Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
248 PM EDT Thu Sep 26 2019
Valid 12Z Mon Sep 30 2019 - 12Z Fri Oct 04 2019
Guidance reasonably advertises an energetic and steadily
progressive Alaskan flow evolution next week in a pattern with
average to above average predictabillity. An amplified and
warming/shielding upper-level ridge shifts eastward over the
eastern interior and southeast Alaska early to mid next week. This
occurs as an unsettling and amplified Arctic/Bering Sea/North
Pacific Ocean upper trough shifts slowly eastward and splits, with
the southern portion carving out a significant Gulf of Alaska
closed upper low and surface cyclogenesis/frontogenesis. This will
threaten maritime interests and also support heavier precipitation
from southern to southeast Alaska. Expect more limited
precipitation for the North Slope and Interior.
Upstream, upper troughing should amplify from the Bering Sea to
North Pacific mid-late next week and then reach western Alaska and
dig more in ernest into the Gulf of Alaska late next week. This
will offer a renewed heavy weather threat from the Aleutians into
western/southwest to southern Alaska along with an offshore
maritime threat.
The WPC medium range product suite was primarily derived from a
composite blend of best clustered solutions of the 12 UTC GFS/00
UTC ECMWF and 00 UTC ECMWF ensemble mean days 4-8, albeit with
increased day 7/8 forecast spread. This solution maintains decent
WPC continuity.
Schichtel
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
Hazards:
- Heavy rain across portions of the Alaska Panhandle and mainland
Alaska, Sun-Tue, Sep 29-Oct 1.
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