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ESFAK 



Hydrologic Outlook 

NWS Alaska Pacific River Forecast Center Anchorage AK 

1PM AKDT FRI APR 5 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_20240405.pdf 







...SPRING BREAKUP OUTLOOK FOR ALASKA... 





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



April 1 ice thickness data across the state are near normal. Recent 

snowpack measurements show normal to above normal snowpack at most 

locations across interior Alaska. Climate outlooks are indicating 

temperatures to remain colder than normal across most of interior 

Alaska through mid April.





...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 March and early April measurements 

indicate that ice thickness is near normal across the state. 

Observations from the Interior range from 85%-110% 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 March reports indicating that river ice has 

begun to deteriorate, and/or soften in some locations. 





...Freezing Degree Days...



Cumulative freezing degree days (FDD) as of April 1, which can serve 

as a proxy for river ice thickness, are near normal across most of 

Alaska including Southcentral and across interior Alaska. Colder 

than normal conditions were observed across coastal sites along the 

Gulf of Alaska (Homer to Sitka), where FDD was reported to be 120% 

to 200% of normal. 





...Snowpack... 



The April 1st Naturual Resources Conservation Service (NRCS) 

analysis has not been released yet. The March 1 analysis indicates 

above normal snow for the majority of the state and the preliminary 

April 1 data indicates the Alaska snowpack percent of normal likely 

has not changed significantly. 



The Yukon Basin end of March NRCS analysis combined with the early 

March Yukon Canada snowpack analysis indicate normal to above normal 

snowpack in the basin. The Porcupine and Fortymile basins are 

reporting well above normal snowpack approaching 150%.



The Northslope snowpack is likely normal to below normal based on 

limited measurements. 



The upper Kuskokwim River basin is below normal however the number 

of reported measurements is very small. Recent observations from 

observers at various communities indicate above normal snowpack 

other climate analyses also indicate likely above normal snowpack.



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

above normal. 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 above normal, with the 

snowiest locations in the eastern headwaters, bordering the Copper 

Basin.



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 April 4 outlooks favor normal to 

colder than normal temperatures through the third week in April. 

This outlook would indicate an increased liklihood of a fairly rapid 

warm up over interior Alaska in late April as temperatures are 

forecast to warm toward normal. The April-May-June forecast is for 

above normal temperatures across Alaska.

  



The next Spring Breakup Outlook will be published April 14, 2024.  





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DPS