Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 615 PM EST Sun Feb 16 2025 Valid 12Z Thu Feb 20 2025 - 12Z Mon Feb 24 2025 ...Overview... A parade of shortwaves and surface lows rounding the base of a broad trough/upper low in the Bering Sea/Aleutians will continue to bring an active/wet pattern to coastal portions of Alaska, particularly the Southern Coast and into the Southeast/Panhandle. The guidance shows three main lows within this pattern - the first towards the Kenai region on Thursday, the second into the southern Panhandle around Friday, and the third into the Gulf/Southern Coast Sunday into Monday. This should bring daily chances for moderate to heavy precipitation to these regions. Meanwhile, upper ridging will persist over much of the Mainland, bringing a period of much above normal temperatures across the state. ...Guidance Evaluation and Preferences... There continues to be general agreement on the large scale pattern described above, but a lot of variability and uncertainty with individual lows and shortwaves into the Southern Coast and Panhandle. This lends still to a low confidence forecast in the specifics, including track and intensity of any given low, but there is increasing consistency in the low pressure systems described above. This generally sets up a pattern of persistent onshore flow into Southeast Alaska. There was enough agreement early in the period for a multi-model blend. But increasing variability in low placements and tracks forced a gradual increase in the ensemble means into the blend by later in the period. The Day 8 blend included 70 percent ensemble means with 30 percent total of the 12z GFS, ECMWF, and CMC. This approach maintained reasonable continuity with yesterdays WPC forecast as well. ...Weather/Hazards Highlights... A heavy rain threat will be ongoing across the Kenai Peninsula/Prince William Sound and vicinity by the middle to latter part of next week, as a surface low lifts towards the region. Heavy rainfall is possible along the immediate coast, but heavy snow is possible in the higher terrain. The threat may wane some later in the weak, but remain wet, and increased precipitation is again expected later in the weekend to early next week as another low skirts towards the region. The most widespread focus for moderate to heavy rainfall will be for the Southeast/Panhandle region as ample moisture is directed into this region ahead of a parade of shortwaves. Elsewhere, the Alaska Peninsula to Aleutians should be generally wet and unsettled underneath of the parent upper low. A weak front through the interior portions of the state may also bring some light showers to some places. Upper ridging persisting through the period will keep temperatures well above normal through the period, with some locations across southwest and southern Alaska possible to see daytime highs 20 to 30 degrees above normal. The exception to this may be the North Slope region where temperatures could be near to below normal underneath some weak upper troughing. Santorelli 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