Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 747 PM EDT Tue May 30 2023 Valid 12Z Sat Jun 03 2023 - 12Z Wed Jun 07 2023 ...Overview/Guidance Evaluation/Preferences... Over the weekend, an upper and surface low feature looks to move east across Southeast Alaska. There are some slight timing differences with this low track but within typical model spread at this lead time. Farther north, another upper low centered just north of Alaska should shift northeast over the weekend, again with some minor variations in the position, with perhaps the 12Z ECMWF and UKMET a bit slower/farther south compared to the GFS/CMC runs. But the main weather feature affecting Alaska through the period is ample energy over the Bering Sea and vicinity this weekend into much of next week. There is likely to be an initial stacked low just north of the Aleutians Day 4/Saturday before additional energy and low pressure comes into the same region. There are some model differences in the evolution of the combination of these energies and the eventual track of the conjoined low. In general models have trended toward a setup of the low farther south compared to yesterday's forecast, atop the eastern Aleutians/Alaska Peninsula rather than staying north in the Bering Sea. ECMWF guidance particularly shows this farther south track, with the 12Z CMC and GFS perhaps showing a better middle ground position closer to the ensemble means. As this low sets up, narrow ridging may build into Southeast Alaska northwestward into the northern Interior. With these considerations, a blend of mainly deterministic 12Z guidance was used early in the forecast period, and the percentage of ensemble mean guidance was gradually increased with time to about half by the latter part of the period. ...Sensible Weather and Potential Hazards... A round of light to moderate rain is likely to affect Southeast Alaska this weekend into early next week coincident with the upper and surface lows moving through. Light rain amounts could also be in store for the Mainland this weekend, followed by a drier trend for both regions. Meanwhile the strengthening deep layer cyclone over the Aleutians into next week should bring increasing moisture flow onshore to the Aleutians first for some moderate rain amounts there, followed by increasing precipitation chances and amounts for the Alaska Peninsula eastward into Southcentral and the Kenai Peninsula. These areas are most likely to see heavy amounts of mainly rain, though with some snow possible in the highest elevations. Strong winds could also be a threat ahead of the lows especially over marine and adjacent areas. After below average temperatures prevail across much of the state on Saturday, through likely less cold than in the short range period, a warming trend will be noteworthy particularly across the northern half of Alaska as a warm front moves north and troughing associated with the upper low north of the Mainland lifts out. Afternoon highs will likely rise into the 70s for lower elevations of the Interior for Monday-Wednesday, with lows perhaps staying in the low 50s by midweek. However, the upper low and the coincident rain and cloudiness chances could keep high temperatures down below normal along the southern coastal regions. Tate Hazards: - Heavy precipitation across portions of mainland Alaska, Mon-Tue, Jun 5-Jun 6. 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