Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
711 PM EDT Fri Apr 29 2022
Valid 12Z Tue May 03 2022 - 12Z Sat May 07 2022
...Guidance/Predictability Assessment...
An active flow pattern is expected to evolve over the region
through the extended period with a couple of storm systems likely
to bring unsettled weather to portions of Alaska. The 12Z model
guidance showed good agreement and clustering with the large scale
pattern through much of next week, but seemed to vary more with
timing and strength of individual systems, especially later next
week. A general deterministic model blend (with more emphasis
towards the better clustered ECMWF, GFS, and UKMET) sufficed as a
starting point Tuesday and Wednesday. After this time, there is
some disagreement in timing of a second system towards the Gulf
later in the week, with the CMC noticeably faster than the ECMWF
and GFS, although there is some north/south variance in the ECMWF
and GFS as well. The GFS and ECMWF show good agreement with a
deeper low dropping south along the west coast of Alaska mid-week,
but also begin to diverge a little in terms of timing and location
late week. Thus, a trend towards more of the ensemble means was
used for days 6-8, though modest amounts of the ECMWF and GFS were
maintained for some added system definition.
...Weather and Hazard Highlights...
A low pressure system in the Gulf when the period begins on
Tuesday will meander until about Wednesday before it weakens as it
interacts/gets wrapped into a compact upper low dropping south
across Western Alaska. Ample moisture ahead of the attendant cold
front should direct towards the Panhandle and Southern Coast
region with moderate to locally heavy rainfall possible Tuesday
and into Wednesday. Moisture may linger, but precipitation should
lessen in intensity mid to later next week as the low weakens, but
some kind of upper troughing maintains over the Gulf. Meanwhile, a
stationary boundary as well as the upper low along the West Coast
should keep some scattered rain and snow showers across parts of
southern Mainland Alaska and southwest Alaska as well. The next
low into the Gulf next Friday into Saturday should stay south
enough of the Aleutians to limit impacts, but an uptick in
moisture for parts of the Southern Coast and Panhandle is once
again possible by next weekend as the low drifts more into the
Gulf.
Temperatures across southern Alaska/the Panhandle and also the
North Slope region should remain near or below normal through next
week as systems move through. Across central and especially
east-central Alaska, upper level ridging should keep daytime highs
above normal, and combined with a remaining snow pack in the
region, could lead to some flooding concerns across portions of
the Yukon River Basin in eastern Alaska.
Santorelli
Hazards:
-Flooding possible across portions of mainland Alaska, Mon-Fri,
May 2-May 6.
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