Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
646 PM EDT Thu Jun 11 2020
Valid 12Z Mon Jun 15 2020 - 12Z Fri Jun 19 2020
...Overview and Weather Highlights/Threats...
For the forecast period /Mon-Fri/, a couple of storm systems will
brush south of the Alaska mainland and move across the North
Pacific and Gulf of Alaska. The first will be weakening as it
approaches the far southeast Alaska area while further west over
the Aleutians, low pressure again organizes with a deepening
trough. That system is forecast to deepen and move northeast over
the North Pacific by the mid/late portions of the week. Further
north over the mainland, generally upper ridging is expected,
anchored over eastern Alaska and western Canada. This should
support a continuation of slightly above average temperatures and
mesoscale driven sensible weather characterized by showers and
thunderstorms in the afternoon.
...Guidance/Predictability Assessment...
After starting out with above average agreement, the latest
forecast guidance shifted to below average from the mid to late
periods as a stronger storm system develops along and south of the
Aleutians. The 12Z ECMWF, GFS, and CMC were incorporated with near
equal weight for day 4 /Mon/. However, the GFS quickly becomes out
of favor as it is too deep and slow with low moving out of the
Gulf of Alaska mid-week, and also is way too fast with the area of
low pressure developing by day 7/8. Therefore, the blend
incorporated more of the ECMWF, ECENS, and GEFS means which should
fairly good agreement and continuity.
Taylor
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:
No significant hazards are expected over Alaska during this
forecast period.
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