Area Forecast Discussion

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

A few lingering showers remain across the coastal mountains, as today's low has substantially diminished in strength. A southeasterly wind regime has lead to a few pockets of sunshine on the lee side of the Chugach and Kenai Mountains and around Kodiak Island - if these pockets remain overnight, temperatures could drop lower than forecast, and fog may develop by morning - something to watch out for in the forecast. Otherwise, quiet conditions are forecast overnight before the next round of precipitation moves in from the eastern Gulf early Wednesday through Thursday, primarily effecting areas around the the Prince William Sound and Kenai Peninsula, though light precipitation could move further inland as far as Anchorage, the Mat-Su and the Copper River Basin by late Wednesday/early Thursday morning. This system will bring gusty mountain winds, but won't be quite as warm aloft, nor as dynamic; therefore, while there will be a rain- snow mix below 1500 ft (snow above), amounts should be much lighter.

Generally cooler and drier conditions are in store for the end of the week. However, the active pattern continues with another round of showers likely by Sunday.

-AB

.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days 1 through 3)...

Currently, northwesterly winds with cold air advection across the Bering to as far south as the Aleutians and North Pacific is driving scattered ocean effect snow showers across the region. With a low to the east in the Gulf and an emerging North Pacific low from the subtropics, this interaction is tightening the pressure gradient across these areas as well, which is elevating gap winds across the eastern half of the Aleutian Chain and Alaska Peninsula this afternoon.

Freezing fog is likely (60 to 70% chance) for the Kuskokwim Delta for areas like Bethel Wednesday morning as light northwesterly winds shift to southwesterly and an onshore component with moisture advection off of the Bering works into the region. Forecast model soundings do show a subtle low level inversion setting up as well, but as surface temperatures slowly warm late Thursday morning, the inversion will erode and fog will begin to dissipate.

Also by Wednesday morning, a North Pacific low's front sideswipes the North Pacific side of the Central Aleutians with a round of high end small crafts and gales, with the strongest core of these winds staying well offshore. Warm air advection ahead of the front and rising snow levels should allow for most of it associated precipitation to fall as rain (30 to 40% chance of rain/snow mix possible on the leading edge of precipitation). The GFS today has become more in line with other guidance and the track of the low has been shifted farther south with this afternoon forecast package. This low pressure system moves eastward through Wednesday afternoon and tracks south of the Eastern Aleutians and Alaska Peninsula as it does so. Expect high end northerly to northwesterly small craft winds in the wake of this system to be enhanced through the gaps of the Central Aleutians Wednesday night. Gap winds pick up again for the Alaska Peninsula by midday Thursday in the wake of the exiting North Pacific low.

Another relatively deep North Pacific low is on track to move south of the Aleutian Chain Friday morning as a weaker system approaches the Western Aleutians.

-AM

LONG TERM FORECAST (Days 4 through 7: Friday through Monday)

Friday starts with less active weather across Southwest and Southcentral Alaska as weak ridging builds over the Bering and weak features move the Alaska mainland. Cold air advection drops into Southwest Alaska, allowing for scattered snow showers. The northerly flow will allow for small craft level gap winds in the Eastern Aleutians and Alaska Peninsula areas and scattered showers over much of the Bering. Also, another low moves into the Shemya area from the west, bringing another round of gusty winds and rainfall.

Saturday sees this low move further into the Bering, allowing for the low's front to progress and bring rain to much of the Aleutians. Gusty winds also will impact the Aleutians with the front. Meanwhile, Southcentral sees a low move south of the Gulf of Alaska, turning winds more northwesterly along Kodiak Island and allowing for gap winds in the waters around the island. There is much uncertainty on Sunday in the Bering with regards to the low track. It will progress eastward, but it is uncertain where it will track to. However, whichever track it takes should still bring rain and snow to the Southwest Mainland and gusty winds along the Aleutians. Southcentral's forecast is still uncertain at this point with many low level features moving through and bringing rain/snow and elevated winds wherever they move. Monday is even more uncertain with a ridge building somewhere in the Bering and a low moving into the Gulf of Alaska. However, the exact track of these features and their impacts is too uncertain to be clarified at this moment.

-JAR

AVIATION

PANC....VFR conditions are expected to prevail through the TAF period. Light rain will continue into the afternoon, with ceilings generally remaining above 4000 ft. Northerly winds will gradually shift easterly through the afternoon, increasing to around 10 kt with gusts up to 18 kt. Low-level wind shear will remain possible as stronger easterly winds around 35 kt persist at 2000 ft AGL.

Rain showers will taper off later this afternoon, with vicinity showers possible through the evening. Ceilings will gradually lift overnight, with VFR conditions continuing through Wednesday morning. Winds will shift back northerly and diminish overnight, becoming light and variable by Wednesday morning. Low-level wind shear is expected to diminish overnight as stronger winds aloft weaken.

-LM