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Old 04-12-2012, 04:41 AM
 
Location: Leeds, UK
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Quote:
Originally Posted by deneb78 View Post
IMO I think the main difference between the coastal california climates (Csb) like San Fran and places like Seattle and Portland are the winter temperatures more than the rainfall. Summers in both places have similar temperatures.. often even Seattle and particularly Portland will be much warmer than SF despite being much further north.
That's because they are warmer then San Francisco in summer, especially Portland which is usually sunny and dry in summer.
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Old 04-12-2012, 06:04 AM
 
Location: Leeds, UK
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Sydney is a lot wetter though.
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Old 04-12-2012, 09:29 AM
 
Location: Western Massachusetts
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Quote:
Originally Posted by wavehunter007 View Post
As MrMarbles quite correctly points out – even the two driest months (July/August) at stations like Portland/Seattle, they still have more than half an inch of rainfall, and the others dry months of June/August/Sept receive 1.50 inches of rainfall (roughly). Seattle averages 4.59 inches of rainfall in the 4 warmest months (June – Sept). Compare that with stations like San Diego, Los Angeles, Santa Barbara,...etc which average about 0.31 to 0.49 inches of rainfall from June through Sept (and 3/4 rainless months are not uncommon).
Coastal California, especially Southern California has unusually dry summers for a Mediterranean climate. Naples gets 5.891 inches of rain from May-Aug (Sep is not part of the dry season even though its about the same temperature as June). Naples is a bit atypical, but Lisbon get 2.307 inches of rain from Jun-Sep, Perth 2.146. Still less than the PNW, but the difference is less drastic.

Quote:
It seems unfair to group these climates together based on their amount of summer precip. Seattle or Portland do have dry summers - but they hardly have the true genetic Mediterranean climate controls with close to zero summer precip, frequent cloudless skies, and desert like humidty values that are often the rule in the Mediterranean summer.
Again, and myself and other posters brought up coastal California. The summer relative humidity values in coastal california are definitely not low or desertlike. Frequently mostly cloudy at night and in morning then clears up (for example in San Francisco / Oakland). I noticed the same exact pattern further north, in Seattle and by the Washington Coast. Thought that was kinda interesting. Almost no chance of drizzle by the Bay Area, but drizzle wasn't that common in Seattle. The climate genetics felt close in the summer.

Also, Mediterranean climates don't have desert like dew points. Usually not humid subtropic levels, but not desert levels. Dew points along the US west coat are typically in the 50s, up to around 60 by San Diego. Dew points don't typically get to 40s until you go inland. True US desert climates get dew points around 40°F. I think Perth gets dew points in the high 50s, far from desert like. European Mediterranean climates can be quite sticky. Compare Los Angeles to Western Mass in August 2011. Identical summer highs, summer lows were warmer in Los Angeles. Los Angeles dew point was 3°F cooler, not a huge difference, but the dew point stayed in a narrower range; one feature I noticed about west coast climates. Most Augusts Western Massachusetts records dew points in the mid 40s and in the mid 70s, Los Angeles stays between low 50s to low 60s.
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Old 04-12-2012, 10:06 AM
 
Location: USA East Coast
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Quote:
Originally Posted by nei View Post
I could have said an English summer feels similar to a Long Island summer but cooler (when I meant New England I was including coastal CT). Of course the dew points are much lower in the UK than in the Northeast, but so are the temperatures. Relative humidity is still high. Summer dew points in London average around 55°F; Seattle low 50s; interior New England low 60s. So yea, the UK is a bit closer to the Pacific Northwest but still noticeably different and the British cloud patterns seem different from the Pacific Northwest. I've seen thunderstorms in the UK in the summer, this wouldn't happen in the Pacific Northwest. The Pacific Northwest is dominated by high pressure in the summer; northwest Europe is not. I've spent months in both the Pacific Northwest and the UK.

Also, we're comparing the Pacific Northwest to coastal California not hot Mediterranean climates (as in Csb climates not Csa ones). Coastal California has similar summer temperatures to the Pacific Northwest and similar nighttime cooling patterns (by a little after sunset it cools down quickly to the daily low). But in any case, the diurnal range of LA is lower than Seattle in July.

