Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
254 PM EDT Tue May 28 2019
Valid 12Z Sat Jun 01 2019 - 12Z Wed Jun 05 2019
Upper pattern over the high latitudes will feature a blocking
pattern with slowly moving features. On Sat 01 Jun a slowly moving
upper low is forecast to be centered just south of the central
Aleutians.
The 00Z-06z suite of guidance (GFS/ECMWF/Canadian) clustered
fairly well together and close to the ensemble means (00Z ECMWF
ensemble mean and 06z GEFS Mean). The consensus of these solutions
stayed close to the prior forecast/ continuity through Sunday 02
June, when the low starts to weaken and drift east.
The majority of models have kept yet another upper low over
Wrangel Island to the northwest of northwestern Alaska. The ECMWF
weakens the initial low over the weekend while the GFS maintains
it. By next week, the 00z ECMWF redevelops a low in the area.
On next Tue 04 Jun the models mostly show a new cyclone developing
in the northern central Pacific tot he southwest of the lower
Aleutians. There are latitude differences with the 06z GFS/GEFS
south of the low positions/track vs the further south ECMWF/ECMWF
Ensemble Mean. There is above average agreement on the development
of a low but loose clustering as to the location next Tue and Wed
05 Jun. The 12z GFS is further northeast towards the lower
Aleutians Wed 05 Jun but that reflects the typical fast GFS bias,
greater weighting to the 06z GEFS/00z ECMWF Ensemble means should
bias correct the forecast.
Temperatures will average above normal in northern AK but near to
below normal across the upper Aleutians across southern coastal
areas/Kenai east to the Panhandle, partly influenced by clouds and
higher Pops. Rainfall will generally be light but locally moderate
in favored areas in windward terrain and coastal areas of the
Kenai down into the Panhandle.
Petersen
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
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