Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
614 PM EST Wed Nov 27 2019
Valid 12Z Sun Dec 01 2019 - 12Z Thu Dec 05 2019
Upper troughing will slowly migrate out of the western Bering Sea
into mainland Alaska, giving way to much cooler temperatures over
the northern interior. Upper ridging is forecast to move into the
Bering for the middle of next week ahead of a deepening upper low
in the Gulf of Okhotsk.
Lead system of interest will slide along the AKPEN early Sunday
then toward Prince William Sound early Monday. The 12Z GFS was
closest to continuity and the preferred near-offshore track as the
12Z ECMWF jogged inland across the Kenai. The ensembles were also
displaced to the north but the progressive flow should favor the
flatter GFS-like solution. To the north, however, the GFS appeared
too sharp with the upper trough over the Seward peninsula early
Sunday as it maintained a more folded over orientation of the
upper ridge to the north. Preferred the 12Z ECMWF there despite
the opposite preference to the south as the scenarios should not
be mutually exclusive. Front will continue to move eastward into
the Panhandle by early Tuesday with associated coastal rain and
inland/mountain snow which could be locally heavy.
Next system will likely push into the Bering next Wed/Thu as high
pressure settles into the interior. This will favor much colder
temperatures by the end of the period as even the ensemble means
show temperatures dropping into the -20s/-30s in normally colder
areas. Ensemble consensus approach was sufficient for the Wed/Thu
period but with some details from the GFS/ECMWF given good
agreement along/west 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
Hazard:
- Heavy precipitation across portions of the Alaska Panhandle and
mainland Alaska, Sun-Tue, Dec 1-Dec 3.
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