Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
621 PM EST Wed Feb 02 2022
Valid 12Z Sun Feb 06 2022 - 12Z Thu Feb 10 2022
...Overview...
An upper-level trough axis will extend through northwestern Alaska
through next week, stretching westward from an upper low over
northern Canada and possibly serving to connect an upper low
initially spinning west of the Aleutians Sunday and drifting east.
Farther south, expect a more progressive pattern of shortwaves and
surface low pressures from the Aleutians and southwestern mainland
to the Panhandle. These features will spread periods of
precipitation into the southern part of the state and possibly
northward into central and northern parts of the mainland by the
middle of next week. Precipitation could be heavy particularly
from the Kenai Peninsula into the Panhandle.
...Guidance/Predictability Assessment...
Model guidance is in fairly good agreement with the trough axis
extending from northeast to southwest through much of the
mainland, while the southeastern part of the state sees general
ridging disrupted by shortwave energy especially early in the
week. However, ample differences in the details remain, including
the possibility for an upper low to close off within the troughing
pattern. Most recent guidance does close off a low but the timing
of its development and the placement differ considerably. The
ECMWF deterministic run and the ensemble mean are showing
solutions farther east with the closed low compared to other
guidance, with the low/trough axis remaining over western Alaska
rather than drifting into the Bering Sea by around Wednesday. At
this point attempted to take a middle ground position with the
trough axis (and with the temperature forecasts that are similarly
affected) since both the eastern EC and the western GFS/CMC
solutions seemed reasonable. In terms of features farther south,
an initial surface low near the Kenai Peninsula Sunday has good
agreement among guidance, while models also agree upon a large
surface low/frontal system tracking south of the Aleutians through
the early part of the week, but then end up diverging with its
track and with possibly another surface low upstream. Thus the WPC
forecast utilized a multi-model blend of deterministic guidance
(12Z ECMWF, CMC, and UKMET and 06Z/12Z GFS) early in the period
when there was better agreement, and gradually incorporated more
GEFS/EC ensemble means to about 60 percentÂby day 8.
...Weather/Hazard Highlights...
The overall pattern with troughing over western Alaska will
promote deep layer southwesterly flow, bringing moisture to
especially southern Alaska through the period, while rounds of
surface low pressure will help to focus the moisture and produce
possibly heavy precipitation. Multiple rounds of rain in the
low/coastal areas and heavy, wet snow in the higher elevations
should span from the Alaska Peninsula into the Southeast and
Panhandle through much of next week. There is also a chance for
gusty winds and rough seas with these systems in the vicinity of
the Aleutians and Alaska Peninsula to Southcentral Alaska and the
Panhandle. Snow may become more likely farther north into much of
the mainland by the middle of next week as a surface low is
currently expected to track into the southwestern mainland.
Temperature readings during the period will be generally near to
below normal across much of the state through the early part of
the week but moderating by Wednesday and Thursday, while warmer
than average temperatures are likely in southeastern Alaska and
the Panhandle underneath overall ridging.
Tate
Hazards:
- Heavy precipitation across portions of the Alaska Panhandle into
southern coastal Alaska, Sat-Wed, Feb 5-Feb 9.
- Heavy precipitation across portions of southern coastal Alaska,
Tue-Wed, Feb 8-Feb 9.
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