Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
528 PM EST Mon Jan 31 2022
Valid 12Z Fri Feb 4 2022 - 12Z Tue Feb 8 2022
...Overview...
The large scale pattern over Alaska will be fairly stagnant late
this week into early next week, with a col generally in place over
Alaska, separating deep layer low pressure west of the Aleutians
and an upper high retreating well northwest of the state while an
upper low slowly drifts east over far northern Canada. The upper
level gyre just west of the Aleutians will produce shortwaves
pivoting around it, sending them northeastward along the southern
part of the state. These shortwaves and their associated surface
lows are expected to track across southern coastal Alaska along
with multiple rounds of precipitation, with the heaviest rain/snow
from the Kenai Peninsula to the southeast Panhandle.
...Guidance/Uncertainty Assessment...
The 12Z model guidance suite is initially in good synoptic scale
agreement over the Alaska domain and has a good handle on the
storm system over the eastern Gulf and the shortwave approaching
the eastern Aleutians for the end of the week, with the exception
of the 12Z UKMET that is much stronger and slower with a closed
low over the Gulf. For the second system entering the Gulf on
Sunday, models are more divergent with the ECMWF farther east than
the stronger GFS/CMC solutions. A much stronger storm system
approaches the Aleutians by early next week with a decent signal
in the CMC/ECMWF/GFS solutions for this, with the ECMWF/GEFS mean
offering a reasonable middle ground solutions between the farther
west GFS and the southeast CMC solution. The models are also
stronger with building an arctic trough across the northern half
of Alaska going into the weekend and into Monday, with the GFS
among the colder solutions compared to the ensemble means.
Therefore, the WPC fronts/pressures forecast was primarily derived
from a CMC/ECMWF/some GFS for Friday/Saturday, and then gradually
increasing contributions from the ensemble means through the
remainder of the forecast period.
...Weather/Hazard Highlights...
Three separate pressure/frontal systems tracking northward to
coastal southern Alaska and the southeast panhandle region will
advect copious moisture into the southern part of the state.
These storms will provide forcing for multiple rounds of coastal
rain and heavy mountain snow across the Alaska Peninsula,
south-central Alaska, and the Panhandle late this week into early
next week. Gusty winds and rough seas are also likely from the
Aleutians eastward to the Alaska Peninsula. Farther north, arctic
high pressure will be in place across northern Alaska, keeping the
Interior dry and cold through late week. Some snow showers over
the northern mainland may be possible early next week as the
surface high retreats. Below normal temperatures across much of
the Interior will gradually retreat to the North Slope and the
western mainland by early next week, while generally above average
temperatures are forecast for southern Alaska owing to the
influence of onshore flow and increased cloud cover.
Hamrick
Hazards:
- Heavy precipitation across portions of the Alaska Panhandle and
mainland Alaska, Thu-Sat, Feb 3-Feb 5.
- High winds across portions of mainland Alaska, Thu, Feb 3.
- Much below normal temperatures across portions of mainland
Alaska, Thu-Fri, Feb 3-Feb 4.
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
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