Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
330 PM EST Tue Nov 12 2019
Valid 12Z Sat Nov 16 2019 - 12Z Wed Nov 20 2019
...Aleutians to Gulf of Alaska Stormy Pattern...
...Guidance/Uncertainty Assessment and Weather
Highlights/Threats...
Model and ensemble guidance seems fairly well clustered this
weekend with the overall pattern evolution and for the most part a
number of potentially well organized weather focusing systems.
Unsettling mid-upper level troughing will settle from Southwest
Alaska northeastward through the Interior/North Slope to the
Arctic. Limited moisture and lift will support periods of snow for
the region this weekend in gradually easing low level easterly
flow.
Lead multi-stream low/jet energies are meanwhile slated to work
underneath toward southern/southeastern Alaskan from the Gulf of
Alaska. These systems pose a maritime threat and the circulations
is expected to wrap moisture onshore to sustain some threat of
locally heavy precipitation for coastal areas and especially
favored terrain this weekend into early next week. A preferred
composite solution of the latest models and ensembles seems to
offer a reasonable basis for the effects associated with these
systems in a pattern with slightly above average overall
predictability.
The main weather focus will then shift westward toward the
Aleutians and southern Bering Sea by early next week and spread
steadily toward Southwest and south-central Alaska into next
midweek with advance of a series of deep lows. These systems
should have closed upper low/trough support and may deepen enough
to entrain some deeper lower latitude moisture. Expect a maritime
and coastal threat for high winds/waves and heavy precipitation in
a pattern with near average predictability. WPC progs used a blend
of the GEFS/ECMWF ensemble means amid growing model forecast
spread, but manually depened the surface lows given favorable
upper support and continuity.
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
Hazards:
- Heavy precipitation across portions of the Alaska Panhandle and
mainland Alaska, Fri-Tue, Nov 15-Nov 19.
- High winds across portions of mainland Alaska, Fri-Sat, Nov
15-Nov 16.
- High significant wave heights for coastal portions of the
Aleutians, Sun-Tue, Nov 17-Nov 19.
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