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Here’s a Europe vs. North America question I’ve always wondered about: why does the mediterranean rainfall pattern extend further north in the Pacific Northwest of North America than it does in Europe? We’re talking 5 degrees of latitude further north probably. Possibilities I’ve thought of: the rainshadow effect from coastal mountains (but that can’t be the whole reason); the colder water offshore of N.A. (vs the Gulf Stream in Europe). And that’s all I can think of?
Maybe it has something to do with the North Pacific High extending further north in the summer?
Maybe it has something to do with the North Pacific High extending further north in the summer?
I think it might also have something to do with the fact that somewhere like Asturias has a body of water to the north, while Oregon at the same latitude only has water to the west. Northerly winds will blow over warm water on its way to the north coast of spain. Going north from the PNW, it’s land all the way to the Arctic.
Here’s a Europe vs. North America question I’ve always wondered about: why does the mediterranean rainfall pattern extend further north in the Pacific Northwest of North America than it does in Europe? We’re talking 5 degrees of latitude further north probably. Possibilities I’ve thought of: the rainshadow effect from coastal mountains (but that can’t be the whole reason); the colder water offshore of N.A. (vs the Gulf Stream in Europe). And that’s all I can think of?
If I had to spitball a guess, I'd say you're right on the money with the cooler waters in particular. Another factor might be North American Monsoon displacing the Pacific High northward. Europe does not have an equivalent to the North American monsoon, besides the thermal low which develops over Iberia (Spain and Portugal) and the Sahara Desert during summer. I'm guessing that if the Mediterranean Sea didn't exist, there would be a much more substantial thermal low over this area during summer which may have the effect of displacing the Azores (North Atlantic) High northwards during summer, extending the Mediterranean pattern further northward with it.
The water off the PNW coast is significantly cooler than equivalent latitudes of the Atlantic off the European coasts. There are small areas of water, just off the coasts of Curry County, OR, as well as Mendocino and Sonoma Counties, CA where the average the SST in June, July and August combined is 12C (53.6F), which for Atlantic comparison, is the same SST as an area of the Atlantic south of Iceland at around 60N. Nowhere along the Atlantic coasts of W Europe or NW Africa (south of 60N) comes close to having a SST that low.
I'm guessing that the cooler waters of the Pacific allows a more stable environment for the North Pacific High to ridge further northwards, allowing the Mediterranean summer minimum in precipitation. I think because of how much wetter the PNW is outside of summer from the orographic precipitation, the summer dryness stands out in comparison to the rest of the year. Europe has faw fewer areas of high mountains like the west coast of the Americas have, so the orographic precipitation is much less pronounced. As far as locations along the immediate Pacific coastline go, 47N (around Aberdeen, WA) seems to be the furthest north that the average July rainfall is below 30mm (1.81 inches). North of this, Csb climates extend about halfway up the eastern coast of Vancouver Island to Campbell River (50N). In comparison, the relatively warmer waters in Atlantic, to the west of Europe provides more fuel for the Icelandic low to spawn cyclones and fronts which regularly dig south into the low-mid 40s latitude over Europe in summer. This gives NW Europe it's characteristic oceanic climate which lacks the pronounced summer reduction in rainfall seen in true Mediterranean climates. Along the immediate Atlantic coasts of Europe, the Mediterranean climates stop around N Spain (43.8N), however, to the north of this, there are isolated pockets along the north and west coasts of France that marginally scrape a monthly mean under 40mm including Cap de La Hague in Normandy at 49.7N, where June is the mean driest month. In these areas, the Mediterranean rainfall pattern is so marginal that it's essentially a coin flip as to whether the dry months will go over or stay under 40mm.
The images below were both taken on 27 July 2021 around 2:00PM locally.
For those who mention that the gulf stream has no affect, how can it not have an affect on places that come in contact with it or have the typical wind blowing from the stream to the shore.
Fished for years back in the day on a charter boat out of Hatteras, NC where the stream is within 15 miles of the coast. (the closrest north of Stuart/Ft Pierce FL). In March there is literally a 15 to 20 degree temperature difference between the deep purple GS and the "inshore" green water. Zigzagging the line I'd be roasting in my bibs/jacket on the stream side and quite chilly once we hit green water. It can be the same difference when fishing off MD where the GS is much farther out. We fish eddies that brake off of it off MD and you can tell the temp change when entering the warmer water.
Likewise, here on MD's coast there is a big difference in temperatures in the winter when the system and wind is coming from the west (cross continent and Appalacians) verses coming from the SE Atlantic and gulfstream). If from the SE, we have really nice winter days typically. From the NW, not so much.
How I've understood, that's why England and Norway have mild (for their Latitudes) climates. Also, dreary and wet as well. The countries by the Med would have no effect of the GS as it doesn't get towards Europe until the higher Latitudes.
For those who mention that the gulf stream has no affect, how can it not have an affect on places that come in contact with it or have the typical wind blowing from the stream to the shore.
Fished for years back in the day on a charter boat out of Hatteras, NC where the stream is within 15 miles of the coast. (the closrest north of Stuart/Ft Pierce FL). In March there is literally a 15 to 20 degree temperature difference between the deep purple GS and the "inshore" green water. Zigzagging the line I'd be roasting in my bibs/jacket on the stream side and quite chilly once we hit green water. It can be the same difference when fishing off MD where the GS is much farther out. We fish eddies that brake off of it off MD and you can tell the temp change when entering the warmer water.
