Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 604 PM EST Wed Nov 04 2020 Valid 12Z Sun Nov 08 2020 - 12Z Thu Nov 12 2020 ...Guidance/Predictability Assessment... Successive troughing is forecast to push through much of the state in progressive flow next week, squashing upper ridging at times nosing out of the northeastern Pacific into eastern/southeastern areas. The 12Z guidance offered reasonable clustering to start the period Sunday as a system out of the north central Pacific moves across the AKPen/southwestern areas. Guidance still diverge on where to track the parent low before the triple point low takes over into the Gulf and how quickly the front will progress eastward, perhaps slowed by a surface wave on the southern portion (per the GFS). Opted to form a consensus of the models, though varied, which maintains the general continued thinking that the parent low will weake across western coastal Alaska and the triple point takes over near Kodiak to move eastward into the Panhandle around early Monday. To the north, a boundary should linger/waver astride the North Slope and Brooks Range as the old upper trough weakens ahead of the next Bering system. Late Sun into early Mon, next Bering system will move in from the west toward the Bering Strait. Models/ensembles remain rather diverse with embedded features within and around the larger trough/upper low leading to low confidence in details. Preferred to maintain the more simplified depiction of the system taking the parent low toward the Bering Strait, the cold front into western areas, and the triple point redeveloping near the Kenai peninsula around late Tue into early Wed. Trended to solely an ensemble mean blend between the 12Z GEFS mean and 00Z ECMWF ensemble mean with only a small minority 12Z ECMWF weighting as it was the closest of any model to the means. At the least, this was again close to continuity from 24 hrs ago. Troughing may carry a weak cold front around its southwest/south side at the end of the period. ...Weather/Threats Highlights... Modest to locally heavy coastal rain and inland snow will accompany the lead system Sunday over southwestern portions of the state. Precipitation may be heavy especially in terrain-favored areas with several inches (liquid) possible. Heavy snow is also possible in some areas that stay cold enough. In-house bias-corrected QPF shows 2-4 inches over southeastern Kenai eastward toward Yakutat and some locally higher amounts into Mon (4-6"). Next system over/near the western to central Bering Sea Mon-Tue should spread another area of precipitation and strong winds across the Bering Sea/Aleutians. This will move into Southcentral by mid week next week but perhaps with less precipitation than the lead system Sunday. However, this may bring significant precipitation to western areas from the Y-K Delta northward to Kotzebue as milder air surges north-northeastward in advance of the cold front. Above normal temperatures are forecast to remain over much of the Interior (generally west and north of the Alaska Range) next week. By contrast, below normal temperatures are expected over the Panhandle and southeastern areas. Fracasso Additional 3-7 Day Hazard information can be found on the WPC medium range hazards chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php Hazards: - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sun-Mon, Nov 8-Nov 9. 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