Yakima Climate Controls and Comparison

Yakima has a very unique climate because of the climate controls that influence the area. A few meso-scale situations effecting the area are the atmospheric circulations, its proximity to the Pacific ocean and orthographic influences from the Cascade mountain range. As stated in my previous blog, Yakima can be influenced by maritime tropical (mT) and continental polar (cP) fronts. The moist maritime tropical does not bring much precipitation to the area because orthographic lifting causes much of the moisture to dump on the west side of the mountain range leaving little that reaches the east. But the front does produce slight humidity in the area.



http://www.personal.psu.edu/gmm5106/blogs/meteorology_410/se.html
The digital elevation map above shows the Cascades and how they can be a huge topographic barrier effecting the climate of the Yakima Valley.

The continental polar air effects the area mainly in the winter when the jet stream lowers. This brings dry cold air with not a lot of precipitation resulting in low snowfall rates compared to other states at that latitude. During the summer, Yakima receives some humidity from continental tropical (cT) air that eludes the Cascades and enters from the southwest. The Cascades definitely have an effect on the area. Not only do the mountains block moisture they aid in the warming and extreme temperatures in the summer. As the air mass travels over the Cascades, it warms according to the dry adiabatic lapse rate and enters the Yakima Valley. The area also experiences Chinook winds that build up seed coming down the mountains and blow through the valley. The area also experiences some micro-scale situations affecting the climate especially its proximity to irrigation. Yakima has a cute nick-name which is the “Palm-Springs” of Washington. The area is known for its agriculture. There are many apple orchards and vineyards. The area is not a naturally lush area because of the lack of precipitation. So most of the agriculture and economy of Yakima is dependent on irrigation. Lots of irrigation results in increased humidity due to transpiration and evaporation.

The graph I made above shows the average temperature and precipitation of Yakima. The data I found is the average for the period of 1961-1990. The relationship in the graph shows that higher temperature coincides with low precipitation and low temperature coincides with higher precipitation. This also coincides with the air masses that effect the area. The continental polar brings snow in the winter because the orthographic effect is not as important with this front. The maritime tropical cannot bring the moisture in the summer as it is blocked by the Cascades.



http://lindenhillsweather.blogspot.com/
The map above was displayed in Sam's blog. It shows the jet streams for the winter and summer. Even though the two cities are at similar latitudes, they are affected differently by the jet stream and the air masses.

I compared my blog to Sam Epperly's blog on Minneappolis, MN. I chose this location because it has a similar latitude but different environmental effects.  They both receive cold dry air in the winter from the continental polar fronts. This causes the two areas to have really cold temperatures from the air masses. The maritime tropical air effects the two regions differently. Yakima receives a little precipitation and humidity from the maritime tropical air from the pacific. Minneappolis recieve a much warmer and moisture filled maritime tropical air from the Gulf Coast. This brings a lot more precipitation to the area and thunderstorms. It also creates a great environment in the state for tornados which is something that is not really experienced in the Yakima valley. I think Sam's blog and my blog are great examples of how locations at the same latitude are affected by so many different environmental situations to create different climates.

 Sam's blog link: http://lindenhillsweather.blogspot.com/

References:

http://www.wrcc.dri.edu/cgi-bin/clilcd.pl?wa24243