Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 549 PM EST Fri Mar 12 2021 Valid 12Z Tue Mar 16 2021 - 12Z Sat Mar 20 2021 ...Overview and Guidance/Uncertainty Assessment... The latest guidance continues to suggest a blocky pattern early in the period from the Bering Sea through much of the eastern Pacific. Here, the latest deterministic guidance shows reasonable agreement for day 4 and day 5 and blends well from continuity. By day 6 however, there is increasing model spread with respect to the evolution of shortwave energy around 160W and its phasing with northern stream energies. The GFS and GFSP were quicker to lift this feature through the Aleutians while the ECMWF/CMC hold it back and lift it more to the north/northwest. Downstream effects from the GFS mean a faster/flatter flow over the eastern Pacific developing by day 7 while the ECMWF/CMC offer a more blocky amplified solution. At the surface, a couple waves of low pressure will lift toward the southeast coast and southern mainland early in the period then with some ridging expected to develop aloft for day 6-8, a more benign stretch of sensible weather is forecast. The WPC blend consisted of the 12Z ECMWF/CMC/GFS/UKMET blend for day 4 and day 5 followed by mostly a ECENS/NAEFS blend for day 6-8. ...Weather/Hazards Highlights... Aside from possible waves of low pressure brushing or affecting the southeastern coast and Panhandle early on, the rest of the period is increasingly looking relatively quieter from a sensible weather perspective, especially for most of the mainland. Aside from the North Slope (where temperatures are forecast to be above normal), the rest of the region is expected to see slightly below normal temperatures. Rausch/Taylor No significant hazards are expected over Alaska during this forecast period. 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 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