Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
752 PM EDT Mon Sep 2 2024
Valid 12Z Fri Sep 6 2024 - 12Z Tue Sep 10 2024
...Guidance Evaluation/Preferences...
The 12Z model guidance suite features good overall synoptic scale
agreement across the Alaska domain for the end of the work week,
with the main exception across the Aleutians and the Bering Sea
region. There are some noticeable timing differences with both
the 12Z CMC and UKMET, which delay the arrival of the next Bering
Sea low and thus keep the surface high pressure ridge to the west
of the GFS/ECMWF and their ensemble means. The AI guidance from
the ECMWF favors something closer to the GFS/ECMWF solutions for
the first half of the forecast period, so the forecast was hedged
more in this direction for fronts/pressures. The lingering Gulf
low is still depicted reasonably well going into Saturday, but
greater model differences appear across the Arctic going into
early next week, and also across the Alaska Peninsula and Bering
Sea region. The ensemble means accounted for about 60% of the
overall forecast for fronts/pressures going into next Tuesday.
...Weather/Hazards Highlights...
A weakening low pressure system near Kodiak Island Friday slowly
drifts east across the northern Gulf and eventually dissipates,
and this will keep conditions quite rainy from South-Central AK
into northwestern portions of the Alaska Panhandle as the mid-to
upper-level trough remains in place through about Saturday. A
total of 3-6 inches of QPF is likely across the favored terrain,
which is not especially unusual for early autumn. Gale force
winds are expected for the coastal and offshore waters, which
could lead to higher tides. The incoming low pressure system
across the Bering by Sunday may also result in periods of rain for
western mainland Alaska, accompanied by some stronger winds near
the coast. Northern stream shortwaves move across northern
Alaska, keeping the arctic drape near the Brooks Range and
generally cooler conditions across the North Slope.
Hamrick
Additional 3-7 Day Hazard Information can be found on the WPC
medium range hazards outlook 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