Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
749 PM EDT Fri Apr 19 2024

Valid 12Z Tue Apr 23 2024 - 12Z Sat Apr 27 2024

...Deep cyclone will bring very strong/high winds to the western
Aleutians early next week...


...Overview with Guidance Evaluation and Preferences...

A relatively stagnant synoptic pattern is forecast to prevail in
the vicinity of Alaska through next week, with a slow-moving but
weakening deep cyclone over Bering Sea coupled with a ridge
extending north into mainland Alaska.  This will be in stark
contrast with a fast west-to-east storm track across the northern
Pacific.  The deep cyclone over the Bering Sea will likely bring
very strong to high winds for at least the western portion of the
Aleutians early next week before a gradual weakening of the
cyclone is forecast to take place through midweek while it lingers
over the Bering Sea.  Model guidance is in general agreement with
this synoptic pattern through midweek.  Toward the end of the
week, guidance shows some divergence regarding how long the Bering
Sea low will linger and how far east a developing low pressure
system from the North Pacific will track toward the Gulf of Alaska
and how deep it will turn out to be.  A general compromise of the
model guidance is adopted (with 40% 00Z/12Z ECMWF, 40% 12Z
GFS/GEFS, and 20% from the 12Z CMC/CMC mean) which yields
solutions that are quite compatible with yesterday's WPC 500mb and
surface prognostic charts.  The Day 8 depicts a modestly strong
occluded cyclone sliding northeast just off the Alaska Peninsula.


...Weather/Hazards Highlights...

The strong storm near the western Aleutians will be the main
system of interest early next week as it should gradually trend
weaker after Tuesday.  This storm should also produce areas of
strong winds across at least the western Aleutians and into Bering
Sea where a high wind area is depicted on the Hazards map. 
Meanwhile, a leading front will likely focus higher moisture
contents toward the eastern Aleutians and the Alaska
Peninsula/Kodiak Island ahead of the occluded front and a
triple-point low through midweek.  Some of this activity may also
be heavy but models are keeping the QPF amounts modest thus far. 
Surface low/front details over the Aleutians/Bering Sea become
more uncertain later in the week but there is a good signal for
the general persistence of cyclonic flow with rising pressures. 
Some lingering precipitation is possible along the southern coast
early in the week due to the initial shortwave over/near the
southwestern corner of the mainland.  The weak system tracking
across the northeastern Pacific may bring a period of mostly light
precipitation to the southern Panhandle toward the end of next
week with a lower confidence due to the model spread.  Meanwhile,
the guidance spread appears far enough south to keep the Panhandle
mostly dry.

Most of the state should see above normal temperatures during next
week, with the highest anomalies tending to be over the Interior. 
To the north of a front settling over the central mainland, cold
high pressure over the Arctic may keep temperatures near to
somewhat below normal across the North Slope.  Locations near the
Southcentral coast and northern Panhandle may also see near or
slightly below normal readings.

Kong/Rausch


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