Likewise, here on MD's coast there is a big difference in temperatures in the winter when the system and wind is coming from the west (cross continent and Appalacians) verses coming from the SE Atlantic and gulfstream). If from the SE, we have really nice winter days typically. From the NW, not so much.
I have experienced the same thing over the years. I have lived along the coast and in many beach towns along the Atlantic coast, and wind direction makes so much difference in winter. When I lived in Virginia Beach, any wind with a south/southwest direction was warm, even in mid-winter. Even here on the coast of Long Island Sound (in Connecticut) when the wind is out of the south for even a few hrs. temps seem to warm up.
It's not surprising, if you look at the Gulf Stream even in late winter (coldest water temps of the whole year) there is still 60 F water less than 200 miles off the Middle Atlantic coast:
Pic from NOAA site:
Here are photos of a 46N latitude location in the US, much more northern looking than the European counterparts at the same latitude line- other than the higher elevations of the Alps:
For those who mention that the gulf stream has no affect, how can it not have an affect on places that come in contact with it or have the typical wind blowing from the stream to the shore.
Fished for years back in the day on a charter boat out of Hatteras, NC where the stream is within 15 miles of the coast. (the closrest north of Stuart/Ft Pierce FL). In March there is literally a 15 to 20 degree temperature difference between the deep purple GS and the "inshore" green water. Zigzagging the line I'd be roasting in my bibs/jacket on the stream side and quite chilly once we hit green water. It can be the same difference when fishing off MD where the GS is much farther out. We fish eddies that brake off of it off MD and you can tell the temp change when entering the warmer water.
Likewise, here on MD's coast there is a big difference in temperatures in the winter when the system and wind is coming from the west (cross continent and Appalacians) verses coming from the SE Atlantic and gulfstream). If from the SE, we have really nice winter days typically. From the NW, not so much.
How I've understood, that's why England and Norway have mild (for their Latitudes) climates. Also, dreary and wet as well. The countries by the Med would have no effect of the GS as it doesn't get towards Europe until the higher Latitudes.
I know I'm late, but I've seen some maps that the Gulf Stream far enough out into the ocean is a swimmable 22-23C+ even off the Outer Banks in the winter. Is it true?
It would be funny if it was because you'd literally be able to do Miami style winter swimming in a mid ground Cfa with the warmest winter month of 12.1C. Comfortable as Cape Hatteras winters are, they are not swimming weather, which makes this very amusing.
I know I'm late, but I've seen some maps that the Gulf Stream far enough out into the ocean is a swimmable 22-23C+ even off the Outer Banks in the winter. Is it true?
It would be funny if it was because you'd literally be able to do Miami style winter swimming in a mid ground Cfa with the warmest winter month of 12.1C. Comfortable as Cape Hatteras winters are, they are not swimming weather, which makes this very amusing.
The "break" is about 15/20 miles or so off Hatteras, NC. Stream temps will be in the 70's, even in the dead of winter. Blue marlin are a warm water fish and have been caught in every month off the outer banks (Oregon Inlet and Hatteras). Nobody fishes for them in the winter as they are scarce but some are there as they will be feeding on the tuna, which are sought commercially in the winter. 68 to 74 degrees is prime for yellowfins.
Likewise, longliners will work off the Mid-Atlantic coast, about 100 to 120 miles or so off MD and target tuna. They'll be in the same temperature of water.
But this is off the coast a bit. Deffinately not swimming weather! But I remember surf fishing there in late Nov/Dec and taking a bit of water over my waders and actually feeling the warmth of the water compared to the air.
Thats why southerly winds in the winter can bring nice temperatures.
The "break" is about 15/20 miles or so off Hatteras, NC. Stream temps will be in the 70's, even in the dead of winter. Blue marlin are a warm water fish and have been caught in every month off the outer banks (Oregon Inlet and Hatteras). Nobody fishes for them in the winter as they are scarce but some are there as they will be feeding on the tuna, which are sought commercially in the winter. 68 to 74 degrees is prime for yellowfins.
Likewise, longliners will work off the Mid-Atlantic coast, about 100 to 120 miles or so off MD and target tuna. They'll be in the same temperature of water.
But this is off the coast a bit. Deffinately not swimming weather! But I remember surf fishing there in late Nov/Dec and taking a bit of water over my waders and actually feeling the warmth of the water compared to the air.
Thats why southerly winds in the winter can bring nice temperatures.
Although not particularly common, I do think those water temperatures could be taken advantage of on particularly warm days. This February Cape Hatteras reached 23C, which is similar to the 23.8C average February high in Miami Beach, and with the similar water temperatures as well it would most definitely have been swimmable on that day.
Should you ever end up there on a day like that, you might just be able to enjoy the air and water together!
If I had to spitball a guess, I'd say you're right on the money with the cooler waters in particular. Another factor might be North American Monsoon displacing the Pacific High northward. Europe does not have an equivalent to the North American monsoon, besides the thermal low which develops over Iberia (Spain and Portugal) and the Sahara Desert during summer. I'm guessing that if the Mediterranean Sea didn't exist, there would be a much more substantial thermal low over this area during summer which may have the effect of displacing the Azores (North Atlantic) High northwards during summer, extending the Mediterranean pattern further northward with it.
It's amazing how far north the Af climate zone extends in the Atlantic--almost to the latitude of NYC according to that map, thanks to the Gulf Stream.
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