textproduct: Anchorage

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

Key Messages:

- Another system moves across Southcentral late tonight through Monday, bringing widespread rain to lower elevations and snow to higher elevations and mountain passes.

- Gusty offshore winds continue this weekend, strongest along the coast through favored gaps and passes.

- A colder pattern settles across Southcentral Sunday night through midweek, with near-freezing temperatures and frost possible in colder inland valleys Tuesday and Wednesday morning.

Discussion:

Much of Southcentral, including along the coast, have remained cloud free overnight has allowed many areas to fall into the 40s this morning. There are some exceptions such as Kodiak where increased cloud cover has kept their temperatures in the 50s and some of the favored gap flow areas such as Seward, Whittier, and Valdez have stayed in the 50s given gusty winds early this morning. Temperatures will warm back up into the 50s and 60s by this afternoon despite increasing cloud cover through the day.

The next system is on its way and is currently making its way towards the Seward Peninsula, before it drops across Alaska towards Prince William Sound by tomorrow afternoon. This Arctic low will be fairly dynamic as it moves south, and brings much colder air with it. This means that snow is anticipated for higher elevations and the mountain passes, including Broad, Tahneta, Isabel, and Thompson Passes. Snow it also likely along sections of the Denali Highway. Road temperatures may be warm enough to limit accumulation on road surfaces, but light accumulations are possible until temperatures warm back above freezing. For lower elevations, another round of more widespread rain is expected. Precipitation will initially move into the Susitna Valley then spread south and east with time as the low drops south and into the Gulf. The southern end of the Kenai Peninsula and Kodiak will miss the built of this system; however, Kodiak will see an embedded system race through with rain just skirting the southern end of the island. Cooler and drier air is move in behind the system, helping to clear lingering showers and cloud cover. With the cooler airmass and clearing skies, Tuesday morning looks to be the coldest morning since spring with many areas dropping near, or below, freezing. Areas across the lower Susitna Valley, Mat Valley, Eagle River/Anchorage, and portions of the western Kenai should be prepared for patchy to widespread frost Tuesday morning. Wednesday morning will also be chilly, but frost potential does not look as widespread as temperatures will moderate some. As such, actions should be taken now to protect cold susceptible plants over the next several mornings.

Offshore winds will continue to be gusty over the next several days, especially through favored gaps and passes.

- PP

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

An upper level ridge extending out of the North Pacific, through the eastern Bering Sea and across the Bering Strait will still be in place on Wednesday. By late Wednesday, the upper-level pattern looks to become more amplified, with the North Pacific Ridge moving east and lifting across the Southern Mainland Thursday morning. The eastward progression of this ridge will allow a trough over the western Bering to deepen, resulting in a stout southerly wind flow between the two features. A strong shortwave will move north along a stalled frontal boundary, leading to the development of a surface low somewhere between the Pribilofs and Kuskokwim Delta coast. This feature, along with its surface front, will drive into Southwest Alaska with another round of heavy rain and gusty southwesterly winds along the coast for Thursday.

The eastern progression of the upper level ridge and low will continue through Saturday, at which time the ridge will be in the eastern Gulf of Alaska. The large upper level low that will be just east of the Kamchatka Peninsula on Wednesday will have drifted eastward and encompass the entire Bering Sea by Saturday. This will usher in southwesterly flow aloft for both the Southwest mainland and Southcentral by next weekend. This will also allow the heavy rain in Southwest Alaska on Thursday to migrate eastward into Southcentral Alaska for Friday into Saturday.

Model agreement is converging on this solution in regards to the timing and location of these two main features so confidence in the forecast is increasing.

AVIATION

PANC...VFR conditions will persist through late tonight. Cloud deck will increase through the day with ceilings gradually lowering. Rain showers expected to move into the terminal by 12Z Monday.