Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
402 PM EDT Tue Jul 09 2019
Valid 12Z Sat Jul 13 2019 - 12Z Wed Jul 17 2019
Models/ensembles show general agreement that upper ridging should
weaken somewhat, but remain in place across central/northern
mainland Alaska through the extended forecast period. Arctic
shortwave energy should generally remain north of the upper ridge,
potentially skirting by the middle of next week. Meanwhile, a
broad and persistent upper-level low initially across the western
Bering Sea on Sat should gradually shift eastward, reaching the
Gulf of Alaska by next Tue-Wed. A couple shortwaves rotating
around the upper low should move a couple surface low pressure
systems across/near the Alaska Peninsula and into the Gulf, the
first passing south of the Peninsula on Sat and the next crossing
the Peninsula and moving into the Gulf Tue-Wed. Model consensus
was a bit better than average with respect to forecast details
given relatively good large scale agreement. Thus,a blend of the
ECMWF and GFS served as a forecast starting point during days 4-5
(Sat-Sun), with gradually increasing weight placed on ECENS/GEFS
ensemble means during days 6-8 (Mon-Wed). In general, the ECMWF
was weighted more heavily than the GFS throughout due to
differences in the Arctic, with the GFS digging a deep upper low
much farther south than consensus, into the Chukchi Sea by the
early to middle portion of next week. In general, this pattern
should favor continued above average temperatures across much of
Alaska, albeit not to the extreme degree seen recently.
Additionally, scattered showers and thunderstorms will be possible
through much of the forecast period, especially across the Alaska
Peninsula and southern/central 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