Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
759 PM EDT Mon Mar 27 2023
Valid 12Z Fri Mar 31 2023 - 12Z Tue Apr 04 2023
...Overview...
The medium range Alaska period begins late week with troughing
across the mainland while a surface low is present over the Gulf
of Alaska, causing some modest precipitation for the Panhandle
while the bigger threat may be gap winds on its backside across
parts of the Alaska Peninsula/Kodiak Island/Kenai Peninsula.
Meanwhile a persistent surface and upper ridge is forecast farther
west across the northern Pacific/eastern Aleutians, causing the
storm track to be pushed toward the western Aleutians, while upper
energy could spill into the mainland this weekend before the flow
may flatten a bit early next week.
...Guidance Evaluation/Predictability Assessment...
Model guidance is in reasonably good agreement initially, with a
Gulf of Alaska upper low embedded within troughing across the
mainland and a weak upper ridge to the west. Models diverge
somewhat with the positioning/axis/amount of energy spilling into
the mainland this weekend to the east of the
Pacific-Aleutians-Bering Sea upper ridge, but with no true
outliers noted. Additionally, some differences emerge with a low
coming west of that ridge over the weekend. The CMC suite seems to
be a bit east of consensus across the Aleutians. Model variations
increase as the period progresses from that point. Thus the WPC
model blend was based on a deterministic 12Z GFS/ECMWF/UKMET blend
at first, and increased the EC and GEFS ensemble mean proportions
by early next week.
...Weather/Hazard Highlights...
Gales are expected across portions of the AK Peninsula and Upper
Aleutians from Thursday into Friday as a cyclone develops in the
northeast Pacific/Gulf of Alaska. This system will produce
precipitation for south-central Alaska and the Panhandle but
amounts should remain modest. Precipitation is also possible
across the Aleutians, which may be locally heavy depending on the
low track, and energy passing through the mainland could lead to
some light snow there at times. The North Slope is likely to be
the coldest area across the state with some subzero but also the
most above normal area across the state. Farther south
temperatures are expected to be slightly below normal in terms of
highs at least.
Tate
Hazards:
- High winds across portions of mainland Alaska, Fri-Sun, Mar
31-Apr 2.
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