Kelowna IS Semi-Arid?

[OREZ]

Thanks for the info Glacier. I'm still surprised the Kelowna is that much wetter than Kamloops - 36%, wow. Then again after a week like this, I suppose I shouldn't be. lol

Lots of areas around Kelowna do look quite desert-like to be sure but when you get out there and explore it's surprising how lush some of the areas you come across are as well. (not compared to the coast I realise, but compared the dry okanagan stereo type) For me, this valley has a nice variation; although once we get to about mid-August it often doesn't seem that way. It's important to remember that records for the entire year are taken into account.

[Glacier]

I will also add that the Semi-arid definition I provided is a a crude approximation at best, so these classifications are not synonymous with vegetation boundaries. Of course, semi-arid plants like most plants will not grow past a certain line because of a number of factors other than aridity (soil type, how quickly summer transitions into winter, no seed source, etc. ).

Whether or not the experts want to call Kelowna semi-arid, semi-semi-arid, or something else, there is no question it is dry and hot around here. Plus, we get a lot of semi-arid plants growing here.

Here are a couple of interesting maps:
1) Biogeoclimatic Zones of BC
2) Western Canada precipitation map

Addendum:

The really interesting thing about BC is how the climate can vary significantly in a very short distance. For example, the Kelowna Airport gets 391 mm/year, while McCulloch gets 728mm/year.

Addendum 2: You would probably be surprised how widespread the prickly pear cactus is. It can be found near Ft. St. John and on some of the Gulf Islands.

[Glacier]

Upon further research, Kelowna is semi-arid after all, but there are no arid regions in Canada. Because the Köppen climate classification that I referenced previously is an extremely crude approximation, I felt compelled to dig around until I could find an accurate method for calculating aridity.

Aridity is simply calculated by dividing the precipitation by the potential evapo-transpiration (how much water could evaporate during the year). The trick is finding a good way to estimate the PET.

There are 4 dry climates:
If the number you get is <0.05 then the place is Hyperarid.
If the number is <0.2 then the place is Arid.
If the number is <0.5 then the place is Semi-arid.
If the number is <0.65 then the place is Dry subhumid.

The Penman-Monteith is the most accurate method for calculating Potential Evapo-Transpiration, but you require quite a few variables (wind, relative humidity, sun, etc.)



Using a little program I have obtained, I was able to accurately calculate aridity indexes for Canadian cities as follows.
City ------------Aridity
Kamloops ------------------0.282
Osoyoos---------------------0.308
Medicine Hat---------------0.330
Penticton-------------------0.339
Lytton-----------------------0.368
Lethbridge------------------0.376
Whitehorse-----------------0.414
Cranbrook -----------------0.440
Regina----------------------0.441
Puntzi Mountain-----------0.446
Calgary----------------------0.461
Princeton -------------------0.487
Kelowna --------------------0.499
Williams Lake -------------0.619
Fort St. John --------------0.642
Toronto --------------------0.930
Castlegar--------------------0.937
Revelstoke -----------------1.51
Vancouver ------------------1.65

NOTES:
-Wind is a huge factor, which is why Prairie places can be arid despite a colder climate.
- For Kelowna, I was using the airport which is far less windy and over a degree colder than much of the city, which means most of Kelowna is more arid than that.

[Symbonite]

Another reason why having green Lawns In Kelowna is a waste of actual water that we dont have.

[Big Bacardi]

I checked the Canadian Climate Normals and here's what I came up with. The rain and snow is what each place gets in an average year, and the temperature is the highest ever recorded there.

Spences Bridge ~the driest of the dry: 239mm of rain and JUST 29.5cm of snow. Highest Temp 42.5
Medicine Hat: 249.3mm of rain and 95.2cm of snow. Highest Temp 42.2
Kamloops (Airport): 217mm of rain and 75cm of snow. Highest Temp 40.6
Osoyoos (West): 267mm of rain and 49.6cm of snow. Highest Temp 39.5
Oliver: 280mm of rain and 46.9cm of snow. Highest Temp 42.8
Keremeos: 256mm of rain and 66.8cm of snow. Highest Temp 39.5
Lethbridge: 271.1mm of rain and 130.5cm of snow. Highest Temp 39.4
PLACES THAT GET MORE RAIN THAN KELOWNA: 0 SNOW: 1

Lillooet (BCHPA): 297mm of rain and 32.4cm of snow. Highest Temp 41.5
Summerland: 261.2mm of rain and 67.9cm of snow. Highest Temp 40
Penticton: 279.6mm of rain and 67.2cm of snow. Highest Temp 40.6
PLACES THAT GET MORE RAIN THAN KELOWNA: 0 SNOW: 0

