Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
647 PM EST Mon Nov 7 2022
Valid 12Z Fri Nov 11 2022 - 12Z Tue Nov 15 2022
...Synoptic Scale Overview...
A powerful low pressure system is forecast to approach the central
Aleutians for the end of the week and then weaken as it enters the
Bering Sea. There should be a broad area of low pressure over the
Bering and Aleutians through next weekend with multiple shortwaves
reinforcing the trough axis here. Upper level ridging and surface
high pressure will continue to govern the overall weather pattern
across the Interior. Areas of heavy precipitation are expected
from the eastern Aleutians to the Kenai Peninsula with moist
onshore flow.
...Guidance/Predictability Assessment and Preferences...
The strong storm for the Aleutians late in the week is handled
well in the 12Z model guidance suite, although the latest 18Z GFS
run along with its ensemble mean begins diverging as early as
Friday afternoon with a more southerly track and then weakening
over the Gulf, whereas the CMC/ECMWF/ECENS support the idea of the
low reaching the southern Bering and then weakening through early
Saturday. Going forward into the weekend, a second synoptic scale
trough sets up residence in the same general area, and here the
18Z GFS is generally a stronger solution with a more impactful
surface low. The upper ridge axis across the Yukon and the
eastern Interior remains the most confident aspect of the extended
range forecast. The WPC fronts/pressures forecast was primarily
derived from a multi-deterministic 12Z model blend, followed by
increasing use of the ensemble means by early next week.
...Sensible Weather and Potential Hazards...,
Temperatures will continue to moderate going into the extended
forecast period with highs returning to the 20s to middle 30s for
most of the mainland, with the exception of some 10s in the more
sheltered valley locations, and 40s for the southern coastal
areas. Mostly cloudy conditions should be prevalent across most
of the state. Rain chances are expected to be highest across the
central/eastern Aleutians and near the higher terrain of the
southern coastal areas, with the potential for several inches of
QPF for the Friday through Sunday time period, with this mainly in
the form of heavy snow for the higher elevations and heavy rain
near the coast as an atmospheric river affects the region. Winds
should be highest across the southwestern mainland into the
Aleutians, depending on the eventual track and strength of the
North Pacific storm system, with widespread gale to storm force
winds expected on Thursday and Friday for the coastal waters.
Hamrick
Hazards:
- Heavy precipitation across portions of mainland Alaska, Sat, Nov
12.
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