Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
535 PM EDT Fri Oct 16 2020
Valid 12Z Tue Oct 20 2020 - 12Z Sat Oct 24 2020
...Guidance/Predictability Assessment...
Upper ridging is forecast to move into western coastal Alaska from
the Bering Sea by midweek next week, blocking much of the Interior
from significant precipitation. The 12Z guidance showed good
agreement overall to start the period Tue-Wed and a deterministic
blend sufficed. Thereafter, the 12Z GFS strayed from the 12Z
ECMWF/Canadian/UKMET and ensemble mean consensus with its its
handling of a northern central Pacific system next week--remaining
farther south with its sfc low rather than near the western
Aleutians Wed-Thu. Thereafter, the GFS came back into agreement
with the ECMWF and ensembles as it takes the surface low eastward
just south of the Aleutians with a lead system weakening and
flattening in the southern Gulf. With generally good agreement to
next Sat, split the difference evenly between the GFS/ECMWF and
their ensemble means.
...Weather/Threats Highlights..
Upper ridging will bring above normal temperatures to much of the
Interior, especially over the North Slope, with dry conditions.
Temperatures may be 10-15 degrees above normal along and north of
the Brooks Range, and 5-10 degrees above normal north of the
Alaska Range. Areas of eastern/southeastern Alaska and especially
the Panhandle will see near to below normal temperatures as high
pressure delivers easterly flow to the region. Rainfall will be
confined to the Aleutians and coastal Southcentral areas, as well
as into the Panhandle as lingering surface low pressure weakens
Tue-Wed. It will be rather breezy over the southern Bering due to
the tightening pressure gradient between mainland high pressure
(nearing 1040mb) and low pressure near the western Aleutians
(perhaps 980s or even lower).
Fracasso
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