Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 748 PM EDT Wed May 29 2024 Valid 12Z Sun Jun 02 2024 - 12Z Thu Jun 06 2024 ...Overview... A closed upper low advances across the Aleutians over the weekend, reaching the northeast Pacific early next week. This pattern will support a mean low across the Aleutians, the Gulf of Alaska and southern portions of the state; which will be supportive for precipitation to spreading along the Southern Coast of Alaska with cooler than normal temperatures. Upper ridging to the northeast of this storm track should promote mild to warm temperatures over the Interior with some convective showers, at least into the weekend, but with more uncertainty early next week as Arctic energy may approach. Another round of precipitation for southern/eastern Mainland and moderate/locally heavy rain possible for the Panhandle latter in the week. ...Guidance Evaluation and Preferences... The latest guidance has shown an increase in the clustering of the pinwheeling energies over the Gulf of Alaska/North Pacific during the initial and middle part of the forecast period-- an improvement of an additional 1-2 days from prior forecast before the spread increases beyond Tuesday. With that said, there continues to be a degree of variability with the energy/low that drops south from the Arctic whether is will remain offshore over the Bering or move over portions of West/Southwest Mainland the later half of the extended period. To the north and east of the storm track, a generally ridgy pattern aloft should be in place across much of the Mainland into late week. Model guidance does show some possibility of Arctic energy diving southwest toward or into the northwestern Mainland by the weekend or early next week. This could increase the potential for convective showers across the Mainland however this feature remains an uncertain aspect of the forecast with low confidence. A combo of the ECWMF/GFS/CMC/UKMET was utilized through hour 144 before introducing a small weighting of the EC ensemble and GEFS means by hour 156. As the UKMET was dropped off the inclusion of the means were slowly increased by the end of the period. ...Weather/Hazards Highlights... During this period no significant weather hazards are forecast. There may be instances were the convective showers over portions of the Interior during the afternoons and evenings produce heavy rain which may lead to very local impacts, however the exact location and timing is uncertain. In addition, lightning associated with the convection may increase the risk for wildfires if strikes hit drier locations. Depending on the eventual flow pattern over the Mainland next week, precipitation may become more widespread and heavier, but this remains uncertain. River flooding is a possibility in a spot or two with the seasonal ice breakup; see the Alaska-Pacific River Forecast Center for details. For the Southern Coast of the state--across the Alaska Peninsula (and Kodiak Island) to the Kenai Peninsula and Prince William Sound to the Panhandle--can expect some precipitation chances given the favorable troughing and expected low tracks. Some localized heavier totals in typically favored areas of terrain are possible, but heavy amounts should not be widespread. With weak riding in place over central/northern portions of the Mainland daily temperatures will be near or above average. Interior Alaska is likely to see the mildest temperatures across the state, with highs in the 60s to low 70s late this week into early next week, around 5-10 degrees above average. The North Slope is likely to be closer to or below average, with highs just above the freezing mark in the Arctic Coast communities. For the southern coast, temperatures at least for highs are forecast to stay below normal given the troughing and active pattern in place, with 40s and 50s for the most part. However, 60s look to sneak into Anchorage to Talkeetna. Campbell 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