Strong deep cold air over interior Alaska coupled with low pressure in the Gulf of Alaska produced the typical strong gap winds through the mountain passes and channeled terrain of the Chugach Mountains. The wind peaked at 97 mph during this event.
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.
The episode as NWS AFC wrote it up.
Strong deep cold air over interior Alaska coupled with low pressure in the Gulf of Alaska produced the typical strong gap winds through the mountain passes and channeled terrain of the Chugach Mountains. The wind peaked at 97 mph during this event.
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 Dec 20, 5:00 AM AKST, 4 hours earlier.
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 AM AKST THU DEC 20 2012
.ANALYSIS AND UPPER LEVELS...
HIGH AMPLITUDE PATTERN CONTINUES TODAY. THE KAMCHATKA LONGWAVE SENDS
A DEEP SOUTHERLY FLOW FROM THE NORTHWESTERN PACIFIC THROUGH THE
BERING STRAIT. A STEADY STREAM OF WARM AIR ADVECTION FROM THE SOUTH
IS BUILDING THE RIDGE TOWARD THE WEST COAST OF ALASKA WITH THE WARM
FRONT STRETCHING FROM THE PRIBILOF ISLANDS SOUTHWARD THROUGH THE
EASTERN ALEUTIANS. THE ASSOCIATED COLD FRONT IS CURRENTLY DRAPED FROM
THE NORTHWEST BERING SEA SOUTHWARD OVER THE WESTERN ALEUTIANS. OVER
THE MAINLAND WE ARE BACK IN AN OUTFLOW GAP WIND PATTERN. ARCTIC AIR
BANKED UP IN THE COPPER RIVER BASIN IS BEING FORCED THROUGH THE GAPS
AS UPPER LEVEL SUPPORT INCREASES THIS MORNING IN THE MATANUSKA VALLEY
AND VALDEZ/THOMPSON PASS AREAS.
.MODEL DISCUSSION...
GUIDANCE IN GOOD AGREEMENT THROUGH THE REST OF THE WEEK BUT BEGIN TO
DIVERGE OVER THE WEEKEND AS A CUT OFF LOW IS FORCED WESTWARD FROM THE
YUKON BY THE REMAINDER OF THE BERING SEA RIDGE...WHICH WILL CUT OFF
AND MOVE NORTHWARD INTO THE ARCTIC. THERE IS CONSISTENCY AMONG MODELS
BOTH RUN TO RUN AND MODEL TO MODEL THAT THIS LOW WILL SLOWLY DEVELOP
AS IT PROPAGATES WESTWARD TOWARD THE KENAI PENINSULA. HOWEVER THE
TRANSIENT NATURE OF THE CUTOFF ARE MAKING DETAILS HARD TO COME BY AT
THE CURRENT JUNCTURE.
.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...WITH THE OUTFLOW PATTERN TAKING HOLD
AGAIN...COLD DRY AND BREEZY CONDITIONS WILL CONTINUE THROUGHOUT THE
DAY. WINDS WILL APPROACH WARNING LEVELS THIS AFTERNOON FOR THE
MATANUSKA VALLEY AS THE SURFACE GRADIENT TIGHTENS BETWEEN ANCHORAGE
AND GULKANA AS WELL AS INCREASING AND UPPER LEVEL SUPPORT. AREAS OF
BLOWING SNOW AND DUST WILL BE POSSIBLE WHILE THE WIND CONTINUES TO
BLOW. THE HIGH WIND WARNING CONTINUES FOR THE NORTHEASTERN PRINCE
WILLIAM SOUND AREA AS WEAK COLD AIR ADVECTION PULLS ARCTIC AIR OVER
THE CHUGACH AND ACCELERATES IT SOUTHWARD THROUGH THE AREA. THE
STRONGEST WINDS THROUGH THOMPSON PASS COMBINED WITH COLD AIR IN PLACE
WILL RESULT IN BITTER WIND CHILLS. A WIND CHILL ADVISORY HAS BEEN
ISSUED FOR THOMPSON PASS.
SOUTHWEST ALASKA...THE MAINLAND REMAINS BETWEEN WEATHER SYSTEMS.
BREEZY NORTHERLY FLOW REMAINS IN PLACE BUT WILL BE SLACKENING
THROUGHOUT THE DAY AS A RIDGE PUSHES EASTWARD FROM THE BERING SEA.
CLEAR SKIES AND DRY CONDITIONS WILL REMAIN THROUGH THE REST OF THE
WEEK.
BERING SEA AND ALEUTIANS...A WARM FRONT PUSHING EASTWARD OVER THE
CENTRAL BERING SEA WILL BRING GUSTY SOUTHERLY WINDS TODAY AS WELL AS
SNOW CHANGING TO RAIN AS THE FRONT PROGRESSES. THE FRONT WILL STALL
BY THE TIME IT REACHES THE AKPEN. A COLD FRONT FROM THE SAME LOW
PRESSURE SYSTEM WILL MOVE FROM THE WESTERN ALEUTIANS TODAY THROUGH
THE AKPEN ON FRIDAY.
.LONG TERM FORECAST...
THE EXTENDED FORECAST WILL BEGIN SOMEWHAT OF A PATTERN CHANGE FROM
THE CURRENT ONE. AN UPPER LOW FROM THE YUKON WILL MOVE WESTWARD OVER
THE SOUTHCENTRAL ONCE THE BERING SEA RIDGE CLOSES OFF AND MOVES
TOWARD THE ARCTIC. THE EVOLUTION OF THE SYSTEM IS UP IN THE AIR BUT
IT LOOKS LIKE THE CHANCE FOR SNOW WILL INCREASE PAST THE WEEKEND IN
TO EARLY NEXT WEEK FOLLOWED BY A MORE PROGRESSIVE PATTERN THROUGH THE
MEDIUM RANGE.
.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WARNING 111 131 135
MARINE...STORM WARNING 127
GALE WARNING 121 126 128 129 130 132 150 172 176 179 185
HEAVY FREEZING SPRAY WARNING 121 125 126 127 128 129 130 132
138 140 141 150 160 180
FIRE WEATHER...NONE
MTL DEC 123 high wind. Local standard time, as filed.
Wind is estimated based upon nearby observations and analysis of the surface map.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Alaska in 2012Every state in 2012This day in weather historyWarnings in Alaska, December 2012
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: 418796, 418795, 416970.