Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
634 PM EDT Fri Apr 07 2023
Valid 12Z Tue Apr 11 2023 - 12Z Sat Apr 15 2023
...Cold pattern for much of Alaska next week and beyond...
...Overview with Guidance Evaluation/Predictability Assessment and
Weather/Hazard Highlights...
A cold closed upper low will meander over mainland Alaska through
at least next midweek underneath a rather blocky upper-level
pattern across the Arctic. System influence should weaken later
next week. Expect a threat for much colder than normal conditions
for western and southwest/central Alaska through midweek,
moderating some later next week as the upper low erodes. Scattered
occasional light snows are also expected from the Interior to the
North Slope. The overall cold pattern is expected to hold for much
of Alaska this April as per the Climate Prediction Center (CPC).
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 northern Gulf of Alaska next Wednesday and
linger/deepen/re-develop over the eastern Gulf into late next week
as further aided by northern stream energy. The forward speed of
the front and the triple-point low will likely limit the threat of
heavy precipitation across the Aleutians/Alaskan Peninsula/Kodiak
Island, but periods of high winds/gap winds are possible in the
wake of the low. A period of light snow can be expected across
southwestern Alaska Tuesday into Wednesday as the triple-point low
and fronts pass through. Unsettled weather should linger into late
week along the southern coastline of Alaska, but especially the
Southeast Panhandle as the low is forecast to meander over the
eastern Gulf of Alaska. Precipitation amounts do not appear to be
excessive, but should be widespread and enhanced as usual over
favored terrain.
The WPC Alaskan medium range product suite was primarily derived
from a composite blend of well clustered guidance of the 12 UTC
GFS/ECMWF/UKMET/Canadian Tuesday into Wednesday to preserve as
much smaller scale detail as feasible. This solution has very good
ensemble support. Prefer a model and ensemble mean blended
solution mid-later next week with an eye toward manual
modifications applied to allow the lingering of more cold air
through midweek given historical closed feature and blocky pattern
nature/guidance bias. Overall though, WPC Alaskan medium range
product continuity is well maintained.
Schichtel
Hazards:
- Much below normal temperatures across portions of mainland
Alaska, Mon-Wed, Apr 10-Apr 12.
- High winds possible across the eastern Aleutians, Fri, Apr 14.
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