Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 741 PM EDT Fri Jun 17 2022 Valid 12Z Tue Jun 21 2022 - 12Z Sat Jun 25 2022 ...Overview... A ridgy pattern will stretch from the Alaska Peninsula into the northeastern mainland Tue-Wed of next week, separating a closed upper low moving from the Gulf of Alaska into the Alaska Panhandle/British Columbia and rounds of troughing across the Bering Sea and possibly influencing northwestern Alaska. The upper high is forecast to be shunted southeastward into the southern mainland as the week progresses as longwave troughing becomes more established atop the Bering Sea. This pattern will allow for a wet pattern over the southeastern mainland and the Panhandle around midweek, then increasing rain chances for the Aleutians and western Alaska later next week. ...Guidance Evaluation/Predictability Assessment... Most deterministic models remain in generally good agreement with the upper low coming into the southern Panhandle/British Columbia Tue-Thu, though once again the 12Z GFS indicated a slower track with the feature compared to consensus of the other guidance. Meanwhile guidance agrees well on the ridge/upper high farther north and west of the upper low. Recent guidance has shown a trend toward more troughing approaching the western mainland around midweek compared to models from a day or so ago, though likely not to the extent of the 00Z deterministic ECMWF that even cut off a low and drifted it south across the mainland through the latter part of the week. The newer 12Z EC looked more reasonable. Thus through the first half of the medium range period, a 12Z multi-model deterministic blend worked well. By Fri-Sat, model guidance shows broad scale agreement for troughing stretching across the Bering Sea, but with fairly typical individual model differences with the details of phasing, shortwaves, and associated surface lows coming into the Bering and Aleutians. So the WPC forecast gradually transitioned to some inclusion of the means late next week, but was able to maintain a majority deterministic model blend since the overall pattern seemed to be handled okay. ...Weather and Hazard Highlights... Moist inflow associated with the Gulf of Alaska to Panhandle/BC lows will promote rainy conditions for the Panhandle streaming into eastern parts of the mainland especially for the first half of next week. There could be some terrain enhancement of amounts for parts of the Alaska Range where a typical surface trough should set up, and across parts of the North Slope/Brooks Range in the vicinity of a stationary boundary. The trend will be toward drier conditions by the latter part of the week over the mainland with ridging and high pressure, though some showers may linger. Meanwhile increasing rain chances are likely for the Aleutians and into western parts of the mainland for the latter part of the week near low pressure systems and just ahead of upper troughing. Temperatures will be near to below normal over southeastern Alaska into the Panhandle initially, though moderating/warming later next week. Southwestern to Southcentral Alaska should gradually warm to above normal through next week as well. Periods of cooler than normal high temperatures are likely for the Brooks Range into the North Slope, however, and the western mainland may be below normal at times given the troughing aloft. Tate No significant hazards are expected over Alaska during this forecast period. 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