Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 759 PM EDT Wed Nov 01 2023 Valid 12Z Sun Nov 05 2023 - 12Z Thu Nov 09 2023 ...Overview with Guidance Evaluation and Preferences... Relatively benign weather is anticipated for much of mainland Alaska through the medium-range period as the Alaskan domain remains sandwiched between an omega block over the Arctic Ocean and a large-scale cyclonic circulation passing at some distance south of the Gulf of Alaska. Meanwhile, an upper low caught in between the aforementioned regime is forecast to linger near the west coast of Alaska but without too much in the way of active weather. Much of the model uncertainty has been associated with the cyclonic circulation(s) south of the Gulf of Alaska for much of the forecast period, though the agreement among the model solutions has improved in the past few runs. The ECMWF continues to favor a separate and stronger cyclone to head closer toward the coast of British Columbia and the southern Panhandle of Alaska late this weekend into early next week, with the EC ensemble mean showing a slower progression of this cyclone. On the other hand, the GFS and CMC continue to favor binary interaction with another cyclone center farther to the west, resulting in a single deep cyclone farther offshore. By the middle of next week, ensemble means (GEFS, EC mean, and CMC mean) are in fairly good agreement to slide the upper low near the west coast of Alaska southeastward and merge with the large-scale cyclone south of the Gulf of Alaska. The merger and interactions appear to reinvigorate and expand the large-scale the cyclone offshore. Meanwhile, a more persistent southerly flow in the mid to upper-levels is becoming more evident across the southern Alaskan coast, as a more vigorous shortwave across the North Pacific passes to the south of the meandering upper low near the west coast of Alaska. This persistent and deepening southerly flow regime will be monitored for raising the potential of heavy precipitation near the southern coastal sections of Alaska by midweek next week. Thus the WPC forecast for the Alaskan domain was based on a 40% blend of the 06/12Z GFS and 12Z GEFS, with 40% of the 12Z ECMWF and 00Z/12Z EC mean, and 20% of the 12Z CMC and CMC mean, transitioning to mostly a blend of the GEFS/CMC/EC ensemble means by Day 8. ...Weather and Hazards Highlights... Precipitation across the state should be generally light through the forecast period, with the southern perimeter of the state expected to receive the highest amounts of precipitation. Portions of the Kodiak Island into the Kenai Peninsula could see some enhanced totals late this weekend into Monday when a shortwave is forecast to round the base of the meandering upper low near the west coast of Alaska. In terms of precipitation types, rain is expected in the lower elevations and some snow in the Southcentral. Toward the middle of next week, persistent and deepening southerly flow from the Pacific could result in an increasing threat of heavy precipitation reaching the south-central perimeter of Alaska. Temperatures will generally be slightly above normal from the interior Alaska southward, and above normal across the North Slope. Western Alaska will likely be near or slightly cooler than normal under the meandering upper low. Kong No significant hazards are expected over Alaska during this forecast period. 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