Why does winter linger in Central Oregon like a particularly stubborn case of toenail fungus? Meteorologist Adam Clark of KOHD has the answer – sort of.
As Clark describes it, it’s all a matter of latitude and altitude. Bend is at a relatively high latitude (44 degrees) and a relatively high altitude (3,500 feet), which means that the winter sun hits us at a low angle. That allows things to get cold here in the winter, and it takes a while for the sun to warm us up in the spring.
Which neatly explains why it gets cold in Bend, but doesn’t explain why it STAYS so cold for so damn long.
Other places get cold – very cold – in the winter but still manage to warm up nicely in the spring. For instance, the average daily high temperature in Minneapolis in May, according to The Weather Channel, is 70 degrees – five degrees warmer than Bend’s average daily high for the month of 65. (Minneapolis is at the same latitude as Bend – 44 degrees.)
Denver, “the Mile-High City,” is even balmier, with an average daily high in May of 72.
So what’s the real explanation? In the absence of a better one, here’s our own theory:
Every year in March, Spring timidly ventures north from California toward Bend and makes it as far as Chemult. But at that point it takes a look at the cold, bleak, dreary landscape of Central Oregon, becomes terrified, turns around and goes back. And it doesn’t work up the nerve to try again until mid-June.
This article appears in May 7-13, 2009.
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I have weather for Siberia on my browser, it seems that when I check it it is really close to the Bend weather. Lately it has been warmer there.
Umm… altitude has no effect on the angle of incident sunlight. In general, the higher the elevation, the colder the atmosphere gets. This is mostly just a function of the expansion of air as the pressure drops; it has nothing to do with sunlight angle. The angle of incident sunlight is entirely a function of the latitude and the tilt of the earth (the tilt gives us the seasons, of course).
But there is more to weather than just the combination of altitude, earth tilt, and elevation. You can’t easily compare Minneapolis or Denver to Bend using just altitude and elevation.
The high heat capacity of large bodies of water tends to moderate changes in temperature nearby and winds help to extend the reach of this influence. At high altitudes, the jet stream, which moves roughly from west to east, carries some of this maritime influence with it and helps to make much of the inland west more temperate than east coast weather. On the east coast, weather tends to change much more quickly than in the west. The lack of a maritime influence on Minneapolis helps to give it colder winters but it also means that it warms up quicker.
Mountain ranges also mess with weather patterns. Our mountains to the west give us a rain shadow. The Rocky Mountains do the same for Denver but I think that’s pretty much the only similarity to Bend. The Rockies are much more extensive and Denver much further inland and at a lower latitude. And as far as I know, we don’t get the warming chinook winds that Denver gets where the winds rushing down from the high mountains gets warmed as the pressure increases.
I’m sure there are plenty of other influences involved. The KOHD weatherman mentioned the jet stream trough in passing but as far as I understand it, it’s a bit of stretch to say that the trough *causes* the weather differences. I believe it’s the other way around; the path of the jet stream sort of follows the border between the cold north and warmer south; so it seems the jet stream path is just yet another result of the same mishmash of influences that causes the rest of the weather we see… but I’m not a meteorologist so maybe I’ve misunderstood the significance.
Ric
> But there is more to weather than just the
> combination of altitude, earth tilt, and
> elevation. You can’t easily compare Minneapolis
> or Denver to Bend using just altitude and elevation.
Oops… that’s redundant. I meant “latitude and elevation”.
Ric
“On the east coast, weather tends to change much more quickly than in the west.”
I spent the first 30 years of my life on the East Coast and that wasn’t my experience at all. The weather in Bend is by far the most changeable I’ve experienced anywhere. The saying people have in Bend is: “If you don’t like the weather, stick around — in five minutes it’ll change.” That’s only a slight exaggeration.
“I’m sure there are plenty of other influences involved.”
No doubt, but I can’t figure out what they are. One possibility that I’ve toyed with has to do with Bend’s high plateau location. The prevailing winds come in from the West and hit the Cascades, which force the air upward several thousand feet, which causes it to cool and drop its moisture as snow or rain. Then the chilled, dry air flows out eastward onto the plateau, keeping things cold.
