Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
656 PM EDT Fri Apr 23 2021
Valid 12Z Tue Apr 27 2021 - 12Z Sat May 01 2021
...Overview and Guidance/Uncertainty Assessment...
The weather pattern is forecast to be relatively uneventful across
most of Alaska during the medium range period. The upper level
flow pattern is expected to feature a slow moving upper low over
the Gulf of Alaska, while an upper ridge axis to the west helps to
hold back any other significant energy from lifting north/east
into the state. This is expected to keep the main storm tracks and
significant sensible weather confined to the southern coastal
areas. By the end of the period, an increase in moisture could
bring more unsettled weather to the southeastern areas as low
pressure finally lifts northward in a bit more progressive upper
level flow pattern.
The latest model guidance showed fairly good agreement and
predictability for early to mid next week. The main difference was
a faster and more amplified trough solution with the 12Z CMC
across eastern Siberia. By Thursday, the GFS stands out with a
strong upper low over the northern Bering compared to the other
guidance, and this persists into the weekend. This was not
supported much by the ensemble means, so it was weighted less in
the forecast. The WPC blend leaned toward the 12Z ECMWF/CMC/EC
mean along with some previous WPC continuity.
...Weather/Hazards Highlights...
The majority of the state should remain dry through the first half
of the period with any precipitation chances confined to the
Aleutians and the Alaska Peninsula areas through the middle of
next week. By late in the week, low pressure lifting northward
across the Gulf of Alaska is expected to advect higher moisture
into the area. With better forcing and dynamics, widespread
precipitation is expected from Kodiak Island to the southeast
Panhandle region. Some of this rainfall could be locally heavy.
No significant temperature anomalies are forecast during this
forecast period.
Hamrick
Hazards:
-Heavy precipitation across portions of the Alaska Panhandle,
Wed-Thu, Apr 28-Apr 29.
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
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