Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 637 PM EDT Fri Jul 10 2020 Valid 12Z Tue Jul 14 2020 - 12Z Sat Jul 18 2020 ...Overview and Weather/Hazard Highlights... A relatively progressive flow pattern looks to persist across the North Pacific through much of the extended forecast period, with Alaska on the northern periphery of this area. Ensemble guidance suggests a gradual amplification of the flow over time, with troughing becoming more prominent across the Aleutians, and ridging building north into the Gulf of Alaska and Southeast Alaska by late next week. An area of low pressure over the Gulf of Alaska Tue will bring showers to Southeast Alaska before the system moves inland. Farther west, another low pressure system is expected to cross the Aleutians through the mid to latter part of next week, bringing an increase in showers and perhaps some gusty winds - although model spread with respect to this feature was relatively high and confidence in the details of the forecast is below average. Farther north, the setup across the North Slope an portions of the Interior will be a rather chaotic one, with an arctic upper low initially north of the Bering Strait retreating westward through time, and a rather murky picture of what happens in its wake, but with some potential for additional arctic shortwave energy to move southward and affect northern Alaska, keeping some risk for scattered showers and below average temperatures in place. ...Guidance/Predictability Assessment... Model/ensemble guidance showed relatively good consensus early in the extended forecast period, but this degraded quickly at the smaller scales over time, despite some consensus on the described amplifying large scale pattern across the North Pacific next week. The 12Z CMC/ECMWF showed perhaps the closest fit with the overall consensus early on, and a blend of these solutions served as a basis for the WPC forecast during days 4-5 (Tue-Wed). After that, weight placed on ensemble means (ECENS and NAEFS) was increased through time, and served as a majority of the forecast blend from day 6 (Thu) through day 8 (Sat). This ensemble-heavy blend later in the forecast period served to smooth out what were some rather large differences among the deterministic guidance when it comes to the timing/intensity of individual, smaller-scale systems with low predictability. Ryan 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 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