Just an idea. If anybody has the real explanation I’d love to hear it.
…..to chase away whiners and flatlanders.
I grew up in Bend and have lived in Moscow, Russia for a few years. I thought the weather would be horrible here but was shocked to find that by mid-April, it’s sunny and warm. I look at the Bend news and am always surprised in April and May that it’s quite a bit warmer in Moscow than in Bend. Last couple years it seems Bend has had Tax Day snowstorms, right?
I can say with absolute certainty that spring comes faster here in Moscow than in Bend, and Moscow is much farther north than Bend – at 55 degrees north latitude. But I would also say that winter tends to come faster too.
Here is my theory:
Central Oregon is a volcanic landscape. There are billions of tons of exposed basalt and lava rocks lying around. These rocks have a lot of what they call “thermal inertia.” Even more than water. Native Americans used to heat up rocks like these in their campfires and then put them in their tents at night to stay warm.
It takes these rocks a long time to heat up – and they only heat up when the sun is shining right on them. So until the weather gets dependably sunny, these rocks suck heat out of the environment and don’t give any back. The wind blows over them and cools the air down. When the sunny season arrives, they heat up slowly throughout the summer. But then in September and October, these rocks are giving back their heat and making things warmer than they otherwise would be.
I know only that the weather was not like this 30 years ago. I used to fly in from Kona 3 or 4 times a winter to ski and was always able to get out of the wind and lay in the sun comfortably. This is a rarity these present years. Now I’ve also experienced much snowier winters and longer winters in McKenzie Br than I used to see 30 years ago. There is more snow on the McKenzie at 1600 ft elevation the last several years than in Bend. I have no answers, but I don’t like it. Maybe our Federal Government can just legislate it away like so many of our freedoms of the past.
You didn’t say where you lived on the East coast. I suspect the further south you get the more maritime influence you get from the bodies of water to the south and south-west. The northern ocean is also much colder in the Atlantic than the Pacific while the southern ocean is much warmer in the Atlantic than the Pacific. But in general, I don’t believe there is any real doubt that if you compare the weather in cities on the same latitude from both coasts, you will find the east almost always experiences the more extreme conditions. On both coasts, the closer to the ocean the less extremes you experience (if we ignore hurricanes) but this maritime influence drops off much more quickly in the east as you move inland because of the difference in prevailing winds. If you remember differently, I suspect either a special local microclimate variation or selective memory (don’t discount the later, confirmation bias bites all of us).
Your theory about the prevailing winds cooling as it passes over the Cascades is of course just another way of saying that the air is cooler at higher elevations, which we’ve already covered.
By the way, that quote is not a local invention. It seems every place likes to adopt some variant of this meme. This seems to be a cultural trait; everyone likes to claim they have it worse than their neighbors… sort of a “grass is greener” bias. A quick googling brings up an similar quote by Mark Twain (“If you don’t like the weather in New England, just wait a few minutes”) but it seems that the general meme might be even older.
Ric
“You didn’t say where you lived on the East coast.”
New Jersey, New York and Pennsylvania. Have you ever lived on the East Coast? If so, where and for how long?
“But in general, I don’t believe there is any real doubt that if you compare the weather in cities on the same latitude from both coasts, you will find the east almost always experiences the more extreme conditions.”
Whoa, dude — first you were talking about changeability; now you’re talking about extremes. Not the same thing. For extreme temperatures (hot as hell in the summer and freeze your ass off in the winter) the Midwest is where it’s at. For changeability (40 degrees one day, 70 the next, then back to 40 the next) I can’t think of any place that tops Bend.
“Your theory about the prevailing winds cooling as it passes over the Cascades is of course just another way of saying that the air is cooler at higher elevations, which we’ve already covered.”
Not quite; maybe I expressed myself poorly. My point was that the air cools as it rises over the Cascades, then stays cool as it flows down onto the high plateau, which is at a considerably higher elevation than the valley on the west side of the mountains. That would explain why our summers also are cooler — we have a kind of natural air conditioning (or refrigeration, if you will).
