textproduct: Anchorage

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

Discussion:

Little change to the short-term forecast...

Water vapor imagery this morning shows the vertically stacked low beginning to exit the far southern Gulf of Alaska while a shortwave trough begins to make its way toward the Copper River Basin, moving east to west in the flow between the low and a stout upper-level ridge over northern Alaska. Precipitation lingers from Cordova south and west across the Gulf this morning. A few isolated showers also linger over the Talkeetna Mountains and far western Susitna Valley. Farther east, shower activity across the southern Copper River Basin is more scattered due to the advancing shortwave.

Today continues to look more active, in terms of convective potential, as northeasterly flow develops across Southcentral in between the departing low and the building ridge to the north over the Interior. This will help drag a much warmer and a more unstable airmass south into the region, supporting a more significant threat for afternoon thunderstorms. The aforementioned easterly shortwave rotating across the Chugach Mountains around the north side of the low will provide extra lift and forcing to help initiate convection. This feature will also provide enhanced easterly flow and up to 25 kts of deep layer wind shear, enough to support some slightly more organized storm clusters that should initially develop over and near the Talkeetna Mountains. Steering flow will easily be strong enough to pull initial storm clusters west into the Mat-Su Valleys during the afternoon and evening. Even Anchorage will have a chance (around 20-30%) to see a thunderstorm moving off of the Hillside into lower elevations during the late afternoon and evening hours.

By Tuesday, Southcentral will shift back into a col (a gap in between larger weather systems) along with much weaker winds aloft. Showers and isolated thunderstorms will again be possible during the afternoon and evening, especially along and near the various mountain ranges as yet another shortwave moves into the Copper River Basin. This feature will move westward as the mid-level flow begins to shift southerly over western Southcentral ahead of a wave moving east from Bristol Bay. This should allow any showers and thunderstorms that do develop over the Kenai and Chugach Mountains to slowly lift northward across the western Kenai, around Anchorage, and into the southern Susitna Valley. In addition, the northern Susitna Valley and Talkeetnas will again have the best shot at seeing more widely scattered thunderstorms. Otherwise, expect another very warm day afternoon in the upper 60s to mid 70s across the interior valleys with an increase in southeasterly gap winds for typical locations beginning Tuesday afternoon.

-AS/PP/TM

AVIATION

PANC...VFR conditions and light winds will persist with westerly winds late morning through late evening. A shower at or in the vicinity of the terminal is possible this afternoon.