Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
703 PM EDT Thu Sep 01 2022
Valid 12Z Mon Sep 05 2022 - 12Z Fri Sep 09 2022
...Guidance/Predictability Assessment...
The WPC Alaskan Day 4-8 product suite was primarily derived from a
composite blend of reaonably well clustered guidance of the 12 UTC
GFS/ECMWF/UKMET/Canadian for days 4/5 (Monday/Wednesday) before
switching to a blend of the still compatable 12 UTC GEFS/ECMWF
ensemble means for days 6-8 amid growing forecast spread. This
forecast strategy was collaborated with local Alaskan NWS offices.
WPC product continuity was reasonably well maintained in this
manner in a pattern with near normal overall predictability.
Forecaster applied adjustments to these resultant blends tend to
mitigate some unwanted embedded system weakening due to the blend
process when upper support or continuity seemed to mandate as
consistent with predictability.
...Sensible Weather and Potential Hazards...
Expect ample upper troughing and moisture laden surface system
activity over the Gulf of Alaska and south/southeast Alaska over
the weekend to quickly lose influence over the region while
working inland into western Canada through early next week. The
primary emphasis of the forecast will transfer to development and
evolution of upper trough energies and embedded lows moving across
the Bering Sea along with how it may interact with North Pacific
flows/surface system. Expect the Aleutians into the Alaska
Peninsula/western mainland will subsequently see rain develop into
Tuesday-Wednesday dependent on the Bering Sea-North Pacific
evolution. Latest progs still bring an organized low/frontal
system across the region that could then reorganize over the
northern Gulf of Alaska next Wednesday-Friday. This would offer an
additional maritime and southern Alaskan threat of enhanced
rains/winds/waves, albeit with stronger guidance signals to emerge
for this longer time frame. Elsewhere, the overall pattern with
lowered heights and passing upper systems should also support some
scattered areas of mostly light precipitation over interior
portions of the mainland over the period.
Schichtel
Hazards:
No significant hazards with sufficient predictability are noted
during this forecast period.
Additional 3-7 Day Hazard Information can be found on the WPC
medium range hazards outlook 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