Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
753 PM EDT Thu Apr 06 2023
Valid 12Z Mon Apr 10 2023 - 12Z Fri Apr 14 2023
...Overview with Guidance Evaluation/Predictability Assessment and
Weather/Hazard Highlights...
A cold upper low will meander over the western portion of mainland
Alaska to begin the medium-range period under a rather blocky
upper-level pattern across the Arctic. The GFS/GEFS today have
come into agreement with the EC/EC mean on lifting this low slowly
across northern Alaska by midweek next week before merging with
another meandering Arctic low across the Canadian archipelago late
next week. Dry but much colder than normal conditions can be
expected for western and southwestern Alaska through next Tuesday,
moderating by Wednesday as the upper low erodes. Occasional light
snow is expected from the eastern mainland to the North Slope.
Meanwhile, the precipitation across southern coastal and
mountainous sections of Alaska into the Panhandle Monday morning
will begin to taper off through the rest of Monday. Both the GFS
and ECMWF since yesterday have trended faster with the occluded
cyclone tracking up into the Gulf of Alaska in better agreement
the CMC solutions. The tighter pressure gradient associated with
the faster-moving low has increased the chance of stronger gap
winds off to the east of the Alaska Peninsula early on Monday.
Models and ensembles continue to show relatively good agreement on
the timing and evolution of the next cyclone of concern coming
into the western Bering Sea by next Tuesday into Wednesday as the
lead frontal system is forecast to pass through the Aleutians at a
relatively quick and steady pace. A triple-point low is forecast
to form over the Gulf of Alaska next Wednesday and linger in the
vicinity into late next week. The forward speed of the front and
the triple-point low will likely limit the threat of heavy
precipitation across the Aleutians, with brief periods of high
winds possible. A period of light snow can be expected across
southwestern Alaska on Wednesday as the triple-point low and
fronts pass through. Unsettled weather should linger into late
week along the southern coastline of Alaska as the low is forecast
to meander over the Gulf of Alaska. Precipitation amounts do not
appear to be excessive.
The WPC Alaskan forecast package was based on a blend of 40% from
the 12Z EC and EC mean, 40% from the 12Z GFS and GEFS, and 20% CMC
and CMC mean for Days 4-6, followed by a slightly increased
weights given to the ensemble means from Day 7 through Day
8.
Kong
Hazards:
- Much below normal temperatures across portions of mainland
Alaska, Sun-Tue, Apr 9-Apr 11.
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