Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
421 PM EDT Tue Aug 20 2019
Valid 12Z Sat Aug 24 2019 - 12Z Wed Aug 28 2019
The upper-level pattern will remain relatively consistent across
Alaska during the extended period, with an area of negative height
anomalies south of the Aleutians and active westerlies from that
region toward the Gulf of Alaska, keeping chances for
precipitation relatively high across the Panhandle. Meanwhile,
persistent weak ridging across eastern Russia and the Bering Sea
should allow negative height anomalies to extend from the Arctic
across the northern half of Alaska, with a few shortwaves
affecting the North Slope.
Began the forecast for the extended period with a multi-model
deterministic blend (ECMWF/GFS/CMC) days 4-5, before transitioning
to heavier weighting of the ensemble means along with some
continued use of the deterministic ECMWF/CMC during days 6-8 due
to somewhat better consensus among those solutions relative to the
ensembles. This solution shows another low pressure system
crossing near/just south of the Alaska Peninsula next Mon-Wed.
Spread remains relatively high with respect to this system,
however, making the forecast likely the continued subject of
future adjustments.
Ryan
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
- Heavy rain across much of the Alaska Panhandle, Fri-Sun, Aug
23-Aug 25.
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