Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
656 PM EDT Sat Mar 14 2020
Valid 12Z Wed Mar 18 2020 - 12Z Sun Mar 22 2020
...Overview and Guidance/Predictability Assessment...
A series of potentially powerful Pacific systems will lift through
a highly unsettled Aleutians and Bering Sea and tend to work along
with precipitation/weather inland into the Interior/North Slope
then Arctic Ocean, with lead snows midweek. This will then include
development of a particularly deep Bering Sea storm
Wednesday/Thursday with well organized frontal structures that
will focus winds and widespread and enhanced/widespread
precipitation. This low will gradually fill and lift poleward
later week in the wake of the lead system, but will remain a
significant focus for weather. Temperatures will overall moderate
across the Interior/North Slope next week, but remain cold enough
to support periods of heavy snow, with a particular risk for
northwest Alaska.
Meanwhile underneath, additional but weaker system trough/jet
energies will break eastward through the Gulf of Alaska in a
pattern with more modest precipitation potential for
southwest/southern/southeast Alaska.
...Weather Highlights/Threats...
The WPC Alaskan medium range product suite valid Wednesday-Friday
was mainly derived from a composite blend of reasonably well
clustered guidance from the 12 UTC ECMWF/Canadian and
GEFS/NAEFS/ECMWF ensemble means. The 12 UTC GFS and to a lesser
extent the 12 UTC UKMET seem outlier solutions that are less
supported by ensembles and WPC continuity. Forecast continuity and
predictability seem above normal during this period. Forecast
spread increases with embedded systems next weekend, so it seems
prudent to rely much upon more consistent and seemingly reasonable
GEFS/NAEFS/ECMWF ensemble mean guidance at these longer time
frames.
Schichtel
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