Fairbanks is already down to a snow depth of only 4 inches, but the snow pack remaining in the hills is quite monumental: the Munson Ridge SNOTEL site at 3100' elevation near Fairbanks is reporting 15" of liquid equivalent water. That's a lot of water to come down the creeks and rivers in the next month.
According to the SNOTEL instrument, 6.8" of liquid-equivalent precipitation has fallen on the hill since March 1 - this is quite remarkable for the (usually dry) time of year. It's believable too; here's a chart of recent precipitation at the top-quality CRN site (1140' elevation).
The massive influx of melt water will almost certainly bring forward the date of break-up at the Nenana tripod, owing to the increased stress caused by high water. There's some evidence of this effect in the history of the Nenana break-up; the chart below shows that when precipitation is very high after March 1, the heat input (thawing degree days) required to reach break-up tends to be lower than normal.
This year Fairbanks has seen 2.86" of precipitation since March 1, which is the highest on record for March 1 - April 21. The previous record for this period was in 1967, which happens to be the year of the great August flood in Fairbanks (hmm...)
Here's the latest break-up summary from the NWS.
HYDROLOGIC OUTLOOK
NWS ALASKA PACIFIC RIVER FORECAST CENTER
ANCHORAGE AK
1 PM AKDT WED APR 22 2020
..SPRING BREAKUP OUTLOOK FOR ALASKA...
Breakup Update: The Forty Mile river upstream of the Taylor Highway
has broken up as well as the Kuskokwim River near Nikolai. The Tozitna
River has broken up with an ice jam forming and releasing. The Aniak
River is reported to have broken up dynamicaly and is mostly open at
the confluence with the Kuskokwim. Ice is beginning to lift on the
Kuskokwim, Yukon and Koyukuk Rivers.
The 2020 Alaska Spring Breakup flood potential is forecast to be
generally above average south of the Brooks Range and average flood
potential for the North Slope. The Flood Potential forecast is based on
observed snowpack, ice thickness reports, and long-range temperature
forecasts and focuses on the Kuskokwim, Tanana , Yukon, Koyukuk,
Copper, and North Slope rivers. Recent observed and forecast
temperatures suggest a generally earlier than normal, more dynamic
type breakup for locations statewide.
Timing of breakup statewide is expected to be several days earlier
than normal. Breakup along the Yukon River upstream of Fairbanks
is expected to be 1 to 3 days earlier than median dates; generally 3 days
earlier at locations downstream from Fairbanks to Anvik; and 3 to 5 days
earlier at locations downstream from Anvik to the mouth. Breakup along the
Kuskokwim River at Nikolia downstream to Tuluksak are expected to be 1
to 2 days earlier than median dates and 2 to 5 days earlier downstream
from Tuluksak to the mouth.
Temperatures - Statewide, temperatures over the past few weeks generally
have been normal to below normal. However, temperatures over the next
several weeks are expected to be normal in areas north of the Brooks
Range and above normal for the remaining parts of the state. Statewide,
temperatures for April and May are expected to be above normal.
Ice - The April 1st ice thickness data indicate that ice thickness is near
normal across the state. A few measurements across interior Alaska
ranged from 32 inches at Galena, which is 82% of average; 33 inches
at Nenana, which is 80% of average; 48 inches at Eagle, which is
117% of average.
Snow - April 1st snowpack by the Natural Resources Conservation Service
(NRCS) indicates greater than normal snowpack across interior Alaska
ranging from 117% in the central Yukon Basin to 197% of average in
the Kuskokwim Basin. The Yukon government is also reporting greater
than normal snowpack across the Upper Yukon River Basin in Canada.
The snowpack is near normal along the North Slope and below normal along
the Gulf Coast and throughout Southeast Alaska.
Climate Outlook:
April and May weather is the most important factor determining the severity
of river ice breakup. Dynamic breakups have a high potential for ice jam
flooding and typically require cooler than average temperatures during March
and into the first few weeks of April followed by an abrupt transition to
warmer than normal temperatures in late April to early May. Thermal breakups
have a low potential for ice jam flooding as river ice generally rots in place.
