Flood in Alaska, May 16 to 19, 2023

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
332 AM AKDT Tue May 16 2023

.SYNOPSIS...
A very active weather pattern continues over Northern Alaska with
ice jam flooding impacting communities along the Yukon River as
well as other large rivers in Alaska. A storm along the West Coast
is bringing an mix of heavy snow at higher elevations and heavy
rain at low elevations while strong chinook winds along the
foothills of the Alaska Range will continue into Tuesday and
combined with low relative humidity levels are producing Red Flag
conditions along portions of the northern foothills of the Alaska
Range. Interior temperatures will be above normal again today
before falling behind a front moving east out of the Western
Interior on Wednesday.

&&

.DISCUSSION...

Upper Levels and Analysis... Aloft at 500 mb A deep upper level
low over the pole anchors a deep longwave trough extending south
along the dateline and into the Central Bering Sea while a strong
ridge holds fast over Western Canada northward into the Yukon and
Eastern Alaska. A second upper level low currently located over
Bristol Bay will push north today into the Lower YK Delta.
Moisture along and ahead of a front extending south of the low
along the West Coast of Alaska will funnel moisture north along
the Coast, the Western Interior and the Western Brooks Range into
Thursday. High pressure aloft will remain over the Eastern
Interior. Leeward side troughing along the northern foothills will
combine with a thermal trough over the southern Interior to
produce gusty winds over the Interior especially to the south of
the Yukon River this afternoon and evening. An areas of winds at
925 mb ahead of a front moving east out of the Western Interior
will aid in the gusty winds. Expect wind gusts in the 25 to 35 mph
range with a few gust over 40 mph this afternoon. A Wind Advisory
has been issued for the middle tanana Valley including the
Fairbanks Area from late this afternoon into this evening. Wind
advisories remain in effect for the the Central and Eastern Alaska
Range as well as the Delta Junction area. The strong winds will
combine with low relative humidity levels to produce Red Flag
conditions for the Eastern Alaska Range north of Donnelly Dome to
Deltana and the Tanana Flats near Delta Junction. Winds are
expected to diminish late tonight and moisture increase as a
front from the Western Interior moves into the area and ends the
warm and dry chinook conditions. Much cooler temperatures and
higher humidity levels are expected in these areas on Wednesday.

Central and Eastern Interior...
One more day of warm and windy before winds diminish on Wednesday
and the dry chinook pattern shifts to a more wet and cooler
pattern. A wind advisory has been issued for the Middle Tanana
Valley as 925 mb winds ahead of a strong front moving east out of
the Western Interior combined with a merging thermal trough and
leeward side trough will produce wind gusts in the 30 to 40 mph
range late this afternoon and into the evening including the
Fairbanks area. Wind Advisories remain in effect until Wednesday
morning along northern foothills of the Alaska Range northward to
near Delta Junction. The strong and gusty winds will combine with
low relative humidity levels along and near the Alaska Range to
produce Red Flag Conditions again today and into this evening.
There is just enough instability in the atmosphere ahead of the
approaching front for some very isolated thunderstorms from near
Bettles to near Nenana this afternoon and evening.

West Coast and Western Interior...
The arctic front will shift westward today, bringing rain with
widespread snowfall on the colder side of the storm. Accumulating
snowfall is expected pretty much everywhere along the West Coast,
with the heaviest amounts along the Seward Peninsula and Saint
Lawrence Island north to the Lisburne Peninsula, where 3 to 6
inches of snowfall are likely. Strong gale force north winds will
accompany the snow as the low shifts north and rapidly deepens
today, with gusts along the coast up to 60 mph. Significant
blowing snow is possible from Saint Lawrence Island to Wales to
Point Hope. See current winter storm warning and advisory products
along the Bering coast for more details.

The low weakens tonight and Wednesday with gradually diminishing
winds and snowfall out west. Showers over the Interior will
continue through Wed night before warming and drying commences Thu
and Fri.