I do agree the Pacific Northwest has more in common with Northwestern Europe and other oceanic climates than anything else. However, in the summer, its weather patterns are unusual from its dryness and high pressure. Someone going from the Pacific Northwest down to say, San Francisco would find the summer weather patterns very similar, except for drizzle being less frequent.
First let me say I find this type of discussion far more interesting than the climate A vs climate B threads (lol)…so forgive me in advance if I run on too much:

First, IMO, relative humidity is not nearly as important as dew point temps in doing justice to the feel sensible weather. So the “feel” of a dew point temp of 55 F and one of 62 - 64 F can feel significant in terms of sensible weather. Also (and I’m sure you already know this), the “averaged out” monthly dew points in a place like New England (even far northern New England) scarcely do justice to the periodic surges of pure tropical air into New England during their summer. Granted there can be a large difference between places in far southern New England and northern New England …but there are times EVERY SUMMER that dew point temps might surge into the middle 70’s well up into northern New England (something the UK would rarely ever see). Combine these types of dew points with the periodic surges of heat (from 85 to 100 F) and the THI numbers (even in upper New England) periodically reach numbers one would rarely if ever see anywhere in the UK. Of course, this is where summer air mass control comes in; The UK has no source region for mTu (maritime tropical) air masses in summer …while New England has a direct flow (when the Bermuda High is strong) of pure tropical air from the Gulf/south Atlantic:



Averaged out - I would think summer would have a far different feel in terms of sensible weather than the UK than even in northern New England: Just look at last summer – take Concord, New Hampshire, here is July. Add about 5 - 7 F to those days of 85 F or higher (I count 16 such days) for dew points/THI and you have many summer days that “feel” like they are in the 90’s (You’d be hard pressed to find that in an English summer on average): Look at July 2012 below:


National Weather Service - Gray, ME


As far as comparing the Pacific Northwest to coastal California: I agree, the difference between Csa/Mediterranean inland climates and a Do/Temperate Oceanic climate like Seattle is much greater than comparing stations on the immediate Pacific coast (this was the point of the diurnal range ).

However, even using stations right on the coast (and Seattle is not on the immediate Pacific coast)….there is still a good deal of difference in the sensible summer weather between Cs stations and Do stations: If you are using strictly coastal stations like Long Beach, CA and coastal Port Angeles, WA for example ; The average high in Port Angeles, Washington in the warmest month (July) is 69 F - its 83 F in Long Beach, CA…the number of rain days in summer (J/J/A/S) is 31 in Port Angeles, WA …its 2 in Long Beach, CA…etc. Add in the intensity of the solar angle at Long Beach (34 south) compared to Port Angeles (49 north), and the “feel” can be quite different even at coastal stations. People wear bathing suits on the central/southern Califorina coast in summer…them tend to wear light windbreakers on the Washington coast in summer.

So while I agree the gradient of change in far less sharp between Seattle and say Fresno or Burbank, CA…there is still a rather large difference in the climate of coastal Cs stations in along the central/southern California coast and coastal Do stations in the PNW.
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Old 04-12-2012, 10:19 AM
 
Location: Western Massachusetts
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Ok, my statement the UK feels closer to New England was definitely hyperbole. What I meant was that UK weather feels in some ways to weather we would during the time of year when our daily highs are in the 70s (changeable weather, some convection). Definitely major differences. In the Pacific Northwest, there was a typical cloud at night, clear in the day pattern similar to coastal California, high pressure and often clear or close to clear blue skies. UK is definitely cloudier than both the northeast and pacific northwest, but like the northeast unlike the PNW, it was unstable and changeable.

Also, I really suggest you don't use southern California as your Mediterranean examples. They're borderline semi-arid.
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Old 04-12-2012, 10:44 AM
 
Location: USA East Coast
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Quote:
Originally Posted by nei View Post
Coastal California, especially Southern California has unusually dry summers for a Mediterranean climate. Naples gets 5.891 inches of rain from May-Aug (Sep is not part of the dry season even though its about the same temperature as June). Naples is a bit atypical, but Lisbon get 2.307 inches of rain from Jun-Sep, Perth 2.146. Still less than the PNW, but the difference is less drastic.



