textproduct: Anchorage

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

Discussion:

Clouds are beginning to spill over the ridge into Southcentral this morning and should help to mitigate fog potential for many areas from Kodiak Island north to the Alaska Range. The Copper River Valley, where this upper level cloud cover has not quite reached yet, could still see some areas of fog before the cloud cover increases. Areas across the lower MatSu Valley and northern portions of the Anchorage Bowl have also seen a 3500-5000 ft cloud deck develop helping to keep their overnight temperatures in the lower 50s. Elsewhere, limited cloud cover for the first half of the night and calm winds allowed temperatures to quickly drop into the 40s for many areas. Today the ridge SW to NE oriented ridge axis will slowly shift eastwards as a system lifts up across the Bering Strait. Its front and southwesterly flow aloft will bring a good fetch of moisture into Southwest Alaska and the Bristol Bay region. This initial front will fall apart as it pushes east today and may provide enough forcing for rain to spread into the western Susitna Valley late this morning into early afternoon. Another system will rapidly move across the northern Bering and into western Alaska by Tuesday morning. A stout jet streak will move over Southwest Alaska with an accompanying fetch of Pacific moisture. Rain will quickly spread inland, from west to east across Southcentral, and exiting the Copper Basin by Wednesday afternoon. The highest rainfall amounts once again look to fall over the northern and eastern portions of the Susitna Valley, where upslope flow along the higher terrain will help to maximize rainfall amounts. Will likely see rainfall amounts of an inch or more for these areas with rises along area creeks and rivers.

In addition to widespread rainfall, this system will also allow for a strong south-north pressure gradient to develop across Southcentral, resulting in strong and gusty gap winds out of the Copper River Valley, Knik Valley and Turnagain Arm for much of the day on Tuesday. Gusty gap winds will subside by late Tuesday night as the system departs and the gradient slackens.

- PP

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

The long-term pattern will remain active across the Bering Sea as progressive west-to-east flow continues. Confidence remains high that a strong system off of the Kamchatka Coast Thursday will move to near Saint Lawrence Island by Friday. Strong southerly to southwesterly winds, small-craft to gale-force will move from the Bering to the Kuskokwim Delta Coast by Thursday afternoon, along with moderate to heavy rain with an atmospheric river accompanying this system. Moderate to heavy rain along the Pribilof Islands and portions of the Western and Central Aleutians will move to inland portions of Southwest Alaska through Thursday night and Friday morning. Light to moderate rain will also move across the Eastern Aleutians and Alaska Peninsula through Friday.

Southcentral Alaska will eventually get in on the rain by Friday. Prior to this rain, Southcentral will have experienced a relatively nice and quiet Thursday. For now, it looks like the heaviest of the rain will fall across Southwest with this system with light to moderate rain across Southcentral. Pockets of heavier rain along the northern Gulf Coast are possible Friday night into Saturday. River levels across the Susitna Valley, such as the Yentna River at Lake Creek will have to be monitored closely with this system for potential flooding concerns.

Steady rain across Southwest will taper to showers from west to east through the day on Saturday as the low tracks into Western Alaska from Norton Sound. Steady rain across Southcentral will move east to the Panhandle through Saturday as a low in the Gulf also moves east. Moisture wrapping around this low will allow rain to linger along the northern Gulf Coast into Sunday with scattered showers across the rest of Southcentral. Showers continue along the mountain ranges across Southwest for Sunday.

Another system, weaker than the Friday system, moves into the western Bering by Saturday and spreads rain across the Western and Central Aleutians through Sunday morning. Rain also makes it to the Pribilof Islands Sunday morning as well. Winds with this system, as of now, are trending to be small-craft or less.

AVIATION

PANC... VFR conditions are expected to prevail through the period as mid-level cloud cover is expected to mitigate fog potential Monday morning. High clouds will gradually lower through the period with rain showers expected to hold off until late Monday afternoon through evening. Light and variable winds will become more southeasterly Monday night as the Turnagain Arm winds begin to increase.