Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
353 PM EDT Thu Aug 22 2019
Valid 12Z Mon Aug 26 2019 - 12Z Fri Aug 30 2019
An upper low is forecast to slowly move eastward through the
Arctic as height falls push into the Bering Sea late next week.
Upper ridging south of the Gulf/Panhandle will nudge eastward into
southern British Columbia. This will favor stretched troughing
from the Gulf of Alaska SSW into the Pacific where a series of
relatively weak areas of low pressure will lift northeastward
ahead of a a main baroclinic zone. The models/ensembles have
trended more stretched (N-S) than yesterday, which would keep the
more organized system well south of the Gulf but allow weaker ones
to skirt the NW side of the upper ridge to the east. The GFS was
in the minority with a more coherent system into the Gulf while
the other deterministic models were more muted. However, all
eventually focused any organized system south of 50N as the
heights falls sink southward.
To the north, main upper low will meander eastward with the
possibility of a shortwave rotating around it, swinging through
the North Slope. The 00Z ECMWF was a stronger representation of
that idea. While plausible, a blend with the other guidance
tempered its depth given the uncertainty at this time range.
Heights will slowly rise later next week as the upper low wobbles
into the Canadian Archipelago.
In the Bering Sea, high pressure will dominate early in the week
before a system moves eastward along the Aleutians. Deterministic
models show a 1-2 reinforcement but regardless a slow but steady
movement eastward is expected.
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
- Heavy rain across portions of the Alaska Panhandle, Sun-Mon, Aug
25-Aug 26.
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