But of course that theory could be full of crap; I don’t know. I sent an e-mail to the state climatologist to see if he can shed any light on this. I hope he responds.
> Whoa, dude — first you were talking about
> changeability; now you’re talking about extremes.
> Not the same thing.
Really? I thought we were talking about “our endless winters”.
Ahh… I see. I think you misunderstood my sentence about how “weather tends to change much more quickly than in the west”. I thought it was clear from the context that I was referring to the seasonal change in the weather not the day-to-day stuff. I imagine the day-to-day changes are also subject to the same moderating influences but that’s not directly relevant to your original thesis.
> For extreme temperatures (hot as hell in the summer
> and freeze your ass off in the winter) the Midwest
> is where it’s at.
No debate there. Isn’t that what I just said? Again, little to no moderating maritime influence.
> For changeability (40 degrees one day, 70 the next,
> then back to 40 the next) I can’t think of any place
> that tops Bend.
Hmm… granted I’ve only lived here for four years now but this seems like an exaggeration. Okay, you got me curious so I just downloaded the temperature data from wunderground.com for both Bend (KORBEND25) and Minneapolis (KMNMINNE17). Just looking at the data since January 1st and plotted the daily highs. I don’t see much of a difference between the two locations in daily “changeability”. The only significant difference I can glean with the naked eye is a that Minneapolis tends to start out colder in January but gets warmer quicker than Bend, more-or-less surpassing Bend sometime last month, which is pretty much what you would expect considering the difference in the maritime influence. But this is just a limited history; should I be looking further back?
I do see a significant difference between the range of the daily highs versus the daily lows. This too is to be expected as the low moisture and clear skies don’t provide much of a buffer for the nighttime plunge. Deserts tend to do that. Perhaps what you are feeling as changeability is this common characteristic of desert climates?
> My point was that the air cools as it rises over the
> Cascades, then stays cool as it flows down onto the
> high plateau, which is at a considerably higher
> elevation than the valley on the west side of the
> mountains. That would explain why our summers also
> are cooler — we have a kind of natural air
> conditioning (or refrigeration, if you will).
Sorry, it doesn’t work that way. If we were at the same elevation as the west side of the mountains, the wind reaching us would probably be a bit *warmer* than the west side. The pressure would be the same but the effect of precipitation on the air mass is to warm the air as it rains/snows. Condensation is a warming physical process, dumping the heat of vaporization into the environment. People getting rained on rarely appreciate the counter intuitive physics of this since when you get wet, the water is usually colder than your skin temperature and the reverse process of evaporation off your skin tends to cool you off even more.
But we aren’t at the same elevation as the west side so the net effect is dominated by the expansion of air due to the pressure difference.
> I sent an e-mail to the state climatologist to see
> if he can shed any light on this.
State climatologist? Is Oregon State still using that title? I thought they retired it after that brouhaha with that global climate change denier who finally retired. I’m pretty sure the Governor asked the university to stop using that title. Odd.
Ric
Hmm… According to a report posted on the Oregon Climate Service website [1], the Cascades is thought to shield us from most of the maritime influence. It mentions instead that east of the Cascades, the temperatures “are tempered by high elevations”.
The terminology is odd. The effect of elevation on the highs is pretty obvious but the report doesn’t elaborate how high elevations could possibly “temper” the winter temperatures. It does not, of course, but it looks like this 2005 report was authored by that climate change denier who retired a little while back so maybe I’m expecting too much in the way of scientific precision.
So, how about another theory [2]… maybe the winter lows in the Midwest are lower than ours because of the Arctic air masses moving down from Canada. And then maybe Minneapolis bounces back a little quicker than us in the Spring because of their lower elevation.
[1] http://www.ocs.oregonstate.edu/page_links/climate_data_zones/climate_oregon.html
[2] Not giving up completely on the theory of maritime influence on local weather but I’m not sure at the moment what evidence would settle that question.
Ric
“Not giving up completely on the theory of maritime influence on local weather but I’m not sure at the moment what evidence would settle that question.”
