Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 642 PM EDT Fri Sep 09 2022 Valid 12Z Tue Sep 13 2022 - 12Z Sat Sep 17 2022 ...Heavy precipitation threat for south-central and southeast Alaska early to mid next week... ...Guidance/Predictability Assessment... The 12 UTC GFS/ECMWF/UKMET/Canadian solutions seem reasonable and well clustered Tuesday into Wednesday from the Bering Sea through the state into the Gulf of Alaska in amplified/energetic flow, but forecast spread increases rapidly midweek to next weekend with uncertain upstream system and stream interactions, including with a west Pacific tropical connection. The 12 UTC GEFS/ECMWF ensemble means solutions are in contrast compatible Wednesday into next Saturday and remain better in line with WPC product continuity at the cost/benefit of blending out embedded small-mid scale systems consistent with predictability. This includes a possible late week low lifting toward the state with a possible tropical origin (93W). ...Pattern Overview and Weather/Hazards Highlights... There is a strong guidance signal that ample energies associated with a deep upper level low/surface cyclone in the Bering Sea will increasingly transfer into the Gulf of Alaska Tuesday into Wednesday. This will keep much of south-central and southeast Alaska wet and unsettled. Onshore winds ahead of an occluded cyclone and cold front moving through the Aleutians and into the Gulf of Alaska will transport moisture and help focus several days of rainfall, heavy at times, along the southern Coast and inland, with heavy snow in the higher elevations. Multi-day rainfall totals of 3 to 4+ inches are possible. Heaviest rainfall then should move to the Panhandle, with a lull mid to late next week across the southern Coast. Details remain less certain, but there is an emerging guidance signal that upper level ridging should meanwhile build back across the Aleutians/Bering Sea in response to approach of an upstream upper low into Wednesday/Thursday along with a rapidly deepening surface low/frontal system. This system offers an increased chance of enhanced rain, winds, and maritime threats offshore and across the Aleutians. The main threat focus may be enhanced with an uncertain influx of tropical system/moisture that may be slated to subsequently work downstream towards Southwest Alaska, the Akpen, Kodiak Island then across the Gulf of Alaska and into south-central Alaska Thursday/Friday then the Panhandle by next weekend. Schichtel Hazards: - Heavy rain across portions of mainland Alaska, Mon-Tue, Sep 12- Sep 13 and Fri, Sep 16. - Heavy rain across portions of the Alaska Panhandle and mainland Alaska, Tue-Wed, Sep 13- Sep 14. - Heavy rain across portions of mainland Alaska, Fri, Sep 16. 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