Warm moist air aloft moved over the cooler temperatures in SE Alaska on 3/12 which caused heavy snowfall for most of the northern sections. This snow was followed by a rapidly developing storm moving up from the SW over the Gulf of Alaska on 3/12 and 3/13.
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 AJK wrote it up.
Warm moist air aloft moved over the cooler temperatures in SE Alaska on 3/12 which caused heavy snowfall for most of the northern sections. This snow was followed by a rapidly developing storm moving up from the SW over the Gulf of Alaska on 3/12 and 3/13. A strong front associated with this front moved onto the coast on 3/13.
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 Juneau, AK wrote its last area forecast discussion before the first event at Mar 12, 6:10 AM AKST, 2 hours 50 minutes earlier.
SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
610 AM AKST FRI MAR 12 2010
.SHORT TERM...A WEAK LOW WILL MOVE N ACROSS THE NRN PANHANDLE
THIS EVENING. A TROF WILL REMAIN ACROSS THE PANHANDLE THRU
TONIGHT BUT WEAKEN LATE TONIGHT.
MAIN FORECAST CONCERN IS SNOWFALL POTENTIAL. SCENARIO IS SETTING
UP FOR A FAIRLY NARROW BUT INTENSE MAINLY N-S ORIENTED BAND OF
PRECIP SOMEWHERE ACROSS THE CENTRAL AREA TODAY INTO TONIGHT...BUT
MODELS DIFFERED ON EXACTLY WHERE THE BAND WILL SET UP ESPECIALLY
THE 00Z RUN. THE GFS AND NAM 00Z RUNS HAD THE BAND SETTING UP
MAINLY ALONG AS S OF FREDERICK SOUND...WHILE THE UKMET AND ECMWF
HAD IT SETTING UP OVER THE PAJN-PAAP CORRIDOR. THE 06Z NAM AND GFS
BOTH SHIFTED THE BAND FURTHER NW TO THE SAME AREA AS THE 00Z ECMWF
AND UKMET HAD IT...SO THAT IDEA WAS USED FOR THIS FORECAST.
STILL...GIVEN HOW NARROW THE BAND WILL BE...NOT A VERY CONFIDENT
FORECAST ON WHERE THE HEAVIEST SNOW WILL FALL. USED A BLEND OF THE
06Z GFS AND NAM FOR QPF...AND ENDED UP ISSUING WINTER STORM
WARNINGS FOR ZONES 21..24..AND 25 THRU TONIGHT...WITH WINTER WX
ADVYS FOR 19 AND 26...WITH THE SNOW IN THOSE AREAS MAINLY OVER THE
SRN AND WRN AREAS RESPECTIVELY. THERE WILL BE SOME SNOW OUTSIDE
THE MAIN BAND ESPECIALLY W OF IT AS LOW MOVES N WITH SMALL COMMA
HEAD LIKE FEATURE MOVING THRU BUT SNOWFALL IN THAT SHOULD REMAIN
BELOW ADVY LEVELS. THE CENTRAL COAST WILL LIKELY WARM ENOUGH TO GO
TO MIXED PRECIP SO AMOUNTS THERE WERE KEPT DOWN...BUT IF THEY STAY
ALL SNOW ZONE 23 MAY NEED TO BE ADDED TO AT LEAST THE ADVY AREA.
OTHERWISE...SNOW SHOWERS WILL DIMINISH THROUGH THE DAY AROUND
PAYA AS SOME STABILIZATION WILL OCCUR AS THE LOW MOVES PAST THEM
TO THE E AND FLOW BECOMES MORE ELY IN LOWER LEVELS. THE FAR SERN
AREA WILL LIKELY SEE SOME CLEARING TODAY AS LOW-MID LEVEL
SHORTWAVE RIDGING BUILDS INTO THERE TODAY AND FLOW BECOMES
OFFSHORE. HOWEVER...THE NEXT FRONT MOVING INTO THE GULF WILL BEGIN
TO SPREAD CLOUDS SLOWLY INTO THE PAKT AREA TONIGHT...BUT THE HYDER
AREA WILL LIKELY REMAIN PARTLY CLOUDY. NOT A LOT OF WIND WITH THE
WEAK LOW AND TROF MOVING THRU THE AREA TODAY INTO THIS EVENING FOR
THE MOST PART EXCEPT FOR A NARROW BAND OF SCA LEVEL S WINDS JUST E
OF THE LOW TRACK TODAY INTO THIS EVENING. SOME INCREASE IN WIND
AREA WIDE IS LIKELY LATE TONIGHT AS NEXT FRONT BEGINS TO APPROACH
THE ERN GULF.
