Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
758 PM EDT Sat Apr 30 2022
Valid 12Z Wed May 04 2022 - 12Z Sun May 08 2022
...Guidance/Predictability Assessment...
Model guidance is in general agreement with keeping a relatively
tranquil synoptic pattern over Alaska as the most active storm
track is forecast to stay well to the south across the northern
Pacific through the medium-range period. A couple of upper lows
are forecast to come into play as they rotate about each other in
the vicinity of Alaska. There continues to be some model spread
regarding the track of an upper low forecast to drop southward
near/just off the west coast of mainland Alaska. The GFS and CMC
swing the upper low farther out across the Bering Sea while the
ECMWF and EC mean keep it closer to the coast. The GFS appears to
indicate a gradual trend toward the ECMWF. Meanwhile, the other
upper low located over the Gulf of Alaska is forecast to gradually
weaken and dissipate.
The WPC forecast package for Alaska was based on a 40% blend of
the 06Z and 12Z GFS/12Z GEFS, 40% of the 00Z EC/EC mean, and 20%
from the 00Z CMC/CMC mean, transitioning towards 75% of the
ensemble means by Day 8. The CMC appears to get progressively
faster than the GFS/EC consensus with time, and thus was gradually
taken out from the blend with time. A slightly more weight toward
the EC solutions was given on Days 6 and 7. The results appeared
very similar to yesterday's forecast package.
...Weather and Hazard Highlights...
An occluded cyclone meandering in the Gulf as the medium-range
period begins will likely be associated with moderate to locally
heavy precipitation across the Panhandle and into portions of
Southern Coast region. Precipitation should lessen in intensity
thereafter as the cyclone weakens. The upper low dropping
southward near the West Coast to the Aleutians by the weekend
should result in modest amounts of precipitation near its track.
Meanwhile, a stationary boundary should keep some scattered light
rain and snow showers mainly across parts of southern Mainland
Alaska and into southwestern Alaska. The next low into the Gulf
next Friday into Saturday should stay well to the south of the
Aleutians with limited impacts to the islands, but an uptick in
moisture for parts of the Southern Coast and Panhandle is once
again possible by next weekend as the low is forecast to head
towards the Gulf.
Temperatures across southern Alaska, the Panhandle and also the
North Slope region should remain near or below normal through next
weekend as a modestly cold high pressure system slides eastward
across the Arctic Ocean. Across central and especially
east-central Alaska, upper level ridging should keep daytime highs
above normal, and when combined with a remaining snow pack in the
region, could present some flooding concerns across portions of
the Yukon River Basin in eastern Alaska.
Kong
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