Area Forecast Discussion
Issued by NWS Anchorage, AK
Issued by NWS Anchorage, AK
714 FXAK68 PAFC 041318 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 518 AM AKDT Thu Jul 4 2024 .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: Today through Saturday)... An upper level ridge now beginning to shift into the northern Gulf is still anticipated to hold out just long enough for most of Southcentral to stay dry for much of the July 4th holiday. Cloud cover associated with an approaching frontal system out west will continue to spill around the ridge and keep us from getting much on the way of direct sunshine, but all but the Talkeetnas and northern Susitna Valley will avoid any meaningful rainfall potential until the tail end of the day. Light rain will fill in from northwest to southeast as the weakening front crosses the Alaska Range into the Cook Inlet region this evening, particularly over higher terrain. West to northwest flow persisting in the upper levels plus drier air in place in the lowest levels should greatly limit how much rainfall reaches the ground near sea level. Light rain should move into the Mat Valley and Anchorage by late tonight, while much of the western Kenai Peninsula and Copper Basin could stay totally dry into Friday morning. A short break in the wetter pattern materializing is expected on Friday as the front and upper shortwave push off to the southeast and the ridging tries briefly to rebound behind it. Gap winds, including through the Turnagain Arm and out of the Copper River Valley, will also become stronger as southerly flow strengthens ahead of a much deeper trough digging into the western Mainland. Once again, don`t expect much of a break in the cloud cover, but it should be a bit drier day overall, except for eastern portions of Prince William Sound. By Saturday morning, the second and likely more formidable rainfall event will begin to take shape as a strong convergence zone and moisture axis set up with southwesterly flow between the trough moving into Southwest and the ridge still lingering over the Gulf. Model guidance has struggled a bit with the placement of the axis of heavier rainfall, with newer guidance suggesting an axis from the Kenai Peninsula to the Prince William Sound could take the brunt of the highest rainfall through Saturday afternoon. Regardless of the exact details, the bottom line is that it looks like a wet day just about everyone, and it`s a good idea to make holiday weekend plans accordingly. -AS && .SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days 1 through 3)... The pattern shifts as a shortwave drops into Southwest Alaska today and combines with a front tracking from the Bering Sea. The pull of moisture from the front bring widespread wetting rains to Southwest and south across the Alaska Peninsula through Saturday morning. High pressure continues over portions of the Bering Sea, bringing areas of patchy fog to the Central/Western Aleutians as well as the Pribilof Islands. && .LONG TERM FORECAST (Days 4 through 7)... The long range models are in more agreement today with the pattern change mentioned in previous discussions. The areas of high pressure that have been persistent over the Bering Sea and the Gulf of Alaska in the early part of the period will start to break down allowing a North Pacific low to track northward into the Gulf. This combined with troughs of low pressure transiting across the Bering Sea and Kuskokwim Delta will track eastward across the region through the end of the period. As a result, expect scattered precipitation and cooler temperatures across the much of the forecast area. Additionally, gusty winds and possible small craft conditions are expected in Cook Inlet and coastal regions of the Kenai Peninsula Saturday afternoon and into Sunday. -DD .AVIATION... PANC...VFR conditions and light winds persist through tomorrow morning. Westerly winds begin shifting southerly this evening as Turnagain Arm winds strengthen ahead of an approaching front. Southerly to southeasterly winds then increase by late Thursday morning, with the potential for gusts 20-25 kt persisting through the afternoon. Light rain is expected late Thursday afternoon through Friday morning, with minor uncertainty in timing. Ceilings will drop with this rainfall, likely below 5000 ft, with some guidance even dropping ceilings to MVFR. && $$