textproduct: Anchorage

LONG TERM FORECAST (Days 4 through 7)

A deep upper low in the northern Bering Sea with an upper level ridge over the Southcentral starts to breakdown Sunday, allowing for moisture advection under southwesterly flow through southern mainland. Winds begin to diminish, but showery precipitation will linger for Southwest Alaska as the front moves inland. A surface low will develop along the front in the Gulf of Alaska, with strong, southeasterly surface winds. Ample moisture is expected to move through the Gulf and Southcentral. Most of the precipitation will be focused toward Kodiak Island, the northern Gulf coast, and Prince William Sound. The bulk of the moisture looks to move into the northeastern Gulf Monday. Southeast flow would promote precipitation enhancement through orographic lift along the windward slopes and downslope drying to the leeside. The amount of precipitation will depend on the progression of the front, the amount of precipitable water in the vertical column, and the location/time of the surface low the Gulf.

Confidence decreases early next week as the main upper level trough starts to phase with a potentially vigorous low emerging from the North Pacific, south of the Aleutians. Some data suggests that this low tracks more north into the Bering (20 to 30 percent chance), but another batch of data (and the current forecast with 50 to 60 percent confidence) suggests a track that remains to the south of the Aleutians, toward the western Gulf. There will be plenty of moisture with this system, but the amount of precipitation for the Aleutians and Alaska Peninsula will depend upon the strength of this low as it approaches the Aleutians. As this combined trough moves east midweek, we start to see additional breakdowns in model consensus (and therefore confidence) for the wind forecast, especially as the front approaches the Gulf and Southcentral. Although the current guidance suggests sustained gale force winds with storm force gusts along the front, this system has the potential to produce sustained storm force winds (20 to 30 percent chance) across the Gulf and along the northern Gulf coast into Prince William Sound. This will be dependent upon not only the strength of low pressure system, but also its placement in relation to the geographic features across southern mainland Wednesday and Thursday. The forecast is expected to evolve - check back for updates.

AVIATION

PANC...Generally VFR with light southeast winds and showers in the vicinity through this evening. The potential for fog (20 to 30 percent chance) and lower ceilings (60 percent chance) returns tonight around midnight through Thursday morning.