Alaska, 2023

Flood in Alaska, May 21 to 22, 2023

May 21 to 22, 2023 · NWS AFC · 1 event in 1 county or zone

An unusually cold spring kept snowpack intact and in place over the Copper River Basin into mid May. Once temperatures started to warm, they did so quickly and rapidly melted snowpack in the basin.

Where it happened

Every event with a place to put it. Tap one for its entry below.

  • Tornadoes
  • Tropical storms and surge
  • Floods
  • Wind
  • Hail
  • Winter weather
  • Heat and drought
  • Cold
  • Fire, smoke and dust
  • Marine and coastal
  • Other

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The toll

Deaths
0
Injuries
0
Property damage
None recorded
Crop damage
None recorded
Events
1

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS AFC wrote it up.

An unusually cold spring kept snowpack intact and in place over the Copper River Basin into mid May. Once temperatures started to warm, they did so quickly and rapidly melted snowpack in the basin. An additional snow event later in May repeated the process creating multiple events where snowmelt would impact Glennallen and Old Edgerton Highway from Moose Creek snowmelt, and Gulkana and Sourdough areas along the Gulkana River.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Anchorage, AK wrote its last area forecast discussion before the first event at May 21, 3:37 AM AKST, 11 hours 42 minutes earlier.

Area forecast discussion, May 21, 3:37 AM AKST, 11 hours 42 minutes before
Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
437 AM AKDT Sun May 21 2023

.ANALYSIS AND UPPER LEVELS...

High pressure ridging holds over Southeast Alaska and along the
north Gulf coast. Meanwhile, a low spins south of the Alaska
Peninsula, its front moving over Kodiak Island, and slowly tracks
into the eastern Bering Sea. Further west still, a weakening low
over the Western Aleutians will spend today pushing into the North
Pacific. Instability over Southwest Alaska yesterday afternoon
produced a couple of weak, isolated thunderstorms embedded within
the passing shortwave. A similar shortwave is en route to pass
over Southern Alaska this afternoon, however, it will be a more
stable environment with a lesser chance for additional
thunderstorm activity. Moving forward in time, a complex system
developing in the North Pacific moves south of Kodiak Island/into
Bristol Bay on Monday.

&&

.MODEL DISCUSSION...

Models remain in good overall synoptic agreement through the short
term. The upper levels show a better handle on a trough moving
across Southern Alaska through this evening.

&&

.AVIATION...
PANC...VFR conditions and light winds today. Southerly winds will
pick up again this evening.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: Sunday
through Tuesday)...

An easterly wave is moving across the AlCan border into the
Copper River Basin this morning. This is expected to bring rain
to the northern and Central Copper River Basin today with rain
lingering across the Alaska Range into the evening hours. Rainfall
accumulations are expected to be less than a quarter on an inch
from Glennallen and south and will increase as one heads
northward. Areas along the Glenn highway from Gulkana northward
as well as the Denali Highway may see amounts close to a half inch
through tonight with the heaviest rainfall toward Mentasta Pass
which could push an inch of rain over the next 24 hours.

The rain over Kodiak Island is due to a front ahead of a low which
is near the Alaska Peninsula early this morning. This low is
rapidly weakening and the front will also weaken as it head
northward through the day. Another front will move to the Kodiak
region on Monday and bring in more rain and wind. This low will
also weaken as it moves south of Kodiak, but this second front
will push some more cloud cover into inland areas of Southcentral
on Tuesday.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING/ALEUTIANS (Days 1
through 3)...

A low pressure system currently situated south of Chignik will
slowly cross the Alaska Peninsula (AKPEN), with continued rain
showers and southeast gap winds for the rest of today. Shower
activity will then spread to the Southwest coast this afternoon as
the parent upper low and main shortwave lifts northward. More
widespread and steady rain is expected this evening into Monday as
a North Pacific low pushes a front into the region. A combination
of the low and Bering Sea high will promote strong east-southeast
gap winds developing early Monday and gradually easing through
Tuesday. Winds funneling through Kamishak gap will also increase
for the eastern corridor of Bristol Bay, especially areas
encompassing Koliganek and New Stuyahok. Further west, a strong
front in the western Bering Sea progresses eastward, bringing rain
and winds across the western and central Aleutians starting
Tuesday.

