Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 338 PM EDT Thu Nov 01 2018 Valid 12Z Mon Nov 05 2018 - 12Z Fri Nov 09 2018 ...Guidance and Predictability Assessment... For the start of the medium range period for Alaska, models are in good agreement and by Day 6, differences become quite apparent. To start, on Monday and into Tuesday, the upper level ridge builds across eastern Alaska while an upper level low slides southeastward into the Bering Sea. By midweek, these features stay put while another upper level low moves into the Gulf of Alaska. Overall, both the 12Z GFS and the 00Z ECMWF agreed with the timing and placement of these features. By Thursday and Friday, the GFS and ECMWF began to deviate. On Thursday, the ECMWF was very aggressive with forming a closed upper level low over the Aleutians, while the GFS just had this feature rotating along the base of the low over the Bering Sea. This was reflected at the surface, forming a deepening low over the Aleutians. Meanwhile, the GFS is faster with the height rises over the western portions of the Aleutians in addition to the upper low upstream over Siberia--which continues into Friday. The 06Z parallel GFS seemed to be a good compromise between the two. WPC ended up with a blend of the 12Z GFS/00Z ECMWF along with the 06Z GEFS ensemble mean/00Z ECMWF ensemble mean through day 6. By day 7 and 8, increased the use of the ensemble means and used some 06Z parallel GFS for detailing. ...Weather/Hazards Highlights... The Alaska Panhandle will start out with the most active weather across the state with rain across the coastal areas and snow farther inland. As the ridge builds across the eastern half of Alaska, conditions will stay dry late Monday and into Tuesday. Precipitation chances will increase across Southwest Alaska and the western portions of the Far North as the upper low moves into the Bering Sea. With temperatures still mild across Southwest Alaska, rain along the coast can be expected with snow farther inland and in the Far North. Precipitation chances will remain in the forecast for the Aleutians eastward into south-central Alaska and the Panhandle as multiple systems track across these areas. Southwest Alaska and the Juneau region will continue to be mild through the week with high temperatures climbing to the mid 30s-40s. The Far North will experience high temperatures in the mid teens to single digits; the rest of Alaska will have high temperatures in the mid 20s to low 30s. Reinhart WPC medium range Alaskan products including 500mb, surface fronts/pressures progs and sensible weather grids can be found at: http://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif http://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml http://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html