Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 742 PM EDT Sat Jun 04 2022 Valid 12Z Wed Jun 08 2022 - 12Z Sun Jun 12 2022 ...Overview... Models and ensembles generally agree upon a mean low at the surface and aloft over the northeastern Pacific for most of the Wednesday-Sunday period while separate bundles of energy initially over/near the northern mainland and dropping down from the Arctic should ultimately consolidate and retrograde west of the mainland. This evolution would eventually allow for somewhat greater coverage of weak upper ridging over the mainland versus a general weakness (or some combination of small-scale impulses/ridges), while at the surface a general axis of relatively lower pressures with a trough/front over southern areas may deepen for a time and then begin to drift northward next weekend. The primary emphasis for precipitation will be across the Panhandle and southern mainland as moisture and frontal systems spin around the Northeast Pacific mean low. ...Guidance Evaluation/Predictability Assessment... For about the first half of the period (Wednesday into early Friday) a blend of the 12Z operational models provided a reasonable depiction of significant features while accounting for uncertainty of smaller-scale details. In this time frame the consensus shows a gradual but steady decline of upper heights with the energy across the northern mainland and retrograding toward the Bering Strait, while a mid-latitude Pacific system quickly replaces a leading system around Wednesday-Thursday. Recent model continuity and the small scale of individual impulses within both mean features would suggest reduced predictability for specifics until the short range time frame. Guidance showed increasing spread and run-to-run variability from later Friday through Sunday. In particular, the 12Z ECMWF strayed faster than most other models and means to eject the northeastern Pacific low and was also the most aggressive to lower heights over the Arctic in response to additional shortwave energy. The new 12Z ECMWF mean and 18Z GFS maintain support for a more persistent Pacific low. However the Arctic forecast looks as uncertain as ever, with the 18Z GFS showing more troughing in contrast to a ridge moving in from the west in the 12Z run, while the ensemble means are fairly ill-defined with flow details near the northern coast. Based on guidance available through arrival of the 12Z ECMWF, the 12Z model blend used earlier in the period transitioned toward a half models/half means (12Z GEFS/00Z ECens) solution by day 8 Sunday while switching ECMWF input from the 12Z run to the prior 00Z version. ...Weather and Hazard Highlights.. Frontal systems and moisture flowing around the Northeast Pacific mean low should bring periods of precipitation with varying intensity to the Panhandle from midweek into the weekend. Southern parts of the mainland will likely see episodes of convection as this moisture continues back to the west and interacts with a surface front/trough. Finer details of timing and amounts will depend on small-scale details that have low predictability at extended time frames. 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 over the North Slope and Southcentral/Panhandle versus above normal readings over the western mainland. Below normal lows should be confined more to the North Slope. 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