Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
756 PM EDT Wed Oct 19 2022
Valid 12Z Sun Oct 23 2022 - 12Z Thu Oct 27 2022
...A storm threat to Gulf of Alaska/coastal communities this
weekend into early next week...
...Active pattern from Bering Sea Lows into Western Alaska through
the period...
...Overview and Guidance/Predictability Assessment and
Weather/Hazards Highlights...
The extended period begins with a surface low tracking across the
northern portion of the Gulf of Alaska ushering in gusty winds and
precipitation to parts of the southern Mainland and the Southeast.
There is decent model clustering with this feature with the
UKMET/CMC favoring a position closer to the coastline and more
northwest than the clustered ECWMF/GFS solutions. However, the
ensemble means are favoring positions closer to that of the
GFS/ECWMF. After Sunday, the UKMET slows progression and is less
amplified than the rest of the guidance so it was not used beyond
initialization. A mean trough/upper low in place over the Bering
Sea back to northeast Russia through the course of the medium
range period will keep much of the West/Southwest in an active and
unsettled pattern. There continues to be notable spread with the
next low that comes out of the Bering Sea and across the
Southwest/western part of the state by the end of the extended
period; but consensus is trending toward developing a deeper low
and the predictability continues to be above average. This system
is expected to cause high winds to portions of the Mainland and
the Aleutians, increased coastal surf and wintry precipitation.
The suite of Alaska products was based off a starting point of the
12Z GFS/ECWMF/UKMET/CMC (leaning more toward GFS/ECWMF). The UKMET
was removed after the first day. The inclusion and weighting of
the GEFS, NAEFS and EC ensemble means began on Monday and were
steadily increased through the middle and later time periods,
ending day 8 with 100% means and 0% of the deterministic
GFS/ECWMF/CMC. This continued to maintain a sense of continuity
while becoming a little more amplified with the height pattern
then compared to the previous forecast package.
Campbell
Hazards:
- High winds across portions of mainland Alaska and the Aleutians,
Mon-Wed, Oct 24-Oct 26.
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