CANNON BEACH - BLOG #2

Cannon Beach experiences abundant rainfall and moderate temperatures all year.   Continental Polar air masses have slight influence in winter and Maritime Tropical air masses may extend north in summer, but by far the major influence on the local weather and climate in Cannon Beach are the Maritime Polar air masses.  Commonly the air masses affecting Cannon Beach start forming far to the west in Asia and Siberia as Continental Polar air masses – cold, dry  and stable.

As these cold and dry air parcels move east over the comparatively warmer ocean, the air parcels change into cool, moist, unstable air masses and are renamed as Maritime Polar.  The Maritime Polar air masses proceed to move across the Pacific Ocean picking up warmth and moisture along the way.  

Cannon Beach is affected by mid-latitude cyclones with warm-type occluded fronts, which means the air behind the advancing cold front is warmer than the cold air parcel it is overtaking.  To the immediate east of Cannon Beach is a line of mountains known as the Coast Range (see map below).  The combination of moist air masses moving off the ocean onto the coast plus the warm-type occluded fronts, and the orographic lifting due to the mountain range topography creates an area of the country with one of the heaviest annual rainfalls.

In summer the ocean is cooler than the continents and the Pacific high is located off the western U.S. coastline, both combining to keep the local temperature moderate and helping to reduce the high amount of rainfall characteristic of winter conditions.

Source:
Textbook, The Atmosphere, An Introduction to Meteorology, 12th Edition, Lutgens &        
                       Tarbuck, Pearson Education, Inc. 2013.
http://www.wrcc.dri.edu/narratives/OREGON.htm
http://www.atmos.illinois.edu/~snodgrss/Midlatitude_cyclone.html
http://www.eoearth.org/article/MoistMid-latitudeClimateswithMildWinters-CClimateType?topic=49664
http://teachers.oregon.k12.wi.us/mahr/assignments/airmases_fronts_storms.pdf