The Climate Outlook for Spring 2020 suggests a more dynamic type breakup this
year. Observed temperatures in March thru the first week of April were generally
below normal to normal. The second and third weeks of April were generally
warmer than normal. Temperature forecasts for the last week in April
indicate near normal temperatures statewide with equal chances for above and
below normal for early may. The mid-March 3-month Climate outlook
indicates increased chances of above average temperatures throughout Alaska.
Further information can be found at the following web sites:
Weather-
https://www.weather.gov/aprfc/AGAK78PACR
Snow-
https://www.weather.gov/aprfc/nrcs_ak_swe
https://www.weather.gov/aprfc/snow_depth
https://www.wcc.nrcs.usda.gov/snow/
Ice thickness-
https://www.weather.gov/aprfc/icethickness
Climate prediction-
http://www.cpc.ncep.noaa.gov/
River Ice Breakup Flood Threat:
The two generalized types of river ice breakup are dynamic (mechanical)
and thermal. A dynamic breakup moves from the headwaters of a river
downstream in a somewhat linear fashion. Ice jam flooding occurs more often
during a dynamic type breakup than a thermal type. A thermal type breakup
results in the river ice rotting in place primarily due to gradual to rapid
warm ups and little snowmelt runoff. Thermal type breakups usually result
in fewer ice jams and less chance of flooding.
Statewide, breakup this year is expected to lean generally to the dynamic
type. Temperatures statewide over the past few weeks generally have been
normal to below normal. However, temperatures over the next several weeks
are expected to be normal in areas north of the Brooks Range with above
normal temperatures for the remaining parts of the state. Temperatures
statewide for April and May are expected to be above normal. South of
the Brooks Range, the expected more dynamic type breakup, above normal
temperatures, and above average snowpack has increased the potential for
flooding this year to above average, while flooding potential north of the
Brooks Range is expected to be average.
THE FOLLOWING TABLE GIVES AN ESTIMATION OF FLOOD POTENTIAL FOR
VARIOUS LOCATIONS AROUND THE STATE 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. THIS IS INITIALLY CALCULATED BASED ON THE FLOOD
FREQUENCY FOR THE 2000 TO 2019 HISTORICAL RECORD AND ADJUSTED
TO REFLECT CURRENT CONDITIONS.
* MEDIAN BREAKUP DATES ARE FOR THE PERIOD 1980 THROUGH 2019 AND ARE
CALCULATED FOR LOCATIONS WITH AT LEAST 5 YEARS OF DATA.
** ACTUAL BREAKUP DATE FOR THIS YEAR
---------------------------------------------------------------------
SNOWMELT FLOOD MEDIAN NO. OF FORECAST
RIVER - REACH RUNOFF POTENTIAL BREAKUP YEARS BREAKUP
VOLUME DATE* USED DATE
------------- ---------- --------- ------- ------ --------
SOUTHEAST PANHANDLE ABOVE
KENAI RIVER AVERAGE LOW OPEN TO SKILAK LAKE
