Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 632 PM EST Sat Jan 25 2020 Valid 12Z Wed Jan 29 2020 - 12Z Sun Feb 02 2020 ...Well below average temperatures for most of mainland Alaska... ...Active pattern with two deep Gulf of Alaska storms bringing heavy precipitation to portions of Alaska Panhandle and mainland next week... Through the medium range period, the latest models and ensemble guidance continues to show above average consensus on the overall synoptic pattern. Upper level troughing should be reinforced through much of the period, only gradually beginning to weaken and shift eastward by next weekend. Forecast confidence remains high for a cold surface air mass settling across much of Alaska well into next week, with max and min temperatures 20+ degrees below normal for some places. An active North Pacific jet will send a series of potentially deep shortwaves/surface lows across the North Pacific and into the Gulf of Alaska. The first of such systems, in place across the central Gulf by next Wednesday, models have consistently shown a central pressures of at least the low 960s mb, with some runs even lower, possibly into the 940s. This low should shift north and weaken in favor of a second deep (970s mb) low just west of the southern Panhandle on Thursday. These lows should keep precipitation chances high across parts of the southern Mainland and much of the Panhandle, with locally heavy precipitation possible. Lingering deep layered cold air could support locally heavy snows even into the lower elevations of southern Alaska and the northern Panhandle. High winds across these regions are also possible. Beyond Thursday, weak broad low pressure maintains across the Gulf, being suppressed a bit south and east as surface high pressure builds across the interior Mainland. In the Aleutians, wind and precipitation chances increase by next weekend as a deep surface low moves towards the western islands. The 12z guidance suite showed very good agreement through much of the period. The led to a total deterministic model (GFS/ECMWF/CMC) blend through day 5. After, opted to slowly increase contributions from the ensemble means to mitigate the smaller scale, less predictable, detail differences. This maintains good continuity both with yesterday's Alaska progs and with downstream preferences over the CONUS. Santorelli 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