North Slope and Brooks Range...
The arctic front is currently stalled over the North Slope
continues to produce snowfall across most of the entire Brooks
Range and N Slope where 48 snow totals of 2-5" are expected. Winds
remain onshore and light thus expect a return to normal temps
through Thu.

Extended Forecast Days 4-7...
Friday and beyond, confidence is now high that a low deep in the
Gulf of AK and a ridge across the Yukon and BC will begin to build
into the Interior. This should usher in warming temps and dry
conditions Friday through Sunday. Interior locations will likely
begin to see 70 degree temps for high temps by the weekend.
Showers will start to be possible by Monday as easterly waves
undercut the ridging.

Coastal Hazard Potential Days 3 and 4...None.

&&

.FIRE WEATHER...
One more day of chinook weather conditions, with Tuesday expected
to be slightly windier warmer and drier across the Southeast
Interior and Tanana Valley, as well as across the AK Range. Thus
the red flag warning was continued into Tuesday night. Isolated
thunderstorms are also possible across most of the Central
Interior and may push into the White Mtns/Yukon Flats, but the
best chance is farther west.

Wednesday, much cooler temperatures and weaker winds, with an end
to the Chinook pattern and red flag conditions.

&&

.HYDROLOGY...
Flood warning is in effect for Stevens Village for ice jam flooding.
Flood watch remains in effect for high water possible from ice jam
flooding along the Yukon River from the Dalton Highway Bridge to
Rampart. The flood watch for ice jams for McGrath is no longer in
effect based on the latest river observations. A flood watch is no
longer in effect for the upper Chena River for snowmelt, however,
waters will remain elevated as snow continues to melt.

We will continue to monitor the Yukon River as the breakup front
progresses down river through the Yukon Flats, Stevens Village
and further downriver to Rampart.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Winter Storm Warning for AKZ213.
     Flood Watch for AKZ220.
     Red Flag Warning for AKZ223-226.
     Wind Advisory for AKZ222-223-225-226.
     Winter Weather Advisory for AKZ207.
PK...Gale Warning for PKZ806-816.
     Gale Warning for PKZ807.
     Brisk Wind Advisory for PKZ810.
     Heavy Freezing Spray Warning for PKZ811-817-854.
     Gale Warning for PKZ811.
     Brisk Wind Advisory for PKZ812.
     Heavy Freezing Spray Warning for PKZ816-851.
     Gale Warning for PKZ817.
     Small Craft Advisory for PKZ850.
     Gale Warning for PKZ851.
     Brisk Wind Advisory for PKZ853.
     Gale Warning for PKZ854.
     Gale Warning for PKZ856.
     Brisk Wind Advisory for PKZ857.
     Brisk Wind Advisory for PKZ858.
&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FAIRBANKS AK
1059 AM AKDT TUE MAY 16 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1047 AM     FLOOD            CIRCLE                  65.82N 144.06W
05/16/2023                   YUKON-KOYUKUK      AK   TRAINED SPOTTER

            05/13/23 25 MILES UPRIVER FROM CIRCLE WATER
            IS FLOODING THE LOW RIVER LEFT FLOODPLAIN.
            EARLY SATURDAY AFTERNOON - BREAKUP FRONT WAS
            20 MILES UPRIVER OF CIRCLE WITH A 90 MILE
            LONG RUN OF ICE AT 90-100% COVERAGE
            UPSTREAM. THINNED OUT 40 MI DS OF EAGLE. ICE
            SHIFTING AT CIRCLE, BUT MAIN BU FRONT 5-6
            MILES UPSTREAM. 28 ABOVE CIRCLE FLOODING ON
            BOTH LEFT AND RIGHT BANK, RESIDENTS REPORT
            HIGHER THAN THEY HAVE EVER SEEN. ABOVE THE
            BU FRONT, A 90 MILE RUN OF ICE EXTENDS FROM
            5 MILES UPSTREAM OF CIRCLE FOR 90 MILES. THE
            LONGEST ICE RUN THE RW TEAM HAS SEEN. NO
            CLEAR PATH THROUGH ICE DOWNSTREAM OF CIRCLE.
            05/14/23 MAJOR TO NEAR RECORD FLOODING IS
            OCCURRING IN CIRCLE THIS EVENING WITH
            LIMITED DETAILS ON CURRENT WATER LEVEL
            TRENDS OR ICE CONDITIONS. REPORT FROM PILOT
            OVER CIRCLE. FLOODWATERS RECEDING, AIRPORT
            AND APRON ARE DRY, AIRPORT ACCESS ROAD STILL
            HAS WATER OVER. WATER HAS RECEDED FROM THE
            STORE.

