Public Forecast of Weather and Backcountry Avalanche Conditions This is Dale at the CAIC with current information on mountain weather, snow, and avalanche conditions recorded at 6:35 am, Tuesday, December 21, 1999. DISCUSSION A fast moving storm system will sweep quickly Southward across CO today bringing snow to the mountains. Drier air tonight will mean partial clearing over most of the C&S mtns, however; the cold Nerly flow will fuel clouds and showers in the N mtns and perhaps as far South as the Aspen to Leadville areas through Wednesday. The forecast details: WEATHER Tuesday: all mtns, cloudy, light snow, perhaps some moderate snow this afternoon, 2-5". Winds shifting all mtns to the N/10-20, G40 above treeline. Highs all mtns, 6 to 16. Tuesday night: N&C mtns from Aspen and Leadville and Northward, cloudy, very light snow, T-3" additional. South of this line in the C&S mtns, partial clearing, 0-1" additional. Winds all mtns ranging from NE to NW/10-20 G30. Lows all mtns 5 to +5 but colder in the valleys of the C&S mtns. Wednesday: N mtns, mostly cloudy, light snow, T-3". C&S mtns, partly cloudy, widely scattered snow showers, 0-1". Winds all mtns NE to NW/10-20 G30. Highs 8 to 18. SNOWPACK This morning an additional 2-3 inches of new snow has been reported from most mountain sites. This new snow is just another layer added to a snow pack that resembles a fragile house of cards. The most widespread avalanche problems are in the N mtns where in the past 2 weeks the consistent NWerly flow has dropped between 2 to 3.5 feet of snow (Bear Lake in Rocky Mtn Nat. Park 22"; Breckenridge, 31"; Winter Park, 32.5"; and Vail, 40"). This is more snow than had fallen in the previous two months. Strong winds and cold temperatures have accompanied this new snow creating tender soft and hard slab conditions. Widespread collapsing, whoompfing sounds, and shooting cracks have been reported on all aspects. Avalanches are even being triggered by people traveling in gentle terrain adjacent to steep slopes. The most impressive example of remote triggering occurred on Monday when the Copper Mountain ski patrol triggered a very large slab 2000 feet across and 5 feet deep while approaching the path from the top. In the C&S mtns the snow pack foundation is just as weak, but relatively little snow has fallen. The recent events in the N mtns are a sign of things to come when snows return to the C&S mtns. For today the backcountry avalanche danger in the N Mtns: below treeline (TL), MODERATE; near and above TL, CONSIDERABLE, with areas of HIGH on N-SE aspects steeper than 30 degrees. An [2]Avalanche Advisory was reissued for the N mtns last night due to the dangerous conditions. We do not expect much natural activity, however, triggered releases by backcountry travelers are probable to even likely on steep wind-drifted slopes and gullies. In the C Mtns: overall LOW, however pockets of CONSIDERABLE near & above TL on N-SE aspects. In the S Mtns: the danger is rated an overall LOW; but locally in the Telluride and north side of Red Mtn Pass areas: MODERATE near and above TL on N-SE aspects steeper than 30 degrees. In the S Sangres and Spanish Peaks areas the danger is rated MODERATE. Be very careful in the backcountry, the Colorado mountain snow pack could easily ruin ones Christmas. As always, the snow conditions weve reported are based on observations and field data. Use this information for guidance only. You may find different conditions in the backcountry and should travel accordingly. We will update this forecast on Wednesday morning. Atkins