Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 632 PM EST Mon Nov 14 2022 Valid 12Z Fri Nov 18 2022 - 12Z Tue Nov 22 2022 ...Overview... An anomalously strong upper ridge and surface high atop the mainland and Panhandle of Alaska in the short range period will persist into the medium range but gradually weaken with time. The ridge could cause record-breaking "warm" temperatures across the North Slope as some areas approach or exceed the freezing mark through Friday. The main storm track will be deflected to the south of the ridge with low pressure systems tracking across the northern Pacific, which could affect the Aleutians/Alaska Peninsula with precipitation and gusty winds, eventually spreading into the southern coast of the mainland and the Panhandle for early next week. ...Guidance/Predictability Assessment and Preferences... Model guidance remains agreeable with the overall pattern of a strong upper ridge and a surface high across the Panhandle and mainland that should both slowly weaken through the period. This good agreement for the synoptic pattern yields fair agreement in the general storm track areas around the ridge as well, but with less certainty on the exact details. Models have continued to waffle regarding the tracks of shortwaves across the Bering that could help position a front near the western mainland through the weekend. In general today's guidance shows perhaps less QPF reaching onshore compared to yesterday's trend toward more, indicating that even these small shifts could have sensible weather impacts. But model consensus is getting better for the timing of potential flattening/suppressing of the northern side of the ridge across the Arctic. Farther south, there is good agreement initially for a surface low south of the Aleutians, but with increasing uncertainty in its track by the weekend and into early next week. The ECMWF and CMC cluster farther east taking the low into the Gulf of Alaska, while GFS runs cross the Alaska Peninsula with the low bringing it toward the southwest mainland. Ensemble members show considerable spread but the means end up generally clustering closer to their deterministic counterparts. Thought it best to lean a bit toward the Pacific solution, but both types of solutions may be plausible. Meanwhile, there looks to be a surface low or two farther east in the northern Pacific through the weekend ahead of this stronger system. These show some notable spread but overall seem to trend toward the Gulf of Alaska early next week. Thus the WPC forecast utilized a blend of the 12Z deterministic model runs to start the period, with gradual increasing of the weighting of ensemble mean components to around half by day 8 given the increasing model spread. ...Sensible Weather and Potential Hazards... A couple of rounds of light to moderate precipitation and perhaps gusty winds are possible for western parts of the mainland, but uncertainty remains on how far east the precipitation could reach. Farther south, some modest precipitation amounts are forecast across the Aleutians into the Alaska Peninsula on Friday, with amounts likely to increase over the weekend and spread eastward into Southcentral Alaska and toward the Panhandle into early next week given increasing Pacific moisture. The details will depend on the eventual surface low tracks though. The overall upper ridge pattern will lead to above average temperatures across much of the state for the period. The North Slope looks to see the highest anomalies above normal, with portions even reaching slightly above freezing. Temperatures in Utqiagvik could reach into the low 30s Fahrenheit into Friday despite polar night approaching, which could be record setting. The rest of the mainland is also likely to be above normal through late week and lasting into early next week, with more of a mix of above/below average temperatures for the Panhandle. 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