Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 730 PM EDT Sun Jun 05 2022 Valid 12Z Thu Jun 09 2022 - 12Z Mon Jun 13 2022 ...Overview... Today's guidance shows reasonable agreement for the large scale pattern evolution, and with decent continuity in principle as latest solutions provide improved definition for significant features versus yesterday. Some embedded details will take a while to resolve given their small scale and thus low predictability. Consensus shows southwestward-digging Arctic energy following closely behind an initial compact upper low near the western coast of the mainland, ultimately leading to an upper low that tracks over the far northern Bering Sea/eastern tip of Siberia. An area of relatively lower surface pressures over the southern mainland should deepen for a time and lift northward as the second upper low forms. Upper ridging over northwestern Canada should extend back over the mainland once the upper low reaches far enough westward during the weekend/early next week. This ridge will likely help to keep an initial Northeast Pacific/southern Gulf of Alaska low in a similar position through the latter part of the period. Models/ensembles continue to support a primary emphasis for precipitation across the Panhandle and southern mainland as moisture and frontal systems/impulses spin around the Northeast Pacific mean low. ...Guidance Evaluation/Predictability Assessment... Adjustments made by the 12Z ECMWF run were very helpful in improving model agreement among the latest array of guidance, maintaining greater persistence of the northeastern Pacific low (instead of ejecting inland per prior two runs) and adjusting early-period energy westward to other guidance. During the first half of the period a composite of the 12Z GFS/ECMWF/CMC/UKMET essentially yielded a deeper version of the ensemble means, reflecting the most agreeable themes for Arctic/western mainland energy and the northeastern Pacific low while accounting for continued spread with some of the specifics. Such issues with the Pacific low and surrounding flow will have meaningful influence on the Panhandle but will take into the short range time frame to resolve. Even later in the period the GFS/ECMWF/CMC were similar enough to each other and the ensemble means to favor adding only 20-30 percent total weight of the 12Z GEFS/00Z ECMWF means in the starting blend. Typical guidance error offers potential for changes at some point in the future, but for now improved agreement on the building of moderate upper ridging over the mainland from later Saturday onward and persistence of the northeastern Pacific low provides incrementally improved confidence in the forecast. ...Weather and Hazard Highlights.. Guidance continues to emphasize the Panhandle and southern mainland for precipitation as moisture/fronts/impulses flow around the Northeast Pacific mean low during most of the period. The Panhandle should see more direct effects from the fronts/impulses while southern mainland convection will be aided by the cyclonic flow of moisture, and for a while interaction with a front/surface trough before it lifts northward. Still expect timing and amounts to depend on small-scale details that have low predictability at extended time frames, though recent trends have signaled potential for some locally enhanced totals over a multi-day time frame. Much lighter and more scattered precipitation may fall at times over other parts of the mainland. For temperatures, the pattern should favor below normal highs from the North Slope through the eastern mainland and Panhandle, in contrast to above normal highs over central/southern parts of the western mainland. Below normal lows should be confined more to the North Slope and central parts of the eastern mainland. Rausch 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