textproduct: Anchorage

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

Key messages:

* Wind Advisory remains in effect for the Anchorage Hillside / Eagle River with wind gusts 55 to 65 mph expected through 1AM tonight.

* Flood Watch is now in effect for the Susitna Valley for areas upstream of Lake Creek and Yentna Rivers through Wednesday afternoon. Rainfall totals of 2 to 4 inches expected. Near the Parks Highway, from Willow through Talkeetna, 1 to 2 inches of rainfall expected.

Discussion:

A broad low pressure system traveling towards the Kuskokwim Delta pushes several shortwaves northward up Cook Inlet into Southcentral Alaska over the next couple of days. Gusty southeasterly winds pick up this afternoon across the Anchorage Hillside north to Eagle River, Turnagain Arm, eastern Kenai Peninsula (especially noticeable along higher elevations), and along the western and northern Prince William Sound. Additional gap areas, including Knik Wind through Butte and Palmer, and the Copper River wind will see elevated winds. Winds are expected to persist through tonight, gradually diminishing through tomorrow morning. The exception will be the southerly Copper River Wind which will remain gusty through Tuesday afternoon.

Widespread persistent rainfall envelops much of Southcentral Alaska this afternoon and tonight as shortwaves move through. Chances for rainfall along Kodiak Island and the Kenai Peninsula dwindle by Monday afternoon as the low out west exits to the north. Lingering shortwaves along the Southcentral Mainland will keep rainfall chances higher through late Tuesday morning.

KM

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

The long-term period starts with an upper-level low situated over Bristol Bay and a surface low over the Alaska Peninsula or extreme western Gulf of Alaska. These features will bring rain across the Southern Mainland through Thursday.

A stronger and potentially more impactful storm for Friday and the weekend across the Southern Mainland begins to take shape upstream in Kamchatka Thursday. A strong shortwave digs south from Siberia to the northern Bering Sea by Friday morning. A gale- force surface low Will move into the northern Bering around St. Matthew Island to St. Lawrence Island by Friday morning. Moderate to heavy rain is likely to overspread the Southern Mainland, starting first with Southwest on Friday, and working east to Southcentral through Saturday. Showers continue across the Southern Mainland on Sunday as the low works farther into Western Alaska.

Trends with this system, deviations in track and strength, will have to be watched closely when it comes to determining coastal impacts along the Kuskokwim Delta Coast. Taking a quick look at ensemble data, the GFS and Canadian ensemble suites are more in line with each other with a slower and stronger solution. The European ensemble guidance is a little faster with the storm track which has the system moving inland of Western Alaska by Friday; this solution also features a weak system. Regardless, there will be a push of on-shore flow with this system, it will be a matter of its magnitude which will be ironed out in due time.

Farther out west, embedded shortwaves moving from west to east atop a strong North Pacific ridge will keep the Aleutian Chain showery at times for Thursday. The northern Bering low's front will also sweep across the Chain for Friday and make it to the Alaska Peninsula (AKPEN) for Friday night into Saturday. The southern AKPEN will see the wettest conditions with this front Friday night into Saturday as it only grazes the Aleutian Chain Friday. The AKPEN will remain showery for Saturday and Sunday as flow turns northerly behind the northern Bering low which is moving inland by then. A surface ridge works in across the Central and Eastern Aleutians Saturday and Sunday as shortwave and another round of showers approaches the Western Aleutians from the North Pacific.

AVIATION

PANC...Low level wind shear is the main challenge for this TAF period as surface winds shift direction and strength throughout the day. Southeast Turnagain Arm wind gusts of 30 to 35 kts will continue through Monday, but the strongest period will be during the overnight hours tonight. VFR is expected, however, periods of rainfall could lower ceilings into MVFR Monday morning.