Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 703 PM EDT Thu Jul 27 2023 Valid 12Z Mon Jul 31 2023 - 12Z Fri Aug 04 2023 ...Pattern overview with Guidance Evaluation/Preferences and Predictability Assessment... The most certain part of the pattern over Alaska during the medium range period next week is upper ridging which essentially stays in place (in some form or the other) across much of the Mainland. Much more uncertain are individual systems through the Bering Sea, reaching this ridge and essentially getting forced either north or southward into the Gulf. Timing, strength, and even existence of some of these features are problematic at this time and may take until even the short range for fully resolve. These systems are dependent on the strength and orientation of the blocky ridge. Generally the models show one upper low skirting the North Slope region early next week, with another compact/weak upper low crossing the Peninsula into the Gulf. The 12z GFS was an outlier with this latter feature wanting to bring it more into Western Alaska than the rest of the deterministic guidance. Later in the period, the CMC features a much stronger ridge over the East Bering Sea and western Alaska forcing an upper low north into eastern Russia while the ECMWF and GFS pull it southward over the Aleutians, originating from an upper low settling over the Kamchatcka Peninsula late next week. The WPC forecast for today leaned closest to the 12z ECMWF given minor issues with the GFS and CMC noted above. Also incorporated the UKMET for days 4 and 5 when it was most consistent with the ECMWF, replacing with the ensemble means later in the period. Despite the significant uncertainty in details, was forced to use more deterministic guidance late in the period than usual due to the ensemble means tending to wash out most systems. ...Weather/Hazards Highlights... Showers can be expected over eastern, northern, and southern parts of the Mainland with some local enhancement along favorable terrain. Wet weather should also advance east through the Aleutians as a couple of systems move through with some showers moving into Southeast Alaska/the Panhandle as an upper low over the northeast Pacific nudges closer to the region. Temperatures are most likely to be above normal across the Interior sections of Alaska where upper ridging should prevail most of the period. Southern and northern Alaska should be more near or below normal given influence from upper troughing. Santorelli 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 No significant hazards are expected over Alaska during this forecast period. 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