Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 730 PM EDT Sat Jul 30 2022 Valid 12Z Wed Aug 03 2022 - 12Z Sun Aug 07 2022 ...Overview... Strong high pressure in both the upper levels and at the surface is forecast to retrograde and meander across the midlatitudes of the Pacific between Alaska and Hawaii. This will allow for a fairly progressive pattern across southern Alaska to the north of the high, with an initial low departing from the Panhandle Wednesday and another upper/surface low forecast to move across the Bering Sea and toward the southwest mainland around Thursday, then across the Gulf of Alaska late week. These features will bring chances of rain to the Aleutians eastward into the southern mainland and Panhandle. Then an Arctic upper low is forecast to edge southward toward Interior Alaska late next week, bringing cooler temperatures and some light precipitation. ...Guidance/Predictability Assessment... The first upper low lingering over the Panhandle as the period begins Wednesday shows good agreement in recent model guidance. Then the next upper low and associated surface low are coming into better agreement with their timing of moving across the Bering Sea and the southern part of the state, with fairly similar timing to yesterday's forecast. More specifically, the GFS/ECMWF/UKMET are all in line, but the CMC still seems to be a slow outlier. So favored the former cluster but also incorporated some ECMWF ensemble mean that was slightly slower than the bulk of the deterministic models. Then troughing is expected to gradually sink into the mainland from the north for the latter part of the week into the weekend. A near even blend of the ECMWF/EC mean/12Z GFS/GEFS mean seemed to handle the timing of that trough reasonably well. There also may be another upper low feature along that southern Alaska track late next week, but with ample timing differences and low confidence in the details at this point. But the above blend handled the feature acceptably at this point. ...Sensible Weather... Rain may be lingering across the southeastern mainland and Panhandle Wednesday with the first low overhead. Then modest rainfall amounts are forecast to shift from the Aleutians into the southern half of the interior, moving west to east with the low system around Wednesday into Thursday, then spreading into the Panhandle Friday and lingering through the weekend. Another southern system could spread another round of rain to southern Alaska late week. Additionally, a cold front moving just ahead of the trough into the northern mainland could cause some showery conditions across the North Slope and into the Brooks Range, which in higher elevations could fall as snow. The low pressure systems will also cause abundant clouds, with perhaps some clearing in between allowing for milder temperatures into the 70s in the Tanana Valley around Wednesday-Thursday. Elsewhere, slightly warmer than normal conditions are forecast for midweek into Thursday across coastal regions of the North Slope and from the Seward Peninsula eastward. As troughing spreads eastward from the southern upper low and southward from the Arctic upper low, temperatures will cool to below average across Alaska, especially the northern interior, by late week into the weekend. Tate 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