Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 629 PM EDT Tue May 12 2020 Valid 12Z Sat May 16 2020 - 12Z Wed May 20 2020 Pattern Overview ________________ An Arctic high will funnel cooler mainland temperatures for much of the North Slope and Interior. A lead main low will pass through the Gulf of Alaska, but well south of the Mainland. Several subsequent lows are expected to pass through the Aleutians/Southwest AK and emerge into the Gulf this upcoming weekend through next midweek. Guidance/Predictability Assessment __________________________________ The WPC medium range Alaskan product suite was primarily derived from a composite blend of reasonably well clustered guidance from the 12 UTC GFS/ECMWF days 4-7 and the 19 UTC National Blend of Models in a pattern with above average forecast predictability. Also included in the composite blend some input from the 12 UTC ECMWF ensemble mean days 4-7 for smaller scale consistency, but especially by day 7 into 8 amid growing forecast spread and uncertainty with embedded weather systems. ECMWF ensembles seem more in line with the 12 UTC GFS/ECMWF than the 12 UTC GEFS. WPC continuity in the larger scale flow evolution was reasonably well maintained. Weather/Hazard Highlights _________________________ Expect cooler temperatures over a majority of the mainland over the upcoming week. Above normal readings should decrease in coverage and become more confined to southern/western areas of the state while the pattern will gradually become more favorable for below normal temperatures over northern and eastern areas. Expect significant precipitation to be fairly limited in coverage during the period owing to the southern extent of the oceanic lows and the surface high governing the overall weather pattern for central and northern sections. A front settling across the southern mainland may focus some activity at times while light precipitation may reach northeastern areas next weekend with the arrival of upper troughing. As the leading Gulf of Alaska system progresses, expect its track to remain far enough south for only limited moisture to reach the southeast Alaska Panhandle. Subsequent organized systems tracking over the western Pacific should bring moisture and wrapping rainfall Sunday-next midweek mainly into the Aleutians/Southeast Bering Sea then the AK Peninsula/Southwest AK. These lows will also offer a maritime hazard. Schichtel 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: No significant meteorological hazards are expected over Alaska during this forecast period. 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