If you are wondering, 20.4°C was observed at 700-mb in the 0000 UTC (1800 MDT) sounding, which is also the highest observed in the sounding records (the old record was 20.2°C).
It really was a dry heat. At the time of the 109°F, the dew point was 26°F, resulting in a dewpoint depression of a remarkable 83°F and a relative humidity of 6%.
Stay hydrated my friends.
Pretty amazing considering how long the 107° record has stood and how many times it has been tied over the years. I was in Portland for the 116° heat dome in 2021 and that actually burned the western sides of the native firs, took a couple years to subside with the new growth.
ReplyDeleteYesterday would have very likely been an all time record hot day even if the KSLC ground cover was the same as 2010 with how warm the 700mb temperatures were. That being said the NWS is being disingenuous if they think the change in ground cover has zero effect on temperatures, especially on light wind days. Study (section 3.2) https://scielo.org.mx/scielo.php?script=sci_arttext&pid=S0187-62362008000200002 on how ground cover changes influence 2m temperatures. This study was 24/7 for 15 days, not a one day field study with hand held instruments.
ReplyDeleteAll observations have instrumentation and representativeness uncertainties. Statistical methods have been developed to adjust for these issues. This is called homogenization.
ReplyDeleteThe NWS mission is weather related, not climate related. Their meteorologists are trained to deal with weather, not things like homogenization. Their sister agency, the National Centers for Environmental Information (NCEI) does the work to remove non-climatic effects from the observations, but typically this is done to monthly or annual data for which such adjustments are more straightforward.
Daily data is more difficult, in part because biases vary considerably from day to day. For example, the urban heat island magnitude is different on a rainy day than a sunny day. The influence of local ground cover also varies. You can't just adjust maximum temperature records, for example, but lowering them all by 1 degree every day because biases relative to other locations or observing site vary a good deal from day to day.
I'm not sure what you would like to see done, but building a micronet at the airport would do little to increase certainty. It would only tell us how the observing site compares to the surrounding area *today*. What would we do for the airport observations in say 1950? How good was that site? Was it representative? Should that observation be adjusted?
So, what exactly do you want done because this doesn't seem like a hill worth dying on.
The first thing that can be done is for the local NWS office to acknowledge that the ground cover at KSLC is not the same as it was in 2010 and it's increasing temperatures a little. A one day field study with hand held instruments a few years back is not going to catch the nuances that a dedicated 24/7 study for a few weeks will, especially on light wind sunny days like yesterday. The second thing that can be done is restore the surrounding area back to how it was in 2010. If that is not possible then the they can move KSLC to the south by 1/4 mile which is an area that was like KSLC was in 2010.
DeleteNote, the all time high for KPHX is 122, set all the way back in June of 1990. Part of the reason that record has still not been broken is because the ground cover at that site had undergone changes similar to what KSLC has experienced so they moved it to a more representative location.
what happened in 2010?
DeleteMr. Chipman will cherry pick single trees for the rest of his life, regardless if it is on a hill, or if it would mean his demise.
DeleteIn 2010 is when KSLC moved from a different airport location to its current airport location.
DeleteWhen the entire valley is developed, and the urban heat island effect exists everywhere, where to you propose to place the KSLC sensor? Do you think increased development and urbanization, which is the big picture story of the history of the KSLC sensor, has anything to do with the changing of our climate?
DeleteBy suggesting we move the sensor to a site that more closely resembles historic conditions of the sensor location, we're also purposely avoiding the measurement of the long term change of the heat island effect.
Perhaps we should bury the sensor in the ground. Similar to some large flightless birds heads.
Ground cover changes directly under and around KSLC is a separate issue from the urban heat island effect which is also increasing KSLC temperatures. Nothing can be done to fix the urban heat island effect but the National Centers for Environmental Information can take it into account, something can be done to fix ground cover changes at KSLC.
DeleteWhat NCEI does is make adjustments for non-climatic biases. This implicitly includes ground cover changes.
DeleteThey do this to limit the influence of non-climatic effects on regional and global trends. What they do cannot be used to adjust daily maxima and minima because there is a lot more variability in bias from day to day then there is from month to month or year to year, creating greater uncertainty in how to make adjustments for daily temperatures as opposed to monthly or annual.
Even in the absence of human development, one could argue about how representative the airport is of the Salt Lake Valley. It is in cold pools more often in the winter and at night, especially compared to the benches and south valley. When the observing site was moved from Downtown SLC to the airport in the late 1920s, there was a substantial drop in mean minimum temperature, reflecting this local microclimate.
Today, the airport is a hodge-podge of land-surface types, from concrete, to asphalt, to developed, etc. In contrast, much of the Salt Lake Valley is developed, with development intensity varying significantly.
Many years ago we searched for a few observing sites to measure turbulent, sensible heat, and latent heat fluxes in "representative" areas of the valley. They don't exist. We live in a very heterogeneous, developed valley.
So, this is how I learned to stop worrying and love the airport observations (h/t to Dr. Strangeglove). There is no ideal observing location. Records at the airport are simply extremes based on wherever the measurements have been taken.
It's also unclear to me why historical observations are held on a pedestal as truth. The error bars on those observations are definitely larger.
The real news was 96f at entry 4 Sunday at the bird at 11a! WTF!?!
ReplyDeleteAt the end of June 2026 the all-time country high was reached in quite few European countries: including Germany, Poland, Belgium, Czechia, Slovakia, Hungary, Denmark.
ReplyDeleteThe new all-time high for Czechia was broken on 27th June (40.9°C) and again on 28th June (41.9°C or 107.4°F). Previous high was 40.4°C or 104.7°F from August 2012.
So only for two weeks, Doksany (Czechia) could boast having a higher all-time high than Salt Lake City (Utah). But Utah responded with 109°F, that is 42.8°C and that is a bigger beast ;-) I guess the El Niňo is contributing to so many all-time highs getting broken both in Europe and in the U.S west this year?
Thanks for sharing those. It has been a remarkable summer. I'm not sure the linkage between summer temps in western North America and Europe is strong enough to draw such a conclusion. We just moved into moderate El Nino too, so it's not super strong yet (but developing). That said, it's not my area so I'll defer to other pros.
DeleteLast night I read the article in The Salt Lake Tribune called "Salt Lake City set a record high of 109 degrees. Then came the conspiracy theories." which has some great information. The one great piece of information is the chart that compared seven nearby stations that have been in operation for 30+ years with KSLC. The chart shows a positive trend and an increase of 1.05 F at KSLC since 2010 compared to the seven stations, 2010 is when KSLC moved to its current location.
ReplyDeleteWikipedia States on Salt lake City that The average number of days that reach 100 or higher is five in a year. How far have we fallen from this outdated statistic?
ReplyDeleteYeah, another stat left on the dustbin.
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