Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
630 PM EDT Sat Jun 12 2021
Valid 12Z Wed Jun 16 2021 - 12Z Sun Jun 20 2021
...Guidance/Predictability Evaluation...
The WPC Alaskan medium range product suite was primarily derived
from a blend of best clustered guidance of the 12 UTC GFS/ECMWF,
12 UTC GEFS/ECMWF ensemble means and the 19 UTC National Blend of
Models Day 4-8. However, deemphasized the deterministic models
over time due to increased variability and continuity issues with
embedded systems in a pattern with lowering predictability.
Manually adjustments were applied mainly to offshore lows to
maintain strength consistent with predictability and upper support
to offset weakening inherent to the blending process/forecast
spread.
...Weather/Threats Highlights...
Lingering northern stream upper troughing from the Arctic Ocean
into northern Alaska will support unsettled maritime weather, but
minimal onshore precipitation next week as upper ridging builds
northward from a warmed Interior. Meanwhile, an active southern
branch storm track will progress near/just south of the Aleutians
and a series of complex/uncertain lows and frontal systems will
focus unsettled weather over the region, then downstream across
the Gulf of Alaska with system proximity and to a lesser extent
coastal southern and southeast Alaska.
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