Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 659 PM EST Wed Jan 18 2023 Valid 12Z Sun Jan 22 2023 - 12Z Thu Jan 26 2023 ...Next wave of heavy precipitation to reach the southern coast and Panhandle late Sunday with heavy precipitation threat continuing through midweek... ...Synoptic Overview and Sensible Weather... The medium-range forecast period will begin on Sunday as an occluded cyclone rapidly dissipates near the southern coastline where precipitation is expected to taper off further. Some residual moisture from this system should make it northward into northeastern Alaska and precipitate as light snow on Sunday ahead of an arctic upper low which is forecast to dig into northwestern Alaska. Meanwhile, the next occluded cyclone of concern will begin to edge closer toward the Aleutians on Sunday. The main energy associated with this system is forecast to shear off to the east and bring the next surge of Pacific moisture toward the Gulf Coast. Heavy rain near the immediate coast along with heavy mountain snow will once again impact the southern coastal sections into the northern Panhandle beginning Sunday night and into Monday. Winds are expected to increase near and just off the Gulf Coast Sunday night as something resembles a triple-point low develops. Thereafter, models agree that onshore flow from the south will be maintained through midweek next week. This will keep the Gulf Coast region under a prolonged threat of heavy precipitation from the southern coastline to the Panhandle, especially when low pressure waves form just off the coast. In addition to the influx of moisture, the onshore flow will likely keep temperatures relatively mild by January standards across southern Alaska, especially near the coast. The coldest weather is expected to be north of the Brooks Range where subzero high temperatures are likely most days. ...Model Guidance Assessment... The 12Z model guidance suite has a very good overall depiction of the synoptic scale pattern pattern as described above across the Alaska domain through the medium-range period. Both the ECMWF/EC mean and the GFS/GEFS support a cyclone track farther to the southeast off to the south of the Aleutians Sunday night versus a more northerly track by the CMC. A blend of the EC & GFS is preferred, allowing more energy from this system to shear off to the east toward the southern coastline and the Panhandle. This has decreased the heavy precipitation threat across the Alaska Peninsula but increased the threat across the Panhandle. The WPC forecasts begin with a 40% blend of the 12Z ECMWF/00Z EC mean, 40% 12Z GFS/GEFS, and 20% 12Z CMC/CMC mean. The CMC is gradually eliminated by Day 6 in favor of the EC mean/GEFS solutions toward the end of the forecast period. This scheme yielded a solution compatible with the previous WPC forecast package but allowed low pressures to advance toward the Gulf of Alaska ahead of the cyclone south of the Aleutians. Kong Hazards: - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sun-Wed, Jan 22-Jan 25. 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