Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
700 PM EDT Mon Apr 08 2024

Valid 12Z Fri Apr 12 2024 - 12Z Tue Apr 16 2024

...Major winter storm likely late this week across much of western
Alaska...

...Synoptic Overview...

A major winter storm will be ongoing as the period begins Friday
across western Alaska with an amplified trough moving through the
state bringing gusty winds, maritime impacts, and moderate to
heavy snowfall - especially in the higher elevations. Shortwave
energy rounding the base of this trough may briefly close off
another upper low in the Gulf this weekend, keeping conditions
unsettled for Southeast Alaska. Upper ridging will build over the
state Sunday-Monday before another potentially strong trough moves
towards northwest Alaska with some indications for another strong
storm system to impact the state.


...Guidance Evaluation and Preferences...

The 12z model guidance today continues to show a good overall
depiction of the synoptic scale pattern especially regarding the
high impact storm across Western Alaska late this week. The CMC
was slightly slower with this system than the better consensus so
it was not used in todays blend. There remain some differences in
the details of this system, but increasing confidence for an
impactful weather event. Increasing agreement for shortwave energy
rounding the base of the system allowing for brief surface low
development in the Gulf, which should quickly translate
southeastward, with some timing inconsistencies still as well.
Compared to previous days, the guidance has also trended stronger
with a compact system that slides south of the Aleutians this
weekend with some uncertainty still in eventual phasing of this
with a larger system lifting northward from around Hawaii early
next week. There is some indication from the models for another
round of amplified troughing to edge towards western Alaska, but
some significant timing questions. 12z ECMWF was much slower than
the GFS/CMC with this and so was not used in the late period. The
WPC blend for today used the GFS/ECMWF/UKMET for the first half of
the period, increasing the ensemble means the second half, along
with the GFS.


...Weather/Hazards Highlights...

For Thursday-Friday, a system moving into the western Mainland
will bring likely moderate to heavy snow across much of the West,
along with gusty winds and maritime impacts. Heavy snow is
especially possible in the higher terrain. Farther South general
troughing should keep the Southern Coast/Southeast/Panhandle
generally unsettled through at least the weekend. The West may dry
out this weekend, but an additional cold front from the north may
bring another round of rain/snow to parts of northwest Alaska
early next week, with some locally heavy precipitation in spots.
Temperatures across the southern half of the state should stay
cool much of the period, trending warmer at times, with rounds of
troughing. The highest anomalies are likely across the Southeast.
Northern Alaska should stay warmer than normal the entire period,
but moderating somewhat this weekend as additional shortwave
energy slides through the region.

Santorelli


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