Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
746 PM EDT Thu Apr 28 2022
Valid 12Z Mon May 2 2022 - 12Z Fri May 6 2022
...Guidance/Predictability Assessment...
An active flow pattern is expected to evolve over the region
through the extended period with several storm systems likely to
bring unsettled weather to portions of Alaska. The 12Z model
guidance showed very good agreement and clustering through early
next week, so a deterministic model blend sufficed as a starting
point through next Tuesday. The low pressure initially over the
Gulf of Alaska late Sunday/early Monday weakens as the next
stronger closed low tracks across the Aleutians Monday into
Tuesday. That system then occludes and stalls over the Gulf
through the middle to end of the week, keeping the unsettled
weather in place along the southern mainland and southeast
Panhandle. Toward the end of the period, a second shortwave
approaches the Gulf and is likely to become absorbed into the
existing closed low over the Gulf, reinforcing the pattern in
place through next Friday. There was increased use of the
ensemble means for days 7 and 8, whilst still keeping some of the
operational GFS and ECMWF.
...Overview Weather/Hazard Highlights...
A series of storm systems and frontal passages will keep southern
Alaska and southeast areas unsettled with periods of moderate to
perhaps heavy precipitation, especially across coastal terrain
that is orthogonal to the onshore flow. The best periods of
heavier rain look to be Sunday into early Monday and again Monday
evening into Tuesday, particularly across southeast Alaska, as a
stronger low settles into the Gulf. By Wednesday and into
Thursday, another storm system may bring active weather to the
southeast Panhandle, but details that far out remain uncertain.
The potential exists for several inches of total rainfall for
portions of the Kenai Peninsula, and also the southeast Panhandle.
For the remainder of the state, the interior regions will be
under the influence of high pressure and this should lead to a
prolonged period of near to above normal temperatures, especially
for parts of the Interior. The combination of above normal
temperatures and remaining snow-pack could lead to flooding across
portions of the Yukon River basin in the western mainland.
Hamrick
Hazards:
Flooding possible across portions of mainland Alaska, Sun-Thu, May
1-5.
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