Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
659 PM EDT Sat May 07 2022
Valid 12Z Wed May 11 2022 - 12Z Sun May 15 2022
...Overview and Guidance/Predictability Assessment...
The 12z model guidance from today continue to have a fairly good
handle on the large scale pattern through the extended range time
period. This features a rather amplified pattern with troughing
over the mainland/Gulf of Alaska and ridging across the Aleutians
and into the western Bering. A system well to the south of the
Aleutians will translate east, and eventually phase with Gulf
troughing bringing a closed low into the region. West of the
Aleutians, another deep closed low will meander and shift only
slightly southward as it becomes blocked by the amplified ridging.
The greatest uncertainties surround the details of a couple weak
shortwaves over the mainland and the eventual evolution of Gulf of
Alaska low pressure the second half of the period. The UKMET was
an outlier early on being too quick to erode the ridge and bring
the deep low west of the Aleutians farther north/east than the
other models and the ensembles. The WPC forecast for today used a
blend of the ECMWF, GFS, and CMC the first half of the period,
leaning more on the ensemble means the latter half.
...Weather and Hazard Highlights...
Increasing precipitation chances are likely across portions of
interior Alaska next week as troughing and a surface front cross
the area. The precipitation should spread into southern and
southeastern Alaska and the Panhandle by later in the week, but
heavy totals are generally not expected. Increased precipitation
with moderate to locally heavy totals are possible by next weekend
as a frontal system works its way through the Gulf. River
flooding, significant in some places, is expected to be ongoing
owing to rising temperatures, ice jams, and snow melt.
Temperatures across much of Alaska should be below normal through
the period underneath of amplified upper level troughing. The
exception to this could be far southwest Alaska where upper
ridging may try to sneak in.
Santorelli
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