Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 340 PM EDT Wed Apr 10 2019 Valid 12Z Sun Apr 14 2019 - 12Z Thu Apr 18 2019 There is general agreement in the guidance that a moderately progressive North Pacific pattern should transition toward a slower and more amplified regime, highlighted by a mean trough around 150-160W longitude by next Wed-Thu. Supported by energy initially just upstream from the northwestern mainland, mean troughing may also develop along the western coast of the mainland. Within this consensus evolution there are multiple detail/phasing uncertainties that considerably lower confidence in specific details. Thus while the pattern should eventually favor increasing precipitation chances along the Panhandle and southern coast, the precise timing and magnitude of the precipitation are unclear. One notable change from yesterday involves the combination of short range upper low energy over the northwestern mainland and initial energy over the Gulf, with latest trends leading to a more persistent Gulf low aloft during Sun-Mon. At the same time there has been a trend toward a more consolidated upper system reaching the central Pacific by day 5 Mon (possibly interacting with some lingering Aleutians energy). This ultimately leads to slower progression of low pressure that tracks south of the Alaska Peninsula and Kodiak Island. During the latter half of the period a further complication comes into play with potential eastern Siberia into eastern Bering/western mainland upper low energy (more prominently signaled in operational guidance so far) and/or upstream energy possibly interacting with the North Pacific trough. Yet another significant wild card will be an initial central Pacific wave. Some solutions like the 00-06Z GFS/00Z CMC phase it with the upper system south of the eastern Aleutians and Peninsula around Tue-Wed, while the 12Z GFS and faster 00Z ECMWF keep the wave separate with a track to or just south of the Panhandle. This wave gets lost in the means but the means do have a modest weakness that could in theory contain a progressive wave. Today's forecast incorporated various ideas from the models and ensemble means in an attempt to reflect the most agreeable aspects of the guidance while downplaying or reflecting a compromise for more contentious details. The first part of the period tilted somewhat more toward the 00Z ECMWF/00-12Z GFS relative to the 06Z GEFS/00Z ECMWF means, followed by greater ensemble mean weight later. Some NAEFS was also included mid-late period due to being a little deeper with low pressure than the GEFS mean. Rausch Bullet points from the WPC Days 3-7 Hazards chart can be found at: https://www.wpc.ncep.noaa.gov/threats/threats.php - 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