Extreme Cold in Alaska, December 18, 2009

Name: Extreme Cold in Alaska, December 18, 2009
Start: 2009-12-18T10:00
End: 2009-12-18T23:30
Location: Alaska

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

A 979 mb low in the eastern Yukon Territory on the morning of the 18th weakened and moved east during the day. The low produced a period of stronger wind along the Steese Highway summits.

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 979 mb low in the eastern Yukon Territory on the morning of the 18th weakened and moved east during the day. The low produced a period of stronger wind along the Steese Highway summits. A west wind of 25 to 35 mph combined with temperatures of 25 to 30 below to produce wind chills as low as 65 below. The strongest wind and lowest wind chills were observed at Eagle Summit.

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 18, 6:03 AM AKST, 3 hours 57 minutes earlier.

Area forecast discussion, Dec 18, 6:03 AM AKST, 3 hours 57 minutes before

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
603 AM AKST FRI DEC 18 2009

.DISCUSSION...
THE NAM AND GFS COMPUTER MODELS BOTH FORECAST THE
LARGE...ELONGATED LOW ALOFT NOW EXTENDING FROM KOTZEBUE SOUND TO
THE KENAI PENINSULA TO SWING AROUND TO EXTEND FROM GAMBELL TO NOME
THROUGH NORTHWAY AT 3 AM AKST SATURDAY. FOLLOWING THIS...THE
MODELS FORECAST THE WEST END OF THE LOW ALOFT TO FORM A LOW OVER
THE GULF OF ANADYR AT 3 AM AKST SUNDAY...WHILE THE EAST END
BECOMES A SHORT WAVE THAT IS MOVING UP OVER THE ARCTIC COAST EARLY
SUNDAY.

THE SIGNIFICANT DEVELOPMENT BEGINNING SUNDAY IS THE BUILDING HIGH
ALOFT FROM THE EAST GULF OF ALASKA OVER THE EASTERN MAINLAND ON
SUNDAY. THE SOUTHERLY FLOW ON THE WEST SIDE OF THE RIDGE WILL
CAUSE A BIG RISE IN TEMPERATURES OVER ALL BUT THE EAST INTERIOR ON
SUNDAY...AND THE EAST INTERIOR WILL SEE SOME MODERATION IN
TEMPERATURE BY MONDAY. THE WEST COAST UP TO THE SOUTHERN SEWARD
PENINSULA COULD SEE SOME READINGS APPROACHING PLUS 30 DEGREES
ABOVE ON MONDAY AND TUESDAY. AS HAD BEEN EXPECTED EARLY THIS
WEEK...THE PRESENT COLD SPELL HAS NOT BEEN SEVERE AND IT WILL END
UP WITH A DURATION JUST OVER A WEEK. THE COLDEST READING WAS 47
BELOW AT THE KAIYUH FLATS REMOTE AUTOMATIC WEATHER STATION AT
12.21 AM AKST ON THURSDAY. THE KAIYUH FLATS STATION IS LOCATED
ABOUT 40 MILES SOUTHWEST OF GALENA. A GOOD DEAL OF THE INTERIOR
ONLY REACHED DOWN TO 20 BELOW OR SO.

THE THURSDAY EVENING MAP IS A TYPICAL INTERIOR WINTER TIME SNOW
MAP. THERE IS A SHARP RIDGE OF HIGH PRESSURE EXTENDING FROM THE
CENTRAL INTERIOR DOWN OVER THE TANANA VALLEY THROUGH TOK. THERE IS
COLD AIR ALOFT...CLOSE TO -28 DEGREES C AT 850 MILLIBARS /NEAR
5000 FEET ABOVE SEA LEVEL/ AT FAIRBANKS AND -10 DEGREES C ALONG
THE YUKON BORDER. THIS COLD AIR ALOFT IS EXPECTED TO SHIFT QUICKLY
NORTHWARD TONIGHT...AND A STRONG INFLOW OF WARMER AIR ALOFT WILL
FORM OVER THE THE WESTERN MAINLAND AND THE EAST BERING SEA TONIGHT
AND SATURDAY. THE STRENGTHENING SOUTHERLY FLOW IS EXPECTED TO SET
UP A CHINOOK WIND OVER THE ALASKA RANGE ON SATURDAY...AND RUN
THROUGH THE WEEKEND. THIS IS REFLECTED IN THIS MORNINGS INTERIOR
ZONE FORECASTS.

THE MEDIUM RANGE COMPUTER MODELS ARE IN BETTER THAN USUAL
CONSISTENCY...BOTH INDICATING A GRADUAL BUT NOT SIGNIFICANT DROP
IN TEMPERATURES DURING THE UPCOMING WEEK.

EARLY MORNING POLAR ORBITING SATELLITE IMAGERY SHOWS MAINLY CLEAR
SKIES FROM BERING STRAIT DOWN PAST SAINT LAWRENCE ISLAND.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FOR AKZ218-AKZ219-AKZ220-AKZ224-AKZ225-
AKZ226.
&&

TF DEC 09

Event by event

1 extreme cold/wind chill. Local standard time, as filed.

Extreme Cold/Wind Chill, Yukon Flats Nearby Uplands

When: December 18, 10:00 AM AKST to 11:30 PM AKST
Where: Yukon Flats Nearby Uplands forecast zone
Reported by: Department of Highways

What these are

Extreme Cold/Wind Chill: Temperatures or wind chills at or below the local warning criteria, or cold that caused deaths.

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: 200596.