Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 533 PM EST Sun Dec 01 2019 Valid 12Z Thu Dec 05 2019 - 12Z Mon Dec 09 2019 ...Heavy rain/snow possible for southern coastal areas late this week into the weekend... Upper ridging will meander in the East Siberian Sea toward the North Pole, favoring troughing to its south from Kamchatka eastward through the Bering next Thu-Mon. This will take an initial Bering system in a couple waves eastward to deepen around Saturday before translating into the Gulf. Slow movement this coming weekend may favor locally heavy rain/snow for areas around Cook Inlet. Its eastward progression is a bit of a question, as the broad expanse of the upper trough suggests sfc wave development along the front that will slow is movement toward the Panhandle. In the interior, cold high pressure will slowly shift into Canada after a couple cold nights. Multiple low centers in the Bering suggest a consensus approach, but using mostly 12Z deterministic models. This should coalesce into a deeper system by Fri/Sat as the front continues eastward. GFS/Canadian became quicker with the front than the ECMWF, but preferred to stay on the slower side given the broad upper trough over the central Pacific that suggests trailing height falls to help induce sfc wave development along the front and likely slow its progression. Ensembles seem to favor this scenario too, but confidence was no higher than average since small timing changes in the near term can amplify differences by 7-8 days out. Downstream CONUS pattern (building western ridging into BC) should favor a slower timing as well. Precipitation will focus over the Aleutians and AKPEN initially then expand across Southcentral where it could be locally heavy (coastal rain, inland/terrain snow) as the triple point develops near Kodiak this weekend. Ensemble QPF guidance highlight the west side of Cook Inlet and southeast-facing areas of Kodiak and especially the Kenai peninsula where 5-10" of liquid-equivalent QPF is depicted (even a bit higher in the GFS/ECMWF). 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 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