A developing low ran north along a deep baroclinic zone into Dixon Entrance. A cold air mass with 850 temperatures of around -10C coupled with northward dry cold air at the surface created a very efficient overrunning event across the southern Panhandle into Saturday.
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.
A developing low ran north along a deep baroclinic zone into Dixon Entrance. A cold air mass with 850 temperatures of around -10C coupled with northward dry cold air at the surface created a very efficient overrunning event across the southern Panhandle into Saturday.
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, 3:32 PM AKST, 1 hour 58 minutes earlier.
Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
332 PM AKST Fri Mar 12 2021
.SHORT TERM...Snow showers associated with deep and cold
instability across the gulf led to impressive local snowfall
across the eastern Gulf Coast, especially Pelican Thursday night.
Five inches of snow fell in Pelican overnight with a heavy snow
shower covering Sitka with a quick 2 inches in one hour. Snow
showers have been occasionally intense in the northern Panhandle,
but total amounts do not have us so concerned.
This leads us to the south where the most attention has been paid.
Model ensembles have a strong surface low clustered into Annette
Island (the EC ensembles) and just to the east (GFS Ensembles).
All of this suggests heavy snow and cold temperatures just to the
northwest and north of the system with high confidence heavy QPF
overriding a cold air dome. Given the approach of the surface low,
we should have northwest winds drive down drier, cooler air. With
oceans of moisture lifting northward this evening, we expect an
efficient overrunning event over the southern Inner Channels and
Misty Fjords. We are looking at a foot plus of snowfall for Hyder
Friday night through Saturday afternoon after a presumed
changeover to rain occurs. In Ketchikan, admittedly our snowfall
amounts might be overkills, but we do believe 6 to 10 inches of
snowfall will fall over the city. This is a significant change
from the 1 to 4 inches we originally forecast in the city. Should
the low come in too far west, the warm air will wash our snow
forecast away. But if the low follows the GFS ensemble cluster,
then it could be one of the biggest snowfalls Ketchikan has seen
in a couple of years.
Farther north and west, we did place two advisories. One for
western Prince of Wales with lower advisory thresholds of 3
inches, and another for Wrangell/Petersburg. Late runs of both the
ops Euro and GFS have spread QPF up into the central Panhandle
along the coast Mountains, so it seemed reasonable to cover our
bases with this possibility. Snowfall amounts could potentially be
lower here should the low come in farther east.
For the north we begin preparing for outflow winds as strong gales
arise in Lynn Canal overnight into the weekend with gusty winds to
50 mph from Downtown Juneau to Skagway. Currently, we do not feel
these will reach 60 mph but of course, conditions will be
monitored.
In order to support all of this to the south, we did lower
temperatures below guidance in line with snowmelt cooling.
Confidence is lower than what we would like, but too high too
ignore its impactful possibilities. ECMWF, GFS, and their
associated ensembles were used to develop our forecast changes.
.LONG TERM...Sunday through Friday as of 10 pm Thursday/The long
range forecast begins with the panhandle toward the end of a
chilly weekend (for Mid-March) due to cold high pressure to the
north. During the day and into the night Sunday, the predominant
flow will shift southerly as the high moves off to the west. Skies
will clear some late in the day and through the overnight which
should allow for some radiative cooling, so one more chilly night
looks to be in store. The warmer southerly flow really begins to
take hold Monday to begin a warm up to start the work week.
Precip associated with low pressure moving toward the region from
the west should arrive in the region Late Sunday night into
Monday. Still a lot of uncertainty with this event in regards to
timing and precip totals, but the southern panhandle looks to be
the recipient of the greatest QPF amounts. Temps will be cold
enough at the onset to support snow in the forecast with several
areas standing a chance to see some decent amounts before daytime
warming allows for a change over to rain, but again, if that
timing is delayed any, then final snow totals could be greatly
reduced, especially for the southern panhandle. As far as areas
from around Wrangell to Port Alexander and northward (and Hyder),
a delay would reduce snow amounts for Monday early, but
confidence is pretty good that temperatures will fall back to
freezing and below, allowing for another round of snow. Confidence
is low in the actual placement of that rain/snow dividing line,
as South of it temperatures look to get cold enough to at least
see some snow mix in, but if the line falls further south then
those areas could again get another couple of inches. After this
system passes, chances for showers will linger before another
front moves through the region around mid week. Though models vary
wildly on the solution, late in the week there may be a chance
for some drying out in the north.
