Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 411 PM EDT Mon Apr 23 2018 Valid 12Z Fri Apr 27 2018 - 12Z Tue May 1 2018 ***Guidance/Uncertainty Assessment*** The medium range period begins on Friday with a lower than average level of model agreement that only increases in time through next weekend and into early next week. There is general agreement on the rapid weakening of the Bering Sea low that will be in place through much of this week. The CMC is differing from the model consensus as early as Saturday with a lead surface low crossing the Bering Sea, whereas the ensemble means keep low pressure much farther to the west. Since these differences with the CMC escalate with time, it was not used in the forecast process. The GFS and its ensemble mean are farther south with the surface high over the north Pacific and is a change from WPC forecast continuity. However, it is closer to the consensus with the main surface low over eastern Siberia. Given that the ECMWF is more in line with the ensemble means over most of the forecast domain, it was preferred over the GFS for this portion of the forecast period. ***Weather/Threats Highlights*** For Friday into the weekend, mostly dry weather is expected for most areas with high pressure governing the overall weather pattern. Strong winds may affect the central and western Aleutians later in the period as the strong low over eastern Siberia begins to exert its influence over the Bering Sea and northern Pacific. Precipitation chances also increase for the western third of the state by Saturday as this system gets gradually closer. The coldest temperatures, as expected, should be confined to north of the Brooks Range, and gradually moderating readings across most of the Interior. 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 www.wpc.ncep.noaa.gov/alaska/akmedr.shtml http://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html D. Hamrick