Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
628 PM EDT Thu Jul 06 2023
Valid 12Z Mon Jul 10 2023 - 12Z Fri Jul 14 2023
...Overview and Weather/Hazards highlights...
A compact upper trough/low and associated lead frontal system with
showers will continue to lift slowly from the eastern Bering Sea
and western Alaskan mainland this weekend to the southern Arctic
Ocean and across the North Slope/Northern Interior with very
gradual system demise through early-mid next week around the
periphery of an upper ridge lingering over eastern and Southeast
Alaska.
Additional upstream upper trough energies and impulses to the west
of the state remain less well depicted or as well organized in
guidance, but should be monitored for any growing guidance signals
next week. However, a mid-late late next week system that now has
a growing system works into the western Bering as a maritime
interest.
Meanwhile, additional systems are set to split across the
Aleutians and southern Bering Sea into Southwest Alaska and the
Alaskan Peninsula along with associated surface system and energy
to support modest to locally moderate rainfall chances by early
next week. The guidance signal for this organized system has
increased. This main system will subsequently, along with
rainfall/unsettled weather chances, break underneath the Alaskan
southern tier and then increasingly with time next week lead to
the carving out an amplified upper trough/system well offshore
over the Gulf of Alaska as mainly a maritime interest.
...Guidance Evaluation/Preferences and Predictability Assessment...
A composite of best clustered 12 UTC GFS/ECMWF and GEFS/ECMWF
ensemble mean guidance decently preserves WPC product continuity
for next week in a pattern with seemingly near average
predictability, albeit with increasing forecast spread over time.
More progressive Arctic flow of the 12 UTC UKMET/Canadian seems
less likely given flow history and upstream upper ridge amplitude.
Schichtel
Hazards:
- Heavy rain for western mainland Alaska, Sun, Jul 9.
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