Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
638 PM EST Mon Feb 17 2020
Valid 12Z Fri Feb 21 2020 - 12Z Tue Feb 25 2020
Troughing along 180 is favored late this week through the weekend
and into next week as subtropical ridging off Asia meanders
offshore. The 12Z models were in good agreement to start as a
system settles toward the Kenai Peninsula early Fri. Occluded/cold
front will push through the Panhandle as the old parent low
dissipates on Sat. Models have again become a bit more bullish on
a trailing sfc low and front that may skirt northward just
offshore the Panhandle as its front moves into British Columbia
late Sat. Blend of the 12Z guidance proved a best bet with timing
differences remaining. Farther west and at the same time, another
system will likely push eastward just south of the Aleutians
through next Monday before lifting northward as heights rise
downstream into the Gulf. Utilized a blend of the 12Z
ECMWF/Canadian with the 12Z GEFS and 00Z ECMWF ensemble means to
minimize any unforecastable smaller sfc lows (per the GFS) that
have no predictability (though the GFS was not necessarily
implausible).
Temperatures near to above average in interior/eastern areas will
trend back toward below average as colder air is dragged down from
the north behind the lead system. The Panhandle should see nearer
to average temperatures (but still trending a bit cooler) with
mainly westerly onshore flow and a nearly daily chance of
precipitation. Highest rain/snow totals are likely over the
southeast side of the Kenai Peninsula Fri around the sfc low,
eastward from around Yakutat and southeastward through the
Panhandle, perhaps with additional heavier amounts over the
southern Panhandle with the passing of the trailing sfc low
Saturday. More rain/snow will spread across the Aleutians Sat-Tue
as the next system (or two) move through.
Fracasso
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:
- Heavy precipitation across portions of the Alaska Panhandle,
Thu-Fri, Feb 20-Feb 21, and portions of mainland Alaska, Mon, Feb
24.
- Heavy snow across portions of the Alaska Panhandle and mainland
Alaska, Thu-Fri, Feb 20-Feb 21.
- Much below normal temperatures across portions of mainland
Alaska, Thu-Sun, Feb 20-Feb 23.
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