Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
624 PM EDT Fri May 13 2022
Valid 12Z Tue May 17 2022 - 12Z Sat May 21 2022
...Overview and Guidance/Predictability Assessment...
A rather amplified upper level pattern is expected across the
Alaska domain for next week, with a strong upper ridge and
potentially closed high over the Bering remaining nearly anchored
in place with a potential rex block developing by the end of the
week. Some upper level troughing will likely be in place across
the Arctic Coast region. At the surface, a low pressure system
over the Gulf will gradually weaken and move inland early next
week, while a broader, elongated low develops south of the Bering
high.
The 12Z model guidance suite is in good synoptic scale agreement
across much Alaska and vicinity through about Thursday. One of
the main differences early in the extended period is a weaker
solution with the UKMET/GFS regarding the extent of the upper
ridge across the Aleutians/Bering, and the 12Z GFS stronger with
the upper low approaching the British Columbia Coast. By Friday
night and into next Saturday, there is still good consensus for a
southeast-northwest oriented ridge axis across the southwestern
mainland, although model differences are greater across the Arctic
region with the GFS generally stronger with a trough north of the
Yukon. The WPC forecast was primarily derived from a
multi-deterministic model blend through early Thursday, with
slightly greater weighting towards the ECMWF/CMC solutions, and
then a gradual increase in the GEFS/ECENS for Friday and Saturday
whilst still maintaining some of the deterministic guidance.
...Weather and Hazard Highlights...
There are chances for modest precipitation across portions of
mainland Alaska into next week as upper disturbances/surface
fronts work across the area, but the main threat should remain for
any river flooding associated with snow melt and ice jams.
Offshore to the south, a well organized upper low/trough and
associated surface system lingering over the eastern Gulf of
Alaska will favor a periodic focus for light to moderate terrain
enhanced precipitation over Southeast Alaska/Panhandle into
early-mid next week, but otherwise a rather benign precipitation
pattern for the state.
Temperatures across much of the mainland for earlt next week are
likely to remain below normal, with the greatest anomalies for
northern Alaska as a deeper shortwave drops in through the region.
Temperatures are forecast to moderate going into the middle to
end of the week, with parts of western Alaska and the Peninsula
likely having above normal highs as the Bering Sea ridge slowly
works inland next week.
Hamrick
Hazards:
- Flooding possible across portions of mainland Alaska, Mon-Fri,
May 16-May 20.
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