Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
601 PM EDT Wed Jul 29 2020
Valid 12Z Sun Aug 02 2020 - 12Z Thu Aug 06 2020
...Overview and Guidance Evaluation...
An upper low over the Bering Sea will move eastward into
Southwestern Alaska then the Gulf next week. A lead upper low in
the Gulf Sunday will weaken and move out on Monday. The latest 12Z
deterministic guidance showed good agreement with the ensembles
Sun-Tue with the Bering system before they dispersed from the
ensemble consensus with upstream (and weaker) systems. Opted to
rule out the stronger 12Z Canadian next Wed with its much deeper
system in the Gulf, though it remains plausible. By Wed/Thu,
increasingly favored the ensembles (12Z GEFS mean and 00Z ECMWF
ensemble mean) with some weighting of the GFS/ECMWF as the upper
flow becomes more progressive, flatter, and therefore more
uncertain regarding system timing/track.
...Weather Highlights/Threats...
Lingering upper low in the Gulf will provide a waning focus for
some modest rain over the Panhandle Sunday as the old parent low
dissipates. More robust system in the Bering will be the main
driver of heavier rain, initially over southern coastal areas
(Southwest through Southcentral) as the triple point takes over
east of Kodiak late Mon into Tue. This will progress eastward to
southeastern areas into the Panhandle by Tue into Wed as the front
moves eastward into Canada. Much more showery weather is expected
next Wed/Thu over the Aleutians across southern areas under the
upper low.
Expect below normal high temperatures across most of the state
next week, with greatest negative anomalies over the far north
(Brooks Range and North Slope) and south/southeast. Clouds/precip
should promote broader coverage of near to slightly above normal
min temps south of the Brooks Range.
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 possible across portions of eastern Alaska, Sun, Aug
2.
- Heavy rain possible across portions of coastal southern Alaska,
Sat-Mon, Aug 1-Aug 3.
- Heavy rain possible across portions of the Alaskan Panhandle,
Tue-Wed, Aug 4-Aug 5.
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