Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 629 PM EDT Mon Oct 16 2023 Valid 12Z Fri Oct 20 2023 - 12Z Tue Oct 24 2023 ...Synoptic Overview... The extratropical low associated with former Typhoon Bolaven will continue to bring unsettled weather to portions of Southeast Alaska through Thursday. Meanwhile, another area of low pressure will cross the central/western Aleutians before settling southward over the North Pacific and drift away from the Mainland. Otherwise, by the end of the week into the weekend, a strong cold front and upper troughing will bring much colder temperatures to the Mainland before another system is set to move through the Bering Sea early next week. ...Guidance Evaluation and Preferences... The 12Z model guidance suite is generally in above average agreement across the Alaska domain, including through the weekend and into early next week. There has been a solid model trend for the low crossing the central Aleutians to continue tracking southeast away from the state as a result of the strong cold front moving off the mainland while the upper level pattern keeps troughing in place through the weekend. By early next, guidance is coming together that strong upper level ridging will move across the Aleutians and extend into portions of southwest Mainland, all ahead of a stronger low pressure system crossing eastern Russia into the Chukchi Sea by Monday/Tuesday. There is some timing and strength differences among the 12Z guidance, so the preference there was to lean on the ensemble means. The WPC forecast was primarily derived from mainly a GFS/ECMWF compromise along with some CMC and UKMET through Sunday, and then greater incorporation of the ensemble means into early next week, accounting for about 50% of the mix by next Tuesday. ...Weather and Hazards Highlights... A prolonged moderate to heavy rainfall event is expected to begin tapering off going into Thursday across the southeast Panhandle, with an enhanced moisture flux directed towards southern portions of the Panhandle region. Total rainfall from the entire event are likely to be on the order of 3 to 6 inches, and locally higher for the coastal terrain. The system winds down going into Friday and the weekend with the low steadily weakening and moving inland. Temperatures are expected to become much colder across most of the state as the strong cold front associated with the arctic trough sweeps across the state from northwest to southeast. Highs will likely remain below freezing across most of the Interior, and low to mid 30s for highs including the greater Anchorage metro area, to close out the week and going into the weekend. There will probably be some sub-zero overnight lows for the normally colder locations of the North Slope and the Yukon Flats where radiational cooling can be maximized. The next stronger system will move across the western Mainland early next week, spreading a mix of rain and snow though it should be relatively light in intensity. Hamrick/Taylor 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