.LONG TERM...CHANGES TO THE PACKAGE WERE SMALL. CONFIDENCE IN
THE WIND FORECASTS IS AVERAGE, BUT THE DEGREE OF MIX OF RAIN AND
SNOW IS AT OR BELOW AVERAGE AS THE PHASE CHANGES ARE DUE TO
TEMPERATURES JUST ABOVE FREEZING AND DEWPOINTS JUST BELOW
FREEZING. NOTICE THE PUBLIC ZONES HAVE NUMEROUS REFERENCES
TO BOTH SNOW AND RAIN IN SEVERAL TIME PERIODS.
THE LANDFALL OF A WEAKENING LOW IS DISCUSSED IN THE SHORT RANGE
SECTION ABOVE. A LARGE-SCALE COLD TONGUE WILL FOLLOW FROM THE WSW
FRI NIGHT AND PRECONDITION MOST OF THE PNHDL IN THE MARINE-
MODIFIED ARCTIC AMS. A LARGE SCALE WARM OVERRUN OF THIS COLDER AMS
WILL OCCUR SAT AND SAT NIGHT DUE TO A LARGE-SCALE CYCLOGENETIC
SYSTEM MOVING NE INTO THE GLFALSK. THE ASSOCD STRONG OCFNT SHOULD
MOVE ONSHORE THE PNHDL ABT 06Z SUN. THE RESULT WILL BE A SNOW
CHANGING TO RAIN EVENT FOR MUCH OF THE PNHDL SAT AFTERNOON AND
NIGHT. THE CHANGEOVER FROM SNOW TO RAIN, OR AT LEAST MIXING
WITH RAIN WILL OCCUR MORE QUICKLY THAN EVENTS WHERE A TRUE
ARCTIC AMS IS IN PLACE IN THE INNER CHANNELS. THE RESULT WILL
BE SMALLER SNOWFALL AMOUNTS BEFORE THE OVERRUN AMS IS MODIFIED
AND SCRUBBED OUT.
MODELS: USED THE EXISTING WIND GRIDS AS THEY HAVE A USEFUL
AGREEMENT WITH THE 00Z ECMWF, AND THEN USING THE HPC AS A BLEND IN
FOR ABOUT 00Z WED ONWARD.
THE LARGE SCALE PATN HAS LITTLE PROGRESSION. A LARGE-SCALE BROAD
TROUGH ALF XTNDS S FM PADK, WKNG WHILE SLOWLY DRFTG E TO XTND S
PAMD 18Z TUE. THRFTR THE LARGE-SCALE PATN IS MORE PROGRESSIVE.
.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER WEATHER ADVISORY FROM 9 AM THIS MORNING TO 5 AM AKST
SATURDAY FOR AKZ026.
WINTER STORM WARNING UNTIL 5 AM AKST SATURDAY FOR AKZ024.
WINTER STORM WARNING FROM 9 AM THIS MORNING TO 5 AM AKST
SATURDAY FOR AKZ021-025.
WINTER WEATHER ADVISORY FROM NOON TODAY TO 5 AM AKST SATURDAY
FOR AKZ019.
MARINE...GALE WARNING FOR PKZ012.
SMALL CRAFT ADVISORY FOR PKZ034>036-041.
SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ042-043-051-052.
&&
RWT/JBT5 winter storm, 2 high wind. Local standard time, as filed.
A moderate snowstorm hit Juneau on 3/12 into 3/13. A trained spotter observed 6.5 inches of new snowfall for 12 hours ending at 1900 AKST on 3/12.
The downtown Haines COOP observer measured 11.9 inches of new snow for 24 hours ending at 0800 AKST on 3/13. Haines Customs measured 9.0 inches new snow on 3/13 and 17.5 new on 3/14.
Pelican measured 9.0 inches of new snow by 2000 AKST 3/12. Elfin Cove measured 11.0 inches new snow by 1500 AKST on 3/13.
Hidden Falls measured 7.0 inches of new snow for 12 hours ending at 0700 AKST 3/13. |Most of this snow fell on the evening of 3/12. Sitka had considerably less snow.
Hydaburg AWOS measured a peak gust of 54 KT at 1836 AKST on 3/13. Many gusts were in the upper 40s. Lincoln Rock on the other side of Prince of Wales Island in Clarence St. had a gust to 75 KT.
Haines Customs measured 17.5 inches of new snow for 24 hours ending at 0700 AKST on 3/14. Spotters at lower elevations had highly variable amounts.
Annette ASOS had a peak gust og 46 KT at 1953 AKST on 3/13. Lincoln Rock in Clanrance ST. measured a gust of 75 KT. Ketchikan ASOS had gusts to 43 KT.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Alaska in 2010Every state in 2010This day in weather historyWarnings in Alaska, March 2010
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: 223164, 223165, 223167, 223168, 223170, 223169, 223171.