Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
359 PM EDT Thu Jul 25 2019
Valid 12Z Mon Jul 29 2019 - 12Z Fri Aug 02 2019
A relatively progressive flow pattern is expected across Alaska
during the extended forecast period. Several shortwaves are
forecast to progress from the Bering Sea into the Gulf of Alaska
during the period. Meanwhile, model consensus has improved that a
deep upper low should move from eastern Russia and the Arctic
Ocean into northwest mainland Alaska by the middle of next week,
pushing a cold front into western/northwestern Alaska before it
weakens. In general, deterministic solutions showed broad
consensus during the day 4-5 (Mon-Tue) time period, with
relatively minor detail differences. Thus, a blend of the
ECMWF/GFS/CMC was used as a starting point for the forecast during
that time frame. After that, differences gradually increase among
the deterministic guidance, both with respect to the evolution of
the upper low as well as perhaps more amplified energy crossing
the Bering Sea by late next week. Ensembles showed somewhat better
consensus than deterministic solutions, and thus the forecast was
trended to much heavier ECENS/GEFS ensemble mean weighting
starting on day 6 (Wed) and continuing through day 8 (Fri). In
general, this pattern will support scattered showers across much
of the state Mon-Wed as shortwave energy passes over the state.
Precipitation may begin to increase in coverage by later next week
as the more amplified trough takes shape across the Bering Sea and
a weakening low pressure system moves into southern mainland
Alaska.
Ryan
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
No significant hazards are expected over Alaska during this
forecast period.
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