Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
643 PM EST Mon Jan 4 2021
Valid 12Z Fri Jan 8 2021 - 12Z Tue Jan 12 2021
...Overview and Guidance/Uncertainty Assessment...
A rather stormy and unsettled weather pattern is expected to
continue across the Aleutians and the Gulf of Alaska region for
the weekend and extending into early next week. There will be a
weakening storm system that will initially be over the northern
Gulf region on Friday. By this weekend, the models are indicating
a strong system approaching the British Columbia coast and
southeast Panhandle region. Meanwhile, another strong storm
crossing the Aleutians this weekend is expected to enter the
western Gulf and likely merge with the southeastern Gulf system by
Sunday night, and then become a large and broad low pressure gyre
by early next week. There is some longitudinal spread with the
CMC to the northwest of the means, and the GFS to the southeast.
Once the pattern becomes more amplified and defined by Monday, the
deterministic CMC/EC/GFS are in above average agreement for the
Day 6-8 time period, and this justified a general blend of those
models, along with some of the ensemble means, as a starting point
in the forecast process.
...Weather/Hazards Highlights...
The multiple northeastern Pacific/Gulf systems should bring
numerous rounds of moderate to occasionally heavy precipitation to
areas in the general vicinity of the southern coast and Panhandle
region. The greatest rain and snowfall amounts are expected to be
between the Kenai Peninsula and the southeast Panhandle, with
several inches of rainfall possible near the coast over the 5 day
period. Given the predicted intensity of these systems, there
will likely be strong winds and hazardous marine conditions.
Meanwhile, strengthening winds and increasing precipitation should
reach the western Aleutians by late Friday, and then extend across
the rest of the islands during the weekend as the associated storm
system progresses eastward. The upper level pattern will favor
the establishment of generally above normal temperatures across
most areas during the medium range period. Locations over the
northwestern mainland will likely be closer to normal readings.
The above normal anomalies for low temps should generally be
greater than those for highs.
Hamrick
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