Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
617 PM EDT Thu May 06 2021
Valid 12Z Mon May 10 2021 - 12Z Fri May 14 2021
...Guidance/Predictability Assessment...
Models and ensembles show a reasonably similar larger scale
pattern evolution through medium range time scales, but as is
often the case offer increasingly evident over time run to run
differences with small-mid scale embedded weather systems. The 12
UTC GFS/ECMWF/UKMET/Canadian model solutions seem well clustered
day 4/Monday and a composite seems to produce a good forecast
starting point. Gradually increasing forecast spread and
decreasing predictability with these embedded systems seem best
mitigated by a steady forecast shift toward a composite of still
reasonably well clustered guidance of the 12 UTC GEFS/NAEFS/ECMWF
ensemble means and the 19 UTC National Blend of Models days 5-8
(Tuesday-next Friday). This forecast strategy maintains decent WPC
product continuity.
...Weather/Threats Highlights...
Lead upper trough energies and moderate precipitation focusing
surface lows/frontal weather systems will work from the Aleutians
and the Alaskan Peninsula into the Gulf of Alaska and toward
southern/southeastern Alaska early-mid next week, undercutting a
warming/stabilizing mainland upper ridge. Then upstream,
amplified/closed upper trough energy is slated to track over the
southern Bering Sea/Aleutians mid-later next week and deepening
low pressure could support unsettled maritime conditions and some
inland wrapping organized rains/winds across the region, then
downstream into the Alaskan Peninsula/Southwest Alaska by late in
this forecast period.
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 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