1050 AM     FLOOD            1 W FORT YUKON          66.57N 145.27W
05/16/2023                   YUKON-KOYUKUK      AK   TRAINED SPOTTER

            05/14/23 FLOOD WATCH ISSUED FOR FT. YUKON AS
            THE PULSE OF ICE AND WATER WORKS ITS WAY
            DOWN FROM CIRCLE WITH THE POTENTIAL TO CAUSE
            MINOR TO MAJOR FLOODING WITH OVER BANK ICE
            POSSIBLE. BU FRONT IS JUST DS OF FORT YUKON.
            HIGH WATER IS STILL 15-20 MILES UPSTREAM
            FROM FORT YUKON. AN ICE JAM OCCURRED 25 MILE
            UPSTREAM OF FORT YUKON LAST NIGHT AND HAS
            SINCE RELEASED. 05/15/23 THE BREAKUP FRONT
            ON THE YUKON RIVER IS JUST BELOW FORT YUKON,
            A FLOOD WARNING HAS BEEN ISSUED WITH
            FLOODING OF LOW LYING AREAS OCCURRING AND AN
            ICE JAM JUST DOWNSTREAM HOLDING AS OF THIS
            EVENING. AS THE JAM SHIFTS WATER LEVELS
            COULD RISE RAPIDLY AND FLOODING COULD WORSEN
            AT FORT YUKON. TRIBAL HALL FLOODED AND
            LITTLE FLOODING PARTS OF TOWN. WATER DROPPED
            A FOOT 2AM, ICE FLOWING BY FAST, WITHIN
            BANKS. RIVER WATCH TEAM REPORTS OPEN WATER
            FOR 50 MILES BELOW FORT YUKON WITH LIGHT
            RUNS OF ICE.

1055 AM     FLOOD            STEVENS VILLIAGE        66.00N 149.03W
05/16/2023                   YUKON-KOYUKUK      AK   TRAINED SPOTTER

            05/15/23 RIVER WATCH TEAM REPORTS THAT
            AROUND 1 MILE ABOVE THE CANYON THERE IS A
            LOCAL BREAKUP FOR ABOUT 30 MILES WITH
            SHIFTING OF LARGE SHEETS AND PANS. SOME OF
            THESE ARE BACKING UP AT THE HARDER, INTACT
            ICE AT THE TOP OF THE CANYON. THE ICE
            SHIFTED LOCALLY IN FRONT OF STEVENS VILLAGE
            AND WATER IS LOW. THE SURGE OF WATER AND ICE
            IS EXPECTED TO ARRIVE THIS EVENING (MON
            15TH). A FLOOD WARNING IS IN EFFECT FOR
            STEVENS VILLAGE AS THIS WATER/ICE ARRIVES
            AND MAY JAM AT THE CANYON.

1057 AM     FLOOD            BEAVER                  66.36N 147.40W
05/16/2023                   YUKON-KOYUKUK      AK   TRAINED SPOTTER

            05/15/23 RIVER WATCH TEAM REPORTS THAT THERE
            IS A 40 MILE LONG RUN OF BANK-TO-BANK CHUNK
            ICE AND HIGH WATER MOVING PAST BEAVER AT 1PM
            TODAY. WATER IS HIGH BUT NOT FLOODING THE
            COMMUNITY. WATER WAS OBSERVED OVERBANK INTO
            THE WILLOWS AND FLOWING BACK UP INTO THE
            SLOUGHS. THE FRONT END OF THE THIS SURGE OF
            ICE/WATER WAS APPROXIMATELY 50 MILES UPRIVER
            FROM STEVENS VILLAGE AROUND 1PM TODAY.

