USGS Map: Chinook Pass 7 1/2. Chinook Pass Falls is located near Tipsoo Lake on the east side of Mount Rainier National Park. From the junction of Highways 410 and 123 at Cayuse Pass, follow Highway 410 east toward Chinook Pass and Yakima for just over a mile and park in the small pull out at the first switchback.
Constriction of blood vessels means that there is less heat radiated to the environment. This is why prolonged cold can lead to frostbite- the fingers and toes don't get enough blood sent to them and the tissues begin to die. Blood vessels dilate to radiate heat to the environment. Due to Homeostasis (maintanance of the internal environment) when your too cold, your blood vessels constrict to preserve heat which makes blood flow slower. when your warm, your blood flows better and mroe heat is released.
For your question, in cold conditions, the small blood capillaries on the surface of your skin constrict to prevent blood flow to them. Since blood carries body heat, it prevents heat loss through convection, conduction and radiation from the skin surface. Remember that the skin is the biggest organ in our body and hence has the largest surface area, heat can be lost/kept effectively. The reverse happens for warm conditions. The blood vessels dilate and allow blood flow to skin surface and heat is lost through convection, conduction and radiation. A little bit of physics involved: Heat energy travels from an region/object of higher temperature (skin) to a region of lower temperature (surrounding environment).