Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
300 PM EST Mon Nov 11 2019
Valid 12Z Fri Nov 15 2019 - 12Z Tue Nov 19 2019
Models showed reasonably good agreement during days 4-5 with a
filling low pressure system across the Gulf of Alaska Fri and
another multi-centered low pressure system entering the Gulf from
the south on Sat. Additionally, the GFS has come more in line with
the general consensus with respect to Arctic shortwave energy that
is forecast to cut off across the eastern Bering Sea Thu
night-Fri, after previously showing a much deeper system than
other guidance. The ECMWF and GFS were both reasonably close to
the overall consensus during this time frame, and a blend of these
two solutions was used for days 4-5. By day 6 (Sun), the second
Gulf system is forecast to reach Southeast Alaska and push inland,
while another low pressure system crosses the Aleutians. One
significant player by late in the medium range will be what is now
Tropical Depression 26W, forecast to be a typhoon as it recurves
east of Japan by later this week. 26W should undergo extratropical
transition by late this weekend as it interacts with the
aforementioned low pressure system near the Aleutians. Model
solutions diverge and become quite chaotic on the specific
evolution of this feature and the potential interaction between
the post-tropical cyclone and the mid-latitude low pressure
system. Nonetheless, there is the potential for a deepening low
pressure system to pass near the Aleutians by next Mon,
potentially crossing the Alaska Peninsula or moving into the Gulf
of Alaska by Mon. Given that confidence was quite low in the
specifics during days 6-8, opted to go heavily toward ECENS/NAEFS
ensemble means during that time frame.
Ryan
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
- Much above normal temperatures across portions of mainland
alaska, Mon, Nov 18.
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