Heavy Snow in Alaska, December 17 to 18, 2009

Name: Heavy Snow in Alaska, December 17 to 18, 2009
Start: 2009-12-17T15:00
End: 2009-12-18T15:00
Location: Alaska

December 17 to 18, 2009 · NWS AFG · 1 event in 1 county or zone

A low pressure center and the associated weather front over the Yukon Territory of Canada produced a local setup for heavy snow over the Upper Koyukuk Valley as moisture overran the cold air in place. 2 inches of snow from the 17th to the 18th, with 9 inches falling from the mid afternoon of the 17th through the mid afternoon of the 18th.

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 AFG wrote it up.

A low pressure center and the associated weather front over the Yukon Territory of Canada produced a local setup for heavy snow over the Upper Koyukuk Valley as moisture overran the cold air in place. The FAA Weather Observers at Bettles recorded 10.2 inches of snow from the 17th to the 18th, with 9 inches falling from the mid afternoon of the 17th through the mid afternoon of the 18th.

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 Fairbanks, AK wrote its last area forecast discussion before the first event at Dec 17, 2:13 PM AKST, 47 minutes earlier.

Area forecast discussion, Dec 17, 2:13 PM AKST, 47 minutes before

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
213 PM AKST THU DEC 17 2009

.SYNOPSIS...

ALOFT...THE MAIN FEATURE IS AN AREA OF LOW PRESSURE OVER ILIAMNA.
THE NAM AND THE GFS INITIALIZE THIS SLIGHTLY TOO SHALLOW...HOWEVER
THE 12Z ECMF WAS CLOSER. THIS LOW STAYS STATIONARY
TONIGHT...HOWEVER SATURDAY MODELS ARE IN GOOD AGREEMENT THAT IT
WILL BEGIN TO LEAN TOWARDS THE WEST AS A RIDGE BUILDS INTO THE
GULF OF ALASKA. SUNDAY THIS RIDGE BEGINS TO PUSH NORTHWARD
CENTERED OVER THE ALCAN BORDER. CONTINUED STRENGTHENING OF THE
RIDGE IS EXPECTED ON MONDAY AND TUESDAY.

&&

.DISCUSSION...

ACROSS THE INTERIOR COLD AIR ADVECTION AT THE SURFACE AND WARMER
MOIST AIR ALOFT WILL BRING ANOTHER SHOT OF WINDS AND SNOW TONIGHT
AND TOMORROW. THIS IS EXPECTED TO CAUSE ADVISORY LEVEL SNOW IN THE
EASTERN INTERIOR WHILE SNOWFALL OF 2 TO 3 INCHES EXPECTED IN THE
FAIRBANKS AREA AND CENTRAL INTERIOR. ADVISORIES FOR SNOW AND
BLOWING SNOW HAVE BEEN ISSUED. FRIDAY NIGHT AND INTO SATURDAY
MORNING SOME CLEARING IS EXPECTED BEHIND THE SYSTEM. THIS COULD
CAUSE TEMPERATURES TO DROP SIGNIFICANTLY IN AREAS THAT DO CLEAR
OUT...ALTHOUGH HOW WIDESPREAD THIS CLEARING WILL BE IS STILL
UNCERTAIN. SUNDAY...AS THE RIDGE BEGINS TO BUILD IN...TEMPERATURES
WILL WARM SIGNIFICANTLY ALOFT WITH LITTLE WARMING AT THE SURFACE
AS A STRONG TEMPERATURE INVERSION SETS UP ONCE AGAIN.

ON THE NORTH SLOPE...AREAS OF FOG AND FLURRIES WILL CONTINUE
TONIGHT. SATURDAY SNOWFALL IS EXPECTED DUE TO WARM AIR OVER
RUNNING THE COLD AIR IN PLACE. THE HIGHEST SNOWFALLS WILL BE ALONG
THE EASTERN ARCTIC COAST. SATURDAY NIGHT INTO SUNDAY...SKIES WILL
BEGIN TO CLEAR AND TEMPERATURES WILL FALL. MONDAY AS THE LOW
PRESSURE SYSTEM MOVES UP THE WEST COAST WINDS WILL PICK UP AND
SNOW AND BLOWING SNOW ARE EXPECTED. STRONGEST WINDS WILL BE IN THE
WESTERN PORTION OF THE NORTH SLOPE. TEMPERATURES ARE EXPECTED TO
WARM EARLY NEXT WEEK AS THE RIDGE BUILDS IN ALOFT.

ACROSS THE WEST COAST THE WINDS ARE CONTINUING TO DECREASE AS THE
GRADIENT RELAXES. PARTLY CLOUDY SKIES AND COLD TEMPERATURES WILL PERSIST
THROUGH SATURDAY MORNING. LATE SATURDAY INTO SUNDAY...MODELS ARE
IN DECENT AGREEMENT THAT A STRONG LOW PRESSURE SYSTEM WILL MOVE
TOWARDS THE WEST COAST BRINGING WARMER AIR AND STRONGER WINDS...ALTHOUGH
THERE ARE SOME DIFFERENCES IN THE STRENGTH OF THE LOW.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY FOR AKZ207-AKZ210-AKZ211-AKZ217.

WINTER WEATHER ADVISORY FOR AKZ218-AKZ219-AKZ220-AKZ224-AKZ225-
AKZ226.

BRISK WIND ADVISORY FOR PKZ210-PKZ220-PKZ225.
&&

MKK DEC 09

Event by event

1 heavy snow. Local standard time, as filed.

Heavy Snow, Upper Koyukuk Valley

When: December 17, 3:00 PM AKST to December 18, 3:00 PM AKST
Where: Upper Koyukuk Valley forecast zone
Reported by: Official NWS Observations

What these are

Heavy Snow: Snowfall reaching the local warning threshold without the other hazards of a winter storm.

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

The same day elsewhere

Every storm in Alaska in 2009 Every state in 2009 This day in weather history Warnings in Alaska, December 2009

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: 201636.