Anchorage, Alaska

A weak low is bringing periods of rain for Prince William Sound as it continues to track to the north through the overnight hours. Some of these showers could make it to Anchorage and the Mat-su Valleys, but most of the moisture will be downsloped from the Chugach Range.

On Monday, a front from a Bering low crosses through the Alaska Peninsula, sending Gale Force sustained winds and rain north into the southern/central Gulf and much of Kodiak Island. Easterly winds will also start to pick up over the Kenai and Chugach Mountains as a northeast to southwest pressure gradient tightens up ahead of the approaching front farther south.

Forecast confidence remains low for Tuesday. Deterministic models are trending the front to track faster through the Gulf, bringing the swath of gale force winds and rain to the northern Gulf in the morning, keeping south of Prince William Sound. Small-craft winds are expected to reach Prince William Sound. The earlier arrival of these strong winds is a notable change to the previous forecast. Cross-barier flow will likely be strong enough to keep most of the Mat-Su, Anchorage and western Kenai Peninsula dry due to downslope drying through Tuesday evening. Stay tuned for updates on this next stronger Gulf system as forecast confidence for the progression of the front improves over the next couple days.

Winds will drastically decrease on Wednesday as the front moves onshore. An upper level trough will bring pieces of energy through the Gulf, continuing precipitation as well as continued downsloping for the same areas.

-SS

Current satellite imagery shows a 950 mb Kamchatka low about 300 miles west of Shemya, with its occluded front pushing past the Central Bering. Along and behind this front there is an elongated area of light- to- moderate precipitation, gale-force southeasterly winds, and patchy fog. Expect strong gap winds tonight through the eastern Aleutians, especially through Cold Bay, gusting as high as 55 mph. Meanwhile, some weak rain/snow showers continue across parts of the Southwest mainland, but are expected to diminish temporarily tonight as a shortwave ridge moves in ahead of the approaching front.

The parent low pushes along the western Aleutians through Monday, with some storm-force winds on the southern end of the island chain. Cold air wraps around the back side of the low, resulting in a slight chance (10-30%) for some isolated lightning strikes in the region. Moving east, a triple point low forms along the occluded front and lifts into Bristol Bay, bringing gale-force east- southeasterly winds to the AKPen and Southwest coastline. Given the off-shore direction of these winds, coastal impacts should be minimal. Temperatures gradually warm through the day with the southeasterly flow aloft; thus precipitation should remain mostly as rain for the lower elevations.

Gale-force winds will taper off across the Southwest by Tuesday morning as the triple-point low pulls to the northwest and the original front stalls out. However, some orographic showers will linger given the strong moisture advection from the southeast. Showers will likely become more widespread across the AKPen and Bristol Bay on Wednesday as another shortwave trough lifts from the Western Gulf and into the region. Looking west, and upper-level low remains nearly stationary over the northern Bering, with a multitude of shortwaves rounding the low through Wednesday. Cold air continues to filter in from Siberia and Kamchatka and into the western Bering. By Tuesday evening temperatures may be cool enough for some snow flakes to mix into showers from Shemya to Atka.

-CW

Multiple strong storm systems will track from the North Pacific across the Bering Sea and into the Gulf of Alaska. These will bring periods of high winds, rough marine conditions and heavy precipitation (rain at lower elevations, mountain snow at higher elevations) focused on the southern coast and Southcentral Alaska.

Systems will affect the southern Bering Sea and Aleutians with strong winds, elevated seas and precipitation, mainly rain, with some mixed or snow possible farther west or at higher elevations, as they track eastward from the north Pacific. They will then intensify over the Gulf of Alaska, where the first system weakens over the northern Gulf by Wednesday. A second system arrives Thursday night and into Friday and a third develops by the weekend, bringing repeated high winds and significant perception. Southcentral Alaska will see lingering moderate to heavy rain and mountain snow from the initial system into Thursday, followed by a brief break and then additional rounds of moderate to locally heavy rainfall and mountain snow, with stronger winds more likely along the coast, including the Kenai Peninsula and Prince William Sound. Slight to moderate weather model differences towards the weekend keep the confidence moderate on the exact timing and of the strongest winds and precipitation accumulations.

-DD

PANC...Northerly surface winds are expected throughout the TAF period. Monday morning, winds aloft will turn to the southeast around and will bring in the potential for low level wind shear.

VRF ceilings and visibilities are likely to prevail through Monday. There will still be occasional shower activity around the terminal through the evening which could lower ceilings to just below 5,000 ft in a shower.