Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
525 PM EST Thu Jan 23 2020
Valid 12Z Mon Jan 27 2020 - 12Z Fri Jan 31 2020
...Well below average temperatures for most of mainland Alaska...
Latest models and ensembles still offer good consensus that an
upper level ridge will build to the west of Alaska and only slowly
weaken/shift westward next week. Arctic energies digging over the
ridge will act to anchor an upper level trough from the Mainland
to the Gulf of Alaska. Forecast confidence is high that there will
be a cold surface airmass settling underneath for much of Alaska
to linger well into next week.
An active North Pacific jet will send various shortwaves/surface
lows across the North Pacific into the Gulf of Alaska, which
should act to reinforce a closed upper low and deep surface low
lingering over the northern Gulf. This setup would keep Southeast
Alaska with relatively high precipitation chances through much of
the period. Lingering deep layered cold low development just
offshore over the northern Gulf will support some locally heavy
snows thru lower elevations of southern Alaska and the northern
Panhandle.
While models agree on the overall larger scale pattern, they
continue to struggle with the evolution and progression of the
series of surface lows entering the Gulf and how they interact
with the larger scale trough over Alaska. Accordingly, the
specifics of this aspect of the forecast remains more chaotic with
below average predictability. As a result, the WPC progs utilized
the more agreeable 12 UTC GFS/ECMWF with the GEFS/ECMWF ensemble
means day 4 into 5, then quickly switch to just these ensemble
means to day 8 in a period with rapidly increasing forecast
spread. This maintains decent continuity.
Schichtel
Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
Hazards:
- Much below normal temperatures for much of mainland Alaska,
Sun-Wed, Jan 26-Jan 29.
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