Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
708 PM EDT Tue May 10 2022
Valid 12Z Sat May 14 2022 - 12Z Wed May 18 2022
...Overview and Guidance/Predictability Assessment...
The upper flow pattern across Alaska over the next week looks to
remain quite amplified/blocky as highlighted by strong ridging
over the Bering Sea and an elongated/multi-stream trough from the
Mainland into the Gulf of Alaska laden with high latitude system
energies from the Arctic. A strong shortwave dropping south
through the mainland leads to a large weekend closed trough/low
over the Gulf. Additional shortwave energies digging to the lee of
the ridge over a unsettled eastern Bering Sea and mainland should
subsequently also act to reinforce low pressure in the Gulf.
The 12 UTC GFS/ECMWF and GEFS/ECMWF ensemble means overall seem
reasonably well clustered over the weekend despite lingering
smaller scale system differences, bolstering forecast confidence
in the larger scale pattern. Embedded system confidence is not as
good considering the more varied Canadian and UKMET solutions and
recent run to run guidance continuity issues, especially but not
limited from northern Alaska through the Interior into the Gulf.
Model differences seem to grow enough there and over the Bering
and Gulf by next week to justify a transition to an ensemble mean
forecast approach. This forecast plan maintains decent WPC Alaskan
product continuity.
...Weather and Hazard Highlights...
Increased light and periods of moderate precipitation are likely
to organize across portions of Northern/Interior Alaska this
weekend into next week with each shifting southward as upper
disturbances and several well organized surface fronts work across
the area. There is some threat for high winds, mainly over the
western mainland, as pressure gradients tighten with system
passages. Even though temperatures across much of the state are
expected to be near to below seasonal spring values, some river
flooding, significant in some places, is expected to be ongoing
associated with snow melt and ice jams.
Offshore to the south, regeneration through the weekend and into
early-mid next week of a well organized upper low/trough and
associated surface system position over the Gulf of Alaska will
also favor a periodic focus for moderate and terrain enhanced
precipitation over Southeast Alaska/Panhandle.
Schichtel
Hazards:
- Flooding possible across portions of mainland Alaska, Fri-Sat,
May 13-May 14.
- High winds across portions of mainland Alaska, Mon, May 16.
Additional 3-7 Day Hazard Information can be found on the WPC
medium range hazards outlook 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