textproduct: Anchorage

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

Satellite imagery this afternoon reveals the fog bank that has been plaguing the Cook Inlet region and northward up to the Susitna Valley has redeveloped, though is more patchy in nature than yesterday and is accompanied by areas of low stratus. Relatively drier air (via a light north to north-northeast wind) has been trying to advect southward across this stretch of Southcentral, and has kept much of the fog from becoming widespread. The MOS guidance is in solid agreement with keeping at least patchy fog around through Tuesday morning. Synoptically speaking, there is little in the way of anything in the next 12-18 hours to completely eliminate fog from the forecast. The combination of residual moisture from recent snowfall and light winds mixing this moisture from the ground to just off the surface is one piece of a prime fog setup. There ideally needs to be a big weather player with strong enough forcing to shut off the fog machine.

The 500 mb flow late Tuesday becomes increasingly difluent in nature downstream of a digging trough in advance of a front pushing into the western Gulf and across Kodiak Island Tuesday night and Wednesday morning. The front does not look to be too terribly impactful, with only small craft sustained winds up to borderline gale force wind gusts. Temperatures for Kodiak also look to remain in the mid to upper 30s, keeping any precipitation that falls in the form of rain. Models have a good consensus on the timing of the front, but differ somewhat on structure and if the front can spin up a low along its trough axis. When the front likely arrives to Southcentral Wednesday afternoon/evening, cross barrier flow and downsloping in lee of the Chugach will help to keep precipitation amounts light across the Anchorage Bowl. The windward slopes, however, could see light snowfall accumulations with rain being the predominant precipitation type for the Prince William Sound. The front will then stall out along the coast as a potentially more impactful system enters the western Gulf and moves closer to Kodiak Island.

-AM

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

A pattern shift to warmer temperatures and precipitation continues to be seen in the long range models.

A ridge builds in the Pacific Ocean and slowly moves eastward through the weekend. On Friday and Saturday, its orientation in the Pacific Ocean results in southerly flow into the Aleutians and a more southwesterly flow into Kodiak Island and Southcentral. This brings warm air advection for the Aleutians resulting in weekend precipitation falling as mostly rain and strong southerly winds; especially through the bays and passes. While a main low rotates well east of the Pribilofs in the Bering Sea this weekend, numerous lows move over the Aleutians bringing periods of heavy rainfall and winds to the area. As the high moves eastward Sunday/Monday, the chances of storms reaching the Mainland increases though confidence in their exact location and strength through the Bering Sea is low at this time.

Southwesterly flow into Kodiak Island and Southcentral Alaska persists this weekend with the greatest chance of precipitation late Saturday into Monday. Right now, mesoscale disagreement remains for timing and amounts of the heaviest precipitation from weak lows moving through from the Pacific Ocean into the Gulf of Alaska. However, this synoptic pattern indicates a warming trend for Kodiak Island and Southcentral this weekend and into Prince William Sound Monday as waves of moisture bring periods of periods of heavy precipitation and gusty winds with warm air advection to the region.

-Johnston

AVIATION

PANC...Dry air continues to mix out the fog this afternoon, though radiation fog developing on Knik Arm continues to be a challenge for the TAF forecast. While it may mix out this afternoon and evening, it's somewhat likely it will develop again overnight due to little change in the overall pattern coupled with cold temperatures over the relatively warmer, ice free water. We will get a pattern change on Tuesday with increased cloud coverage as a weak front lifts into the Gulf. This should allow for VFR conditions to return after sunrise on Tuesday.