Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
732 PM EDT Sat Jun 25 2022
Valid 12Z Wed Jun 29 2022 - 12Z Sun Jul 03 2022
...Overview...
Warm upper ridging over much of the mainland and Panhandle midweek
will slowly shift eastward as an upper trough/low initially in the
Bering Sea moves toward and across western Alaska. This will lead
to cooling temperatures as well as increasing rain chances
generally from west to east across Alaska as the latter part of
the week progresses.
...Guidance Evaluation/Predictability Assessment...
Model agreement is rather good with the general large scale
pattern described above, but with differences in the details,
particularly on timing of the trough moving eastward and details
of energy within it. The ECMWF suite is generally faster with the
eastward movement of the trough than the GFS/GEFS and CMC/CMCE
suites. The 12Z deterministic ECMWF may be questionable as it is
quicker/more northeast with the upper low within the trough
Thursday-Friday, but not necessarily out of the realm of
possibilities. Preferred the GFS/CMC, but had some EC mean in
today's model blend as well for a nod toward a faster solution.
Compared to continuity, utilizing mostly deterministic models
early on led the trough to be somewhat deeper and narrower. But by
next weekend, details of the flow go more awry and transitioned
quickly to a blend favoring the ensemble mean guidance.
...Weather and Hazard Highlights...
Temperatures will continue to be rather warm across much of the
state midweek under the upper ridge, generally 10-15F above normal
especially for lows. Warmth over the Panhandle could lead to a
couple of record highs Wednesday. These temperatures are forecast
to get gradually shunted eastward as troughing influences western
Alaska and beyond, underneath which below average highs and about
average lows are likely. The far eastern mainland and parts of the
Panhandle may stay above average into next weekend as the ridge
stalls.
Just ahead of the approaching trough and a surface low pressure
system, moisture will increase and lead to rainfall chances first
for the Aleutians Wednesday and then spreading into the western
mainland and Alaska Peninsula Thursday-Friday, into central Alaska
Friday-Saturday, and much of the mainland over the weekend, though
perhaps lessening amounts with the eastward progression. The North
Slope may see episodes of light precipitation if a front to the
north gets close enough to the region.
Tate
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