Blog Post 2

Eugene, OR

Blog Post Number 2

As shown from this image, the Eugene, Oregon is primarily affected by Maritime Polar air masses year round. Continental Polar air masses also affect Eugene year round, but it is not as much the normal situation. In certain situations, such as when the polar front moves to the north, Oregon may be affected by Maritime Tropical fronts, although this extremely rare. By far, the most common air mass to affect Eugene is the Maritime Polar, which is characteristic of Eugene's climate, providing cool, moist air.
Image Source: http://www.atmos.illinois.edu/earths_atmosphere/airmasses_fronts.html

This image helps visualize how the air masses flow over the United States with the states outlined clearly.
Image Source: http://teachers.oregon.k12.wi.us/mahr/assignments/airmases_fronts_storms.pdf

This March, 1999 satellite image shows a maritime polar air mass merging with a continental polar air mass, which draws moisture from the maritime tropical and continental tropical air masses from the east over the continent and the Gulf of Mexico, and the west out of the Pacific Ocean.
Image Source: http://www.climate.washington.edu/stormking/HurricanesVsPNWstorms.html

This image depicts a cold front that recently moved through the Pacific Northwest area, including Eugene, and appears to have originated as a result of the Aleutian Low, coming to Oregon in a very predictable pattern. Many continental fronts transform from maritime to continental over the Eugene area
Image Source: http://www.weather.com/maps/maptype/currentweatherusnational/uscurrentweather_large.html

This diagram depicts perfectly how the Aleutian Low affects the Pacific Northwest of the United States.
Image Source: http://bioregionalexplorations.wordpress.com/page/3/

Click to View Animation
This provides an example of a warm front entering the Oregon coast in the Eugene area, then turning to an Occluded front.
Image Source: http://www.hpc.ncep.noaa.gov/basicwx/day0-7loop.html

If the animation above changed this is the next image of the occluded front.
Image Source: http://www.hpc.ncep.noaa.gov/basicwx/day0-7loop.html

Weather moving west to east through the Eugene area, must first rise over an orographic barrier, then sink into Eugene. This makes inversions, fog, and standing weather more common, because weather must rise over a larger orographic barrier to exit the Eugene area. The orographic barrier for weather entering Eugene, creates strong winds in circumstances as well. This terrain map also helps explain how tornadoes are possible in Eugene and north of Eugene. 
Image: Google Maps (Click for full size)