Upslope/Downslope

[billski]

With regard to weather forecasts, what do the terms upslope and downslope indicate?

 

[WinnChill]

It's when air along the surface gets pushed upslope--ascending air, cools, condenses and precips out...when pushed up quick, heavier precip results. Downsloping winds compress, warm and dry out the air...so in our usual northwesterly windflow, northwest facing slopes get more showers, while southeast slopes and areas downstream are clearer and drier.

 

[billski]

Interesting. I always thought that most ski resorts were sited on the north side in order to preserve snowpack. Is it also to take advantage of the prevailing winds and upslope potential?

If so, that should correlate with let's say south-facing Bromley getting significantly less snowfall (forget about elevation for a minute), correct?

 

[WinnChill]

It definately helps..depending on how long ago resorts were set (decades), I'm not sure if that was known back then (how old are most of these resorts anyways?). Or if they had those options when it came to property lines/zoning back then. South facing slopes get the "shadow" effect mostly but can make up for it during nor'easters like the systems this week.

I need to make a list of slope orientation for each resort so we can even further fine tune amounts. We always keep it in the back of our minds but we sometimes have to broadbrush a few things.

 

[billski]

I need to make a list of slope orientation for each resort

I really like your reports; very readable, pragmatic, with a healthy dose of uncertainty as we move out.

A list was started here a few years ago. The largest ones were collected.

http://forums.alpinezone.com/showthread.php?t=11630&highlight=facing+slopes

 

[WinnChill]

Great link Bill, thanks! You beat me to it by 3 years!

I didn't think of the setting sun component. It's definately a factor at vineyards where they orient their crops on east/west valleys so they can catch as much afternoon sun as possible and to avoid shadows. They also plant them further up the slopes so they don't sit down in the valley base where cold air settles.

 

[billski]

I think people in that 4 year old discussion were making a generalization about the northeast and using it to describe the west. I wonder what the prevailings look like there?

 

[billski]

I was then juxtaposing Stowe and Smuggler's, and it sort of bears out the facing story:
http://webpages.charter.net/tcrocker818/