This will be the trend through the week, rain and snow melt during
the day and re-freezing and chances for snow at night. What will
change though is that the rain/snow line at should progressively
move northward each night. Any late week clearing of the clouds up
north would likely cause the line to regress back to the south. A
proverbial ray of sunshine in the forecast though is that many
northern locations of the appear to be in line to see 40 degree
temps for the first time in months, perhaps as early as Wednesday!
&&
.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Winter Weather Advisory from 6 PM this evening to noon AKST
Saturday for AKZ026-027.
Strong Wind from late tonight through Saturday afternoon for
AKZ025.
Winter Weather Advisory until 6 PM AKST this evening for AKZ022-
023.
Winter Storm Warning from 6 PM this evening to noon AKST
Saturday for AKZ028.
Winter Storm Warning from 6 PM this evening to 3 PM AKST
Saturday for AKZ029.
Strong Wind from 9 PM AKST this evening through Saturday
afternoon for AKZ018.
MARINE...Gale Warning for PKZ012-013-032-033-051.
Small Craft Advisory for PKZ011-021-022-031-034-041>043-052-053.
&&
JWA/JDR
Visit us at http://www.weather.gov/JuneauSpecial Weather Statement National Weather Service Juneau AK 1230 PM AKST Fri Mar 12 2021 AKZ026>028-130100- Inner Channels from Kupreanof Island to Etolin Island- Dixon Entrance to Cape Decision Coastal Area- Southern Inner Channels- Including the cities of Petersburg, Wrangell, Kake, Craig, Klawock, Ketchikan, and Metlakatla 1230 PM AKST Fri Mar 12 2021 ...EARLY WEEKEND SNOW FOR KETCHIKAN AND THE SOUTH CENTRAL PANHANDLE... After a dry Friday, precipitation develops quickly Friday evening across the southern Inner Channels including Ketchikan, Saxman, Metlakatla, Hollis, Thorne Bay, Kasaan, and Meyers Chuck. Precipitation may initially begin as rain but will quickly change over to snow. We are currently forecasting temperatures across this region in the mid 30s falling into the lower 30s. Snow will likely intensify across the region through the night. Due to milder temperatures, the highest probability snow forecast for the region is 1 to 4 inches. However, actual snow amounts could be much higher depending on very small changes both in temperature and in the track of the narrow band of heavy precipitation. Likewise we are studying the possibility that Prince of Wales Island, Wrangell, and Petersburg could also see accumulating snow from this event, with 4 inches or more possible. There are scenarios where Ketchikan and the southern Inner Channels could receive well over 6 inches of snow and others where it could see little if any. Please monitor NOAA weather radio, weather.gov/Juneau, and local media for important weather updates on this winter event.
2 winter storm, 2 heavy snow. Local standard time, as filed.
Trained Spotter 10 N of Ketchikan reports 10 inches of snow. By the end of the storm over 20 inches of snow had fallen sinking 3 boats in the harbor, causing multiple accidents on local roadways and shutting down the city facilities due to snowfall.
Trained Spotter 9 Miles South of Wrangell reported 6.75 inches of snow.
Trained Spotter South of Wrangell Reports 8.25 inches of Snow in under 12 hours.
Over 7 inches of snow had fallen at the COOP Observer in Hyder with heavy snow falling as of 7 am on Saturday.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Alaska in 2021Every state in 2021This day in weather historyWarnings in Alaska, March 2021
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: 951782, 951783, 951784, 951785.