textproduct: Anchorage

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

Discussion:

Moderate to heavy rainfall has been ongoing overnight across Kodiak Island with light to moderate rainfall for areas further north along the eastern kenai Peninsula and Prince William Sound as a nearly stacked upper level low off southern AKPEN Gulf-side coast. Several perturbations embedded in the flow around the low have allowed for rounds of rain to move northward over the Gulf bringing these heavier rain showers to the coastal areas. Some of these showers have spilled over the Kenai and Chugach Mountains, but these have been pretty isolated and light. The parent low will start to weaken today as the long-wave trough shifts east over the Gulf as ridging begins to build eastwards over the Bering Sea. Once of these perturbations have become more defined on satellite imagery as the surface low and associated front lift towards the Gulf coast. Strong winds of gale to storm force have developed over the northern coastal waters this morning as the front nears...with gusty winds moving into the immediate inland coastal areas. The front will then continue to lift into inland Southcentral through the day.

Precipitation will have a better chance of spilling over the mountains with the passage of the front with a period of light rain for the western Kenai Peninsula, then up into Anchorage, the Mat-Su Valleys, and the southern Copper Basin. Periods of snow will be possible at higher elevations with snow levels fluctuating between 2500 ft to 4000 ft along the Kenai and Chugach Mountains. Favored gap flow winds will increase as the gradient tightens in response to these perturbations moving through.

The upper trough will slowly translate eastwards the remainder of the week before reaching the Panhandle this weekend. As such, the unsettled weather pattern will continue with more intermittent showers for inland Southcentral and more continuous rainfall along the coast.

- PP

LONG TERM FORECAST (Days 4 through 7)

High confidence exists in a brief drying trend across Southcentral on Sunday as lingering Gulf troughing is absorbed by a system shifting into the panhandle. Farther west, ensemble guidance suggests a frontal boundary advancing into the Bering Sea on Sunday, bringing a 50% to 70% chance of rain and elevated winds across the Aleutians; however, confidence remains low regarding the exact spatial placement and track of this boundary.

Forecast spread increases heading into early next week, though clusters consistently favor a potent North Pacific low tracking south of the Aleutians and Alaska Peninsula late Sunday into Monday. There is moderate-to-high confidence in gusty, potentially gale-force winds and steady rain impacting the Nikolski and Unalaska corridors early Monday. As deep moisture lifts northward ahead of the system, precipitation chances increase rapidly across Southcentral as early as Sunday night. The potential for moderate to locally heavy rainfall remains highest from Kodiak and the northern Gulf coast through Monday, though specific rain totals will ultimately hinge on the system's exact track.

AVIATION

PANC...VFR conditions are expected to continue through the period, however, there is a chance that a period of light rain later this afternoon and evening could bring a brief reduction in visibility. Otherwise, LLWS concerns will develop this morning and continue into the afternoon hours as northerly surface winds will be overrun by strong cross-barrier (easterly) winds higher up.