Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
531 PM EST Mon Nov 30 2020
Valid 12Z Fri Dec 04 2020 - 12Z Tue Dec 08 2020
...Stormy Gulf of Alaska offers a heavy precipitation and high
wind threat for southern and southeast Alaska....
...Guidance and Uncertainty Assessment...
Model forecast spread and run to run continuity remains less then
stellar, so system details remain more suspect than usual.
GEFS/ECMWF ensemble means lack details, albeit being more
consistent with uncertainties. Accordingly, the WPC Alaskan medium
range product suite was primarily derived from the mainly
compatible 12 UTC GEFS/ECMWF ensemble means and the 19 UTC
National Blend of Models, with only limited additional input from
the 12 UTC GFS/ECMWF. This solution was collaborated with local
Alaskan offices.
...Weather/Hazards Highlights...
An overall more benign weather pattern settles into much of the
North Slope and the Interior heading into the weekend. Underneath,
a lead Pacific system lifting up through the eastern Gulf of
Alaska Friday into the weekend offers less than ideal model
forecast spread, but does show potential to focus heavy
precipitation and high winds from a stormy Gulf into
southern/southeast Alaska. A subsequent deeper low with more
amplified upper trough/low support has an emerging guidance threat
signal for additional maritime disruption and heavy
precipitation/high winds across the Gulf and onshore back into
southern and southeast Alaska later weekend into early next week.
Schichtel
Hazards:
- Heavy precipitation across portions of the Alaska Panhandle and
mainland Alaska, Sun-Mon, Dec 6-Dec 7.
- High winds across portions of the Alaska Panhandle and mainland
Alaska, Sun-Mon, Dec 6-Dec 7.
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