March 22, 2012
Weather Education Episode #1: Importance Of Understanding How Mountains Impact The Weather
RedOrbit Meteorologist Joshua Kelly
One of the first things that you will learn when you attend college to become a meteorologist is geography. Here in this lesson we are going to take a look at one piece of that geography -- mountains. Mountains play a major role in the climate of a region, the amount of precipitation that they receive and also how our weather systems move around them are just a few of the things that need to be thought about when forecasting around mountains.
Let´s examine the first part “Climate.” How can mountains impact climate, you may ask? First, there are two sides of the mountain -- one is called the windward side and the other the leeward side. Windward indicates which side is facing the wind and leeward indicates which side is not facing the wind. Next, as we examine area #1, which is the Cascades, we will first identify that Seattle gets its share of rain. However, just across the Cascades, there is a rain shadow. What a rain shadow means is the area does not get much rain as it is blocked by the mountains. So, if we look at Spokane, Washington versus Seattle, Washington we will note that Seattle is by far a wetter climate than Spokane.
Now looking at the second mountain range and what makes it unique to weather forecasting is the Sierra Nevada´s, which lay right between the CA/NV border. If you recall, the dessert is found just on the east side of this mountain range. Also these mountains are responsible for some of the fastest winds called the Santa Anna winds, which can create very dry conditions and lead to large fires in CA.
The third area is the Rocky Mountains. The importance of them is when it comes to severe weather forecasting in the United States. They hold all the cold air in the upper levels that is needed to mix in with the warm moist air to create our world famous Tornado Alley just to the east of them. Also the Rockies can be host to some of the coldest temps in the lower 48 states because of their high elevation.
The fourth region is known as the Black Hills of South Dakota. This region is also special in the fact that it is the highest place east of the Rockies. Here it´s common to find situations where we see what are referred to as Shinook Winds. These winds are known for the capability of warming the temps very fast in a short amount of time. Another huge forecast item that goes unknown sometimes because our famous weather models can´t catch this all the time.
Our Last region is the Appalachian Mountains along the East Coast. These mountains play a crucial role in the weather forecasting along the East Coast and also along parts of the Gulf Coast. During the winter we always hear about the major northeast storms that bring heavy amounts of snow to the coast. Imagine these mountains acting as a road block and the snow driving towards them. What happens is the snow hits the mountains and then falls back to the surface leading to heavy snow in places. The second term is known as Cold Air Advection when the winds are out of the Northeast they do a great job trapping that cold air from Canada along the eastern seaboard creating some cold conditions in the winter. Also along the Gulf Coast these northeast winds can bring down temps that fall below freezing.
This concludes our first weather education lesson. Hope you enjoyed.