March 24, 2003 SOUTH COAST REGION WEATHER: Storm snow amounts varied somewhat depending on region, but up to 40 cm of new fluff arrived in a series of dustings since Friday. Winds were moderate and occasionally strong from the SW, dropping off significantly Monday. The sun managed to make an appearance Sunday as well, bringing some of the first good visibility in the alpine for a few days. The weather forecast calls for broken clouds and light to moderate SW winds to continue, followed by some more moisture on Wednesday. Temperatures will continue to be mild. SNOWPACK: A wind slab has formed at the surface, and the sunshine later in the weekend has added to it^Òs stiffness as settling continued to occur. The bonds within and below the storm snow are beginning to instil confidence. The February 15th surface hoar layer down about 140 cm and a very deep layer near the snowpack base both showed up as new natural failures reacting to the continued loading from snow and wind transport. AVALANCHES: Natural activity was somewhat widespread Saturday, failing in the storm snow layers. By later Sunday, natural activity tapered off but the isolated incidents that did occur were deep and big! FORECAST OF AVALANCHE DANGER UP TO WEDNESDAY EVENING (March 26th) ALPINE - Considerable TREELINE - Considerable BELOW TREELINE ^Ö Considerable, increasing during the afternoons TRAVEL ADVISORY: Although the frequency of natural activity that peaked Saturday has subsided, the fact that naturals are still occurring on deep layers is cause for concern. North facing aspects will represent the highest danger, as well as the best skiing and riding. We^Òre in that time best described as, ^ÓYou can probably get away with a fairly bold line, but the possibility of finding a weakness susceptible to a trigger for something big are still quite high, and the consequences of you finding that variability are quite serious.^Ô NORTH COLUMBIA REGION WEATHER: Snowfall increased in intensity throughout Friday night and into Saturday. A front ripped through the region mid-day Saturday, bringing SW winds to a peak of 100 km/hr in the alpine. As the front passed, temperatures dropped, skies cleared and winds died. A second wave of heavy moisture occurred Sunday afternoon. Monday presented clear blue skies and bright sunshine. The weather forecast calls for broken cloud gradually deteriorating to some serious moisture again by Wednesday. Temperatures will remain mild. SNOWPACK: Up to 50 cm of storm snow has accumulated since Friday, with all areas reporting some wind slab as a result of the Saturday wind event. The storm snow surface was rain soaked to approximately 1800 m late Saturday, and some breakable crust has formed there now. From valley bottom up to 1600 m, a 50 cm thick layer of wet or moist snow is found below the storm snow. The deeper instabilities have become active as failure zones since the weekend loading event. AVALANCHES: Fairly widespread storm snow avalanches occurred Saturday, with some reports of stepping down to lower layers, some as deep at the November crust. Cornice fall was reported several times Sunday and Monday as a trigger for deep layers once it hit the slopes below. FORECAST OF AVALANCHE DANGER UP TO WEDNESDAY EVENING (March 26th) ALPINE ^Ö Considerable, areas of High TREELINE ^Ö Considerable, areas of High BELOW TREELINE ^Ö Considerable, high in the afternoons TRAVEL ADVISORY: We are in a time where the frequency of avalanches is going down, but the size of the events that do occur is increasing. This tendency will continue until Wednesday, when a return to heavy snow and rapid warming may put danger levels into the high range at treeline and above. North facing aspects will represent the greatest danger, particularly just below ridgelines and near treeline. SOUTH COLUMBIA REGION WEATHER: A healthy dose of storm snow arrived this weekend, with up to 50 cm falling since Friday, followed by a further 20 on Monday. Winds became very strong Saturday as a front passed, while cooler air and calmer winds followed in behind the front. By Monday, skies had cleared and the sun was bright and inviting. The weather forecast calls for broken cloud to develop late Monday, slowly deteriorating to possibly heavy moisture by Wednesday, with the