1038 AM     FLOOD            EAGLE                   64.79N 141.20W
05/16/2023                   SOUTHEAST FAIRBANKSAK   CO-OP OBSERVER

            05/09/23 THE COOP OBSERVER AT CHICKEN
            CONFIRMED AN ICE JAM AT THE TAYLOR HWY
            BRIDGE OVER THE MOSQUITO FORK. THERE IS NO
            IMPACT TO THE ROAD BUT THERE IS FLOODING IN
            THE SURROUNDING WOODS. OBSERVER REPORTS THE
            JAM EXTENDS ABOVE AND BELOW THE BRIDGE. THE
            IGAGE OBSERVATION SUPPORTS THIS. THE ICE IS
            ALMOST TOUCHING THE BASE OF THE BRIDGE.THE
            UPPER YUKON RIVERWATCH TEAM FLEW THE
            FORTYMILE NEAR CHICKEN. THEY REPORT THE JAM
            AT MOSQUITO FORK IS IN PLACE. TOE IS TWO
            BENDS DOWNSTREAM FROM THE BRIDGE, WELL SHORT
            OF THE RUNWAY. WATER OVERBANK RIGHT BELOW
            THE BRIDGE. FLOWS BACK INTO THE RIVER, DS
            JAM. ICE MIGHT BE UP TO LOW CHORD ON THE S
            END OF BRIDGE. RIVER LOOKED CLEAR UPSTREAM
            FROM JAM. NO SIGNIFICANT RUNS OF ICE TO MAKE
            IT WORSE. ONE PROPERTY DS RIVER RIGHT THAT
            HAD WATER SURROUNDING EQUIPMENT, BUT NO
            OTHER IMPACTS NOTED. NO OTHER LOWLYING
            PROPERTIES THREATENED. 05/10/23 SEVERAL ICE
            JAMS OR EVIDENCE OF PRIOR ICE JAMS WERE
            OBSERVED TODAY ON YUKON TRIBUTARIES... TWO
            OF WHICH WERE SOMEWHAT IMPACTFUL. ONE THAT
            FLOODED PART OF THE STEESE HIGHWAY WHERE IT
            CROSSES BIRCH CREEK (~ 14 MILES SE OF
            CIRCLE) AND ONE ON THE FORTYMILE BY THE
            TAYLOR HWY BRIDGE AT MOSQUITO FORK (UPRIVER
            FROM CHICKEN). NWS RIVER OBSERVER REPORTS
            ICE JAM IS STILL IN PLACE WITH THE ICE LEVEL
            WITH THE BOTTOM OF THE BRIDGE. SOME OPENINGS
            IN THE ICE JUST DOWNSTREAM FROM THE BRIDGE.
            05/11/23 RIVER GAUGE ON THE MOSQUITO FORK
            INDICATES THE ICE JAM IS SHIFTING OR MOVING
            WITH ALMOST 6FT DROP IN THE RIVER READING
            AROUND 4AM THIS MORNING. 05/12/23 MOSQUITO
            FORK AT TAYLOR HWY RIVER GAUGE INDICATES AN
            ~10 FOOT DROP IN THE RIVER LEVEL AT 11PM THU
            NIGHT MAY 11TH SHOWING THE ICE JAM HAS
            RELEASED.

