---------------------------------------------------------------- INSTITUTE FOR SNOW AND AVALANCHE RESEARCH DAVOS NATIONAL AVALANCHE BULLETIN NO. 180 valid to Thursday, 8 May 2008 issue date 5.5.2008, 18:30 hours ---------------------------------------------------------------- FAVOURABLE CONDITIONS FOR BACKCOUNTRY SKIING IN THE MORNING, WET SNOW AVALANCHES DURING THE DAY ---------------------------------------------------------------- CURRENT CONDITIONS Sunday night was mostly overcast. Below approximately 2800 m the snowpack was barely able to freeze. During the day the weather was mostly sunny. Midday temperatures at 2000 m were about plus 5 to plus 7 degrees in the west and south and plus 4 degrees in the northeast. The wind was light to moderate and changed direction from northwest to east. Above approximately 3000 m, the snowpack on north facing slopes remains dry, as in the winter. The entire snowpack is wet, soft and prone to triggering below approximately 3000 m on south facing slopes and below approximately 2600 m on north facing slopes. It may become stable as the near-surface layers freeze during the night. In the inneralpine regions of Valais and Grisons, the snowpack base is weak over a wide area. DEVELOPMENT From Tuesday 6 May until Thursday 8 May, the weather will be sunny with some convective cloud during the afternoon. During the nights the skies will be mostly clear. On Wednesday 7 May and Thursday 8 May, it will be partly cloudy in the south. During each of the nights here, the outgoing longwave radiation may be reduced. Temperatures will generally increase slightly. After clear nights, the conditions for backcountry skiing will be favourable in the morning. Detailed weather information is contained in the daily Alpine report from MeteoSchweiz (telephone 0900 162 138 in German or www.meteoschweiz.ch). WARNINGS OF AVALANCHE DANGER In all regions of the Swiss Alps, the danger of dry avalanches is "low" (level 1). Isolated avalanche prone locations are to be found, in particular, at high altitudes on west to north to east facing steep slopes. If an avalanche is released, caution should be exercised especially in exposed terrain because of the danger of falls. The danger of wet snow avalanches will increase during each of the coming days, reaching the danger level "considerable" (3). On the southern flank of the Central Swiss Alps, the danger level "moderate" (2) will be reached. Below approximately 2800 m, wet snow avalanches are to be expected in all aspects, especially in the afternoon and the first half of the night. In the inneralpine regions of Valais and Grisons in particular, isolated large avalanches are also possible and capable of releasing the entire snowpack. Backcountry touring, ascents to refuges and hiking close to the snow line are to be concluded early. INFORMATION The next avalanche bulletin will appear at the latest on Thursday 8 May at 5:00 pm. If you wish to be notified of the next avalanche bulletin via SMS, please send an SMS with the message "START SLF SOMMER" to tel. no. 9234. You can cancel the service anytime by texting "STOP SLF SOMMER". An SMS costs 20 Rappen.