Climate Change

Based on the report it can be seen that changes in climate experienced in the southern California area will not be as drastic as other more continental locations. With that being said the changes that are possible could still alter the climate considerably. The report predicts that the average temperature experienced will increase. How this will effect weather dynamics is unclear but it could be argued that the climate would shift from a more arid dry climate to one that experiences more precipitation. The cold ocean currents on the coast would be weakened by increases in ocean temperature which in turn could increase weather patterns seen in more tropical regions. San Diego does not experience extreme weather very often. This would undoubtedly change increasing the frequency of extreme weather events such as tropical storms and thunderstorms both of which are not currently frequent occurrences.

source:http://en.wikipedia.org/wiki/1939_California_tropical_storm

California could experience another tropical storm like the one which struck in 1939 the only known occurrence. Even though a small change in climate is forecasted this small change could have a much bigger impact than other locations in the world. This is primarily due to the high population densities not only in San Diego but California in general. Any disturbance in resources such as food and water and even public services like power outages could be more frequent occurrences due to more extreme weather. The impact of these events have been seen in recent years due to blackouts where the whole city shuts down solely due to a power outage.

source:http://www.bloomberg.com/news/2011-09-09/power-outage-affects-thousands-of-people-in-southern-california-arizona.html

Another impact of climate change being seen presently is the rise in sea level and subsequent beach erosion. Many homes situated along the coast have been swallowed by landslides and erosion with thousands more sitting perilously close to the edge.

source:http://scrapetv.com/News/News%20Pages/usa/pages-5/Southern-California-beach-erosion-best-in-a-decade-Scrape-TV-The-World-on-your-side.html

There has been little action to try and mitigate current and future changes in climate and the subsequent effects. Being that the state of California is dealing with present issues that are not related to climate change there is little time and money to be spent on problems that may be encountered in the future. This is the case for many other cities around the world. San Diego has published a climate change action plan that documents the many current and future problems that must be dealt with. As of now this is only a blueprint as many of the problems documented have not been solved and or mitigated.

Meso and Micro Scale Climate

There are several factors that impact the mesoscale climate of southern California and specifically San Diego. These include orographics the proximity to the pacific ocean. For the most part San Diego sits in an area with many orographic features that affect the regional climate. These features include canyons and valleys with the creating a very uneven and hilly environment. These local variations in topography can create a lot of orographic lifting. In the winter months when there is a predominately westerly wind pattern bringing moist pacific air these orographics provide lifting of air masses causing large precipitation events. In the summer months this wind pattern shifts and brings dry warm air from the inland deserts of the western states. Any moisture left in these air parcels is squeezed out from the several mountain ranges to the east creating very dry conditions not typically associated with an area located so close to a water body. These dry warm winds race west across the area sometimes reaching 100 miles per hour and can cause havoc starting wildfires that in recent years have devastated areas in and around the San Diego area. The picture below shows how impactful these wind patterns, labeled the Santa Anna winds, can be.

source:http://interwork.sdsu.edu/fire/purpose.htm

The most predominate micro-scale climate aspect of San Diego would have to be the fairly drastic temperature variation from the coast to the inland. It is pretty obvious that this is created by the proximity of the cold water currents off of the pacific coast. This cool air can only penetrate several miles inland while areas several miles further inland don't benefit from this cooling effect. This requires the local forecasters to delineate temperatures between the coast and areas further inland.

It can be seen that for the most part there is not a drastic change in the average min and max temperatures for both January or July. With that in mind there is a much greater difference in the average max and min for the month of January. This is most likely due to the fact that the weather in the winter months is much more unpredictable than that of the predominately dry and warm summer months. The Koppen-Geiger climate classification for that of San Diego is a Bsk cool steppe, however San Diego can also be classified as a semi arid Mediterranean climate or Csa as it sits on the edge of both variations of climate.

source:http://snow.cals.uidaho.edu/clim_map/koppen_usa_map.htmsnow.cals.uidaho.edu/clim_map/koppen_usa_map.htm

