textproduct: Anchorage

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

KEY MESSAGES:

1) Pockets of freezing drizzle and snow from Anchorage north to the Mat-Su Valleys continue through this afternoon.

2) Widespread snow remains likely across Southcentral through midweek; highest snowfall amounts are expected across the Copper River Basin and Prince William Sound

Overnight, satellite and radar showed waves of moisture stretching from the Kenai Peninsula to the Mat Valley crossing the region. Surface observations reported and AK511 web cameras showed freezing drizzle and snow making its way to the surface during this time. This caused visibilities to range from over 6 miles to 1 mile quickly and frequently over a short distance. A winter weather advisory remains in effect for this region through noon today for these conditions to continue before the precipitation departs.

A polar low progresses across the Interior towards the Bering Strait the next 48 hours. This will result in an Arctic trough stretching from the Bering Sea to Kodiak Island pushing northward today. This northward progression allows for a compact low in the Gulf of Alaska to move toward Prince William Sound today through Wednesday. It will continue to bring widespread snow from the Copper Basin then westward to the Mat-Su Valley. Confidence remains high in the snowfall amounts ranging from 4 to 8 inches for these inland locations through Wednesday evening. A Winter Weather Advisory remains in effect through Tuesday across most of the Copper Basin. Snowfall amounts will be higher in Thompson Pass ranging from 15 to 20 inches by Wednesday morning.

Through Wednesday, a trough over the Bering Sea deepens and digs into the North Pacific. This shift allows for a second Gulf of Alaska low toward the Kenai Peninsula/Kodiak Island. A track of this path would bring accumulating snow to the Kenai Peninsula and Anchorage Bowl. Current accumulations range from 3 to 6 inches.

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

The long term forecast for both Southcentral and Southwest Alaska is characterized by a messy pattern. Many upper level features will make their way into Alaska from the North Pacific, which will bring a mix of weather from snow, rain, and winds.

For Southcentral, these upper level features will stream into the Gulf of Alaska through Wednesday. The Gulf Coast is likely to see periods of precipitation as these features push inland. Due to a warmer air mass from southerly flow, rain or a rain/snow mix is the likely precipitation type for these waves. Any precipitation that makes it further inland will likely be snow. Due to the "messy" nature of this pattern, day to day changes in the forecast are likely as small features become better resolved.

Southwest Alaska will be a little different. Cold air from the large Arctic trough will linger on for Thursday, allowing for snow showers in the Bering and more constant snow in the Eastern Aleutians. There will still be some gusty winds for the Unalaska region, so blowing snow potential remains until Friday night/Saturday morning. After this point, enough warm air will make it in to start transitioning snow to a rain/snow mix. Meanwhile, the Southwest Mainland will have periods of snow, rain, and elevated winds due to the many small features moving in through Sunday.

-JAR

AVIATION

PANC...Light snow at the terminal is reducing vsby/cigs to IFR this morning, accompanied by light northerly winds. A subtle shift in the upper trough position will cause snow intensity to diminish later this morning, potentially causing the snow to taper off or change over to intermittent freezing drizzle. In the event of freezing drizzle, ice accumulations would be less than one tenth of an inch as the lower rate of precipitation continues through tonight. Ceilings may remain as low as IFR, but are generally expected to improve back to MVFR or even VFR along with visibilities with the lighter/end of precipitation. Snow returns heavier on Tuesday, though there remains a large range of timing differences in the models. In general, expect snow to begin/reintensify on Tuesday morning and become heavier through the afternoon, with cigs/vsby dropping back to IFR.

Quesada