&&
.LONG TERM FORECAST (Days 4 through 7: Wednesday through Saturday)...

The long term forecast begins on Wednesday with upper-level lows
located near the Alaska Peninsula and near the western
Bering/Aleutians. A ridge of high pressure builds over the central
Bering/Aleutians in between the two lows. The low near the Alaska
Peninsula will track east across the Gulf on Thursday and then
reach the east Gulf coast on Friday. The low near the western
Bering/Aleutians will generally track to the east over the Bering
through Saturday. While the large low spins over the Bering,
various upper shortwaves will pinwheel around it and across much
of Southern Alaska and the Aleutian Islands. In addition, a series
of surface fronts are expected to lift northeastward across the
same regions. As a result, an active pattern with prolonged
chances for precipitation looks to be the main theme for the long
term forecast. The Bering/Aleutians and Alaska Peninsula will
likely see the heaviest and steadiest precipitation with the
aforementioned fronts, and Southwest and Southcentral Alaska
should experience a more showery regime as the fronts weaken over
land. Temperatures at 850 mb indicate a cooling trend initially
across the Bering as the large, slow moving upper low continually
wraps colder air from the north around itself.

&&

SYNOPSIS AND MODEL DISCUSSION...KM
SOUTHCENTRAL ALASKA...EZ
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MF
LONG TERM...AF

In the hours before

Local storm report, May 21, 9:43 AM AKST, 5 hours 36 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1043 AM AKDT SUN MAY 21 2023

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

0452 PM     NON-TSTM WND DMG SOLDOTNA                60.49N 151.09W
05/20/2023                   KENAI PENINSULA    AK   PUBLIC

            AT LEAST TWO REPORTED INTENSE DUST DEVILS.
            1ST NEAR STERLING HWY, OBSCURED ALL FOUR
            LANES OF TRAFFIC. 2ND BEGAN SW OF HOSPITAL,
            ENDED WEST OF AIRPORT NEAR K-BEACH RD. BLOWN
            DEBRIS TRANSPORTED OVER DISTANCE, INCLUDING
            TRAMPOLINE. TELEPHONE LINE DAMAGE. TREE
            BREAKAGE AND FENCE DAMAGED. ROOF PANEL AND
            SHINGLES BLOWN OFF HOUSE. PERSONAL
            GREENHOUSE DAMAGED.

&&

KUTZ
Local storm report, May 21, 9:59 AM AKST, 5 hours 20 minutes before
PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE ANCHORAGE AK
1059 AM AKDT SUN MAY 21 2023

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

0900 AM     FLOOD            NAPASKIAK               60.71N 161.76W
05/20/2023                   BETHEL             AK   DEPT OF HIGHWAYS

            ALASKA DOT CR REPORTS, WATER LEVEL RUNNING
            HIGH, HOWEVER NO FLOODING OR FLOODING
            IMPACTS YET.

0900 AM     FLOOD            AKIACHAK                60.90N 161.42W
05/20/2023                   BETHEL             AK   DEPT OF HIGHWAYS

            ALASKA DOT CR REPORTS, HIGH WATER BUT NO
            SERIOUS FLOODING. AIRPORT AND AIRPORT ROAD
            HAVE NOT BEEN AFFECTED.

0900 AM     FLOOD            KWETHLUK                60.79N 161.44W
05/20/2023                   BETHEL             AK   DEPT OF HIGHWAYS

            DOT CR REPORTS, MAJOR FLOODING IN KWETHLUK.
            AIRPORT CLOSED, RUNWAY AND RAMP APPEAR TO BE
            MOSTLY ABOVE WATER BUT ACCESS ROAD IS
            SUBMERGED. WATER LEVEL APPEARS TO BE GOING
            DOWN.

