Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 630 PM EDT Fri Aug 26 2022 Valid 12Z Tue Aug 30 2022 - 12Z Sat Sep 3 2022 ***Heavy rain and flooding becoming more likely for portions of southeast Alaska next week with multiple atmospheric river events*** ...General Overview... An active weather pattern is expected across the Alaska domain for next week, with a gradually weakening upper low situated over the Gulf for early in the week, and then a strong storm system is progged to cross the Bering and affect western Alaska by the middle of the week. Much of the region remains within a broad upper trough by the end of the forecast period, with upper ridging across central/western Alaska tending to keep the trough in place for longer than usual. ...Guidance/Predictability Assessment... The 12Z guidance suite remains in above average agreement on the synoptic scale through Thursday night, and thus a multi-deterministic model blend worked well as a starting point. By next Saturday, the GFS becomes stronger with the next Gulf low taking shape, and thus more weighting was applied to the ECMWF/CMC along with increasing contributions from the GEFS/ECENS. This maintains good continuity from the previous WPC forecast. ...Sensible Weather and Potential Hazards... A highly impactful and long duration heavy rainfall event is likely across portions of the southeast Panhandle region next week, with multiple atmospheric rivers impacting the region. There will likely be some lulls during this time period. Anomalous moisture flux oriented nearly orthogonal to the terrain will likely lead to daily 1-3 inch rainfall maxima for the southern portion of the Panhandle, and weekly totals reaching into the 6-12 inch range are well within the realm of possibility for interior portions of the panhandle bordering British Columbia. This could lead to some serious flooding issues, and this is something that will continued to be closely monitored. Elsewhere across the state, isolated to scattered showers are possible each day as the overall weather pattern remains unsettled. In terms of temperatures, readings are likely to be below average for most areas with highs generally in the 50s for western Alaska, and 60s for east-central Alaska, and lows mainly in the 40s south of the Brooks range. Hamrick Hazards: - Heavy rain across portions of the Alaska Panhandle and southern mainland Alaska, Mon-Fri, Aug 29-Sept 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