Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
600 PM EST Wed Jan 11 2023
Valid 12Z Sun Jan 15 2023 - 12Z Thu Jan 19 2023
...Overview...
The latest guidance continues to have a fair handle on the large
scale pattern through the extended period. An area of lingering
weakness aloft is expected to remain in proximity to the
Arctic/North Coast while much of the Mainland will have ridging,
although is will be slowly weakening. Meanwhile, as an initially
deep Aleutians storm weakens, an elongated trough will setup from
the Bering Sea to portions of the northern Pacific and will
feature some areas of low pressure to pass though. This large
scale pattern looks to maintain itself through the extended period
which will keep precipitation focused along the southern part of
the mainland while lighter amounts forecast for the Southeast and
the Aleutians. At the surface the mainland will remain in a
gradient between strong high pressure over higher latitudes of the
Arctic and the various surface lows to the south/southwest.
...Guidance/Predictability Assessment...
More or less the latest models continue to show a consensus of
multiple low tracking through the mean elongated trough from the
Bering to the Gulf of Alaska, albeit with varying degrees of
spread. The ECWMF continues to be the leader with the pattern
evolution with the CMC and GFS jockeying for a close second and
third. Those solutions at times are either too fast/slow, not was
strong/stronger etc but overall pair well with the ECWMF and its
ensemble mean. Additionally, there is a growing consensus that
another low develops will lift through the northern Pacific/Gulf
of Alaska later in the extended period. The WPC blend leaned
heavier on the ECWMF but also included the CMC, GFS, GEFS mean, EC
Ensemble . Small inclusion of the UKMET early on and then the
weighting of the means increased to 30 percent by day 8.
...Weather/Hazards Highlights...
Areas of generally light to moderate precipitation will fall
across portions of the Alaska Peninsula, Kenai Peninsula and along
the southern and southeast coast. At times, there may be heavier
intensities over the AK and Kenai Peninsulas periodically as these
is where the best potential will be throughout the extended period
given fairly persistent easterly low level flow. Otherwise most of
the mainland away from the southern coast should stay fairly dry.
The Aleutians should see unsettled conditions through the period,
but with low confidence for any individual lows that could focus
precipitation/wind beyond the initial deep low over the area on
Friday. The gradual weakening of upper ridging over the state
over the course of the period should promote a colder trend for
temperatures. Lows may may still be above normal over most
locations by early next week after starting out well above normal
on Friday, but gradually increasing coverage of below normal highs
will be possible over the interior and North Slope.
Campbell
No significant hazards are expected over Alaska during this
forecast period.
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