Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
510 PM EST Thu Mar 04 2021
Valid 12Z Mon Mar 08 2021 - 12Z Fri Mar 12 2021
...Overview and Guidance/Uncertainty Assessment...
The medium range period begins on Monday with a broad upper level
ridge axis over east-central Alaska, and a broad upper level gyre
over eastern Siberia and the western Bering Sea region. By the
end of next week, a broad upper trough will likely exist across
the Gulf of Alaska region along with a possible low pressure
system, and an upper ridge trying to build back in across the
Aleutians and Bering Sea.
The 12Z deterministic model guidance is in good overall synoptic
scale agreement over the Alaska domain through about Tuesday.
Overall model agreement has improved for most of this forecast
period compared to yesterday, and the strong low that has been
advertised for the middle of the week has trended farther south
and slower, although the operational GFS is stronger and closer to
the coast, so that will continue to be monitored. The
fronts/pressures forecast was primarily derived from a GFS/GFS
parallel/ECMWF/EC mean blend, with some of the GEFS mean
introduced later in the forecast period.
...Weather/Hazards Highlights...
Much of mainland Alaska is expected to have widespread light to
moderate snow as moisture flows northward ahead of the strong
Bering Sea storm system early next week, especially for the
western half of the state where some 6+ inch snowfall totals are
possible. Moderate to locally heavy precipitation is likely for
the southern coast and adjacent mountain ranges with moisture
advecting northward from the Gulf of Alaska through midweek. More
widespread impacts are possible if the Gulf low tracks closer to
the coast or becomes stronger than currently forecast.
Temperatures will likely be near to above average through
Wednesday before a return to below average readings to close out
the week.
Hamrick
Hazards:
- Heavy precipitation across portions of mainland Alaska, Mon, Mar
8.
- High winds across portions of mainland Alaska, Sun-Mon, Mar
7-Mar 8.
Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards 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