Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
633 PM EST Wed Jan 05 2022
Valid 12Z Sun Jan 09 2022 - 12Z Thu Jan 13 2022
...Stormy Pattern For Alaska...
...Overview...
It pretty much remains the case that a blocky and persistent upper
upper ridge over northeastern Russia/the Bering Sea should finally
weaken some and retreat westward during the medium range period.
This will lessen its influence on Alaska and allow for lower
mid-upper heights to come into the state, with a busy storm track
situated near/south of the Aleutians and the northern Pacific/Gulf
of Alaska. This will favor increasing moisture and brisk winds
into southern parts of Alaska from the Aleutians into Southcentral
Alaska and the Panhandle by the weekend through mid next week.
...Guidance Evaluation and Preferences...
The latest model guidance, particularly the ensemble means,
continue to show good agreement on the overall synoptic scale
pattern, but increasing uncertainty in the details. Nearly all of
the models agree that a blocky high over northeast Russia should
retreat westward by Saturday as an upper low retrogrades westward
across the warming mainland Alaska and into the southeast Bering
through Sunday. South of the Aleutians and into the Gulf of Alaska
however remains rather chaotic as the models struggle to resolve
details surrounding multiple streams/surface lows rotating around
a main region of upper level low pressure. Eventually, mainland
system energy should merge into the broader low south of the
Aleutians, creating a persistent plume of moisture directed
towards southern and southeastern Alaska. Model guidance varies to
with the timing, strength, and placement of the surface
lows/frontal systems. However, there has been a favorable trend in
that the 12 UTC ECMWF/Canadian now seem reasonably well clustered
with GEFS/NAEFS/ECMWF ensemble means. The GFS tends to be an
outlier with some embedded systems.
Accordingly, the WPC Alaskan medium range product suite was
primarily derived from a blend of the 12 UTC ECMWF/Canadian and 12
UTC GEFS/NAEFS/ECMWF ensemble means along with large input from
the seemingly reasonable 19 UTC National Blend of Models due to
continuing guidance access issues at WPC and beyond.
...Weather/Hazard Highlights...
It also generally remains the case that increasing moisture is
likely by the weekend across south-central Alaska and the
Panhandle as lead flow from low pressure over the northern
Pacific, works across the Gulf. The frontal system should help
direct a persistent plume of deep Pacific moisture towards the
region Sunday-Wednesday. There's a pretty decent signal in the
guidance for a potentially significant precipitation event, with
multiple days of moderate to heavy precipitation from roughly
Kodiak Island to much of the Panhandle. A strong pressure gradient
setting up between low pressure in the Gulf and high pressure to
the north of Alaska by early next week will result in very windy
conditions. Additional low genesis is likely for the Gulf into
mid-late week.
Elsewhere across Alaska, the weather should generally be dry, with
the exception of a few light showers across higher terrain inland.
The Aleutians should also remain rather unsettled and wet through
the weekend under the influence of low pressure south of the
region. Temperatures across the state should start out chilly and
much below normal, especially across western and eastern Alaska
where daytime highs could be 20-30 degrees below normal. However,
by early next week, temperatures should quickly moderate to above
normal across much of the state, except the North Slope region
which remains stuck beneath surface high pressure through much of
the period.
Schichtel
Additional 3-7 Day Hazard Information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
Hazards:
- Heavy precipitation across portions of the Alaska Panhandle and
mainland Alaska, Sat-Wed, Jan 8-Jan 12.
- High winds across portions of the Alaska Panhandle and mainland
Alaska, Sat-Sun, Jan 8-Jan 9.
- Much below normal temperatures across portions of mainland
Alaska, Sat-Sun, Jan 8-Jan 9.
- Much below normal temperatures across portions of mainland
Alaska, Sat, Jan 8.
WPC medium range Alaskan products including 500mb, surface
fronts/pressures progs and sensible weather grids can also be
found at:
https://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml
https://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html