000
SRAK48 PACR 230014 RRA
RVAAK
ALASKA SPRING BREAKUP SUMMARY
NWS ALASKA PACIFIC RIVER FORECAST CENTER
ANCHORAGE AK
400 PM AKDT SUN MAY 22 2022
..RECENT NOTABLE EVENTS OR FORECAST CHANGES:
The large ice jam located upstream of Grayling has released, sending
heavy bank-to-bank ice flows down river from Grayling to Russion
Mission. The degrading sheets of ice that were in place between
Grayling and Anvik have also cleared out and moved down river,
minimizing the threat of additional ice jam formation in this
region. A rise in water levels along this reach of the Yukon River
have occurred since the start of the jam release, but remain below
bankfull at this time. Recent satellite imagery shows water
immpounded by the large ice jam continuing to flood low lying areas
east of the main chanel, and moving southeast towards the Innoko
River near the community of Shageluk.
An ice jam formed on the Buckland River late yesterday evening,
casuing water levels to rise and minor flooding to occur in the
Buckland community. Local observations indicated a minor release of
the jam, sending runs of ice down river. Large sheets of bank-to-
bank ice remain jammed up river of Buckland. Residents of Buckland
should continue to monitor the situation and expect rapid rises of
water levels and heavy ice runs once the jams up river release.
..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.
The spring breakup flood potential for major rivers in Alaska:
..Middle and Upper Yukon River: Above average
..Lower Yukon River: Average
..Koyukuk River: Above average
..Upper Kuskokwim River: Above average
..Lower Kuskokwim River: Average
..Susitna River: Above average
..Tanana River and Chena River: Above average
..North Slope rivers: Average
..Copper Basin rivers: Average
This outlook is based on observed snowpack, ice thickness reports,
and seasonal temperature outlooks. It is important to remember that
while Alaska has experienced mostly mild winters for the past
decade, `average` is defined over a longer period. Average flood
potential may be higher than in recent memory.
...River Ice...
The two generalized types of river ice breakup are dynamic
(mechanical) and thermal. A dynamic breakup moves from headwaters
downstream in a somewhat linear fashion. Ice jam flooding occurs
more often during a dynamic breakup. A thermal breakup occurs when
the ice rots in place usually caused by a gradual warm up resulting
in very few and only minor ice jams.
April ice thickness data are available for a limited number of
observing sites in Alaska. Ice thickness is near normal across the
state. Cumulative freezing degree days (FDD), which can serve as an
indicator of ice thickness, are normal statewide from a marginally
colder than normal winter. FDD are 90 to 110% of normal for
Southcentral, the Interior, the North Slope, and the West Coast;
coastal locations around the Gulf of Alaska are 150 to 200% of
normal.
...Snowpack...
The May 1st NRCS Alaska snowpack analysis by the Natural Resources
Conservation Service (NRCS) indicated an above normal snowpack for
the majority of the state. Persistent average to below average
temperatures during the middle and late April delayed signficant
snow melt across the interior. Snowpack across the interior remains
well above average. The Kuskokwim basin has been omitted, as
it consists of only two data points, one of which has melted out.
May 1st Alaska Snowpack:
..Arctic: Near normal
..Upper Yukon Basin (largely in Canada): 210% of normal
..Central Yukon Basin: 190% of normal
..Tanana Basin: 320% of normal
..Koyukuk Basin: 120% of normal
..Lower Yukon Basin: 150% of normal
..Copper River Basin: 190% of normal
..Matanuska and Susitna basins: 180% of normal
..Kenai Basin: 130% of normal
...Climate Outlook...
Current weather models and NOAA`s Climate Prediction Center (CPC)
outlook through the end of May indicate near normal temperatures for
parts of eastern and northern Alaska, and above normal temperatures
across southwest, southcentral, and central interior Alaska.
Slightly drier than normal conditions are likely for southwest
Alaska, while eastern mainland Alaska favors above normal
precipitaiton. Through the first half of June, CPC guidance
indicates above average temperatures and below normal precipitation
across most of the state. The Alaska Panhandle is expected to be
cooler than normal with above average precipitation during the first
few weeks of June.
...Flood Potential...
The following table gives an estimation of flood potential for
various locations around Alaska and basin runoff volumes.
--------------------------------------------------------------------
SNOWMELT RUNOFF VOLUME...EXPECTED WATER VOLUME FROM SNOWMELT DURING
THE MELT SEASON.
FLOOD POTENTIAL...THE LIKELIHOOD OF FLOODING FROM SNOWMELT AND/OR
ICE JAMS.
* Median breakup dates are for the period 1980 through 2021 and are
calculated for locations with at least 5 years of data.
