Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
426 PM EDT Mon Sep 30 2019
Valid 12Z Fri Oct 04 2019 - 12Z Tue Oct 08 2019
Models and ensembles are finally starting to come into better
agreement with the longwave pattern over the high latitudes.
GFS/GEFS remain a bit quicker than the ECMWF/ECMWF ensemble
members with both the track/pace of Typhoon Mitag (likely
extratropical in four or five days) and downstream ridge/trough
couplet. With a slowing trend overall opted to heavily weight the
ECMWF ensemble mean through the period as its spread 24 hrs ago
that washed out the amplitude has now tightened its forecast
spread and shows better definition. Confidence remains average at
best given the details yet to be resolved upstream.
Lead system through the Bering Strait will push through western
areas Friday as its parent low skirts the Brooks Range. Triple
point low will redevelop in the Gulf and move into the Panhandle
by Sunday/Monday bringing low elevation rain and higher elevation
snow from Southcentral eastward. Ridging ahead of ex-Mitag will
push through the Aleutians/Bering Sea Sunday as the main surface
low lifts along the eastern Kamchatka coast toward the Gulf of
Anadyr by the end of the period.
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
- Heavy precipitation across portions of the Alaska Panhandle and
mainland Alaska, Sat-Mon, Oct 5-Oct 7.
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