Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
630 PM EDT Wed Apr 27 2022
Valid 12Z Sun May 01 2022 - 12Z Thu May 05 2022
...Guidance/Predictability Assessment...
An active, fast/progressive flow pattern is expected to evolve
over the region through the medium range 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 at least day 6 and this led to average to above average
forecast confidence heading into the middle of next week. Low
pressure Sunday in the Gulf will weaken through Monday as the next
stronger closed low tracks across the Aleutians Monday into
Tuesday. That system then occludes and stalls over the Gulf
through the remainder of the period, keeping the unsettled weather
in place along the southern mainland and Panhandle. Toward the end
of the period, fast moving shortwave energy closes off and is
likely to become absorbed into the existing closed low over the
Gulf, reinforcing the pattern in place through day 8. For the WPC
forecast blend, the ECMWF/GFS were favored along with the UKMET
through day 6 then increasing weights of the ECENS/GEFS means were
included for day 7 and day 8 to account for some increasing
forecast model spread and uncertainty and also to maintain WPC
continuity.
...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. 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. Toward the end of the period,
Wednesday/Thursday another storm system may bring active weather
to Panhandle but details that far out are too uncertain. 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 northern and western Alaska. The combination of above normal
temperatures and remaining snow-pack could lead to flooding across
Yukon River in the western mainland.
Taylor
Hazards: Flooding possible across portions of mainland Alaska,
Sat-Wed, Apr 30-May 4.
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