** Actual breakup date for the current year.
--------------------------------------------------------------------
SNOWMELT FLOOD MEDIAN NO. OF FORECAST
RIVER - REACH RUNOFF POTENTIAL BREAKUP YEARS BREAKUP
VOLUME DATE* USED DATE
------------- ---------- ---------- ------- ------ ---------
SOUTHEAST PANHANDLE AVERAGE
KENAI RIVER AVERAGE LOW
ANCHOR RIVER ABOVE LOW 04/17 19 04/01**
MATANUSKA RIVER ABOVE LOW-MOD
SUSITNA RIVER ABOVE
GOLD CREEK MOD
SUNSHINE LOW-MOD 05/02 33 05/05**
YENTNA RIVER ABOVE
LAKE CREEK LOW-MOD 05/01 30 05/05**
SKWENTNA RIVER ABOVE
SKWENTNA LOW-MOD 04/29 27 04/27**
COPPER RIVER BASIN ABOVE
GAKONA @ HWY MOD 04/29 34 Unknown**
GULKANA @ HWY MOD 04/29 32 05/07**
CHENA RIVER ABOVE
FAIRBANKS MOD 04/25 29 04/30**
TANANA RIVER ABOVE
CHISANA @ NORTHWAY LOW-MOD 04/25 31 04/27**
SALCHA MOD
FAIRBANKS MOD 04/29 21 05/05**
NENANA MOD 04/29 42 05/02**
MANLEY MOD 05/03 31 05/08**
KUSKOKWIM RIVER ABOVE
NIKOLAI LOW 04/23 36 04/25**
MCGRATH MOD 05/03 42 05/09**
STONY RIVER LOW-MOD 05/02 34 05/05**
SLEETMUTE MOD-HIGH 05/01 33 05/08**
RED DEVIL MOD-HIGH 05/03 36 05/08**
CROOKED CREEK MOD 05/03 36 05/08**
ANIAK MOD-HIGH 05/06 39 05/01**
KALSKAG MOD 05/05 33 05/08**
TULUKSAK LOW-MOD 05/07 30 05/04**
AKIAK LOW-MOD 05/07 36 05/05**
KWETHLUK MOD-HIGH 05/03 10 05/04**
BETHEL LOW-MOD 05/09 42 05/05**
NAPAKIAK LOW-MOD 05/10 27 05/05**
YUKON RIVER (UPPER) ABOVE
DAWSON, YT LOW-MOD 05/03 42 05/07**
EAGLE MOD 05/03 42 05/07**
CIRCLE HIGH 05/09 38 05/09**
FORT YUKON MOD 05/11 38 05/10**
BEAVER LOW 05/11 26 05/11**
STEVENS VILLAGE MOD 05/11 24 05/11**
RAMPART LOW-MOD 05/11 26 05/11**
YUKON RIVER (MIDDLE) ABOVE
TANANA MOD 05/07 37 05/09**
RUBY LOW 05/09 36 05/11**
GALENA MOD 05/11 41 05/11**
KOYUKUK MOD 05/10 16 05/11**
NULATO MOD 05/11 24 05/12**
KALTAG LOW-MOD 05/11 36 05/12**
ANVIK LOW-MOD 05/14 33 05/18**
YUKON RIVER (LOWER) ABOVE
HOLY CROSS LOW-MOD 05/14 35 05/18**
RUSSIAN MISSION LOW-MOD 05/15 35 05/18**
MARSHALL LOW-MOD 05/15 30 05/15**
PILOT STATION LOW-MOD 05/14 25 05/09**
MOUNTAIN VILLAGE LOW-MOD 05/14 35 05/10**
ALAKANUK/EMMONAK MOD-HIGH 05/19 36 05/15**
KOYUKUK RIVER ABOVE
BETTLES LOW 05/10 40 05/06**
ALLAKAKET MOD 05/11 35 05/06**
HUGHES MOD 05/11 35 05/07**
SEWARD PENINSULA AVERAGE
BUCKLAND MOD 05/15 32 05/21**
KOBUK RIVER ABOVE
KOBUK MOD 05/14 38 05/17**
SHUNGNAK LOW 05/15 31 05/20**
AMBLER LOW 05/15 37 05/20**
NOATAK RIVER AVERAGE
NOATAK LOW 05/19 24 05/19-05/25
BROOKS RANGE - NORTH AVERAGE
COLVILLE @ UMIAT LOW 05/26 20 05/23-05/29
COLVILLE @ COLVILLE LOW 06/04 22 06/01-06/07
SAGAVANIRKTOK RIVER AVERAGE
DALTON HWY LOW
FOR MORE DETAIL AND TO SEE A FLOOD POTENTIAL MAP REFER TO OUR WEB
SITE AT HTTPS://WWW.WEATHER.GOV/APRFC/FLOODPOTENTIAL
The breakup summary will be issued daily.
$$ jmw kvp
Visit us at http://www.weather.gov/aprfc
The current breakup outlook can be found here: https://www.weather.gov/aprfc/FGAK78PACR