No question that proximity to large bodies of water has an influence on weather and climate, but I’d imagine Bend is too far away from the Pacific Ocean for it to have much moderating influence on our weather.
“Sorry, it doesn’t work that way. If we were at the same elevation as the west side of the mountains, the wind reaching us would probably be a bit *warmer* than the west side. The pressure would be the same but the effect of precipitation on the air mass is to warm the air as it rains/snows. Condensation is a warming physical process, dumping the heat of vaporization into the environment.”
Maybe I’m just stupid, but this doesn’t make any sense to me. Air cools when it rises. Cold air can’t hold as much moisture as warm air. So water vapor condenses, clouds form and rain or snow falls. The process of precipitation might release some heat into the surrounding air, but it remains much cooler than it was before it rose. Otherwise the air temperature at the summit of Mt. Bachelor would be the same as, or higher than, the air temperature at the base.
“It mentions instead that east of the Cascades, the temperatures “are tempered by high elevations”. The terminology is odd.”
It certainly is. Unless they’re saying the summer heat is tempered (moderated) by the high altitude.
Your maritime theory would explain why Minneapolis has hot summers and very cold winters, but not why Chicago (on the shore of Lake Michigan) also does.
Re the “state climatologist”: I didn’t send the inquiry to him personally but to the Oregon Climate Service at OSU.
> No question that proximity to large bodies of water
> has an influence on weather and climate, but I’d
> imagine Bend is too far away from the Pacific Ocean
> for it to have much moderating influence on our weather.
It’s not so much the distance as much as the water-wringing effect of the intervening mountains. But the mountains aren’t high enough to effect the jet stream and I’m pretty sure the jet stream also carries some of the maritime influence. Hence, I’m not ready to give up on the theory that we still have some local maritime influence.
> Maybe I’m just stupid, but this doesn’t make any sense
> to me. Air cools when it rises. Cold air can’t hold as
> much moisture as warm air. So water vapor condenses,
> clouds form and rain or snow falls. The process of
> precipitation might release some heat into the surrounding
> air, but it remains much cooler than it was before it rose.
> Otherwise the air temperature at the summit of Mt. Bachelor
> would be the same as, or higher than, the air temperature
> at the base.
This is all true. I think I said pretty much the same thing. But the part you’re missing above is that once the air moves down off the mountains, it heats back up again. Expansions cools it, compression heats it back up. Precipitation can also heat it up but the net effect in our case appears to be that we’re still cooler than folks on the west side (Is this always true, I wonder… how do the summer temperatures compare?).
To see an example where winds coming down from higher elevations results in a net warming effect, you have merely to feel the Chinook winds that Denver experiences or the Santa Ana winds that Southern California endures.
> Your maritime theory would explain why Minneapolis has
> hot summers and very cold winters, but not why Chicago
> (on the shore of Lake Michigan) also does.
Chicago is on the western shore near the southern tip of the lake. I believe the prevailing winds are coming from the west and north-west so I’m guessing the lake’s influence on Chicago weather is probably minimal.
Ric
“But the part you’re missing above is that once the air moves down off the mountains, it heats back up again.”
Ah, but it DOESN’T heat up again — or not much.
“To see an example where winds coming down from higher elevations results in a net warming effect, you have merely to feel the Chinook winds that Denver experiences or the Santa Ana winds that Southern California endures.”
I have never experienced Chinook winds here, and I’ve lived here more than 20 years. We get a thing called “the Pineapple Express,” which is a warm, moist air mass swirling up from Hawaii, but that’s not the same as a Chinook and the mountains have nothing to do with it.
“Precipitation can also heat it up but the net effect in our case appears to be that we’re still cooler than folks on the west side (Is this always true, I wonder… how do the summer temperatures compare?).”
We are generally a little cooler than the Valley in summer and a lot colder in winter. Average daily highs in Salem and Bend for July and August are about the same (82 and 81, respectively) but the average daily low in Bend for those months is 46 and in Salem it’s 52. The sun warms us up on the long summer days, while the Valley has more cloud cover.
You’re right about Chicago.
