Reflection Blog #1

I will be comparing my site, Portland, to Liverpool (www.liverpoolweather.blogspot.com).  These locations have both commonalities and differences that this blog will discuss.  Both locations are on or near the western shorelines of their continents.  Portland's latitude is 45.5 Degrees North, while Liverpool's in 53.4 Degrees North.  When comparing average monthly high and low temperatures, Portland experiences slightly higher temperatures in the summer months, and nearly the same winter temperatures as Liverpool.  Both locations receive the moderating effects of the adjacent oceans, therefore these temperature differences are due to latitude and continentality differences.  Portland also experiences greater variability in monthly precipitation, due to geographic and topographical differences.  Portland is approximately 60 miles inland, with the Coast Range separating it from the Pacific Ocean, while Liverpool is within a few miles of the Irish Sea.

Both regions experience the effects of Maritime Polar and Continental Polar air masses, as well as Maritime Tropical.  Liverpool also can be effected by Continental Tropical and Maritime Arctic air masses.  Liverpool to be affected this way due to geographic and topographical differences between the cities.  Liverpool's higher latitude allows the Maritime Arctic air to occasionally bring cold, wet air masses, responsible for snowfall in the region.  In Portland, the Cascade Range to the east will block Continental Tropical air masses, whereas Liverpool as no such barrier.

One additional factor is the rain shadow affecting Portland.  This is due to the Coast Range to the west creating orographic lift and precipitation, reducing available moisture reaching inland in Portland.  

Works Cited:

Lisa Ritchie. www.weatherinportland.blogspot.com, Blogs 1 and 2

Eben Dennis.  www.liverpoolweather.blogspot.com, Blogs 1 and 2

Portland, Oregon Blog #2

Portland's weather is affected dominantly by Maritime air masses.  In winter, the region is primarily affected by Maritime Polar air, bringing moisture and moderating temperatures.  Continental Polar air can also enter into the region, bringing cold, dry air.  In summer, Portland is more likely affected by Maritime Tropical and occasionally Continental Polar air.  

The maps below show the air masses and the associated weather.  

Pictures source: http://www.sci.uidaho.edu/scripter/geog100/lect/05-atmos-water-wx/05-part-6-air-masses/ch5-part-6-air-masses.htm

Portland's latitude can receive mid-latitude cyclones, as well as warm, cold, and occluded fronts.  Generally, the occluded fronts here are warm occluded fronts, as diagrammed in the picture below.

Picture source: Chambers, Frederick. Moisture and Precipitation Processes-Part 2. PowerPoint Presentation, Slide 10, Geography 3232. April 2, 2012.



Meteorologist Nick Allard of Portland NewsChannel 8 predicted on Tuesday, April 3rd "Rain is moving in this morning as a slow moving cold front hits the area.", "Once the rain starts it will stick around for most of the day becoming showers by mid to late afternoon.  Highs will be in the low to mid-50s.

After the cold front moves through cooler air will push in and keep the pattern unsettled.  In fact we'll see showers and possibly hail showers or even thunderstorms on Wednesday and Thursday.  Look for a few more showers on Friday but we'll be drying out overall into the weekend.", "NICE!"

Current weather maps for the Portland region show a cold front approaching. 

Picture source: http://www.kgw.com/weather/maps?radar=63612987&img=9&c=y

Portland has topographic features that influence weather.  Portland lies in the valley between the Coast and Cascade Ranges.  Warmer moist air from the Pacific Ocean is forced to rise over the Coast Range, which receives precipitation.  Portland is warmer and dryer than the Coast Range because air warms adiabatically as it comes down over the mountains into the rain shadow.  This air is then again orographically lifted over the Cascade Range, condensing and cooling, allowing for precipitation.

This picture highlights how prevailing winds and topography affect the weather in the Portland region.

Picture source: http://www.wildpnw.com/2011/06/20/rain-shadow-effect-pacific-northwest/#.T3tC5mBhwVk