Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
526 PM EST Sat Nov 30 2019
Valid 12Z Wed Dec 04 2019 - 12Z Sun Dec 08 2019
Storm track will largely stay in the Bering and across the
Aleutians into the AKPEN and near Southcentral next Wed-Sun,
forced by an incoming robust upper low. Upper ridging will move
eastward across the North Pacific into western British Columbia
ahead of the upper low. This will favor a quiet period for
interior/northeastern Alaska where some clearing skies and modest
surface high pressure will allow temperatures to fall to the
-20s/-30s and perhaps around -40 in the colder areas overnight.
Models/ensembles continue to show good agreement overall with
expected detail differences in how the systems evolve in the
Bering. Ensembles depict potential for a deeper system in the 960s
mb assuming one low eventually takes over and deepens, but the
deterministic models do show two lows initially across the
Aleutians around Thu, perhaps consolidating but then again
detaching as a triple point across the AKPEN. Either way,
precipitation will expand across the island chain and into
southwestern areas and eventually Southcentral. Favored the 12Z
ECMWF/Canadian over the GFS by the end of the period as the GFS
was likely too quick to bring the front into the Panhandle by next
Sunday. Preferred the slower solutions given the fairly amplified
flow and general blockiness in the Pacific east of the Dateline.
Fracasso
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