Again, and myself and other posters brought up coastal California. The summer relative humidity values in coastal california are definitely not low or desertlike. Frequently mostly cloudy at night and in morning then clears up (for example in San Francisco / Oakland). I noticed the same exact pattern further north, in Seattle and by the Washington Coast. Thought that was kinda interesting. Almost no chance of drizzle by the Bay Area, but drizzle wasn't that common in Seattle. The climate genetics felt close in the summer.

Also, Mediterranean climates don't have desert like dew points. Usually not humid subtropic levels, but not desert levels. Dew points along the US west coat are typically in the 50s, up to around 60 by San Diego. Dew points don't typically get to 40s until you go inland. True US desert climates get dew points around 40°F. I think Perth gets dew points in the high 50s, far from desert like. European Mediterranean climates can be quite sticky. Compare Los Angeles to Western Mass in August 2011. Identical summer highs, summer lows were warmer in Los Angeles. Los Angeles dew point was 3°F cooler, not a huge difference, but the dew point stayed in a narrower range; one feature I noticed about west coast climates. Most Augusts Western Massachusetts records dew points in the mid 40s and in the mid 70s, Los Angeles stays between low 50s to low 60s.
It is true, that in a way, Mediterranean California is a rather extreme version of Cs (or Csa in parts) climates. In a way, (not to rile up our friends in Mediterranean southern Europe) – California is MORE of a Mediterranean climate than the region for which it is so named. This is why (see above), it seems so silly to me, to try to group any part of the PNW (coastal or inland) with most of California. When I see and think of much of central/southern CA I think desert...when I see and think much of the PNW I think rainfall and green (Eastern WA is of course quite dry). It would be like trying to group Orlando and NYC into the same climate group because their wettest months both occur at the time of high sun.

In terms of humidity values, my point was about the interior regions of California and other Csa Mediterranean climates at the time of high sun have humidity values are much closer to those of deserts than of humid middle latitude climates. Places in interior southern California do indeed have desert or near like humidity values; In fact, much of southeastern CA has the lowest average summer (J –A ) humidity values in American desert southwest (NM/AZ/CA). Below is a map of average summer humidity, you can see that just east of the CA coast, average humidity values drop off to 45 %. Remember these running 3 month averages (smoothed out over 30 years), there are several times each summer month when R/H values might be 20% in the eastern areas of CA (Some of the lowest known RH values in the world are around the Egyptian Sahara – where RH values as low as 5 % have been measured): Add surface air temperatures of 85 to 120 F…intense subsidence aloft, a cloudless skies…and you have a recipe for potential evaporation rates that are staggering:




As far as last summer in LA and western Mass…yes they did have monthly mean temps not too far apart. Of course (and I’m sure you know this), Mass had summer mean temps 2 F ABOVE normal…and much of California had summer mean temps 2 F BELOW normal. No doubt dew points can get quite high up where you are in summer (see above) and average higher than coastal California. Of course, just a few miles inland and the dew point temps are often much higher in New England than CA.
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Old 04-12-2012, 01:15 PM
 
Location: Laurentia
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Those climates that are arid, semi-arid, or on the hot/dry margin are not the kind of Mediterranean climates we're talking about. Desert-like humidity simply isn't part of having a Mediterranean climate. Sure, some Mediterranean climates may have that feature, but it's like having some snow in the subtropics; many subtropical climates feature some snow, but it isn't part of having that climate type, just like the difference between Washington and New Orleans, or even between New Orleans and Memphis.

