Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 758 PM EDT Sun Oct 15 2023 Valid 12Z Thu Oct 19 2023 - 12Z Mon Oct 23 2023 ...Synoptic Overview... There will several main storm systems of interest going into the extended forecast period. The first will be the extratropical low associated with former Typhoon Bolaven, and this low is forecast to be over the Gulf of Alaska by the middle of the week and bring rain to the southeast Panhandle region through Thursday. The second system will be a low crossing the central/western Aleutians that will settle south across the North Pacific and well away from the mainland. The third will be an amplified arctic upper trough/closed low that will envelop much of the mainland by the end of the week, and this will herald the arrival of colder weather. There will likely be another low pressure system approaching the Bering Sea region by Monday of next week. ...Guidance Evaluation and Preferences... The 12Z model guidance suite is generally in above average agreement through Friday across the Alaska domain, and decent synoptic scale agreement exists going into the weekend as well. 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. However, there is greater model uncertainty with a potential secondary reinforcing arctic trough across northern Alaska, and also with a potential storm system by next Monday that originates from eastern Siberia. The WPC forecast was primarily derived from mainly a GFS/ECMWF compromise along with some CMC and UKMET through Friday, and then greater incorporation of the ensemble means going into the weekend and next Monday, accounting for about 50% of the mix by next Monday. . ...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. Winds could also be an issue with this event for the southern portion of the panhandle with wind gusts of 40-50 mph possible near the coast early on Thursday. This will abate 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. Hamrick 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