Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 800 PM EDT Tue Oct 11 2022 Valid 12Z Sun Oct 16 2022 - 12Z Thu Oct 20 2022 ...Another round of heavy precipitation expected for southern coastal Alaska into the northern Panhandle this weekend into Monday... ...Overview and Guidance/Predictability Assessment... Another moisture plume from a weakening cyclone over the northeastern Pacific is forecast to be directed northward ahead of a relatively slow-moving occluded low over the Aleutians to bring the next round of heavy rain toward the southern coastal sections and the northern Panhandle by this weekend. Model guidance today remains in good agreement on this scenario, with perhaps a slight tendency for the heavy precipitation to linger into Monday. Behind this system, the next cyclone from the central Pacific, this time with at least partial connection with a tropical system, is forecast to deepen as it tracks generally toward the Gulf of Alaska early next week. The GFS and CMC take this system on a more northeastern course toward the Alaska Peninsula while the ECMWF (including the 12Z run) takes it more of a east-northeast course toward the Panhandle by midweek. The EC mean, on the other hand, places the cyclone center much farther west than its deterministic solution, which is in much better agreement with the GEFS mean and the CMC mean. The EC mean is still east of the GEFS mean and the CMC mean positions of the cyclone center though. Thus, a minimal amount of ECMWF was included in today's blend for Days 5-7, in favor of the ensemble means. The blend begins with 40% from the 12Z GFS/12 GEFS, 40% from the 12Z ECMWF/12Z EC mean, along with 20% from the 12Z CMC/12Z CMC mean, transitioning to mostly a blend of the ensemble means by Day 8 (with minimal amount of 12Z EC for Days 5-7 as noted). The resulting solutions are in very good agreement with yesterday's Alaskan forecast products. ...Weather/Hazards Highlights... The next surge of Pacific moisture is expected to reach the southern coastal Alaska into the northern Panhandle on Saturday, with heavy rain at lower elevation and heavy snow over high terrain. A few inches of liquid precipitation amounts can be expected each day through the weekend before a tapering trend sets in by Monday. For areas farther inland, periods of freezing rain an/or sleet can also be expected over the lower elevations downwind from the Alaska Range. Gusty winds may be a concern, but the surface low is not forecast to be significantly strong enough to cause widespread issues. Lighter snow is forecast to spread farther north into northern Alaska by Monday. Behind this round of heavy precipitation, a break in the activity can be expected before the next round of possiblly heavy precipitation associated with the next cyclone reaches the southern coasts and into the Panhandle by next Wednesday. Kong 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 Hazards: - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sat-Mon, Oct 15-Oct 17. 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