Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
650 PM EDT Sat Mar 20 2021
Valid 12Z Wed Mar 24 2021 - 12Z Sun Mar 28 2021
...Stormy pattern for Alaska next week...
...Guidance/Uncertainty Assessment...
The latest model guidance shows relatively good agreement in the
upper level pattern, featuring a faster zonal flow at the start of
the period transitioning to a more unsettled/active setup with a
couple digging shortwave troughs by day 7-8 over the mainland and
Aleutians. This will lead to a couple of lows tracking through the
Gulf of Alaska and toward the Southeast region. The blended
forecast was primarily derived from the 12Z
ECMWF/GFS/GFSP/CMC/UKMET for day 4-5 followed by a blend of the
ECMWF/ECENS/GFS/GFSP/GEFS for days 6-8. Composites tend to
mitigate the less predictable smaller scale differences. WPC
continuity is well maintained with this forecast methodology in a
pattern with above normal predictability overall.
...Weather/Hazards Highlights...
A pair of storms are expected to bring unsettled to active weather
later in the forecast period. The first system at the start of the
period will bring precipitation mainly to the western mainland
before weakening/dissipating. This will be followed a stronger low
impacting the southern mainland by late in the upcoming work week
or early next weekend. A final system at the end of the period is
likely to track across the Bering Sea into the western mainland,
though this could be just beyond the current forecast period,
depending on timing. Temperatures are expected to at or above
normal for nighttime lows for much of the upcoming period while
highs generally range below normal for the southern mainland and
southeastern areas with some above normal departures for the
northern mainland.
Taylor
Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards 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