Location Comparison: San Diego and Seattle

San Diego California and Seattle Washington have some similarities when it comes to their weather. First they are both located on the west coast of the United States meaning that the cool Pacific ocean currents impact both locations in addition most of the precipitation in both locations occurs in the winter months although Seattle sees much more precipitation. Both locations also experience the weather phenomenon termed the "Pineapple Express" which is a fairly constant stream of moisture that comes from Hawaii. This is characterized with a precipitation pattern that can last for as much as a week, although those that live in Seattle would say that this lasts all year long! That is where the similarities end. The average annual temperature in Seattle Washington is around 52 degrees a full 12 degrees lower than that of San Diego California at an average annual temperature of 64 degrees. When comparing the climate graphs of both locations it can be seen that San Diego has a more moderate climate with a smaller difference in monthly high and low temperatures than that of Seattle. In addition the climate graph for Seattle seems to show more continentality meaning there is a fairly large range in temperatures from season to season. This explains the occasional snowfall in the winter months, which is very rarely seen in Southern California.

source:http://drought.unl.edu/archive/climographs/SanDiegoANC.htm

source:http://drought.unl.edu/archive/climographs/SeattleANC.htm

snow covered Cuyamaca Mountains east of San Diego

Air Masses and Weather Patterns

San Diego and Southern California in general are impacted primarily by maritime tropical(mT), and continental tropical(cT). Wintertime in San Diego is generally cool and wet which means that during this time of year the area is mostly affected by maritime tropical air masses accounting for most of the precipitation received throughout the year. On the other hand summers are much different with warm and dry conditions which can be attributed to the predominately continental tropical air masses with occasional maritime tropical air masses bringing some summertime precipitation. Mid-Lattitude cyclones do affect San Diego with primarily warm, cold, and warm occluded fronts. when it comes to occluded fronts the warm type is only seen on the west coast of North America including San Diego. Current conditions show that a weak cold front has recently passed by not affecting temperatures too much as the a San Diego is experiencing a seasonal high of around 60 degrees for today and even warmer in the days to come.

source:http://www.weather.com/maps/maptype/currentweatherusnational/uscurrentweather_large.html

One weather feature unique to San Diego and Southern California is the "June gloom" this is generally characterized by a thick marine layer that is present mainly along the coast while it sometimes ventures inland. This is due to warm moist air masses moving over the cool ocean currents which causes an inversion and in turn forming a "lid" in the atmosphere trapping these low lying clouds. Generally this inversion is lifted in the afternoon as the sun heats up the atmosphere. This can put a damper on your hopes of enjoying a nice sunny day at the beach so plan you vacation accordingly!

source:http://weathersandiego.blogspot.com/b/post-preview?token=Bt87hjYBAAA.g8qfHXhcy2_n_AnElkAs9w.IYoqJ7sHWz0Hwv8RmxnrEA&postId=8608715569712052574&type=POST

Typical "June gloom" as you can see it generally hugs the coast.

source:http://gocalifornia.about.com/od/calamenu/ig/Manhattan-Beach-Pictures/June-Gloom.htm

This is what you can come to expect in June along the coast.

Average Weather and Climate

As you can see from the charts and graphs below there is a fairly small difference in seasonal temperatures, on the other hand the amount of seasonal precipitation fluctuates greatly from season to season. It can be seen that there is an inverse relationship between temperatures and precipitation. As temperatures increase in the summer months the precipitation amounts tend to be low and vise versa.

source:http://www.usclimatedata.com/climate.php?location=USCA0982

source:http://coastalsandiego.com/about-san-diego/san-diego-climate

San Diego has a very moderate climate due to it's geographic setting on the west coast of North America. Being on the west coast helps moderate its climate even more due to the cold ocean currents that move from the North Pole to the Equator. Because of its location on the coast San Diego experiences higher humidity than that of a continental location. These higher humidity rates lend to a lower Bowen Ratio which is the amount of sensible heat to latent heat. It can be estimated that the amount of latent heat is about twice as much as that of sensible heat meaning a ratio around .5. In the Geebit model when increasing albedo by .1 the temperature decreases by 13.1 degrees Fahrenheit to 28.8 degrees, when decreasing the albedo by .1 the temperature increases by 12.1 degrees Fahrenheit to 54 degrees. when increasing the green house factor the temperature increases by 7.9 degrees Fahrenheit to 49.8 degrees, when decreasing the green house factor the temperature decreases by 8.3 degrees Fahrenheit to 33.6 degrees. These changes observed will have an effect on the average temperatures experienced but to a lesser degree than that of a continental location due to the moderating effect of it's coastal location.