textproduct: Anchorage

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

Discussion:

A series of fronts will push through the region from south to north this afternoon into the weekend from a low in the Bering Sea. The initial front will generate gap winds for the Copper River Basin as well as winds over the Turnagain and Knik Arm. There is higher confidence for Turnagain Arm winds than Knik Arm winds given the orientation of the front. The winds will be strongest this afternoon into the evening hours, which will clip Turnagain Arm and the Hillside potentially gusting 40 to 55 mph. A few gusts of 40 mph is possible this afternoon for Palmer. These winds will begin to diminish overnight as the surface high weakens.

A NW to SE oriented front that is currently between Kodiak Island and Kenai Peninsula will push into Prince William Sound before tomorrow morning. This front has a swath of gale forced winds and precipitation. The front will push over the Chugach and Kenai mountains tomorrow afternoon, but most of the moisture should be downsloped. Hence, 30% chance of rain for Anchorage, Matsu Valleys, and Kenai into tomorrow evening.

A brief lull in precipitation will occur in the overnight hours, before another front pushes into the area early Sunday morning. This will bring rain for a swath of Southcentral through Sunday afternoon with at least 40% confidence of at least 0.10 inches of rain. Clouds remain overhead with showers for the rest of the weekend into next week as remaining waves of energy from the low propagate into the region.

-SS

LONG TERM FORECAST (Days 4 through 7: Tuesday through Friday)

The long term period starting out on Tuesday will feature a complex trough moving over the southern Mainland and Alaska Gulf, with a surface low moving over the northeastern Gulf near Yakutat. Gusty northwest winds will likely be ongoing through gaps and passes along the coast of Southcentral, particularly near Kodiak Island and the Barrens. Out west, cool northwesterly flow extending from the Bering Strait down along the western coastline will bring seasonably cool temperatures in the 30s and 40s down into much of Southwest Alaska through midweek. A low-amplitude ridge is anticipated to be progressing across parts of the central Bering and Aleutian Chain, allowing for relatively quiet conditions to prevail initially. However, a low moving out of Kamchatka will likely reach the central/western parts of the Bering and Aleutians by Tuesday afternoon, sending gusty southeast winds and rain across the region as the low and leading frontal boundary push east with time.

Looking towards the end of next week, models diverge in regards to the progression of the low approaching the southwestern Bering earlier in the week. The deterministic 12z ECMWF is a notable outlier at this time, as it depicts the ridge over the Bering remaining much farther west through Thursday and Friday. It also attempts to dig a separate trough south from northern Kamchatka down into the AKPen and Gulf region between Tuesday and Thursday, ultimately becoming a deeper low in the southern Gulf on Friday as it interacts with another system driving up from the Pacific. In contrast, most of the other deterministic and ensemble guidance supports the Bering low and attendant upper trough remaining as as the dominant system, showing the low continue to track mainly east along the Aleutian Chain through Friday. Assuming this more favored solution plays out, gusty south to southeast winds and rain along the low's front could shift from the Bering and Southwest into Southcentral between Thursday and Friday. Most of the heavier rain would likely be focused mainly along the Gulf Coast, with most of the interior parts of Southcentral staying drier towards the second half of next week.

-AS

AVIATION

PANC...VFR conditions will persist through the TAF period. There continues to be a high degree of uncertainty regarding potential for southeast winds to make it into the terminal. A few gusts from the southeast could clip the terminal this afternoon, but it now looks like gusty winds at the surface could hold off until late tonight or early tomorrow morning. During any period where southeast winds do not reach the terminal at ground level, LLWS will be possible due to strong southeast flow aloft developing this afternoon into Saturday morning.

-AS