dalton Highway it is well below normal, extending to near period-of-

record maximum near the Yukon River; overall the basin is 125% of 

normal.  The Lower Yukon Basin, which includes the villages of 

Tanana, Ruby, Galena, and Anvik, have stations reporting between 150 

and 200% of normal at the lower elevations and closer to normal at 

the higher elevations.



The Kuskokwim Basin has a normal to above normal snowpack. Telaquana 

Lake in the far southeast Kuskokwim headwaters is below normal due 

to a mid-February warm up; McGrath avoided the warm up and is 

reporting a near normal snowpack.  Lower in the basin, between Aniak 

and Bethel, observers are reporting above normal snowpack.



For the Arctic, the three stations along the Dalton Highway are 

reporting below normal snowpack.



In Southcentral Alaska, the snowpack in the Copper Basin is notably 

above normal, ranging between 120-140% of the March 1st average. All 

monitoring sites in the basin are reporting above-normal snowpack 

levels. Notably, eight sites in the basin rank within the top five 

of historical records for snowpack levels, with three sites 

reporting record highs.  However, despite this above-average 

snowpack, it's worth noting that the basin's average snowpack 

remains lower than the levels observed in 2022 (175-200%) and 2023 

(160-180%).  Glennallen experienced flooding both of those years. 

The Susitna Basin is reporting 122% of normal, with the snowiest 

locations in the eastern headwaters, bordering the Copper Basin. 

Stations in the Kenai Basin are reporting generally above normal 

with the highest returns in the Kenai River specifically. The basin-

wide snowpack can be approximated at 121% of normal.



The next NRCS statewide snowpack summary is expected after the first 

week of April.





...Climate Outlook...



The most important factor determining the severity of ice breakup 

remains the weather during April and May.  Dynamic breakups, with a 

high potential for ice jam flooding, typically require cooler than 

normal temperatures in early April followed by an abrupt transition 

to warm, summer-like temperatures in late April to early May.



NOAA’s Climate Prediction Center outlook favors above normal 

temperatures through April for all of Alaska.  Across interior 

locations from the Alcan Border to the West Coast, there's a 40-50% 

chance of above-normal temperatures.  In southwest and southcentral 

Alaska, the probability is slightly lower, with a 33-40% chance 

still favoring above-normal temperatures. Looking ahead for the next 

three months, including April, May, and June, there's an elevated 

probability (40-60% chance) of above-normal temperatures across all 

of Alaska.



This temperature pattern would reduce ice jam related flood risk 

along the Kuskokwim and Yukon Rivers. These larger rivers are 

westward flowing and warmer temperatures on the west coast would 

result in ice degradation prior to the arrival of snowmelt runoff, 

decreasing the chances for a dynamic breakup.   



The next Spring Breakup Outlook will be published April 5, 2024.  





$$ 

JSO/JW