textproduct: Anchorage

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

A deep occluded low is currently in the south-central Gulf of Alaska with its front bringing widespread rain showers to coastal communities. Now that cooler air has wrapped back into the low, lapse rates have become quite steep above the near surface temperature inversion. That, coupled with numerous shortwaves rounding the low, has brought freezing rain to lee-side areas from Birchwood south to Ninilchik despite strong cross-barrier winds. Most of these showers aren't making it far over the mountains, leading to the highest lee-side freezing rain accumulations in the greater Anchorage Muni near the mountains, and on the western Kenai from Sterling east to Cooper Landing.

Moving through the day today, a strong shortwave rounding the upper low will swing back into the Kenai Peninsula, bringing another round of moderate rain to the Kenai Mountains, and a high chance of more freezing rain from Anchorage south into the western Kenai. Meanwhile, the surface low will move near the Barren Islands, resulting in increased northerly winds from the Mat Valley, into west Anchorage and south into the Cook Inlet. This will have some drying effect, particularly for the Mat Valley, but areas near the mountains are less likely to get the winds and therefore most likely to get more rain tonight. Temperatures have already climbed near 40 for the Mat Valley, and will likely warm through the rest of the main population centers around Cook Inlet through the day. Despite the temperatures above freezing, rain falling onto frozen roadways and cold surfaces are likely to cause difficult travel conditions. For more interior areas, generally overcast skies and above normal temperatures are expected for the next few days.

Moving into Friday the low will quickly weaken along with the winds and precipitation for most areas. Kodiak and the eastern Kenai are likely to get continued rain with some weak shortwaves and east to southeast flow. For Saturday and Sunday, a shortwave ridge will set up leading to calmer and drier weather, as a broad low moves into the far southern Gulf.

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

The large scale pattern and storm track will remain unchanged through the extended forecast period, with a downstream ridge over the western U.S. and western Canada extending to the Alaska Interior and a mean trough over the north Pacific, southern Alaska, and much of the Bering Sea/Aleutians. Under this pattern, storm systems will develop over the northeast Pacific and track into the Gulf before rotating westward and weakening. Expect a new storm system each day or two. This will bring a series of fronts across the Gulf, Kodiak Island, and coastal Southcentral, bringing rounds of strong winds and moderate to heavy precipitation. A persistent influx of warm air will lead to low elevation rain and mountain snow for the eastern Kenai Peninsula and Prince William Sound regions. Inland areas of Southcentral will be much drier largely due to downslope winds, though some of the short-waves moving in from the Gulf look strong enough for some light precipitation to make it inland. Areas in the lee of the coastal mountains would likely see mixed precipitation (rain, snow, freezing rain) while interior areas of Southcentral would likely see mostly if not all snow. The details will have to be worked out later, as we gain confidence in the track and strength of individual features.

Features will weaken as they track westward toward Southwest AK and the Bering Sea. Still, expect rounds of winds and precipitation to cross the region. Bristol Bay and the Alaska Peninsula look to be warm enough for rain or mixed precipitation, while the Kuskokwim Valley and Kuskokwim Delta will likely remain cold enough for mostly snow. Weather across the Bering Sea and Aleutians will be quieter with weaker short-waves embedded in the upper flow and persistent northerly flow at the surface.

-SEB

&&.AVIATION...

PANC...A shortwave moving west across the chugach this morning will bring light rain and virga to the Terminal through around 15Z before drying out a bit. The low bringing the precipitation is currently in the southern Gulf and will move near the Barren Islands over the next 24 hours. This will induce some breezy northerly winds later today. An additional shortwave will move over the Chugach this afternoon and evening, bringing another round of rain through early Friday morning. The winds and precipitation will come to an end early Friday morning. Conditions should be VFR given the cross barrier winds over the mountains and northerly winds at the surface.