Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
649 PM EST Wed Dec 11 2019

Valid 12Z Sun Dec 15 2019 - 12Z Thu Dec 19 2019

The upper level pattern across the Alaska domain is expected to be
rather amplified during the medium range period this weekend and
lasting through the middle of next week.  A broad upper level
ridge axis should reside over the Interior and Arctic Coast, and
two deep low pressure systems traversing the Aleutians and Gulf
region.  A third storm system may approach the western Bering Sea
by the end of the forecast period on Thursday.  A rapidly
developing surface low near the Panhandle region is possible early
next week if trends with the ECMWF come to pass.

Models and ensembles appear to be in above average agreement
through most of the forecast period.  With the first storm system
on Sunday, the GFS and GEFS mean are slightly farther north than
the ECMWF and CMC positions, and this trend continues through
Monday before the low weakens and becomes absorbed.  The second
storm crosses the Aleutians on Tuesday, with the GFS indicating a
slightly farther north progression, and then becomes slower by the
end of the forecast period.  It also appears likely that a triple
point low will form on the occluded front, with average model
spread regarding that.  Taking everything into account, the
forecast was primarily based on a blend of some previous WPC
continuity, along with the CMC, GFS, ECMWF, and some of the
ensemble means.  More of the deterministic solutions were used
through day 6, followed by gradually increased use of the ensemble
means.

In terms of sensible weather, rain and windy conditions are likely
across the southern Alaska coast and also extending eastward to
the Panhandle region, and snow farther inland.  Cold and dry
conditions will continue to remain the case across the Interior
and extending north to the Arctic Coast.

Hamrick


Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards
<a href="https://www.wpc.ncep.noaa.gov/threats/threats.php"><u>https://www.wpc.ncep.noaa.gov/threats/threats.php</u></a>

Hazards:

No significant hazards are expected over Alaska during this
forecast period.


WPC medium range Alaskan products including 500mb, surface
fronts/pressures progs and sensible weather grids can also be
found at:

<a href="https://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif"><u>https://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif</u></a>
<a href="https://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml"><u>https://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml</u></a>
<a href="https://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html"><u>https://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html</u></a>