Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 936 PM EDT Sat Aug 28 2021 Valid 12Z Thu Sep 02 2021 - 12Z Mon Sep 06 2021 ...Heavy rainfall possible for portions of the southern Coast region during the middle part of next week... ...Pattern Overview and Model Guidance... The models are still handling this evolution fairly well during the extended period given the typical spread on specific details. A combination of the 12Z ECWMF/CMC/GFS has been the preferred starting point recently and still seems to be the path solution. The inclusion of the ensemble means increase through the middle and later periods. During the extended period ridging will be in place over much of the interior and southeast and will shift eastward as a upper trough progresses across the Aleutians into the Gulf of Alaska. As this happens an upper low will begin to settle in over the Bering Sea and a series of short waves will pass through the base of the trough, spinning up a couple of surface fronts that will track across the Aleutian Chain and into southern coast/Alaska peninsula. Meanwhile, to the north, a strong polar vortex and associated mid-level westerly flow will be in place across the Arctic and North Slope early in the week before heights begin to rise again across the region and the Polar Vortex retreats to the north. ...Sensible Weather... Temperatures will be below seasonal average across the northern and central parts of the state near a draped boundary. High pressure will keep much of the interior and parts of the panhandle drier. By Friday, much of the state could have daily temperature near or above normal underneath of amplified upper-level ridging. Rain is expected to track from the peninsula to the southern Mainland as a low pressure system lifts into the eastern Bering Sea, as it's attendant cold front drifts eastward through the Gulf. During this time, there will be periods where the rain will be moderate to heavy, especially from upper portions of the peninsula, Kodiak Island, Kenai and the Cook Inlet into Friday. The heavier rain may reach into far southeast Alaska late Friday and through the weekend. These areas may also experience gusty winds. Campbell Hazards: - Heavy rain across portions of southern Alaska, Wed-Thu, Sep 1-Sep 2. 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