Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 631 PM EDT Sat Nov 04 2023 Valid 12Z Wed Nov 08 2023 - 12Z Sun Nov 12 2023 ...Multi-day Heavy Precipitation Threat from Southern to Southeast Alaska later next week... ...Guidance Evaluation and Preferences... Guidance solutions remain reasonably well clustered through medium range time scales. A preferred composite of the 12 UTC GFS/ECMWF/UKMET/Canadian models and the 12 UTC GEFS/NAEFS/ECMWF ensemble means seems to offer a good forecast basis in a pattern with seemingly above normal predictability and continuity. Guidance run to run trends toward slightly slower progressions again today seems reasonable given the amplified nature of the surrounding upper flow. Manual adjustments applied to the composite deepen best signal supported systems as consistent with individual predictability as an offset to the inherent weakening as per the blending process. Additional manual adjustments to the composite blend increased winds to better match deepened system flows and collaborated thresholds. QPF and PoPs were also adjusted to favor windward versus leeward slopes. WPC product continuity is overall well maintained with this forecast strategy. ...Overview and Weather/Hazards Highlights... A series of dynamic/amplified upper troughs and deepened surface lows/frontal systems are expected to work from the southern Bering Sea and northern Pacific into and across the Gulf of Alaska next week. A lead storm in this forecast period is expected to work across the Gulf of Alaska Wednesday/Thursday with another hot on its heels on a likely track from the southern Bering Sea/Aleutians through the Gulf of Alaska Thursday into next weekend. Yet another storm may reach the Bering Sea in this pattern later next weekend. All these systems offer protracted maritime wind/wave threats. High winds and a deepened lead/rotating moisture feed looks to increasingly fuel development of an emerging heavy precipitation pattern, especially from Southcentral to Southeast Alaska. This will include threats for heavy coastal rains and inland/mountain snow, with ample precipitation totals and impacts accumulating midweek through next weekend. Meanwhile, lingering lowered heights and periodic pockets of modest moisture rotating over an unsettled Interior and North Slope may support scattered light snows next week with protracted easterly fetch winds offering blowing snow situations to monitor locally. Schichtel Additional 3-7 Day Hazard Information can be found on the WPC medium range hazards outlook 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