Blizzard in Alaska, December 17, 2009

Name: Blizzard in Alaska, December 17, 2009
Start: 2009-12-17T07:30
End: 2009-12-17T11:00
Location: Alaska

December 17, 2009 · NWS AFC · 1 event in 1 county or zone

A storm in Prince William Sound produced heavy snow and strong wind in Thompson Pass that resulted in a blizzard through the pass.

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.

A storm in Prince William Sound produced heavy snow and strong wind in Thompson Pass that resulted in a blizzard through the pass.

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 Dec 17, 5:50 AM AKST, 1 hour 40 minutes earlier.

Area forecast discussion, Dec 17, 5:50 AM AKST, 1 hour 40 minutes before

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
550 AM AKST THU DEC 17 2009

.ANALYSIS AND UPPER LEVELS...
A COLD CORE LOW IS CURRENTLY CENTERED JUST NORTHEAST OF ILIAMNA. A
RIDGE OVER THE CENTRAL ALEUTIAN ISLANDS IS NEGATIVELY TILTED BACK
TOWARDS RUSSIA. FURTHER WEST A LARGE TROUGH IS CENTERED OVER THE
RUSSIAN KAMCHATKA PENINSULA WITH A SHORTWAVE HUNDREDS OF MILES
SOUTHWEST OF SHEMYA.  AT THE SURFACE...A COMPLICATED SERIES OF LOWS
ARE UNDERNEATH THE MAINLAND COLD CORE LOW GENERATING WIDESPREAD
PRECIPITATION FROM COOK INLET TO PRINCE WILLIAM SOUND. HIGH PRESSURE
EXISTS AT THE SURFACE UNDER THE UPPER LEVEL RIDGE OVER THE CENTRAL
ALEUTIANS. A POTENT LOW PRESSURE IS DEVELOPING BENEATH THE UPPER
LEVEL SHORTWAVE OUT IN THE WESTERN PACIFIC.

.MODEL DISCUSSION...MODELS ARE IN GENERAL CAPTURING FEATURES
ACCURATELY.  HOWEVER...ONLY THE HIGH RESOLUTION NAM AND LOCAL MODELS
HAVE BEEN ABLE TO CAPTURE THE COMPLICATED PRECIPITATION OF THE LOWS
IN COOK INLET AND WESTERN PRINCE WILLIAM SOUND. FOR THE SHORT TERM
THE MODELS ARE AGREEING ON THE SLOW RETROGRADE OF THE MAINLAND
LOW...THE EASTWARD PROGRESSION OF THE RIDGE AND THE NORTHEAST
PROGRESSION OF THE ALEUTIAN LOW.  MODELS BEGIN TO DIVERGE ON THE
INTENSITY AND POSITION OF THE BERING LOW BY FRIDAY NIGHT.  THE GFS IS
THE MORE CONSISTENT SOLUTION AND WAS RELIED UPON FOR THE LONG TERM.
HOWEVER...THE ECMWF HAS BEEN CAPTURING THE MAGNITUDE OF THE RECENT
WINDS MORE ACCURATELY SO IT WAS USED FOR LONG TERM WINDS.

.SHORT TERM FORECAST...
.SOUTHCENTRAL...
SNOW CONTINUES TO PERSIST FROM COOK INLET AND PRINCE
WILLIAM SOUND UP THROUGH THE ANCHORAGE BOWL AND MAT-SU VALLEYS DUE TO
THE PRESENCE OF TWO SEPARATE LOWS.  ONE IS CURRENTLY OVER THE CENTER
OF COOK INLET...WHILE THE OTHER IS CENTERED NEAR WHITTIER. STEADIER
SNOW LOOKS TO DIMINISH SHOWERS AS THE WEAK SURFACE LOWS WEAKEN.
SHOWERS WILL DIMINISH FROM WEST TO EAST AS WELL AS THE SUPPORTING
UPPER-LOW  AND MOISTURE BEGIN TO MOVE AWAY FROM THE SOUTHERN MAINLAND
BY THE WEEKEND.

.SOUTHWEST...STRONG WINDS WILL CONTINUE THROUGHOUT MUCH OF THE WEST
DUE TO THE TIGHT PRESSURE GRADIENT BETWEEN THE MAINLAND LOW AND
ALEUTIAN RIDGE.  THIS COMBINED WITH STRONG COLD AIR ADVECTION ALONG
THE BACK SIDE OF THE LOW CONTINUE TO SUPPORT ADVISORY WIND CHILLS
THROUGH BRISTOL BAY AND THE KUSKOKWIM DELTA. SCATTERED SNOW SHOWERS
WILL FALL MAINLY ALONG THE ALASKAN PENINSULA DUE TO THE SLOWLY
PROGRESSING MAINLAND LOW. MOISTURE FROM THE APPROACHING ALEUTIAN LOW
NOSES INTO BRISTOL BAY THIS WEEKEND.

.ALEUTIANS...IT IS STILL FAIRLY QUIET IN THE CENTRAL AND EASTERN
ALEUTIANS WITH ONLY LIGHT SNOW REPORTED AS THE RIDGE CONTINUES TO
PROGRESS EAST. HOWEVER...BY THURSDAY EVENING AN APPROACHING LOW WILL
BRING GALE TO STORM FORCE WINDS AND STEADY PRECIPITATION TO THE
WESTERN AND CENTRAL ALEUTIANS.

.LONG TERM FORECAST...AS THE MAINLAND LOW PROGRESSES NORTHWARD...A
RIDGE WILL BEGIN TO BUILD OVER THE SOUTH.  THIS WILL RESULT IN
WIDESPREAD SOUTHERLY WINDS AND A RETURN TO WARMER TEMPERATURES ACROSS
THE SOUTHERN PART OF THE STATE. THE WEATHER WILL REMAIN STORMY IN THE
ALEUTIAN ISLANDS THROUGH THE WEEKEND AS A SERIES OF LOWS PROGRESS
THROUGH THE REGION.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD 121
MARINE...STORM...411 175 176
         GALE...351 352 412 413 125 128 130 132 136 150 155
160                    165 170 172 185
HEAVY FREEZING SPRAY...414 121 127 129 130 132 136 138 140 141 150
155                          160 165 180 185

ELN/JAM DEC 09

Event by event

1 blizzard. Local standard time, as filed.

Blizzard, Nern P.W. Snd

When: December 17, 7:30 AM AKST to 11:00 AM AKST
Where: Nern P.W. Snd forecast zone
Reported by: Department of Highways

Thompson Pass Department of Transportation reported blizzard conditions through Thompson Pass.

What these are

Blizzard: Sustained winds or frequent gusts of 35 mph or more with falling or blowing snow that cuts visibility below a quarter mile for three hours or longer.

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: 200102.