Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
520 PM EST Wed Jan 12 2022
Valid 12Z Sun Jan 16 2022 - 12Z Thu Jan 20 2022
...Guidance/Uncertainty Assessment...
The overall synoptic scale pattern across the Alaska domain is
generally handled well by the 12Z guidance. A couple of weaker
shortwave troughs will pass through the northern Gulf region
during the Sunday-Monday time period, with one affecting the
southern mainland while another low lifts northward into the
Panhandle region. Both of these systems gradually become absorbed
by the mid-upper level flow and weaken. Meanwhile, guidance
continues to show a rather large, closed low settling across the
western Aleutians and then settling southeastward across the North
Pacific through the early to middle part of next week. There is
still significant model spread within this feature, with several
embedded pieces of vorticity rotating through the flow that are
difficult to time and pinpoint during this time range. There are
signals of low pressure developing on the southern periphery of
this system which then lifts northeast toward the mainland. Most
of the deterministic models have this signal but with wide range
in timing and track.
Taking these factors into account, the WPC fronts/pressures
forecast was primarily derived from a UKMET/CMC/ECMWF blend
through Monday, and then more of the ensemble means while still
maintaining some of the ECMWF/CMC/GFS through Day 8.
...Weather/Hazard Highlights...
A series of low pressure systems will impact the Alaska panhandle
going into the 16th/17th, and these disturbances could bring
widespread moderate to locally heavy precipitation (mountain snow,
valley rain) as well as high winds and waves along the coast. The
rest of the mainland is expected to be relatively dry (a weakening
system will pass through the southern mainland days 3-4) as a
closed low settles over the Aleutians. By the end of forecast
period, waves of low pressure will become possible underneath the
closed low and this could bring widespread precipitation to the
eastern Aleutians and the southern mainland later next week.
Hamrick/Taylor
Hazards:
- Heavy precipitation across portions of the Alaska Panhandle,
Sat, Jan 15.
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