Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
627 PM EDT Wed Aug 12 2020
Valid 12Z Sun Aug 16 2020 - 12Z Thu Aug 20 2020
...Guidance Evaluation and Preferences...
Overall, model/ensemble guidance showed near to above average
consensus through the extended forecast period. A blend of the 12Z
ECMWF/GFS was used heavily as a forecast starting point initially
on day 4 (Sun). A gradual trend toward increased weight placed on
ensemble means (ECENS/GEFS) was shown through time, with majority
ensembles in the blend during days 7-8 (Wed-Thu). Overall,
guidance is consistent in showing a fairly amplified pattern
continuing, with an upper trough persistent across the Gulf of
Alaska, and ridging (likely somewhat transient) attempting to
build across the Bering Sea next week.
...Weather Highlights/Threats...
A low pressure system across the Gulf of Alaska this weekend will
weaken by early next week, but could bring heavy rain to portions
of the Alaska Panhandle through Sunday. A second low pressure
system is forecast to cross the Bering Sea Sun-Mon, with a triple
point low near the Alaska Peninsula becoming dominant by Tue, and
the system expected to once again move east across the Gulf of
Alaska from there through the middle of next week, keeping
precipitation a distinct possibility across southern mainland
Alaska as well as the Panhandle. Farther north, a weakening
frontal boundary expected to settle into the Interior should bring
scattered showers by next Tue-Wed. In general, this pattern should
favor temperatures several degrees above average across much of
the state. The North Slope will see decreasing temperatures in the
wake of the cold front next week, with high temperatures expected
to drop to a few degrees below average.
Ryan
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 rain across portions of the Alaska Panhandle, Sat-Sun, Aug
15-Aug 16.
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