textproduct: Anchorage

LONG TERM FORECAST (Days 4 through 7: Sunday through Wednesday)

No significant changes to the long term forecast depicting a persistent active pattern with widespread unsettled weather across most of the forecast area.

By Sunday, the global models are in fairly good agreement and depict a large, occluded area of low pressure system moving into the southwestern Gulf of Alaska by Sunday morning. Cold air advection and a stout northwesterly flow in the boundary layer will lend to gale-force winds and gusts through bays and passes of the AKPen and eastern half of the Aleutian Chain through Sunday morning. Farther east, there remains good agreement that the front associated with the low will be over the northeastern Gulf coast. However, there is uncertainty in how far east and how far west the barrier jet ahead of the front will extend. The GFS continues to be the outlier with this jet still extended into Prince William Sound. Showers will also linger for the AKPen, Kodiak Island, and Southcentral coast Sunday as moisture continues to wrap around the low with precipitation enhanced by various vorticity lobes also rotating around the upper-level low.

By late Sunday into Monday, attention shifts back to the western Bering and Aleutians as yet another strong Kamchatka Low swings a high-end gale to storm force front over this area. This system becomes more complex as various surface lows spin up along the front with what looks to be a second surface low diving south, undercutting the aforementioned low, and reinforcing both a core of very strong winds and heavy precipitation. There is high uncertainty between the various forecast models as to how this complex low setup evolves as it moves east over the Bering and toward the mainland. However, the main takeaway is that there is high confidence in the development of a broad upper-level trough and surface low over the southern Bering by Monday with very strong westerly winds across at least the western two thirds of the Bering and Aleutians and strong southeasterly winds along a front driving east toward coastal Southwest Alaska. By late Monday into Tuesday, this system looks to remain somewhere over the eastern or southeastern Bering with its front moving over the Gulf of Alaska and the Kenai Peninsula. This solutions would favor another strong wind event for the Gulf of Alaska coastal waters, strong gusty southeasterly gap winds for typically favored locations, and yet another round of heavy precipitation for the coastal mountains and upslope areas of the Talkeetna and Alaska Ranges. The threat for gusty winds and heavy precipitation remains into Wednesday.

-TM

AVIATION

PANC...Low level wind shear is likely into this afternoon with variable surface winds and southeasterly winds 25 to 35 kt at 2000 ft or less. Sometime late this afternoon to early evening, the southeasterly wind through Turnagain Arm will move over the airport with winds gusting 25 to 30 kt. there is potential for these winds to move in and out over the course of the day which would make wind conditions rather erratic until the stronger Turnagain Arm winds take over by this evening.

Rainfall will be light and ceilings are expected to be mainly VFR. However, there may be some brief periods of MVFR ceilings this morning. Some more persistent rain is expected to develop this evening and overnight, but VFR conditions are expected to prevail due to the wind keeping the lower atmosphere mixed enough to keep it from saturating. If winds end up being weaker, there would be a better chance for ceilings to dip into MVFR conditions this evening and overnight.