Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
742 PM EDT Thu Apr 11 2024

Valid 12Z Mon Apr 15 2024 - 12Z Fri Apr 19 2024

...Synoptic Overview, Guidance Evaluation, & Preferences...

An upper level ridge axis will likely be in place across the
eastern mainland and into the southeast panhandle region for the
beginning of next week.  Meanwhile, a storm system over the North
Pacific tracks in the general direction of the AK Peninsula by
Wednesday and brings a return to more rain and snow for southern
coastal areas of the state.  Meanwhile, a second low pressure
system is forecast to track across the Bering and weaken with
time. 

The 12Z model guidance suite features sub-par levels of agreement
as early as Monday, and these differences only grow in magnitude
over the course of next week.  The CMC is most out of alignment
across the Bering Sea region with more surface high pressure over
that region through midweek, whereas the model consensus favors
low pressure.  Upon examination of the ML guidance from the ECMWF,
there is some support for the stronger GFS solution over the
Bering early in the period, and this also holds true for the
Pacific low lifting northward towards the AK Peninsula.  The UKMET
is also fairly close to the ML and GFS guidance, so the model
blend was based on a UKMET/GFS/ECMWF blend as a starting point
through Wednesday, and then increasing percentages of the GEFS
mean (the EC mean is likely too far south with the low over the
Pacific) to close out the work week.  Given the below average
confidence in the guidance, changes in the forecast are nearly a
certainty in future updates.


...Weather/Hazards Highlights...

Coastal rain and mountain snow is likely to increase going into
the Wednesday-Thursday time period from Kodiak Island to the
Prince William Sound region as moist onshore flow increases ahead
of the Pacific low moving northward, and the QPF forecast has
trended higher compared to yesterday.  However, there are major
timing differences in the guidance and the onset of the heavy
precipitation is subject to change.  Depending on the tightness of
the pressure gradient, strong winds could also be an issue for
portions of the AK Peninsula and extending eastward to the Kenai
Peninsula.  Temperatures are expected to be cold to start the
forecast period across most areas, but gradually moderating
through the week with the upper level ridge building in over the
eastern mainland.

Hamrick


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