Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
623 PM EST Sun Feb 4 2024
Valid 12Z Thu Feb 8 2024 - 12Z Mon Feb 12 2024
...General Overview...
An active winter pattern will continue across the Alaska domain
going into the extended forecast period with multiple North
Pacific storm systems tracking northeast towards the Gulf region,
bringing rounds of coastal rain and inland heavy snow for the
southern mountain ranges. These low pressure systems will be
pivoting around a broader upper level low centered roughly over
the southern Bering Sea region for the end of the week and through
the weekend. Meanwhile, a downstream upper level ridge axis is
progged to extend from western Canada to the central and eastern
mainland of Alaska, keeping relatively mild conditions in place,
especially compared to the recent brutally cold weather.
...Guidance Evaluation/Preferences...
The 12Z model guidance suite has a good overall depiction of the
synoptic scale pattern across the state to close out the work
week. There are some minor timing and placement differences with
the incoming low pressure system approaching the western Gulf by
Friday, with the ECMWF generally southeast of the model consensus
and stronger as it approaches the coast, whereas the CMC/GFS and
the ensemble means favor a more western and weaker track overall.
The UKMET has some support from the ECMWF in terms of placement,
but generally weaker. Looking ahead to the weekend, model spread
grows substantially across the North Pacific and the Gulf with the
timing of subsequent low pressure systems, but the feature with
the greatest model agreement is the general upper ridge axis
across the eastern half of the state. A general model blend
sufficed as a starting point in the forecast process for Thursday
and Friday, followed by more of the ensemble means through the
weekend and then accounting for a majority of the blend by next
Monday.
...Weather/Hazards Highlights...
Precipitation prospects increase going into Friday and Saturday
with the strong low pressure entering the Gulf region and
southeasterly winds advecting moisture towards the coastal terrain
of the Alaska Peninsula and extending eastward to the Prince
William Sound region. Several feet of mountain snow is likely for
these areas, and a cold and heavy rain for the coast. Overall,
there has been an upward trend in model QPF during this time
period. Farther north across the mainland, a mostly dry weather
pattern can be expected. In terms of temperatures, generally
above average conditions are forecast for most inland areas, and
closer to average for the coastal regions. Sheltered valleys with
persistent inversions that are slower to mix out will be
substantially colder than surrounding hillsides.
Hamrick
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