Accuracy of NWS Data

[ahosey01]

This will be a long post, but I'm hoping someone can help me resolve my cognitive dissonance.

Once upon a time, @kinzyjr pointed me to an interesting tool through NOAA where I could select a station and have the historical data delivered to my e-mail.  This was when I had thought I was moving.  Turns out I never moved, which is good because I have 100+ palms, cacti, trees and other interesting plants in the ground that I didn't want to leave behind.

Anyways, through some perusing on that site, I discovered there is a weather station less than a half mile from my house, at nearly the exact same elevation, that has over 100 years of weather records.  "Interesting and useful!" I thought.  I downloaded those records and did some analysis.

According to the historical data from that station, here are the average winter minimum temperatures during each of the preceding 11 decades:

Period	Average
1908-1920	21.08333
1921-1930	19.2
1931-1940	19.5
1941-1950	19
1951-1960	18.9
1961-1970	18.2
1971-1980	18.5
1981-1990	20.2
1991-2000	19.7
2001-2010	20.125
2011-Present	19.4

This averages out to a typical winter minimum of 19F at my house.  The record low in the entire dataset was 10F, recorded three times in the 1940s and 50s.  In fact, all of the super cold minimums are all before the 1990s, except for a 14F reading in 1994.  The coldest reading in the last 20 years was a 15F reading in 2013 and a 16F reading in 2011.  The 2013 reading is super questionable to me - which I'll get into in a minute here. All this data puts us in a solid 8b zone.

Here's where I'm confused...  I have only been in Wickenburg a few years, but I have made many close friends who are also plant nuts.  My best friend, in fact, is an ISA Certified Arborist who deeply resents working on cold damaged trees, and remembers all of the big freezes well.  In my immediate area, at my same elevation, we have tipu trees, sissoo trees, orange trees,  a ~12ft lime tree, some huge grapefruit trees (20ft+), a massive sweet acacia, multiple Eucalyptus that should not be cold hardy to the low teens, tons of Washingtonia robusta, queen palms, an old Bismarckia, weeping bottlebrushes, cascalote, pony tail palms, bottle trees, Grevillea robusta, Mexican fence post cacti, Saguaros, Cardons and multiple Texas olives (Cordia boisseri).   My arborist friend I mentioned works this area specifically, and only remembers the 2007 and 2011 freezes being particularly destructive to the plants I mentioned, and it didn't kill any of them.   I have never seen cold damage on any of the citrus except one - a variegated pink Eureka lemon that my neighbor is growing, but it only ever gets damaged on some outer leaves and always looks good by early summer.  The Cardon cactus I mentioned, as an example, is huge and ancient and doesn't appear to have ever been cold damaged. In fact, my arborist friend tells me, there were some jacaranda specimens up the road a half mile or so that survived 2007 with damage but were killed to the ground in 2011.   He said that as far as he remembers, 2013 was just another winter (when the dataset says we dropped all the way to 15F). Another of my other close plant-head friends is a local old-timer who says that 2007 and 2011 were, by far, the coldest, and remembers nothing significant about 2013.  My neighbor's lime tree, which is probably 12ft tall, is approximately 20 years old, she tells me.  She said it was killed pretty far back in 2011, but came back from the thickest shoots and is doing just fine now and still fruiting.  There's even a carob tree by one of the houses here that you can see in old photos at the museum archive from the 1920s, which would mean it lived through (according to the dataset) 41 freezes below 15F since it was planted.  I don't believe that for even one minute.

Anyways - my real life experience is completely not jiving with the data in the NWS dataset.  There is absolutely no way that we regularly experience freezes into the teens, a normal 8b winter, and the plants I mentioned continue to not only survive, but thrive without damage.  Separately, since I have been here, I measure my yard temperature on the coldest nights, and check weather underground religiously.  The coldest I have seen was 24F in my back yard, and that lasted briefly, and the coldest I can find on a weather underground station near me in the four or so years for which I can find data is 24F, and that was once.  This jives more accurately with what the pros and the old timers in the area seem to think.

So, how accurate is this temp data?  I'm suffering from tremendous cognitive dissonance attempting to understand how, on the one hand, we could be an 8b climate - and on the other hand my neighbor can have a lime tree that doesn't even look burned most winters.

Any input from you weather-heads?

 

Edited May 23, 2022 by ahosey01

[kinzyjr]

@ahosey01 Sometimes they can be off.  There is an example on one of the threads in the weather forums where the Tarpon Springs station recorded a temperature in the 20s with all of the surrounding WU stations recording mid-30s: https://www.palmtalk.org/forum/index.php?/topic/66736-new-climate-normals-1991-2020/&page=2&tab=comments#comment-999898

In your case, there is probably more variability since there are more local microclimates there.  Since it is an arid area, there are things that tend to survive lower temperatures as well (ex. Washingtonia filifera in NM).

Even though Florida is relatively flat, take a look at this graphic from this winter:

(Original Graphic from: https://www.palmtalk.org/forum/index.php?/topic/72065-florida-freeze-january-30th-2022/&tab=comments#comment-1038112)

The location where the 23F is sitting on the map had freeze dried Pygmy date palms, heavily damaged Bismarckias, Dypsis lutescens torched to the ground, dead coconuts and foxtails.  The airport is boxed in green and recorded 30F.  The areas in the red box with 30s have coconuts, Dwarf Betel Nuts, etc. It's entirely possible that your weather station does not reflect your local conditions that well even though it is so close, similar to what occurs here.

[Sabal_Louisiana]

Are you referring to the NWS Coop (cooperative) station at Wickenburg, AZ? i looked it up and apparently it became defunct in March 2011.

For recent observations in you area consult:

https://mesowest.utah.edu/cgi-bin/droman/meso_base_dyn.cgi?stn=MAWA&time=GMT

(Wickenburg Airport)

However, this is an unofficial site.

The attrition of NWS (Coop) stations has been supplanted by mesonets and other unofficial weather networks.