Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
529 PM EDT Wed Aug 05 2020
Valid 12Z Sun Aug 09 2020 - 12Z Thu Aug 13 2020
...Guidance Evaluation and Preferences...
Troughing over the mainland and into the Gulf will weaken/move
eastward as a more robust Bering system pushes into southwestern
areas around the middle of next week. The 12Z models and ensembles
offered a reasonable clustering for most of the features, and a
consensus blend was suitable.
For the lead system in the Gulf, models have shifted in unison to
a quicker and deeper low just off the northern Panhandle by early
Sunday, in contrast to just 24 hours ago. Hard to ignore such a
strong clustering despite the poor continuity, but sfc wave
development can be fickle even at "only" 4-5 days out. Thereafter,
guidance remained quite consistent in the Bering, with the 12Z
models near the ensemble consensus through about next Wed. After
that, parent system may progress inland and shear out eastward,
with possible development along the front back to the southwest.
Farther south, strong upper high is forecast to retrograde
westward, which would at least bump the front enough to make any
scenario of the GFS/ECMWF/Canadian plausible, thus included all
for some detail out to next Thu, but with a slight majority
ensemble weighting.
...Weather Highlights/Threats...
Lead system in the Gulf will bring a chance of modest to locally
heavier rain to the far Southeastern areas and Panhandle Sat
(before this period) into Sun. Farther north, a weakening frontal
boundary and topographical effects will result in scattered
convection across northern portions of the Interior as well as the
Brooks Range that will gradually dwindle through early next week.
Bering system next week Mon-Thu will bring showers/rain to the
Aleutians with breezy conditions as well. Expect at least some
rainfall into western/southwestern areas as the warm front
approaches late Tue/early Wed that is forecast to spread across
Southcentral. In general, lower than average heights along with
abundant clouds and precipitation will keep high temperatures
across much of Alaska several degrees below normal, and low
temperatures near to several degrees above normal.
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:
- Heavy rain across portions of the Alaska Panhandle Sat-Sun, Aug
8-Aug 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