Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
738 PM EDT Tue Oct 06 2020
Valid 12Z Sat Oct 10 2020 - 12Z Wed Oct 14 2020
...Overview and Guidance/Predictability Assessment...
The trend of evolving the closed low over the Bering Sea/elongated
trough over the Gulf/closed low reaching the Mainland from the
northeast into a mean trough over the mainland persists with the
latest guidance suite. Consensus places a lasting surface low near
the Gulf of Alaska while another area of low pressure tracks
southeast from the Bering sea and weakens along the way/absorbs
into the larger circulation.
The GFS has been persistent in being deeper and faster than other
solutions the last several runs, which given the uncertainty of
timing, location and strength, it was used to a lesser degree. The
preferred model, in coordination with the Alaska local forecast
offices, was the 12Z ECWMF. The 12Z ECWMF had a heavier weighting,
but was also paired with the 12Z CMC/UKMET/GFS initially with
gradual inclusion of the 00Z EC ensemble and the 12Z GEFS mean.
...Weather/Threats Highlights...
With the upper-level pattern favoring mean troughing during this
period, precipitation across portions of the southern coast and
the Southeast will be favorable. Heavy precipitation will be
possible for portions of the Kenai Peninsula on Friday. Impacts to
the Southeast remain uncertain at this time. If the low tracks to
the eastern Gulf/south of the panhandle, this favors higher
precipitation to the southern islands and drier further north.
Lowering heights aloft may produce scattered precipitation at
times over the mainland which will be in the gradient between
Arctic high pressure and Gulf low pressure. The Aleutians should
see brisk and unsettled conditions.
In regards to daily temperatures, a majority of the state will
have warmer than average temperatures through mid-month. However,
portions of the Panhandle and the southern coast will have
afternoon highs near or slightly below normal.
A few isolated near to below normal highs may be possible over the
north. Min temperatures will likely be above to well above normal
over most areas, except for near to slightly below normal over the
Panhandle.
Campbell
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 precipitation for the eastern portion of Kenai Peninsula
in southern Alaska, Fri, Oct 9.
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