Abstract
No.
Introduction
At the Salt Lake City International Airport, only 0.26 inches of rain fell in July, compared to an average of 0.72. In August, it was 0.10 compared to an average of 0.76. September? Only 0.19 compared to an average of 1.33. Will it ever rain again?
Data and Methods
I looked at the Global Ensemble Forecast System (GEFS) forecasts for the next week and extrapolated them 7.6 billion years forward to when the Sun will exhaust its fuel and expand as a red giant.
Results
No GEFS members produce precipitation at the Salt Lake City International Airport through 1200 UTC 8 October.
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| Source: NCEP |
Since there's no precipitation forecast for the next week, extrapolation suggests it will never rain in Salt Lake City ever again.
Conclusions
It will never rain again in Salt Lake City. This forecast, however, is contingent on a number of assumptions. In particular, we assume that the forecast for the next week is accurate and will apply for the next 7.6 billion years. Weather variability, anthropogenic climate change, orbital variations, changes in solar luminosity, and other factors may affect this forecast. Therefore, you should take it with a humorous grain of salt, enjoy the splendid fall weather, and hope that we see a transition to a snowy pattern in early November.
What kind of correlation exists between summer and winter (or fall and winter) precipitation for the Wasatch? Is my pessimism about having enough snow to ski on this winter warranted or is it just driven by some kind of recency bias from the bone-dry summer?
ReplyDeleteI've never looked into this. Given the dramatic shift in large-scale conditions and precipitation processes between summer and winter, I wouldn't expect much. Fall to winter, perhaps, but northern Utah is an odd place for these sorts of correlations, so if they exist, I suspect the variance explained isn't large enough to have useful skill.
DeleteHowever, this is a hypothesis, so perhaps someone out there can prove me wrong.
Ok, then.
DeleteI grabbed monthly precipitation data (1980-2020) from https://wrcc.dri.edu/cgi-bin/cliMAIN.pl?ut0072 and calculated the correlation between total winter precip (Dec-Feb) and total fall and summer precip preceding the winter observation. The correlation between fall and winter precipitation was 0.48 and only 0.14 for summer-winter. Looking at the graph of the three separate time series, it looked like the correlation may be driven by the unusually wet (for this sample period) 1980-1985 years. When I recalculated the correlation from 1986 on, it dropped to 0.18 for fall-winter, and 0.031 for summer-winter.
Just eyeballing the graph, there are some low fall observations that correspond to relatively high winter observations. Specifically, the lowest fall observation is 1999, but the following 99-00 winter was above average. There are also spikes in fall precip that closely match winter spikes, like fall 2010 and winter 10-11.
I would have liked to do this with a longer data series but there were a lot of missing values earlier than 1980 from this source.
Finally, someone who does what I ask!
DeleteThanks for digging in. These numbers suggest at best limited skill based on this metric. Some of the issues you've encountered reflect the fact that a few decades seems like a long time, but it isn't for precipitation variability.
Thanks again for sharing.
Jim
No problem. I like having an excuse to dig into non-financial data now and again. Sometimes, it's nice to use my powers for good, instead of evil.
DeleteThanks, this just made my day after accidentally entering the wrong answer on my physics C quiz.
ReplyDeleteI was about to make a joke comment saying that it's time for all of the ridiculous correlation posts, looks like someone beat me to it. 0.1 inches of precip in August means an epic winter! Oh, but 0.19 in September is a bad omen... time to burn some skis
ReplyDeletere: "no"...Thanks for that Jim, first time I've laughed in a week!
ReplyDeleteWeather is great. Fall is my favorite time of year here. Reasonable temps and nice colors. Only downside after a summer with no monsoon storms is that the trails are all now covered in 6 inches of moon dust.
ReplyDeleteOn the first part of the journey
ReplyDeleteI was lookin' at all the climate change
There were plants and birds and rocks and things
There was chemtrails and microwaves
The first thing I met was a AOC with a buzz
And the sky with no clouds
The heat was hot and the ground was dry
But the air was full of CO2
I've been through the desert on a horse with climate change
It felt good to be out of the rain
In the desert, you can remember your climate change
'Cause there ain't no climate change to give you no pain
La, la, la, la-la-la, la-la-la, la, la
La, la, la, la-la-la, la-la-la, la, la
Good god. America? As much as I like sappy 70s music, that song is awful.
DeleteTry Joni Mitchell. "Both Sides" for politically neutral weather lyrics (technically released in 1969) or "Big Yellow Taxi" for left leaning.
I don't see you replacing Wierd Al Yankovik anytime soon.
Jim
;-)