GEOG 3232 Post 3

Seattle Mesoscale Events

A mesoscale event that happens in Seattle is called the Puget Sound Convergence Zone (PSCZ)

This phenomena occurs due to the leeward location of Seattle of the Olympic Mountains and westerly winds from the Pacific Ocean

Data Source : KOMO News

This diagram shows the westerly winds being pushed around the Olympic Mountains and converging on the other side, just north of Seattle 

Data From: KOMO News

Radar shows a clear line of convergence. Note the areas to the north and sound of the convergence line are clear. This is one indication of the PSCZ.  

As stated in Blog 2 the Olympic Mountain Range shields Seattle from sizable amounts of rain, as seen in the visual below.

Data From: Olympic Peninsula Community Museum

Temperature and Precipitation Averages

Data From: NOAA National Climactic Data Center

January temperature averages range from highs around 46.6 degrees to lows around 39.6 degrees. Average January precipitations have varied but average at 5.7 inches. One year to consider is 2006 where the high was above average at 50.8 degrees as well as the low of 42.3 degrees. The precipitation is the highest in this 26 year span with a total of 11.4 inches of rain. This could be caused by a La Nina event, bringing in higher rain to the area. 

Data From: NOAA National Climactic Data Center

July average temperatures range from highs around 76.0 degrees and lows around 55.8 degrees. Precipitation for July averages at 0.6 inches of rain. Comparing the two graphs it is interesting to note January 2006 had the highest rain fall of 11.4 inches, but the summer of the same year was well below the 26 year average, recording 0.1 inches of rainfall. The data suggests 2006 was a La Nina year, with the rainfall figures in January and July.

Overall, comparing both graphs gives us an idea of how temperatures fluctuate between winter and summer months in Seattle. Because this data was recorded at the SeaTac Airport, these figures only give us information for a small piece of the state.  The visual above shows us the range of rain fall averages across the state. 

Cleveland Comparison

Major differences between Seattle and Cleveland are mainly based on location. Cleveland's interior continental location is responsible for its widely varying temperatures between winter and summer. Cleveland is also greatly impacted by the continental polar air mass where Seattle is impacted by the maritime polar air mass. This affects precipitation in the winter time. Seattle experiences most of its rain fall in the late fall months, September into the beginning of December.

Data From: NOAA National Climactic Data Center

 Seattle's temperatures are less of a "frown" based on its proximity to the Pacific Ocean, but because of this weather station's location behind the Olympic Mountain range, and in the city, the frown looks more like a place located more interior continental than maritime.

Data From: Maggie Brown

Cleveland has the attributes of a continental climate with the steep "frown".

Both locations experience mid-latitude cyclones. Seattle experiencing them when they first form, and Cleveland after a warm front has been able to form and is catching up to the cold front. 

Each location experiences weather due to convective lifting. Cleveland has the Lake Effect which brings massive amounts of snow. As Seattle receives potentially hostile weather from the Puget Sound Conversion Zone. These two forces are in no way related to each other. The only similarity is the convective lifting that occurs due to either location (Cleveland) or two air masses colliding (Seattle).  

Data From: http://blog.cleveland.com/pdgraphics/2008/11/large_LAKE-EFFECT-SNOW.jpg

 

Cleveland Lake Effect

Data From: cliffmass.blogspot.com

Seattle PSCZ 

Works Cited

"Average Annual Precipitation in Washington State." Olympic Peninsula Community Museum. University of Washington, n.d. Web. 14 Apr. 2015.

 

Brown, Maggie. "Weather and Climate in Cleveland, Ohio." : Air Masses & Fronts. 1 Apr. 2015. Web. 8 May 2015. 

"Cliff Mass Weather Blog." : When Puget Sound Convergence Zones Don't Stop in Puget Sound. Web. 8 May 2015.  

 

"Lake Effects". Green City Blue Lake. The Cleveland Museum of Natural History, n.d. Web. 08 Mar 2015.

Sistek, Scott. "What Is the Puget Sound Convergence Zone?" KOMO News. Sinclair Interactive Media, LLC, 29 Oct. 2013. Web. 8 May 2015. 

