Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
515 PM EST Sat Jan 22 2022
Valid 12Z Wed Jan 26 2022 - 12Z Sun Jan 30 2022
...Overview...
A cold upper trough will move in from the Bering and replace the
upper ridge that will be over the state through Monday, and
results in much colder weather spreading from west to east through
the middle to end of the week. Meanwhile, a storm system over the
Gulf will lift northeastward towards the southeast Panhandle
region and result in unsettled weather near the coast for the end
of the week, and a couple of big storm systems crossing the
western Aleutians will also tend to keep rain/snow across the
islands through the middle to end of the week.
...Guidance/Uncertainty Assessment...
The 12Z model guidance suite is in good synoptic scale agreement
across most of the domain for the middle of the week, with the
greatest model spread evident over the Gulf region where the 12Z
CMC is displaced with a surface low that is not supported by the
other guidance. By Thursday, the GFS is displaced to the west of
the model consensus and to a lesser degree the GEFS mean with the
longitudinal axis of the upper level ridge building over the
Bering, and this affects the low placement over the Gulf as the
omega block pattern tries to develop. By next weekend, the GFS
appears to be in better alignment with the ensemble means with the
ridge, although still northwest of the consensus with the Gulf
low. Therefore a multi-model blend (greater weighting to the
UKMET and ECMWF) through Thursday night seems to be a prudent
starting point in the forecast process. By the end of the
forecast period next weekend, more of the GFS is used in place of
the UKMET whilst increasing use of the ensemble means.
...Weather/Hazard Highlights...
The pattern change that is forecast to take place across much of
the state will tend to result in less snow showers across the
mainland as arctic high pressure builds into the region. The
exceptions will be across the southern coastal region and the
southeast panhandle where moist onshore flow ahead of the Gulf low
will likely produce widespread precipitation starting on
Wednesday, with very heavy snow for the coastal mountain ranges
and strong winds near the coast. Periods of rain/snow are also
likely through the middle to end of the week for the central and
western Aleutians. The passage of the strong cold front early in
the week will cause temperatures to be near to below normal levels
through mid-week across most of the state as the ridge moves away
from the state and the arctic trough builds back in.
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