Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
622 PM EDT Tue Mar 22 2022
Valid 12Z Sat Mar 26 2022 - 12Z Wed Mar 30 2022
...Pattern Overview and Weather/Hazard Highlights...
An amplifying upper trough south of the Aleutians and then
entering the Gulf by early next week will sustain the development
of a well organized surface low. This will approach the southeast
Alaska mainland and then the eastern panhandle region with the
potential for heavy precipitation. A ridge axis builds northward
across western Alaska and adjacent portions of the Bering and the
Aleutians ahead of the next storm system approaching the Aleutians
by the middle of next week, with more rain and windy conditions
likely.
The developing Gulf low for early next week will likely have gusty
winds, moderate to heavy rain, mountain snow, and even high waves
across the southeast panhandle region for next Monday and into
Tuesday. Strong onshore flow that is orthogonal to the terrain
will enhance precipitation totals for the windward areas. In
terms of temperatures, most of the mainland should enjoy readings
above average through the weekend, followed by a return to
seasonal to below average readings for some areas through next
Wednesday.
...Guidance/Predictability Assessment...
The 12Z model guidance suite is in very good agreement on the
overall synoptic scale pattern through the upcoming weekend. The
main differences by Sunday include a stronger and farther south
solution with the 12Z GFS regarding the maritime low entering the
Gulf of Alaska, and this trend is even more pronounced by Tuesday,
whilst the GFS/ECMWF and the ensemble means all suggest a solution
closer to the south-central Alaska coast and a little weaker. The
UKMET is likely a bit progressive with the next major storm system
approaching the Aleutians/Bering Sea region by late Sunday/Monday,
and by the middle of next week, the CMC is broader with the ridge
axis that is downstream of the Bering low, and it is also south of
the model consensus with an upper low over northern Alaska by this
time.
Taking these factors into account, the WPC forecast is primarily
based on a multi-deterministic blend for Saturday, and then
slightly less weighting on the GFS for Sunday and beyond, and
mainly a ECMWF/CMC/ensemble blend with minimal use of the GFS for
early-middle next week.
Hamrick
Hazards:
- Heavy precipitation across portions of southern mainland Alaska,
Fri, Mar 25.
- Heavy precipitation across portions of the Alaska Panhandle,
Mon-Tue, Mar 28-Mar 29.
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