Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
606 PM EDT Wed May 13 2020
Valid 12Z Sun May 17 2020 - 12Z Thu May 21 2020
...Guidance/Predictability Assessment...
The WPC medium range Alaskan product suite was mainly derived from
a composite of reasonably well clustered guidance from the 12 UTC
GFS/ECMWF/UKMET/Canadian Sunday into Monday along with the 19 UTC
National Blend of Models in a pattern with above average forecast
predictability. Prefer a composite blend of still well clustered
guidance from the 12 UTC GEFS/ECMWF ensemble means into days 6-8
in a period with gradually growing model solution variance. This
maintains excellent WPC continuity.
...Weather/Hazard Highlights...
Arctic surface high pressure will produce cooled temperatures for
much of the North Slope and Interior in a pattern with modest
precipitation potential under weak mean upper troughing. Above
normal readings will be more confined to southern/western areas of
the state. An emerging storm track will meanwhile bring a series
of closed upper lows/troughs and deepened surface system along
with an enhancing moisture and wrapping heavy precipitation threat
from the Aleutians through the Alaskan Peninsula then southern
Alaska. There is a strong guidance signal in support of a lead low
on this track Sunday-Tuesday, with a second storm likely on its
heels Tuesday-next Thursday. These lows will also offer a maritime
wind/wave hazard from the northern Pacific/southern Bering Sea
onward with redevelopment into the Gulf of Alaska.
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:
- Heavy precipitation across portions of southern coastal areas of
Alaska, Tue, May 19.
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