Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
628 PM EDT Sun Apr 28 2024

Valid 12Z Thu May 02 2024 - 12Z Mon May 06 2024

...Guidance Evaluation and Preferences...

The 12 UTC GFS/ECMWF/UKMET/Canadian model solutions now seem well
clustered and supported by multi-model ensemble means Thursday
into Saturday, bolstering forecast confidence to above normal
levels. A composite solution lends a solid forecast basis and
representative detail. Later, prefer the ECMWF ensemble mean that
shows a more vibrant main low transition from the Bering Sea to
the Gulf of Alaska onward into Day 7/8. WPC product continuity is
decently maintained in this fashion, albeit with a continued
recent trend toward a more progressive and deeper main low.
Current satellite imagery of the origin system now exiting China
shows quite the dynamic supporting upper system.

...Weather/Hazards Highlights...

An organized low pressure system with supporting/amplified upper
trough support in a recent series will progress southeastward
across the Gulf of Alaska through later this week and favor areas
of enhanced maritime winds/waves and rainfall that should also
work inland across mainly coastal areas of the southern to
southeast tier of the state to produce some terrain focusing
modertate rainfall, albeit in an overall benign weather pattern
farther inland. A vast portion of the state will experience above
seasonal average temperatures for the start of the month
particularly portions of the Interior where anomalies will be the
highest. Additional upper troughing over the Arctic Ocean is
expected to also settle down into the northern tier of the state.
In this pattern, areas to the north of a surface front settling
over the northern and central mainland in cold high pressure
should keep temperatures below normal, especially across the
unsettled North Slope and the northern Interior. Guidance shows
spotty light precipitation.

Meanwhile, guidance continues to highlight development of a much
deeper low pressure system to mainly affect the Aleutians and
Bering Sea into mid-later week. This deepened low offers a
potentially hazardous multi-day period with enhanced wind
flow/waves and rainfall. Steady progression of this well
organized/deep storm within the amplified pattern will lead to
enhanced lead inflow to fuel precipitation into west/southwest
Alaska into Saturday. Ample Gulf of Alaska redevelopment should
offer renewed maritime hazards along with moderate to potentially
heavier multi-day precipitation inland for the Alaska
Peninsula/Kodiak Island and then SouthCentral to Southeast Alaska
next weekend into early the following week to monitor given some
sensitve terrain.

Schichtel


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