Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
645 PM EDT Thu Mar 12 2020
Valid 12Z Mon Mar 16 2020 - 12Z Fri Mar 20 2020
...Overview and Guidance/Predictability Assessment...
A series of potentially powerful Pacific systems will lift through
a highly unsettled Aleutians and Bering Sea and work inland into
the Interior/North Slope, temporarily breaking through a lead
upper level ridge position. These systems offer potential for the
development of deep lows and well organized frontal structure that
would focus winds and widespread and enhanced/widespread
precipitation. Temperatures will warm across the region over the
next week, but remain cold enough to support widespread and
locally heavy wintery weather in many areas. System timings seem
fairly periodic with main effects occuring roughly every two days
in this pattern next week.
Meanwhile underneath, additional system trough/jet energies will
break eastward through the southern portion of a lead main upper
ridge position next week over the Gulf of Alaska in a pattern with
more modest precipitation potential for
southwest/southern/southeast Alaska.
...Weather Highlights/Threats...
The WPC Alaskan product suite valid for Monday/Tuesday were
primarily derived from a composite blend of reasonably well
clustered guidance from the 12 UTC GFS/ECMWF/UKMET/Canadian
models, WPC continuity, and the 19 UTC National Blend of Models
(NBM). Forecast spread increases quickly with embedded systems in
the 6-8 day timeframe, so it seems prudent to rely mostly on more
consistent and seemingly reasonable GFS/NAEFS and ECMWF ensemble
mean guidance and the NBM at these longer time frames.
Predictability overall seems near average.
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
Hazards:
- Heavy snow across portions of western Alaska, Thu, Mar 19.
- High winds across western to northwestern Alaska, Wed-Thu, Mar
18-Mar 19.
- High winds across portions of the Aleutians, Tue-Wed, Mar 17-Mar
18.
- Much above normal temperatures across western and northern
Alaska, Sun-Thu, Mar 15-Mar 19.
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