Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
657 PM EDT Tue Jul 11 2023
Valid 12Z Sat Jul 15 2023 - 12Z Wed Jul 19 2023
...Guidance Evaluation/Preferences and Predictability Assessment...
The 12 UTC GFS/ECMWF/UKMET solutions overall seem best clustered
and most in line with ensembles Saturday into Monday, bolstering
forecast confidence to a degree in a composite to smooth the less
predictable smaller scale detail. The 12 UTC Canadian offers an
outlier solution that digs more ample Bering Sea/Western Alaskan
upper trough energies down to the Alaskan Peninsula and Gulf of
Alaska. While less likely, this scenario is plausible given
potential interaction with a highly anomalous upstream Pacific
upper ridge poking northward into the Aleutians. Later into next
week, prefer a composite of still compatible 12 UTC
GEFS/NAEFS/ECMWF ensemble means amid growing forecast spread and
uncertainty, albeit with some manually applied adjustments to
maintain better day to day system strength continuity given
support.
...Weather/Hazards Highlights...
Moist inflow ahead of deep and persistent Bering Sea mean
troughing will lead to bouts of light to moderately heavy rains
across particularly the western Mainland and into the Alaska
Peninsula into this weekend, and with less organization spreading
into much of the Mainland and southern tier areas into next week.
Southwest Alaska seems to have the best chance for locally heavier
rains and unsettled weather conditions in proximity to a main
surface low and frontal system associated with upper trough
lobe/height fall approach this weekend. Otherwise, rainfall
amounts do not look to be too heavy overall, but more showery and
diurnally driven, with enhanced amounts possibly over the Alaska
and Brooks Ranges.
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