Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 739 PM EDT Thu Jun 27 2024 Valid 12Z Mon Jul 01 2024 - 12Z Fri Jul 05 2024 ...Overview and Guidance Evaluation/Preferences... The ensemble means from the GEFS, EC, and CMC remain in good to excellent agreement on the evolution of the upper-air pattern across Alaska through the medium-range period. The Rex Block upper-air pattern setting up in the vicinity of Alaska during the short-range period will persist into much of the medium-range period. Models continue to depict an initially deep Bering Sea low will weaken as it slides to the south of an upper ridge that will be anchored across northern Alaska. Since yesterday, models have further slowed down the eastward motion of the low into the Gulf of Alaska by the middle of next week. The deterministic solutions are even slower in this regard, with the CMC begins to hint at a retrograting pattern setting up by late next week. The WPC medium-range grids for Alaska was based on a general model compromise of 40% from the 12Z GFS and GEFS, 40% from the 00Z EC means and 12Z ECMWF, and 20% from the 12Z CMC and CMC mean. This blend yielded a solution very compatible with yesterday's forecast package. ...Weather/Hazards Highlights... The medium-range period will begin with a rainy pattern across the Aleutians and Alaska Peninsula as the lingering Bering Sea cyclone gradually slides across these areas before drifting farther to the east or southeast by early next week. This gradually weakening cyclone will allow for modest rainfall in its vicinity, but some moderate rain can be expected from the southeast coast of the Alaska Peninisula into Kodiak Island and the Kenai Peninsula on Sunday. The terrain in south-central and northern Alaska are expected to have the best chance of showers and thunderstorms. There is also the possibility of dry lightning strikes during the afternoons and evenings which would increase the risk for fire weather concerns given the dry fuels across the region. Ridging across mainland Alaska will maintain warm to hot temperatures. Afternoon maximums should lie the 80-90F range for the most part across the eastern interior sections. Highs mostly in the 60s and 70s are expected across lower elevations of south-central Alaska, with mainly 50s and 60s in most coastal areas, 50s and 40s across the North Slope, and mid to upper 40s in the Aleutians. Higher elevations in the terrain across south-central and southeast Alaska should fall below freezing overnight. The North Slope will cool down closer to normal temperatures by Sunday as a surface high pressure system gradually sliding from west to east off the northern coastline of Alaska funnels colder air into the area from the Arctic Ocean. Similar temperatures are expected to last into late next week across mainland Alaska but with a gradual expansion of the coverage of scattered showers and emedded thunderstorms when upper shortwave energy from the Arctic Ocean could pentrate the upper ridge and destabilize the atmopshere. Kong/Roth 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