Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
546 PM EST Sun Feb 12 2023
Valid 12Z Thu Feb 16 2023 - 12Z Mon Feb 20 2023
...Overview...
***
A closed low/trough will be present over the Bering/North Pacific
and send shortwave energy toward the Southwest Mainland/eastern
Aleutians. Another upper-level trough developing in the northwest
Pacific will track eastward while deepening into a closed low
through the middle and latter periods. With a potentially strong
low pressure at the surface parts of Alaska with could have high
winds and light to moderate precipitation. This appears most
likely spread across the Aleutians and the southern coast.
...Model Guidance/Predictability Assessment...
The latest runs of the guidance are showing an improvement in the
handling the evolution of the large scale pattern, especially for
the latter periods. The last few days the guidance has the new
closed low/upper trough fizzling out by/after Day 6 as is nears
the western Aleutians; however the new runs keep this feature
together albeit in split camps. The ECWMF/CMC favors a western
position while GFS is much further east; furthermore, the EC
ensemble and GEFS have a closer position to that of the ECWMF/CMC.
By Day 8 another low there is a diffuse pattern featuring a low
south of the far western Aleutian islands with another low well
south of the central Aleutians and high pressure over the eastern
Pacific/southeast Gulf of Alaska. All in all, this is average
confidence pattern.
The WPC leaned toward a combination of the 12Z ECMWF/CMC and the
GEFS/EC Ensemble means with varying degree of weighting of the GFS
due to its more pronounced timing differences.
...Weather/Hazard Highlights...
Most of the active weather will focus from the Aleutians to the
Southeast through the course of the extended period; however light
to moderate precipitation will expand across portions of Southwest
and Central Alaska by the end of the week and into the weekend.
Addition rounds of precipitation across the south-central and
southeast portion of the state as an upper troughing and surface
low pressure tracking eastward likely through the northern
Pacific. The specifics with this system still remain a bit
uncertain however the model guidance has trended to better
consensus on the evolution by Day 7 and 8. Winds are likely to
affect the Aleutians as a frontal system stemming from a Bering
Sea low comes in, which could spread farther east by the latter
half of the week. Temperatures are expected to trend closer to
seasonal average by the end of the week and hold fairly steady.
Campbell
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