Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
750 PM EDT Thu Mar 30 2023

Valid 12Z Mon Apr 03 2023 - 12Z Fri Apr 07 2023

...Overview with Guidance Evaluation/Predictability Assessment and
Weather/Hazard Highlights...

The medium range forecast period for Alaska will begin on Monday
with an occluded cyclone center forecast to move into the Bering
Sea while a triple-point low moves up the Aleutian Island chain. 
Since the 12Z cycle yesterday, the ECMWF had decidedly flipped to
the current regime for this area, allowing the triple-point low to
continue moving through the upper ridge and into the Gulf of
Alaska by the middle of next week.  This solution is now much more
agreeable with the rest of the guidance from both the GFS/GEFS and
CMC.  With this new regime in place, the triple-point low is
forecast to linger over the Gulf of Alaska into late next week. 
The proximity of this system to land means that a higher chance of
precipitation will overspread the southern coastline and down into
the Panhandle starting next Tuesday.  These precipitation chances
are forecast to linger along the southern periphery of Alaska
through next Friday.  In addition, the system will likely bring a
period snow across southwestern Alaska Tuesday and Wednesday even
out to the eastern shorelines of the Kenai Peninsula where the
snow is expected to be the heaviest.  There is also a chance of
high winds near the southern coastline on Wednesday as the system
edges closer to land.  Farther upstream, additional smaller scale
low pressure systems moving across the North Pacific will continue
to introduce uncertainty to the pattern affecting the Aleutians in
the longer range forecasts.  At present, precipitation chances are
forecast to increase from west to east across the Aleutians late
next week as a low pressure wave from Siberia is forecast to reach
the area.  Meanwhile, northern Alaska will be milder than normal
but well below hazards levels.  Temperatures for the rest of
mainland Alaska will average close to normal.

The WPC Alaskan forecast package begins with 40% from the 12Z EC
and EC mean, 40% from the 12Z GFS and GEFS, and 20% CMC and CMC
mean, transitioning to mostly a blend of the 12Z EC mean/12Z EC
(50%), with the rest of the blend derived from the 12Z CMC mean,
and 12Z GFS/GEFS by Day 8 Friday.

Kong


Hazards:
- High winds across portions of mainland Alaska, Sun, Apr 2.


WPC medium range Alaskan products including 500mb, surface
fronts/pressures progs and sensible weather grids can also be
found at:
<a href="https://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif"><u>https://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif</u></a>
<a href="https://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml"><u>https://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml</u></a>
<a href="https://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html"><u>https://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html</u></a>