GEOG 3232 Blog II

Air masses 

Seattle is affected by Maritime Polar and Continental Arctic air masses in the winter, as seen in the diagram below. At times Continental Polar air may dip down into the region due to Rosby waves, leading to lower temperatures than average.

Source: https://ec.gc.ca/air/default.asp?lang=En&n=1F36EFBB-1&offset=4&toc=show

During the summer months, Seattle receives warm humid air from Maritime tropical air masses. The diagram below shows some influence from a Maritime polar air mass, but due to the mass retreating north, this would not have a substantial effect on the region. 

Source: https://ec.gc.ca/air/default.asp?lang=En&n=1F36EFBB-1&offset=4&toc=show

Current Weather

Due to Seattle's location along the Pacific coast, the city sees the beginnings of mid-latitude cyclones. Below is a recent warm front that has pushed through the Seattle region. 

 The warm front begins off the coast in the Pacific and pushes eastward.

 As the front impacts the coast it elongates creating the long warm front seen in warm occluded fronts.

Sourse: http://www.weather.com/weather/map/interactive/1/SEA:9:US?interactiveMapLayer=radar&baseMap=r

Eventually, this system will turn into snow on the windward side of the Cascades and dry on the leeward side. 

Changes in Surface Conditions

These images show the current status of the storm shown above (April 13th and 14th). The warm front occlusion front has passed with the cold front right behind it. 

Source: http://www.weather.com/maps/current

Source: http://www.physicalgeography.net/fundamentals/7s.html

This diagram shows the air flow and convergence/divergence currently pushing through Seattle and into the western United States. 

Unique Features

Olympic Rain Shadow

Due to the Olympic Mountains creating a barrier between Seattle and the Pacific, the amount of precipitation is much less than on the windward side of the Olympic Mountains. The diagram below demonstrates the amount of rain fall the state of Washington receives annually. 

Source: https://content.lib.washington.edu/cmpweb/resources/map-rainfall.html

Note: Seattle sits between two mountain ranges, it is on the leeward side of the Olympic Range and the windward side of the Cascades. Because of this "rainshadow" cast by the Olympics the Seattle region sees between 30 to 60 inches per year were surrounding areas can see upwards of 180 inches. Also note, the leeward side of the Cascades is a more traditional model. The eastern portion of Washington is very dry and has almost desert conditions. 

Works Cited:

"Average Annual Precipitation in Washington State." Olympic Peninsula Community Museum. University of Washington, n.d. Web. 14 Apr. 2015.

"The Georgia Basin – Puget Sound Airshed Characterization Report 2014."Government of Canada, Environment Canada. Government of Canada, 13 Feb. 2015. Web. 14 Apr. 2015.

Pidwirny, Michael, Dr, and Scott Jones. "The Mid-Latitude Cyclone." The Mid-Latitude Cyclone. University of British Columbia Okanagan, 07 May 2009. Web. 14 Apr. 2015.

The Weather Channel. The Weather Channel, 14 Apr. 2015. Web. 14 Apr. 2015.

GEOG 3232 Blog 1

Blog 1                                                          
March 12, 2015

Seattle, WA Weather

1.

This graph demonstrates the monthly average temperatures over a 25 year period per month (1989 - 2014)

                         Data Source: NOAA National Climatic Data Center

This graph demonstrates the monthly average precipitation amounts over a 25 year period per month (1989-2014)

                              Data Source: NOAA National Climatic Data Center

2.The weather station I have chosen is located at Sea-Tac. Seattle's major airport. The airport is located on the east side of the Puget Sound. Across from the airport on the west side of the Sound is a large section of the Olympic National Park, and farther west is the Pacific Ocean. To the east is the Cascade Mountain Range.

3. I would estimate Seattle's Bowen Ratio to be in between a maritime and continental ratio or 0.2, based on the location of the city. It is essentially surrounded by lush forests, ocean to its west and arid land past the mountain range to the far east. This estimate is also based on the amount of moisture this region receives mostly year around.