Merritt: 238.9mm of rain and 83.3cm of snow. Highest Temp 39.5
Calgary (Airport): 320.6mm of rain and 126.7cm of snow. Highest Temp 36.1
Wineglass Ranch: 249mm of rain and 65.2cm of snow. Highest Temp 38.5
Peachland: 310.6mm of rain and 90.6cm of snow. Highest Temp 37.8
Hedley: 297.6mm of rain and 79.3cm of snow. Highest Temp 41.1
Kelowna: 298mm of rain and 101.8cm of snow. Highest Temp 39.5
Princeton: 239.2mm of rain and 146.8cm of snow. Highest Temp 41.7
Cranbrook (City): 274.4mm of rain and 126.8cm of snow. Highest Temp 36
Vernon: 308mm of rain and 102.9cm of snow. Highest Temp 38.5
Grand Forks: 391mm of rain and 118.7cm of snow. Highest Temp 42.2
100 Mile House: 294.3mm of rain and 159cm of snow. Highest Temp 36
Regina (CDA): 296mm of rain and 83.1cm of snow. Highest Temp 43.9!!!
Lytton: 338mm of rain and 117.4cm of snow!!! Highest Temp 42.2
PLACES THAT GET MORE RAIN THAN KELOWNA: 5 SNOW: 7

I cannot believe Lytton gets that much precipitation!! Ive tried to believe it, but I cant. I dont really care that Kelowna isnt considered semi arid. We still get plenty of hot days in the summer and we get just the right amount of rain. Im glad I dont live in Spences Bridge or Ashcroft where you cant even go outside some days and watering restrictions are are a familiar occurance.

I also remember about 12 yrs ago osoyoos hit 50 C
It was big news!


I think your source is flawed...i know kelowna has hit over 40 C on many occasions...

[Static]

No it's not

[MAPearce]

Does this mean I can stop constrution on the Family Arc??

[Glacier]

I also remember about 12 yrs ago osoyoos hit 50 C
It was big news!


I think your source is flawed...i know kelowna has hit over 40 C on many occasions...

Actually, Cumungala's sources are correct.Remember, those backyard thermometers often exaggerate the actual air temperature by 5 to 10 degrees. While Kelowna has recorded 40°C once or twice, it has never been recorded at the airport.

The hottest it has ever been in Canada is 45°C (113°F), which occurred in Saskatchewan back in the 30s, and in July of 1941 Lillooet, Lytton and Chinook Cove (North Thompson) hit 44.4 °C(112 °F). Oliver was 43.9°C (111°F) that month, and Osoyoos did not exist back then.

[Cumungala]

I was really surprised seeing that the highest temperature for Osoyoos was only 39.5. The weather station for Kelowna that i included in the list was the airport. Here's what the other stations for Kelowna say.

Kelowna Burnett Nursery: 77cm of snow and 262.7mm of rain. HIGHEST TEMP 40
Kelowna East: 84.3cm of snow and 331.2mm of rain. HIGHEST TEMP 39.5

BONUS:
Joe Rich Creek: 164cm of snow and 431.5mm of rain. HIGHEST TEMP 37.5
McCulloch: 363.3cm of snow and 364.5mm of rain. HIGHEST TEMP 36.7

As you can see the other two stations get less snow than the airport, but East Kelowna gets more rain. The highest temp downtown was only .5 degrees higher than the airport. I guess it really depends where you are. Im surprised that Joe Rich gets so much rain. That explains why there are so many cedar trees there. McCulloch only gets 60cm less snow than Revelstoke!!!

[Glacier]

I was really surprised seeing that the highest temperature for Osoyoos was only 39.5.

It isn't, but it is for the station you used - during the time frame of it's existence. The hourly Osoyoos station you can view online is right in the middle of the town (subject to the urban heat effect), so it gets over 40 degrees most years. It has been 42.8 there, but that is off-topic.

Back on topic...

I have updated the list above to include more places including Whitehorse and and Castlegar. Having been to all the places on that list (except Toronto), I would agree with how each place shakes down based on the vegetation I saw there. There are cactus in all those semi-arid places excluding Whitehorse, but that could be a seed source issue.

[dodgerdodge]

Upon further research, Kelowna is semi-arid after all, but there are no arid regions in Canada. Because the Köppen climate classification that I referenced previously is an extremely crude approximation, I felt compelled to dig around until I could find an accurate method for calculating aridity.

Aridity is simply calculated by dividing the precipitation by the potential evapo-transpiration (how much water could evaporate during the year). The trick is finding a good way to estimate the PET.

There are 4 dry climates:
If the number you get is <0.05 then the place is Hyperarid.
If the number is <0.2 then the place is Arid.
If the number is <0.5 then the place is Semi-arid.
If the number is <0.65 then the place is Dry subhumid.