ANCHOR RIVER BELOW LOW MOSTLY OPEN
MATANUSKA RIVER ABOVE AVERAGE LOW
SUSITNA RIVER ABOVE AVERAGE
GOLD CREEK MOD
SUNSHINE LOW-MOD 05/02 31 04/26-05/02
YENTNA RIVER ABOVE AVERAGE
LAKE CREEK LOW-MOD 04/30 29 04/27-05/03
SKWENTNA RIVER ABOVE AVERAGE
SKWENTNA LOW-MOD 04/29 25 04/23-04/29
COPPER RIVER BASIN AVERAGE
GAKONA RVR @ HWY LOW 04/29 32 04/23-04/29
GULKANA RVR @ HWY LOW 04/29 30 04/23-04/29
CHENA RIVER ABOVE AVERAGE
CHENA LAKES PROJECT MOD
FAIRBANKS LOW 04/25 27 OPEN
TANANA RIVER ABOVE AVERAGE
CHISANA @ NORTHWAY LOW-MOD 04/26 27 04/17-04/23
SALCHA LOW-MOD
FAIRBANKS LOW-MOD 04/28 19 04/26-04/02
NENANA LOW-MOD 04/29 40 04/24-04/30
MANLEY LOW-MOD 05/02 29 04/26-05/02
KUSKOKWIM RIVER ABOVE AVERAGE
NIKOLAI LOW-MOD 04/22 34 **04/21
MCGRATH MOD 05/04 40 04/30-05/06
STONY RIVER LOW-MOD 05/01 32 04/27-05/03
SLEETMUTE MOD 05/01 31 04/27-05/03
RED DEVIL MOD 05/03 34 04/28-05/04
CROOKED CREEK MOD 05/03 34 04/29-05/05
ANIAK MOD 05/04 37 04/29-05/05
KALSKAG LOW-MOD 05/04 31 04/30-05/06
TULUKSAK LOW-MOD 05/06 28 05/01-05/07
AKIAK LOW-MOD 05/08 34 05/01-05/07
KWETHLUK MOD 05/03 8 04/30-05/06
BETHEL LOW-MOD 05/09 40 05/01-05/07
NAPAKIAK LOW-MOD 05/10 25 05/03-05/09
YUKON RIVER (UPPER) ABOVE AVERAGE
DAWSON, YT LOW-MOD 05/03 40 04/29-05/05
EAGLE MOD 05/03 40 04/28-05/04
CIRCLE MOD-HIGH 05/07 36 05/02-05/08
FORT YUKON MOD 05/10 36 05/04-05/10
BEAVER LOW-MOD 05/09 24 05/04-05/10
STEVENS VILLAGE LOW-MOD 05/10 23 05/05-05/11
RAMPART LOW-MOD 05/10 25 05/04-05/10
YUKON RIVER (MIDDLE) ABOVE AVERAGE
TANANA LOW-MOD 05/07 35 05/01-05/07
RUBY LOW-MOD 05/08 34 05/02-05/08
GALENA MOD 05/10 39 05/04-05/10
KOYUKUK MOD 05/08 14 05/04-05/10
NULATO MOD 05/10 23 05/04-05/10
KALTAG LOW-MOD 05/11 34 05/05-05/11
ANVIK LOW-MOD 05/13 32 05/07-05/13
YUKON RIVER (LOWER) ABOVE AVERAGE
HOLY CROSS LOW-MOD 05/14 33 05/06-05/12
RUSSIAN MISSION LOW-MOD 05/14 34 05/06-05/12
MARSHALL MOD 05/14 28 05/06-05/12
PILOT STATION LOW-MOD 05/13 23 05/07-05/13
MOUNTAIN VILLAGE LOW-MOD 05/15 33 05/08-05/14
ALAKANUK/EMMONAK MOD 05/20 32 05/12-05-18
KOYUKUK RIVER ABOVE AVERAGE
BETTLES LOW-MOD 05/09 38 05/01-05/07
ALLAKAKET LOW-MOD 05/09 33 05/03-05/09
HUGHES MOD 05/10 33 05/03-05/09
SEWARD PENINSULA ABOVE AVERAGE
BUCKLAND MOD 05/15 30 05/09-05/15
KOBUK RIVER ABOVE AVERAGE
KOBUK MOD 05/13 36 05/07-05/13
SHUNGNAK LOW-MOD 05/16 29 05/10-05/16
AMBLER LOW-MOD 05/16 35 05/10-05/16
NOATAK RIVER ABOVE AVERAGE
NOATAK LOW-MOD 05/13 23 05/17-05/19
BROOKS RANGE - NORTH AVERAGE
COLVILLE @ UMIAT LOW-MOD 05/24 19 05/16-05/22
COLVILLE @ COLVILLE LOW-MOD 06/02 22 06/26-06/01
SAGAVANIRKTOK RIVER AVERAGE
DALTON HWY LOW-MOD
For more detail and to see a Flood Potential Map, refer to our Website
at https://www.weather.gov/aprfc/FLOODPOTENTIAL
The next Spring Breakup Outlook is scheduled at 2PM AKDT Friday April 24th, 2020
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