Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
348 PM EDT Mon Oct 08 2018

Valid 12Z Fri Oct 12 2018 - 12Z Tue Oct 16 2018

Ensembles remain in good agreement on the longwave pattern in the
high latitudes with most of the disagreement confined to the
Pacific south of about 50N. Upper low and trough in the eastern
Bering and along 165W, respectively, will be reloading by an
incoming upper low exiting the Sea of Okhotsk on Friday. This will
move eastward (with some north-south uncertainty) near/along the
Aleutians and then slowly into the Gulf next week.

The deterministic models were generally clustered to start but
this pattern makes it tough to retain that past about ~120hrs. The
ECMWF was a bit slower and farther north with the Aleutian system
than the GFS/GEFS with the ECMWF ensemble mean in between, which
arguably was the best consensus position for Sat-Mon. Lead system
into the Gulf this coming weekend will have at least a couple
waves of low pressure lifting northward as the upper ridging gets
chipped away until the upstream upper low promotes it once again.
Continuity in the deterministic models has been poor in the 6-7
day time frame so trended toward the ECMWF ensemble mean and GEFS
mean by next Monday which brings the Bering/Aleutians sfc low
toward Kodiak next Mon/Tue.

Pattern will still favor near to above average temperatures over
most of the state especially north of the Alaska Range to the
North Slope. Heights will be near to above average over the
mainland but even the troughing in the Bering will keep
temperatures to near average. Precipitation will favor
Southcentral areas eastward to the Panhandle where both the NBM
and our in-house bias-corrected QPF paint several inches of rain
(snow where cold enough) but over several days with sustained
southerly flow at the surface (SW to S aloft). Much less
precipitation is forecast north of the Alaska Range and perhaps
little to no precip for the North Slope.


Fracasso


WPC medium range Alaskan products including 500mb, surface
fronts/pressures progs and sensible weather grids can be found at:

http://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif
http://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml
http://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html