Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
725 PM EDT Thu Jul 28 2022
Valid 12Z Mon Aug 01 2022 - 12Z Fri Aug 05 2022
...General Overview...
During the medium range period, a strong upper high will
retrograde through the mid-latitudes between Alaska and Hawai'i,
allowing for progressive flow to its north across the higher
latitudes out of the Bering Sea and through much of mainland
Alaska. Within the flow, two distinct features will affect the
49th state: the first Mon-Wed and the second Wed-Fri next week.
Each will carry with it the chance for light to modest rain over
southern areas of the mainland. Northern areas will remain largely
quiet and cooler than normal.
...Guidance/Predictability Assessment...
The models/ensembles have mostly sped up with the timing of the
lead system out of the Bering and then moving quickly across
Southcentral Tuesday and into (and out of) the Panhandle by
Wednesday, with a lingering upper/sfc low in the northeastern
Gulf. The 12Z ECMWF was quicker than the rest of the 12Z guidance,
but given the shift quicker already by a general consensus opted
to rely on the multi-model blend that was about 2/3rds closer to
the GFS-led cluster vs the quicker ECMWF. Progressive pattern
would allow for a quicker pattern but that can be reassessed
tomorrow. The second system has trended more robust and have
depicted it as a developed wave along the front attached to the
lead system, moving through the Bering later next week into
Southwestern Alaska by the end of the week. With additional timing
differences increasing by then, included more ensemble mean
weighting from the ECMWF ensembles and GEFS mean. The 12Z Canadian
actually had a good middle ground solution between the quicker
ECMWF and slower GFS, so weighted that model a bit more to day 8.
Confidence was about average given the good agreement but the
quicker pattern leaves room to progress the systems faster than
progged, should trends continue.
...Sensible Weather...
Temperatures will generally be near to below normal for much of
the state with abundant clouds associated with each system.
Clearing in between would allow for a bit milder temperatures into
the 70s in the Tanana Valley. Some areas of the North Slope may
see above normal temperatures with offshore flow. Rainfall will
progress from west to east across areas south of the Arctic Circle
with generally light amounts, but areas of the Alaska Range could
see more appreciable amounts on SW to S flow. The Panhandle may
have a couple days of showery conditions as the upper low (and
weak surface low) will be slow to push through the region late
Tuesday into Wednesday and Thursday. A frontal boundary in the
Beaufort Sea/Arctic Ocean may bring some showers to the North
Slope later next week after high pressure retreats into the
Canadian archipelago.
Fracasso
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