Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
329 PM EST Sun Jan 24 2021
Valid 12Z Thu Jan 28 2021 - 12Z Mon Feb 01 2021
...Bering Sea Storm to Threaten Alaska and the Gulf of Alaska into
mid-late week...
...Overview and Guidance/Uncertainty Assessment...
A powerful Bering Sea storm will slowly fill while spinning toward
West/Southwest Alaska into Thursday-Friday, maintaining a maritime
threat. Ample downstream energy transfers over the AKPen/Kodiak
Island and the Gulf of Alaska meanwhile favor subsequent well
organized maritime low redevelopment into late week. Guidance
forecast clustering remains better than normal, bolstering
forecast confidence.
The WPC Alaskan medium range product suite was derived from
reasonably well clustered guidance from the 12 UTC
GFS/ECMWF/UKMET/Canadian models Thursday into Saturday along with
the 19 UTC National Blend of Models. Increasingly adjusted blend
focus from the models to the compatible GEFS/ECMWF ensemble means
onward into early next week amid growing forecast spread. This
maintains good WPC product continuity.
...Weather/Hazards Highlights...
The deep Bering Sea low will spread heavy wrapping precipitation
and a threat of high winds/waves across the Bering Sea and
gradually fill Thursday-Friday while bringing an enhanced snow
risk into West/Southwest Alaska with approach. Amplified upper
ridging building over the Interior/North Slope in advance of the
deep low will diminish, slated to reform back over the Bering Sea
by next weekend. Forecast spread increases in Arctic stream flow
rounding that retrograded ridge, but WPC guidance again allows a
good venue for trough energies/height falls to dig/spread
southward over a cooling/unsettling and locally snowy North
Slope/Interior in a pattern favoring amplifying flow but limited
moisture.
Underneath, downstream transition across the AKPen/Kodiac Island
will result in a pattern favorable for deepened Gulf of Alaska low
development late week into next weekend. Guidance trends show a
track offshore a cooled Southeast Panhandle and will present a
maritime threat into next weekend.
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
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