Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
259 PM EDT Sun May 26 2019
Valid 12Z Thu May 30 2019 - 12Z Mon Jun 03 2019
Deterministic and ensemble model guidance continues to have a good
handle on the overall synoptic evolution over Alaska through the
medium range period. The upper level pattern favors ridging over
mainland Alaska during much of the period which allows for a
meandering main cyclone near the eastern Aleutians late next week
and into the weekend. This cyclone appears to weaken and dissipate
day 7-8 as another shortwave lifts a second system northward
towards the Gulf. This pattern supports unsettled weather from the
Aleutians to the Panhandle especially during the first half of the
period, with rounds of locally heavy precipitation possible along
the coast and favored terrain across the southern Mainland. Across
central to northern Alaska, mainly showery activity and near to
above normal temperatures are expected. Days 4-6 showed very good
deterministic model agreement so a majority 00z ECMWF/12z GFS
blend sufficed, with small amounts of their respective ensemble
means. After this, increased the weighting of the means to
mitigate the less predictable differences in the details, but the
agreement was still good enough to include modest amounts of
deterministic guidance. This approach maintains reasonable
continuity with yesterday's WPC Alaska forecast as well as
downstream over the East Pacific/CONUS.
Santorelli
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