Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 755 PM EDT Mon Jul 11 2022 Valid 12Z Fri Jul 15 2022 - 12Z Tue Jul 19 2022 ...Heavy Precipitation Threat at times for parts of the Alaskan Southern Tier... ...Overview... The medium-range period will begin with a shortwave trough moving farther away from northeastern Alaska into the Canadian Arctic Archipelago on Friday. Additional upper-level troughs and surface frontal waves from northeastern Siberia are forecast to move toward northern Alaska from time to time as a large upper low from near the North Pole drops southward toward northeastern Siberia. This pattern will maintain a frontal boundary across the northern tier of Alaska through the forecast period. Meanwhile, an occluded cyclone moving across western Aleutians into the Bering Sea late this week should make landfall across southwestern Alaska by Sunday, followed by the remnants of the system most likely sliding across the southern coast toward the Panhandle early next week. ...Guidance/Predictability Assessment... The synoptic evolution depicted by the ensemble means from the 00Z EC mean, 12Z GEFS, and 12Z CMC mean appear quite agreeable with each other through the medium-range period. The GEFS and especially the GFS and CMC are in favor of retaining the Bering Sea low during the weekend. The ECMWF on the other hand is more progressive with pushing the low onshore, so much so that a rather broad cyclonic circulation is forecast to move up into northern Alaska by Tuesday, which appears to be an outlier solution. Therefore, the Alaskan forecasts for today were based on 40% from the 00Z EC mean/12Z ECMWF, 40% from the 12Z GEFS/GFS, and 20% from the 00Z CMC/CMC mean, transitioning to mostly the ensemble means by Days 7 & 8. The results look very compatible with yesterday's forecasts. ...Weather/Hazard Highlights... The forecast period should begin with colder than normal temperatures, especially from the Brooks Range northward, following a fresh early-season snow cover behind a departing frontal wave on Thursday. The arrival of additional shortwaves from northeastern Siberia will keep daytime temperatures cooler than normal for much of Alaska in additional to increasing chance of rain moving into the interior late this week. The southern portion of the Panhandle should see heavy rain threat on Friday with a cyclone passing to the south. Meanwhile, another cyclone will likely move across the western Aleutians into the Bering Sea late this week, bringing a threat of heavy rain for portions of the southern tier later in the weekend, with the heavy rain possibly lingering into early next week. The associated moisture should also penetrate further inland with a more widespread round of rain through the interior sections. Kong Hazards: - Heavy rain across portions of the Alaska Panhandle, Thu, Jul 14. - Heavy rain across portions of mainland Alaska, Sat-Mon, Jul 16-Jul 17. - Heavy rain across portions of mainland Alaska, Sat-Sun, Jul 16-Jul 18. - Much below normal temperatures across portions of mainland Alaska, Thu-Sun, Jul 14-Jul 17. 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