1041 AM     FLOOD            EAGLE                   64.79N 141.20W
05/16/2023                   SOUTHEAST FAIRBANKSAK   CO-OP OBSERVER

            05/12/23 THERE IS A LARGE ICE JAM ON THE
            UPPER YUKON WITH STATIONARY PACKED CHUNK AND
            PAN ICE. THE DOWNSTREAM TOE (AT THE BEND) OF
            THE ICE JAM IS APPROXIMATELY 30 RIVER MILES
            UPSTREAM OF EAGLE AND THE JAM EXTENDS AT
            LEAST 30 MILES UPRIVER IN LENGTH. THE YUKON
            RIVER BREAKUP FRONT IS ROUGHLY 30 RIVER
            MILES UPSTREAM OF EAGLE. THE BREAKUP FRONT
            IS EXPECT TO REACH EAGLE SOON WITH ICE JAMS
            AND FLOODING POSSIBLE. MAIN JAM IS IN PLACE.
            NO FLOODING AT EAGLE YET. DOWNSTREAM AT
            SEVENTYMILE A FEW REC CABINS HAVE WATER
            AROUND THEM. ICE JAM BELOW TATONDUK, WITH
            FLOODING UPSTREAM. ONE CABIN, DOWNSTREAM OF
            THE TATONDUK RIVER, ON THE NORTH SIDE OF THE
            YUKON HAS WATER SURROUNDING IT WITH OUT
            BUILDINGS FLOODED. 05/13/23 THERE IS A LARGE
            ICE JAM ON THE UPPER YUKON WITH STATIONARY
            PACKED CHUNK AND PAN ICE. THE DOWNSTREAM TOE
            (AT THE BEND) OF THE ICE JAM IS
            APPROXIMATELY 30 RIVER MILES UPSTREAM OF
            EAGLE AND THE JAM EXTENDS AT LEAST 30 MILES
            UPRIVER IN LENGTH. THERE IS ANOTHER ICE JAM
            DOWNSTREAM OF THE TATONDUK AND UPSTREAM OF
            THE NATION. THERE WAS FLOODING OF MISSION
            ROAD IN EAGLE THIS AFTERNOON, AND SEVERAL
            STRUCTURES DOWNSTREAM OF EAGLE HAVE FLOODED.
            RECENT REPORTS HAVE CONFIRMED THAT WATER
            LEVELS IN EAGLE HAVE DROPPED. 05/13/23 ICE
            HAS BEEN FLOWING STEADILY IN EAGLE FOR ABOUT
            10 HOURS. WATER LEVELS SEEMED TO HAVE PEAKED
            AROUND 4 AM AND HAVE GRADUALLY RECEDED
            SINCE. FRONT STREET IN FRONT OF THE HOTEL
            HAS A LOT OF ICE ON IT, BUT THE STREET
            ITSELF IS MOSTLY DRY AT THIS POINT. WE HAVE
            A COUPLE RESIDENCES THAT TOOK ON A LITTLE
            BIT OF WATER AND SOME LOST OUTBUILDINGS. THE
            ROAD TO THE VILLAGE IS COMPLETELY SUBMERGED.
            50% ICE IN THE RIVER AT THIS POINT. EAGLE
            COMMUNITY SCHOOL - SUCCESSFUL BREAK-UP FRI
            EVENING FOLLOWED BY ICE FLOW THROUGH 07:30
            THIS MORNING. CURRENTLY WE ARE EXPERIENCING
            MORE OPEN WATER AS MOST OF THE DAMMED ICE UP
            STREAM HAS PASSED. WATER IS CURRENTLY
            RECEDING FROM THE SHORELINE. I AM UNABLE TO
            READ THE RIVER GAUGE AS IT IS COVERED WITH
            ICE THAT CAME UP ALONG THE SEA WALL IN FRONT
            OF TOWN. THE ROAD THAT RUNS PARALLEL WITH
            THE RIVER IS IMPASSABLE. AT THE PRESENT
            TIME, THERE ARE NO HOMES LOST DUE TO
            BREAK-UP. SMALLER STRUCTURES ALONG THE RIVER
            HAVE BEEN AFFECTED. THE ROAD BETWEEN THE
            TOWN AND VILLAGE OF EAGLE IS IMPASSABLE, BUT
            ATVS CAN TRAVEL. OUT STREET SIGN HAS BEEN
            KNOCKED DOWN.

&&