Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
709 PM EDT Wed Oct 07 2020
Valid 12Z Sun Oct 11 2020 - 12Z Thu Oct 15 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 once again
with the latest deterministic and ensemble guidance. 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. This
will keep much of the southern coast and the Southeast cloudy with
scattered/widespread precipitation.
The GFS continues to be somewhat of an outlier therefore minimal
inclusion for this package. The 12Z ECWMF was the preferred model
as it handled the lows in the Bering and Gulf the best at this
point given the uncertainty of timing, location and strength. The
blend for this issuance was the NBM /12Z ECWMF.
...Weather/Threats Highlights...
Much of the southern coast and portions of the panhandle with have
precipitation throughout the extended period, with periods of
heavier intensity especially the Southeast and areas of higher
terrain by the middle of next week. Cloud cover will hang around
for much of the southern half of the state and for the North Slope
for several days.
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.
Daily highs will mainly range from the 30s to 50s from north to
south this weekend, however cooler air will begin to settle in
over the state. Highs will range from the upper teens near the
Arctic to the 40s in across the southern Mainland/panhandle by
next week and overnight lows will range from the 10s to the
30s/40s. For portions of the Panhandle and the southern coast this
will be near or slightly below normal for mid-October.
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 across much of the Alaska Panhandle, Wed,
Oct 14.
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