051
FXAK02 KWNH 102337
PMDAK

Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
736 PM EDT Fri May 10 2024

Valid 12Z Tue May 14 2024 - 12Z Sat May 18 2024

...Guidance Evaluation and Preferences...

Model guidance continues to indicate broad troughing over Mainland
Alaska for the beginning of next week, with shortwave energy
across the Alaska Peninsula and extending southwest over the
northern Pacific creating a positively tilted trough. This trough
and the associated surface low is forecast to track northeast
toward the Gulf by midweek and gradually weaken, although some
timing uncertainty remains in the guidance.  The strength of the
surface low varies a bit as well but recent models do not show it
to be all that strong.

Farther west, models continue to advertise the next round of upper
level shortwave energy tracking from Siberia across the Kamchatka
Peninsula and leading to the development of a closed low over the
Bering Sea.  While Tuesday-Wednesday has become more agreeable for
the timing of this system to move into the Bering Sea region,
model differences become more significant going into the end of
the week.  Of particular note is a much more amplified GFS
solution with a triple point low that develops near the Aleutians,
and becomes an outlier solution for the second half of the
forecast period.  A mainly deterministic model blend sufficed as a
starting point in the forecast process for Tuesday with a little
more weighting to the ECMWF, and then dropping the GFS by Thursday
and beyond.  The proportion of the GEFS and EC ensemble means
increased to about 60% by Day 8 amid the increasing uncertainty.
This seemed to provide a reasonable middle ground, although
changes are very likely in the days ahead as the guidance comes
into better focus.


...General Overview and Weather/Hazards Highlights...

For the Tuesday-Wednesday time period, a surface low reaching the
northern Gulf should bring additional rain and mountain snow to
much of south-central Alaska.  It appears precipitation amounts
will likely be on the moderate side, with some locally heavier
totals possible but not significant enough to warrant any areas on
the WPC hazards outlook.  Some lighter precipitation in the form
of rain showers and higher elevation snow showers should extend
into the Interior as well. Then there is considerable uncertainty
regarding rain/mountain snow and winds that may affect the western
Mainland and/or Aleutians by midweek and beyond depending on how
the pattern evolves. Low confidence in the sensible weather
persists into the latter part of next week and into next Saturday,
but generally some light to moderate precipitation seems possible
for the southern coast.
In terms of temperatures, highs should generally be in the 50s and
60s for most inland locations, and lows from the mid 30s to mid
40s.  The Arctic Coast will continue to remain colder as highs
slowly break the freezing mark.

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

$$