freezing level once again climbing up the mountainside. SNOWPACK: The storm snow from the weekend was blown into a soft wind slab, and this was further buried under 20 cm of fluff on Monday. Below the windslab, wet snow is found all the way up to 1800 m elevation. The weak layers preserved in the mid and lower snowpack are active again due to the loading at the surface. AVALANCHES: Reasonably significant natural activity occurred Saturday, failing primarily in the storm snow but occasionally in deeper layers, particularly in the Purcells. By Monday, cornice fall was still triggering deep releases, but storm snow avalanches were decreasing in frequency. FORECAST OF AVALANCHE DANGER UP TO WEDNESDAY EVENING (March 26th) ALPINE - Considerable, areas of High TREELINE - Considerable, areas of High BELOW TREELINE - Considerable, high in the afternoons TRAVEL ADVISORY: The continued deeper releases confirm the lingering tendency for human triggering, with potentially serious consequences. North aspects will represent the greatest danger due to wind effect on the weekend. Check the bond below the wind slab before venturing onto alpine terrain and consider avoiding all big alpine slopes unless you are confident the deeper weaknesses will not put you at risk. KOOTENAY BOUNDARY REGION WEATHER: Fresh snow blanketed the alpine again this weekend, with a net result of 40 cm of storm snow accumulated by Monday. Temperatures managed to stay just below zero in the alpine, although valley bottom locations warmed significantly late Saturday, bringing the freezing level to approximately 2000 m. Winds remained moderate from the SW. The weather forecast predicts broken cloud to prevail early in the week, deteriorating to rain and snow by Wednesday, accompanied by rising temperatures once again. SNOWPACK: A variety of layers are evident near the surface, dependant on the weekend weather. Weak crusts, wind slab, fluffy powder, and isothermal moist snow are all found. Deeper weaknesses are disappearing at lower elevations as the snowpack continues to warm. In the alpine, they are still preserved but isolated under one or more crusts, keeping them inactive at the moment unless very large triggers like cornice fall occur. AVALANCHES: Storm snow avalanches occurred on Saturday, but this activity has decreased in frequency. The formation of crusts has helped this to occur. Cornice fall is likely as they continue to grow. FORECAST OF AVALANCHE DANGER UP TO WEDNESDAY EVENING (March 26th) ALPINE - Considerable TREELINE - Considerable BELOW TREELINE ^Ö Moderate, Considerable in the afternoons TRAVEL ADVISORY: If the near surface crusts deteriorate due to heat, expect danger to increase. Cornices will represent a continuous threat to slopes below. Conditions may deteriorate rapidly on Wednesday if heavy snow and rain do occur. SOUTH ROCKIES REGION WEATHER: Temperatures cooled off on the weekend, followed by a total of 20 cm of storm snow falling Saturday and Sunday. Winds remained moderate out of the SW. The weather forecast calls for a mix of sun and cloud, light winds and lows of -7, with daytime highs near zero. SNOWPACK: A healthy crust formed at the surface early in the weekend as the temperatures fell. The 20 cm of storm snow sits on top, with a poor bond at the interface. Below the crust, warm, moist snow is found. The mid snowpack is relatively strong except at low elevations where it is near isothermal. The lower snowpack is still weak but isolated from forces above by the midpack at treeline and above, except in shallow snow areas. AVALANCHES: Some storm snow avalanches failing at the interface with the crust were reported as recently as Monday. FORECAST OF AVALANCHE DANGER UP TO WEDNESDAY EVENING (March 26th) ALPINE - Considerable TREELINE - Considerable BELOW TREELINE - Considerable TRAVEL ADVISORY: Rapid warming may cause the near surface crust to deteriorate, causing a rise in danger. Cautious choice of terrain should allow enjoyable skiing and riding in the light powder layer above the crust. Avoid bunching up into large groups as this may overwhelm the strength of the crust. When the sun pops out, treat south aspects with additional respect. Avoid terrain below cornices as they provide large triggering forces if they fall to slopes below.