Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
758 PM EDT Fri Apr 01 2022
Valid 12Z Tue Apr 05 2022 - 12Z Sat Apr 09 2022
...Overview...
A general pattern of upper troughing is forecast to persist
through much of next week across western Alaska and the Bering
Sea, with periodic reorienting and reloading. By late week,
current forecasts show the southern part of the trough/energy
separating and moving eastward through the Gulf of Alaska. At the
surface, lows could pivot across the southern mainland while
additional lows track south of the state. Likely the strongest low
should track northeastward toward the Panhandle
Wednesday-Thursday. This will promote a wet pattern for southern
Alaska, particularly over the Panhandle, though amounts do not
look to be terribly heavy.
...Guidance/Predictability Assessment...
The latest model guidance continues to show fairly good clustering
with the overall pattern of elongated upper troughing with its
axis initially across the western mainland Tuesday and drifting
slowly westward through around Thursday. Low pressure/frontal
systems are forecast to pass through the Aleutians and linger over
the mainland near the base of the trough. Recent models are more
agreeable regarding a wave of low pressure potentially forming
along the cold front crossing the Aleutians around Wednesday and
tracking across the Gulf Thursday-Saturday, with the ECMWF and
UKMET joining the GFS runs that have been persistent in showing
the low forming by midweek. Additionally, there has been a
multi-day signal for a reasonably strong low to track toward the
Panhandle on Wednesday-Thursday, with only minor differences among
guidance. Thus deterministic guidance seems agreeable enough for a
blend of the operational models (led by the ECMWF/GFS) early in
the medium range period.
By late week, some model spread arises as energy from the southern
part of the trough could detach and track eastward while the
northern side persists over northwestern Alaska. The GFS and ECMWF
runs happen to be fairly similar, but the CMC appears to be a slow
outlier as the southern upper low may separate earlier/more
significantly. This affects the surface low positions as well. At
this point, favored the GFS and ECMWF operational runs along with
the ECWMF and GEFS ensemble means for the late week forecast
blend, since they were reasonably well clustered for a days 7-8
forecast.
...Weather/Hazard Highlights...
Precipitation is possible over southern parts of Alaska from the
Aleutians and Alaska Peninsula east into Southcentral Alaska and
the Panhandle through much of next week near low pressure systems.
Some rain/snow amounts could be enhanced at times especially for
the Southcentral/Panhandle regions, but the heaviest totals
through the period will be dependent on exact low tracks and
timing. One period of precipitation enhancement could be around
midweek as moist inflow increases ahead of a low headed for the
Panhandle. In fact, the forecast continues to indicate southern
portions of the Panhandle may receive the most precipitation
overall, but as it falls over a several day period, it should not
be too hazardous. Interior Alaska should see generally dry
conditions as the storm track stays to the south, though scattered
snow showers cannot be ruled out. Periods of gusty winds are also
possible over the Gulf and Panhandle with the midweek low pressure
system, and breezy northwest winds may impact the Aleutians late
in the week.
Near to below average high temperatures forecast for Tuesday
across much of the state may ease a bit as the week progresses.
The Brooks Range and the North Slope in particular could flip to
above normal later in the week for highs. Meanwhile, low
temperatures will generally be above normal across the mainland,
with the exception of the eastern Interior earlier in the week.
The Panhandle can expect to see below normal highs and around
average lows through the period owing to mostly cloudy skies and
wet conditions.
Tate
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