Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
252 PM EDT Mon Jun 10 2019
Valid 12Z Fri Jun 14 2019 - 12Z Tue Jun 18 2019
...Guidance/Predictability Assessment...
The WPC Alaskan medium range product suite was mainly derived from
a blend of the 12 UTC GFS/GEFS mean, 00 UTC ECMWF/ECMWF ensemble
mean, and the National Blend of Models. Applied greater blend
weightings to the deterministic models day 4/5 to provide detail
consistent with above normal predictability. Forecast spread
remains manageable, but gradually increases through later period.
This supports increasing ensemble weightings day 6-8 in a pattern
with closer to average uncertainty. This solution maintains
reasonable WPC forecast continuity.
...Pattern Overview and Weather/Threats Highlights...
Models/ensembles have been in general agreement in principle with
a slow pattern evolution for the past several cycles. Two slowly
moving upper lows to the north and south of the mainland favor
weak ridging with generally warm and benign weather over the
interior through this forecast period.
In this patern a closed mean trough will meander over the Arctic
and force settlement of a trailing/cooling front down over the
North Slope. Well underneath...a closed mean system stalls and
reforms just south of the Alaskan Peninsula and eastern Aleutians
days 4-8 with precipitation/windy/unsettled conditions spreading
across the region and modestly downstream into Southwest and
Southern coastal Alaska. This system will also offer a prolonged
maritime hazard.
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