Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
605 PM EST Wed Dec 06 2023

Valid 12Z Sun Dec 10 2023 - 12Z Thu Dec 14 2023

...Heavy Precipitation and High Wind Threat from
SouthCentral/Alaska Range to Southeast Alaska...

...Guidance Evaluation/Preferences...

Medium range models and ensembles now overall offer below normal
forecast spread in this stormy pattern with seemingly better than
average predictability and continuity, but vary with smaller scale
system interactions. A preferred composite of best clustered
guidance from the 12 UTC GFS/ECMWF/Canadian models and the
GEFS/ECMWF ensemble means seems to mitigate these variances to
offer a good forecast basis for at least the mid-larger scale
pattern evolution and weather hazards.

...Weather/Hazards Highlights...

An amplified upper trough forged over the southern mainland into
this weekend will offer a period of cold temperatures. The
unsettling upper trough position should linger next week over the
mainland as reinforced by less certain shortwave energies.
Meanwhile, a main storm genesis pattern will emerge just to the
south of the state by early through mid next week with the
development and poleward track across the Gulf of Alaska to the
mainland of a series of complex and deepened low pressure/frontal
systems as stream flows uncertainly interact. The systems will
offer a maritime to coastal high wind/wave threat. Deep layered
moisture will also feed inland by enhanced wind flow around these
storms, with main focus over SouthCentral/Alaska Range through
Southeast Alaska. Expect a multi-day period with periodic surges
of heavy precipitation in the form of coastal rains with potential
runoff issues to heavy inland terrain/mountain snows.
Additionally, gusty terrain enhanced winds expected for this
region that may lead into downslope Chinook winds to the lee of
the Alaska Range down into the southern Interior next week. 

Schichtel


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