Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 619 PM EST Fri Nov 15 2019 Valid 12Z Tue Nov 19 2019 - 12Z Sat Nov 23 2019 ...Very Stormy Alaskan Pattern Next Week... ...Guidance/Uncertainty Assessment... Ensemble and model guidance seems fairly well clustered through much of next week with the overall larger scale pattern evolution aloft and for the most part, a number of potentially deep/well-organized and heavy weather focusing embedded systems within the flow. Forecast confidence is building for these deep lows. The WPC product suite was primarily derived from a composite blend of the 12 UTC GFS/ECMWF and 12 UTC GEFS/NAEFS/ECMWF ensemble means. The blending process typically weakens offshore lows too much, so these systems were manually adjusted to better fit a patterm with seemingly good continuity and model upper support. This forecast strategy was collaborated with the local Alaskan forecast offices. ...Weather Highlights/Threats... A leading deep surface low will track from the Aleutians/southern Bering Sea to southwest/western Alaska Tuesday-Wednesday, then gradally weaken inland Thursday. A second system follows on its heels mid to late next week. Both systems offer a significant maritime threat for high winds/waves, with moisture expected to wrap onshore to sustain some threat of locally heavy precipitation/winds in proximity to and well ahead of the deep lows/frontal systems across the Gulf of Alaska and into southern and southeast Alaska where the heaviest precipitation is expected. The inland threat will focus over favored mountains and coastal terrain. Schichtel 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: - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Mon-Thu, Nov 18-Nov 21. - High winds across portions of the Aleutians, Wed-Thu, Nov 20-Nov 21. - High significant wave heights for coastal portions of the Aleutians, Mon-Wed, Nov 18-Nov 20. 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