> Ah, but it DOESN’T heat up again — or not much.
Sure it does. It’s usually a lot colder up in the mountains.
Let’s look at this another way. Dry air cools at roughly 10 degrees C (or 50 degrees F) for each kilometer of elevation. If we ignore the mountains and just compare two end points, Eugene and Bend, the difference in elevation is nearly a kilometer so that gives us a 50 degree F difference solely from expansion.
But obviously, we aren’t that cold (I’m guessing the real temperature difference is less than 10 degrees F) so what makes up the difference?… probably the fact that it doesn’t start out *dry*. Wringing out the water from the air causes it to warm up and mitigates some of the temperature change caused by the elevation difference.
> We are generally a little cooler than the Valley
> in summer and a lot colder in winter. Average daily
> highs in Salem and Bend for July and August are
> about the same (82 and 81, respectively) but the
> average daily low in Bend for those months is 46
> and in Salem it’s 52. The sun warms us up on the
> long summer days, while the Valley has more cloud
> cover.
I’m guessing the seasonal difference is largely due to the difference in saturation. The warm summer air in the valley probably has more moisture than winter air so the condensation mitigating effect is probably greatest during the summer months.
The difference in the lows is just the standard desert nighttime plunge again. The highs are probably more illustrative of the elevation effect.
Ric
Up thread, “Moscow-is-warmer” offered a theory about the thermal inertia of basalt rocks causing the area to take a while to warm up until “the weather gets dependably sunny”.
I just looked up the specific heat capacity for basalt rock: 0.84 kJ/(kg*K). The specific heat capacity of dry earth is about 1.26 kJ/(kg*K). For water it’s 4.2 kJ/(kg*K).
So just plain old dirt has about 1.5 times more thermal inertia than basalt rock and water has five times more thermal inertia.
So basalt rock ain’t our culprit. If anything it seems that our volcanic landscape should probably have the reverse effect… but I suspect even that effect would be minor.
Ric
Yeah, I didn’t think the rock theory sounded plausible either.
Bottom line: Neither of us really knows why winter hangs on so long in Central Oregon. Maybe nobody does.
I’m curious to see what kind of reply (if any) I get from the OSU Climate Center.
I got a reply to my e-mail from Philip Mote, director of the Oregon Climate Change Research Institute and Oregon Climate Services, that might shed some light on the question. He says:
“What I notice that sets Bend’s climatology apart from other, more western Oregon cities is that the nighttime minimum temperature stops warming from mid-February to early April. Perhaps the longer days are offset by less cloud cover, so there’s more nighttime heat loss.”
He’s right about the nighttime temperatures not warming up in the spring here. The average daily low in February is 25 degrees, in March it’s 27, and in April it’s 30 — not much of a warm-up.
In fact the nights are pretty damn cold here year-round. In May the average daily low is 36 degrees, in June it’s 41 and in July and August it “soars” to 46 before starting to drop again. The average daily low in Bend is at or below freezing six months out of the year and below 40 nine months of the year.
In Minneapolis, by contrast, the nighttime temperatures are very low in February (avg. 12 degrees) but warm up quickly — 23 in March, 36 in April, 48 in May, 58 in June, and peaking at 63 in July. The average spread between the daily high and low in Minneapolis is about 20 degrees from March through May; in Bend it’s almost 27 degrees. In summer it’s even more dramatic — 34 degrees.
Whatever warmth is generated by the sun during the day is quickly dissipated at night because of the lack of cloud cover. The absence of large bodies of water to absorb heat during the day and radiate it back at night probably contributes to this effect.
So, ironically, it could be that the clear skies we’re always bragging about are to blame for keeping it cold here.
But then there’s Yakima, WA, where the springs and summers are considerably warmer than Bend’s. It’s at a lower altitude than we are but a higher latitude, and when you go to city-data.com and check out the charts on sunshine and cloud cover they’re almost identical to Bend’s. And it isn’t near any large bodies of water either — it’s in the high desert, same as us.
I give up trying to figure it out. Maybe Bend is under some kind of cold-weather curse.