textproduct: Anchorage

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

Key Messages:

- Flood Warning remains in effect for the Yentna River including Lake Creek through 1PM Friday. - Overall, rainfall will taper off as high pressure builds across Southcentral. Residual precipitation will linger farther inland, near higher elevations.

Discussion:

Rain will continue through the rest of this morning as southerly flow across Kodiak Island, Kenai Peninsula, and northward through the Susitna Valley weakens throughout the day. High pressure originating from the Gulf of Alaska will start to build across Southcentral later this afternoon and through the end of this week. Residual precipitation could linger farther inland and near higher elevations of northern Susitna Valley, and northern and western Copper River Basin through Friday. Thunderstorm chances are low (10 to 20 percent), but with enough clearing and surface heating, a lightning strike or two cannot be ruled out in the Copper River Basin. Overall, rainfall coverage is expected to taper off and Southcentral will trend drier and warmer.

The general flow is relatively weak, but a slight increase of westerly winds up to around 15 to 20 mph could kick in late tonight through Friday afternoon. The Copper River Basin could see some localized breezy winds, especially through wind-prone gaps from the south or west, such as Tahneta Pass. Whittier could also see an enhancement of winds from the west during this timeframe as well.

Otherwise, expect a relatively quieter weather pattern to continue for the next several days for Southcentral.

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

By the end of the weekend, troughs of low pressure will be moving through the South/Southeastern Bering Sea, moving over the Aleutians in the area. There is a divide between model solutions on where the lows will drop through precisely, and if it would bring gusty winds and/or rain to the Alaska Peninsula Sunday. That being said, the strength of these lows are not impressive, lending to the idea of weaker winds and rainfall totals anyway. Through Tuesday, as the troughs move through, a col may develop over the southern/central Bering Sea, leading to a mixed pattern of showers and confused winds and waves.

Over the Southern Mainland of Alaska, weak areas of high and low pressure are expected to develop through the late weekend and early next week. The resulting weather will be diurnally-driven showers this weekend into next week. This pattern supports more of a scattered shower regime as opposed to widespread stratiform. The challenge will be to gauge instability each afternoon to determine whether or not lightning will be a threat with any robust showers that form. Right now, it looks like the Copper River Basin, along the Talkeetna Mountains, and along the Western Alaska Range feature the most instability through the long-term period.

-CL

AVIATION

PANC...Light westerly flow from Cook Inlet through the terminal is expected for this TAF period. Rain is expected to taper off and peeks of sunshine could return late this afternoon and evening as clouds break up. Thus, MVFR ceilings this morning will lift to VFR by this afternoon. Any clear skies overnight with residual moisture near the surface will increase the chances for fog development.