Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
614 PM EDT Tue May 31 2022
Valid 12Z Sat Jun 04 2022 - 12Z Wed Jun 08 2022
...Overview and Weather and Hazard Highlights..
The extended period begins with a weak ridge over portions of the
mainland that will decrease in strength with time and troughs to
the northwest and northeast of the North Slope/northern tier of
the state. This mean ridge separates Arctic upper troughs/lows to
the north of Alaska that periodically force several fronts through
the North Slope and northern Interior from several closed upper
level/surface lows in the North Pacific. In this flow, a
lead/lingering closed low and effects will slowly weaken well
offshore over the southern/southeastern Gulf of Alaska this
period. This will allow for slightly cooler temperatures initially
before trending warmer. The same applies for increasing chances
for showers early on before trending drier. There is however still
some periodic chance for light to locally moderate precipitation
over southern/southeast Alaska mainly later period with an
uncertain series of easterly waves riding underneath the mean
ridge. Meanwhile, a closed upper trough/low with main/triple point
surface lows will slowly transition from just to the south of the
unsettled Aleutians to well offshore over the western/southwestern
Gulf of Alaska as a moderate maritime threat.
...Guidance/Predictability Assessment...
The current suite of guidance begins with above average confidence
on the clustering of various features across the region but the
degree of small, mid-level differences steadily increase as early
as Sunday morning (June 5th). The impulses that are progged to
trek across the higher latitudes and into the North Slope/Interior
are captured in both the global and ensemble mean solutions
however this is where the differences are the most impactful.
Similar to the previous forecast cycle, the starting point of the
medium range product suite utilized a general blend of the 12Z
ECWMF/GFS/CMC/UKMET for day 4, reduced inclusion of the CMC and
added 12Z GEFS/NAEFS/ECMWF ensemble means for day 5 before
transitioning to equal weighting of the 12Z GEFS/NAEFS/ECMWF
ensemble means for the rest of the periods. Although the later
half of the forecast comprised of 100% ensemble means, the overall
pattern has average to better predictability.
Campbell/Schichtel
Hazards:
No significant hazards are expected over Alaska during this
forecast period.
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