Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 643 PM EST Thu Jan 20 2022 Valid 12Z Mon Jan 24 2022 - 12Z Fri Jan 28 2022 ...A wet pattern with heavy precipitation possible will continue into mid next week for Alaska's southern coast and Panhandle... ...Overview... Guidance continues to show a very warm and wet pattern for early next week, as a strong eastern Pacific mean ridge extends northward into Alaska's mainland and northwestern Canada while a mean trough axis persists farther west, with an embedded initially fairly deep upper low over eastern Siberia that should drift north and east with time. A shortwave/surface low initially near the Alaska Peninsula on Monday will direct a moist flow into the state and bring precipitation for southern parts of the state, and spread eastward with time. Weak upper troughing and cooler/drier surface high pressure is forecast to push west to east across much of the mainland around midweek onward as the ridge axis relaxes and shunts eastward into Canada. ...Guidance/Uncertainty Assessment... The models show fairly good agreement through much of the period on the overall, large scale pattern with differences in placement and the details of individual surface lows lifting into the region. Right off the bat, there's some latitudinal differences in surface low placement near the Alaska Peninsula on Monday. The GFS and CMC are notably north of the ECMWF, although the ensemble means support a more south placement. Differences increase with the next surface low into the Gulf mid-week as well as a deeper low moving towards the central Aleutians. For both, the GFS and ECMWF are closer to the ensemble means than the CMC and are the preferred solutions. At the end of next week, the deterministic solutions all show another strong surface low lifting towards the eastern Aleutians. The ensemble means are noticeably weaker with this final low, suggesting there may be greater uncertainties with this low than the current deterministic runs suggest. For days 4-6, the WPC blend leaned closely to the ECMWF and GFS (slightly more weighting on the ECMWF) with smaller ensemble mean proportions. Beyond, the blend increased to a 50/50 contribution between the ensemble means and the GFS/ECMWF deterministic solutions. This maintained good continuity with yesterdays WPC forecast for days 4-7 as well. ...Weather/Hazard Highlights... The deep layer southerly flow will bring in significant moisture (precipitable water values generally +1.5 to +2.5 standard deviations above normal) into Alaska for the first half of the week. The highest precipitation totals are likely from the Alaska Peninsula into Southcentral Alaska and spreading eastward into mainly northern parts of the Alaska Panhandle. A period of gusty winds are also likely for locations along the southern coast. Some snow should also spread into the western part of the mainland as well as the ridge breaks down and a cold front presses inland. Across the mainland, a drier trend is likely by Thursday/Friday as high pressure builds in. However, wet conditions should continue across the Panhandle region through much of the week as moist flow continues ahead of various systems in/near the Gulf. The central-eastern Aleutians should also see an increase in moisture by later next week and potentially stronger winds, as a deep surface low or two impacts the region. Widespread much above normal temperatures will continue through at least next Monday underneath the upper-level ridge, with temperatures 15-30F above average (locally higher) for much of the mainland except the far western part. Temperatures will moderate closer to normal and even shift to below normal from west to east on Tuesday through Thursday as the ridge moves away from the state. Santorelli Hazards: - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sun-Mon, Jan 23-Jan 24. - High winds across portions of the Alaska Panhandle and mainland Alaska, Mon, Jan 24. Additional 3-7 Day Hazard Information can be found on the WPC medium range hazards outlook 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