National Weather Service United States Department of Commerce

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

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The current breakup outlook can be found here: https://www.weather.gov/aprfc/FGAK78PACR