Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
204 PM EDT Wed Aug 07 2019
Valid 12Z Sun Aug 11 2019 - 12Z Thu Aug 15 2019
...Guidance/Predictability Assessment...
Models and ensembles show an amplified/blocky flow pattern
characterized at medium range time scales by closed upper lows
cenetred over the Bering Sea and just to the northeast of Alaska,
with stretched ridging from the Bering Strait to western Alaska
and the Alaskan Peninsula/western Gulf of Alaska. Models and
ensembles were in decent agreement overall, but with some
continuity issues. The models continue also vary with the handling
of smaller scale embedded systems. These realities seem to limit
forecast confidence to only slightly above normal levels despite
much better than average larger scale agreement days 4-8.
Accordingly, The WPC Alaskan medium range product suite was
primarily derived from a composite blend of the latest GFS/ECMWF
and GEFS/ECMWF ensemble means day 4/Sunday before shifting
weighting substantailly in favor of the more compatable ensemble
means days 5-8.
...Weather/Hazard Highlights...
This pattern is still expected to favor widespread rain over the
Aleutians ahead of the slow-moving front in the Bering Sea over
the course of several days. Scattered rain/convection is likely
over portions of the interior ahead of the baroclinic zone that
will set up on the height gradient south of the Brooks Range.
Temperatures will be below average over much of
northern/northeaster areas on NW flow aloft, but above average
over southwestern Alaska under upper ridging.
Schichtel
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