Plus that spot of low relative humidity is in the desert climate zone, not Mediterranean. Try harder next time .
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Old 04-12-2012, 01:31 PM
 
Location: Western Massachusetts
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Quote:
Originally Posted by wavehunter007 View Post
It is true, that in a way, Mediterranean California is a rather extreme version of Cs (or Csa in parts) climates. In a way, (not to rile up our friends in Mediterranean southern Europe) – California is MORE of a Mediterranean climate than the region for which it is so named. This is why (see above), it seems so silly to me, to try to group any part of the PNW (coastal or inland) with most of California. When I see and think of much of central/southern CA I think desert...when I see and think much of the PNW I think rainfall and green (Eastern WA is of course quite dry). It would be like trying to group Orlando and NYC into the same climate group because their wettest months both occur at the time of high sun.
If you think of desert when you think of California you are imagining a place that does not have a Mediterranean climate. A Mediterranean climate typically has a mix of open forest and grassland, becoming thicker forest in wetter sections. Much of inland California is semi-arid or even arid; it doesn't belong in this comparison. Live oak, chaparral, etc. I keep mentioning coastal and near coastal areas on purpose not interior regions, which you keep bringing up . The southern half of the central valley becomes increasingly dry; Fresno is semi-arid; Sacramento is still Mediterranean. You can continue to bring interior California, but I have little interest in looking at it, especially since much of it isn't Mediterranean or very borderline. Here's a Mediterranean-type vegetation (on the hills of the SF penisula):

As one Californian said they have winter green:



and summer gold:



from File:San Francisco Bay Area Skyline Blvd.jpg - Wikipedia, the free encyclopedia

Quote:
In terms of humidity values, my point was about the interior regions of California and other Csa Mediterranean climates at the time of high sun have humidity values are much closer to those of deserts than of humid middle latitude climates. Places in interior southern California do indeed have desert or near like humidity values; In fact, much of southeastern CA has the lowest average summer (J –A ) humidity values in American desert southwest (NM/AZ/CA). Below is a map of average summer humidity, you can see that just east of the CA coast, average humidity values drop off to 45 %. Remember these running 3 month averages (smoothed out over 30 years), there are several times each summer month when R/H values might be 20% in the eastern areas of CA (Some of the lowest known RH values in the world are around the Egyptian Sahara – where RH values as low as 5 % have been measured): Add surface air temperatures of 85 to 120 F…intense subsidence aloft, a cloudless skies…and you have a recipe for potential evaporation rates that are staggering:
As I said, I didn't have the interior in mind, but southeast California is a true desert; it's part of the desert southwest. The reason regular 50°F + dew points don't extend much into the interior is because mountains create a barrier. But looking at this dry-ish Central Valley station, you can see the average July dew point is in the low to mid 50s:

History : Weather Underground

not high but not really desert-like.

[QUTOE]As far as last summer in LA and western Mass…yes they did have monthly mean temps not too far apart. Of course (and I’m sure you know this), Mass had summer mean temps 2 F ABOVE normal…and much of California had summer mean temps 2 F BELOW normal. No doubt dew points can get quite high up where you are in summer (see above) and average higher than coastal California. Of course, just a few miles inland and the dew point temps are often much higher in New England than CA.[/quote]

I wasn't in the east coast most of last summer, but August I think was close to average; forgot California was below average. But I looked through several years of data for August, and the pattern was similar; Massachusetts reached lower dew points (mid 40s) than Los Angeles ever does (usually Los Angeles' lowest is around 52°F) while at the same time Massachusetts also can reach higher dew points than Los Angeles. The ocean prevents Los Angeles from getting a low dew points; unless there's a Santa Ana wind. The Los Angeles station I used is downtown, not on the immediate coast.

Interestingly, Los Angeles had a higher average dew point (61°F) than Western Massachusetts (59°F) in August 2008, but with lower range (54°F - 65°F) for LA than for Western Massachusetts (43°F - 72°F). That August was a few degrees below average for Western Massachusetts, but it's telling that they're close enough that an overlap is possible.
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Old 04-12-2012, 01:42 PM
 
Location: Western Massachusetts
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Default Does the Pacific Northwest have a Mediterranean climate? Is it similar to Coastal California?

Debate to keep threads from being hijacked.
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Old 04-12-2012, 01:53 PM
 
Location: Top of the South (Nelson), NZ
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Great pics of SF area. That looks so much like the downs (low hill country) around here. It's weird seeing places elsewhere that look so familiar.

Most oceanic climates would have a similar seasonal look in terms of green/gold I would think.
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