The Penman-Monteith is the most accurate method for calculating Potential Evapo-Transpiration, but you require quite a few variables (wind, relative humidity, sun, etc.)



Using a little program I have obtained, I was able to accurately calculate aridity indexes for Canadian cities as follows.
City ------------Aridity
Kamloops ------------------0.282
Osoyoos---------------------0.308
Medicine Hat---------------0.330
Penticton-------------------0.339
Lytton-----------------------0.368
Lethbridge------------------0.376
Whitehorse-----------------0.414
Cranbrook -----------------0.440
Regina----------------------0.441
Puntzi Mountain-----------0.446
Calgary----------------------0.461
Princeton -------------------0.487
Kelowna --------------------0.499
Williams Lake -------------0.619
Fort St. John --------------0.642
Toronto --------------------0.930
Castlegar--------------------0.937
Revelstoke -----------------1.51
Vancouver ------------------1.65

NOTES:
-Wind is a huge factor, which is why Prairie places can be arid despite a colder climate.
- For Kelowna, I was using the airport which is far less windy and over a degree colder than much of the city, which means most of Kelowna is more arid than that.

Er.......... You really need to get out more!

[Deleted]

I was surprised to read about this, I grew up in the valley and it was always said that the desert is where ever the sagebrush grows. And that it ended around OK Falls. But after reading this I looked it up and true deserts don't have sagebrush, the water levels don't permit it. It is interesting the things we can find out here.

[Cumungala]

If the number is <0.65 then the place is Dry subhumid.

Castlegar--------------------0.937

I guess Castlegar is semi-dry subhumid

Castlegar is a microclimate because one part of Castlegar is almost a desert. The North Shore has bunchgrass and the odd sagebrush plant for heavens sake!!

Castlegar Airport 559.7mm of rain and 211cm of snow HIGHEST TEMP 40
Castlegar Dam 518.3mm of rain and 116.9cm of snow HIGHEST TEMP 39 *station on North Shore

Its quite a difference within 11.5km. Just for the record, Castlegar dam gets only 15.1cm more snow than Kelowna and Castlegar Airport gets 109.2cm more snow than Kelowna. Castlegar airport gets a lot more snow because its located right beside the confluence of the Columbia and Kootenay Rivers and systems collide there.

Anyways Im straying off topic. Im not surprised that were on the fringe of being semi-arid and dry subhumid. Climatewise, I think we have a climate more like the North Okanagan. The difference in climate between here and Vernon isnt much, but the difference in climate between here and Penticton is quite big.

Oh by the way, I found some more places to add to the list:
Kleena Kleene: 214mm of rain and 116.4cm of snow. HIGHEST TEMP 37
Lunch Lake: 245mm of rain and 127.9cm of snow. HIGHEST TEMP 35.5
Westwold: 298.5mm of rain and 93.3cm of snow. HIGHEST TEMP 39.4
Heffley Creek: 288.9mm of rain and 120cm of snow. HIGHEST TEMP 37.5
Wasa: 339.5mm of rain and 99.8cm of snow. HIGHEST TEMP 37
Atlin: JUST 192.5mm of rain and 154.8cm of snow. HIGHEST TEMP 30.6
Big Creek: 225.8mm of rain and 111.7cm of snow. HIGHEST TEMP 38.9

[Ari Gold]

[Remember, those backyard thermometers often exaggerate the actual air temperature by 5 to 10 degrees. While Kelowna has recorded 40°C once or twice, it has never been recorded at the airport.

The hottest it has ever been in Canada is 45°C (113°F), which occurred in Saskatchewan back in the 30s, and in July of 1941

Backyard thermometers may not be the most accurtate instruments, but how accurate was the record keeping and thermometers back in the 1930's?

I would suspect that data also.

Also, I thought Al Gore said that the temperatures have been steadily increasing for the last 50 years, and the last 10 years have been the hottest in recorded history...If this is true, then how can the hottest recorded years all be before 1950?

[Glacier]

Cumugala, even using the drier Castlegar location, the cities aridity index changes to 0.788 - still not even close to being arid.

I cannot add the places you listed because there is not enough data to do so (windspeed, hours of sunshine, etc.).

Ari Gold, thermometers were just as accurate in the past as they are today. I actually emailed EC once with 5 or 10 obvious errors I noticed in their database, but they never fixed them (last time I checked anyway). By obvious errors, I mean +28 in Nunavut during the dead of winter.

As for the Al Gore/Global Warming part, the average temperatures have increased based mostly on nightime temperatures being higher. It is a very complex issue as to why average temperatures and maximum temperatures don't rise insync which don't have time to get into tonight.