0900 AM     FLOOD            HANGER                  60.79N 161.75W
05/20/2023                   BETHEL             AK   DEPT OF HIGHWAYS

            ALASKA DOT CR REPORTS HANGER LAKE ROAD HAS
            AREAS THAT ARE PARTIALLY UNDER WATER WITH
            PORTIONS OF THE ROAD CLOSED FOR SAFETY. ICE
            HAS STOPPED MOVING IN FRONT OF THE TOWN SO
            WATER IS BACKING UP.

&&
Local storm report, May 21, 10:09 AM AKST, 5 hours 10 minutes before
PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE ANCHORAGE AK
1109 AM AKDT SUN MAY 21 2023

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

0452 PM     NON-TSTM WND DMG NULL                    60.49N 151.09W
05/20/2023                   KENAI PENINSULA    AK   PUBLIC

            CORRECTS PREVIOUS NON-TSTM WND DMG REPORT
            FROM NULL. AT LEAST TWO REPORTED INTENSE
            DUST DEVILS. 1ST NEAR STERLING HWY, APPROX
            3PM, OBSCURED ALL FOUR LANES OF TRAFFIC. NO
            DAMAGES REPORTED. 2ND BEGAN SW OF HOSPITAL,
            ENDED WEST OF AIRPORT NEAR K-BEACH RD. BLOWN
            DEBRIS TRANSPORTED OVER DISTANCE, INCLUDING
            TRAMPOLINE. TELEPHONE LINE DAMAGE. TREE
            BREAKAGE AND FENCE DAMAGED. ROOF PANEL AND
            SHINGLES BLOWN OFF HOUSE. PERSONAL
            GREENHOUSE DAMAGED.

&&

KUTZ
Local storm report, May 21, 11:42 AM AKST, 3 hours 37 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1242 PM AKDT SUN MAY 21 2023

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

0452 PM     NON-TSTM WND DMG SOLDOTNA                60.49N 151.09W
05/20/2023                   KENAI PENINSULA    AK   PUBLIC

            CORRECTS PREVIOUS NON-TSTM WND DMG REPORT
            FROM NULL. CORRECTS PREVIOUS NON-TSTM WND
            DMG REPORT FROM NULL. AT LEAST TWO REPORTED
            INTENSE DUST DEVILS. 1ST NEAR STERLING HWY,
            APPROX 3PM, OBSCURED ALL FOUR LANES OF
            TRAFFIC. NO DAMAGES REPORTED. 2ND BEGAN SW
            OF HOSPITAL, ENDED WEST OF AIRPORT NEAR
            K-BEACH RD. BLOWN DEBRIS TRANSPORTED OVER
            DISTANCE, INCLUDING TRAMPOLINE. TELEPHONE
            LINE DAMAGE. TREE BREAKAGE AND FENCE
            DAMAGED. ROOF PANEL AND SHINGLES BLOWN OFF
            HOUSE. PERSONAL GREENHOUSE DAMAGED.

&&

KUTZ

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

1 flood. Local standard time, as filed.

Flood, Copper River Basin

When
May 21, 3:19 PM AKST to May 22, 11:25 AM AKST
Where
Copper River Basin County, Gulkana to 13 mi NNW of Copper Center
Cause
Heavy Rain / Snow Melt
Reported by
Official NWS Observations
Coordinates
62.270, -145.380

Snowmelt flooding pushed the Gulkana River to moderate flood levels on May 21-22, 2023. Flooding of lowland areas and impacts to locations such as the Sourdough Campground led to flood advisory issuance. Richardson Highway was surrounded by high water and travelers in the region were notified of threats in the region.

What these are

Flood
Flooding that develops more slowly than a flash flood: rivers leaving their banks, or water standing over land for an extended time.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

More

Every storm in Alaska in 2023Every state in 2023This day in weather historyWarnings in Alaska, May 2023

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1104641.