Ski Arpa, Chile

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6 Day Forecast (free) top: 3740m mid: 3215m bot: 2690m	2 Day Detail (subscribers) top: 3740m mid: 3215m bot: 2690m	9 Day Forecast (subscribers) top: 3740m mid: 3215m bot: 2690m	Piste Map	Weather Maps	Snowfinder

6 Day Weather Forecast for 3215 m altitude, issued (local time): 1 pm 23 Jul 2008

	Days 0-3 Ski Arpa Weather Summary: Mostly dry. Freeze-thaw conditions (max 1°C on Thu afternoon, min -13°C on Wed night). Winds increasing (light winds from the W on Wed afternoon, fresh winds from the NNW by Thu night).									Days 4-6 Ski Arpa Weather Summary: A dusting of new snow. Temperatures will be below freezing (max -1°C on Sat afternoon, min -12°C on Mon night). Mainly fresh winds.
	Wed 23 after- noon	Wed 23 night	Thu 24 morn- ing	Thu 24 after- noon	Thu 24 night	Fri 25 morn- ing	Fri 25 after- noon	Fri 25 night	Sat 26 morn- ing	Sat 26 after- noon	Sat 26 night	Sun 27 morn- ing	Sun 27 after- noon	Sun 27 night	Mon 28 morn- ing	Mon 28 after- noon	Mon 28 night	Tue 29 morn- ing
Wind (km/h)
Summary	clear	some clouds	some clouds	some clouds	some clouds	cloudy	cloudy	some clouds	cloudy	cloudy	some clouds	clear	clear	clear	some clouds	some clouds	snow shwrs	snow shwrs
Snow cm	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	1	-
Rain mm	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-
Max °C	-6	-7	0	1	-3	-3	-2	-7	-2	-1	-5	-4	-3	-9	-4	-4	-9	-9
Min °C	-8	-13	-8	-1	-6	-6	-4	-7	-6	-3	-10	-10	-4	-11	-10	-6	-12	-12
WChill °C	-13	-20	-16	-8	-15	-15	-12	-16	-13	-10	-19	-18	-11	-20	-19	-14	-20	-19
Freezing level (m)	2350	2800	3350	3400	2900	2850	2850	2650	3150	3050	2400	2600	2700	2300	2550	2250	1650	1600
Sunrise	-	-	7:37	-	-	7:35	-	-	7:35	-	-	7:35	-	-	7:33	-	-	7:33
Sunset	17:59	-	-	17:59	-	-	18:00	-	-	18:00	-	-	18:00	-	-	18:01	-	-

The above table gives the weather forecast for Ski Arpa at the specific elevation of 3215 m. Our sophisticated weather models allow us to provide snow forecasts for the top, middle and bottom stations of Ski Arpa. To access the weather forecasts for the other elevations, use the tab navigation above the table. For a wider view of the weather, check out the Weather Map" of Chile.

NOTE ABOUT FREEZING LEVELS AND TEMPERATURES
The freezing level that we forecast Ski Arpa is the  free air freezing level. (More specifically, it is the uppermost free air freezing level). This means that all of the air above this elevation is below freezing however it does not necessarily imply that all of the air below it is above freezing.  We provide this because it best describes the level where falling snow first starts to turn to rain. On average, snowflakes only stay frozen for about 100 metres (300 feet) below the free air freezing level. That's because air temperatures usually increase steadily as you descend - but not always.  For example, a temperature inversion describes a pool of cold air near the ground with a layer of warmer air above it. This is a common occurrence in winter when the wind is light. Such pools of dense cold air can vary from a few metres to several kilometres deep and can persist from hours to several weeks. In an inversion, it can be simultaneously below freezing in a mountain valley, and also at a nearby summit, yet above freezing at some elevation in between. Most visitors to the Alps are very familiar with this. Such conditions can allow snow to fall much more than the usual 100 metres below the top freezing level, even reaching the valley, just as long as snow did not pass through enough warm air to melt. Otherwise, freezing rain or re-frozen soft hail (there is even a German word for it - graupel) reaches the valley instead. Our forecasts allow for these possibilities which is why you may see forecasts of snowfall and frost at elevations far below the free-air freezing level, or valley temperatures that are lower than summit temperatures. You may even see forecasts of rain to fall even though it is just below freezing at the surface - that happens if our model predicts that there is a deep warm layer just above. None of these are as contradictory as they may seem at first.

All of our temperature forecasts for Ski Arpa are for the ground, not the air. These can be very different to free-air temperatures, especially at night. This can lead to what looks like a contradiction. Because the ground is such a good radiator of heat (especially on clear nights when there is a snow cover and the wind is light) surface temperatures often fall more than far below the free air temperatures - sometimes by more than 10 degrees. On such occasions, the snowpack freezes at elevations that are far below the free air freezing level. For example, in the European Alps, snow tends to freeze in valleys on still clear and still nights  even if the free air freezing level is above 3000m simply because snow is so efficient radiating its heat away. In reality there are two freezing levels; one just above the snow surface and another at 3000m with a layer of warmer temperatures in between where the snow may not freeze at all. In summary, the reason we provide surface temperatures is because these determine the condition of the snowpack.

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