Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 656 PM EST Mon Dec 23 2019 Valid 12Z Fri Dec 27 2019 - 12Z Tue Dec 31 2019 ...Below average temperatures persist over much of Mainland Alaska... ...Stormy pattern across the Gulf of Alaska... Upper ridging over eastern Russia and between Hawai'i and California will support a positively-tilted trough from around 50N south of the Aleutians into the Gulf of Alaska for the last several days of December. With an upper low slowly lifting away from the Beaufort Sea, well below average temperatures will only gradually moderate but remain colder than average over the interior. The exception will be for the Panhandle with above average temperatures in a wet pattern. The models continued to struggle with the timing and track of the embedded systems in an otherwise well-modeled longwave pattern. The ECMWF has been the most stable of all deterministic models, but even it has showed variability larger than typical. Utilized a method of removing the most different models which led to inclusion of several current and previous cycles as well, as the newer 12Z guidance did not shift in unison. 12Z GFS was not favored past Friday as it was well northwest with a sfc low nearing Kodiak Saturday rather than the consensus to the east. The next system near 180 by then actually was well-clustered until it stretched ENE Sunday with the triple point low racing into the Gulf. Strong SW flow makes the ECMWF depiction certainly plausible while the 12Z GFS again seemed too far to the NW (into Bristol Bay by late Monday). Utilized more than 50% ensemble means as the 12Z GEFS mean and 00Z ECMWF ensemble mean were fairly close but rather devoid of detail. The coldest days will likely be this Fri-Sun with lows in the -50s in the colder sheltered spots south of the Brooks Range. Into Southcentral, highs may struggle to reach zero in Anchorage while temperatures into the 40s will be common across the Panhandle from Juneau southward. Rainfall (and snowfall) will be quite heavy across the Panhandle given the nearly steady storm track--several inches of liquid equivalent will be possible over the 5-day period. Some models show upwards of 10 inches though this may center just south of the southern Panhandle. 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 Hazards: - Heavy precipitation across much of the Alaska Panhandle, Thu, Dec 26 and Sat-Mon, Dec 28-Dec 30. - Heavy precipitation across portions of the southern Alaska, Sun-Mon, Dec 29-Dec 30. - Much below normal temperatures across portions of mainland Alaska, Fri-Mon, Dec 27-Dec 30. 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