A Narrow View Of Rainfall

Guest Post by Willis Eschenbach

So I came across a news article with the headline:

Philly will have more heat waves, and the Delaware projected to rise more than a foot over the next 25 years

Yeah, right, sez I. The claim is that the flooding will come from increased rainfall in the Philly area. The underlying study is from something named the CRRA:

The Climate Resilience Research Agenda (CRRA) was developed through a collaboration formed in 2019 between the City of Philadelphia, the Delaware Valley Regional Planning Commission (DVRPC), the Academy of Natural Sciences (ANS) of Drexel University, and Drexel University faculty and staff engaged in the Consortium for Climate Risks in the Urban Northeast (CCRUN).

The CRRA Philadelphia folks have put out a document called “A Climate Resilience Research Agenda for the Greater Philadelphia Area“, with the subtitle “Findings from 2021 Working Group Discussions And Updated CMIP6 Projections for the Region”. This is the CRRA Philadelphia Findings document, hereinafter “CRRAP Findings”.

Note that these are not findings from scientific studies. Instead, they are CRRAP Findings from “Working Group Discussions” and downsampled climate models. Clearly science at its finest …

Inter alia the study says:

Philadelphia is expected to become both hotter and wetter in the future through increased
precipitation, a rising sea level, and increased air temperature. In addition to these changes,
extreme weather in the region is projected to continue to increase in frequency and severity,
leading to increased riverine and stormwater flooding, among other impacts.

I started with the tides. The study shows the following, from NOAA.

Figure 1. NOAA sea level rise in Philadelphia

It’s been rising at 3.04 mm/year, that’s about an eighth of an inch. And there’s no sign of acceleration.

Next, here are their projections for future sea levels.

These are relative to the average of the 1995 to 2014 period. For Philadelphia, from the data in Figure 1, that 1995-2014 average is +49 mm. Current sea level there is +95 mm, so it’s gone up by 46 mm since the reference period.

So if it’s going to go up 6 inches by 2035, from today that’s 6 inches less 46 mm. So it has to go up by 106 mm in the next 11.5 years, which is 9.3 mm per year.

In other words, to get to their lowest estimate of 2035 levels, the Philadelphia sea level rise would have to triple tomorrow and stay that high until 2035. And to get to their highest estimate for 2035, the rate of rise would have to go to 24.7 mm per year tomorrow, and stay there until 2035. That’s a sea level rise of almost an inch a year, eight times the current rate, starting tomorrow … yeah, right, that’s totally legit.

Obviously, these folks just grab numbers and never think to ground-test them against reality.

Next, I got to wondering about the claim of “increased precipitation”. So I went to the marvelous KNMI website and got the six weather stations closest to Philly with over 50 years of rainfall data that extended to the present. These are Philadelphia International Airport, PA; Conshohocken, PA; Neshaminy Falls, PA; Indian Mills 2 W, NJ; Wilmington Porter Rsch, DE; and Lambertville, NJ.

Here are those records:

Figure 3. Monthly rainfall totals, six longterm stations in/near Philadelphia

Hmm … very little trend in there, despite decades of warming. Also, in each case the rain has been decreasing over the last two decades. Finally, we see what is called the “Noah Effect”, where one or two of the rainfall totals are much much larger than all the rest. This is a common finding in rainfall data.

How about their predictions for extreme rainfall? Figure 4 shows those fanciful numbers.

Figure 4. Projections of future extreme events, from the CRRAP Findings.

Note the highlighted section. It says that by the 2080s, 10% of the years will have less than 11 days with an inch (25.4 mm) per day of rain, and another 10% of the years will have more than 11 days with an inch per day of rain. Here’s a histogram of how that might play out.

Figure 5. Random proxy data for the 2080s with 10% under 11 and 10% over 14, as in the CCRAP projections in Figure 4. Yellow/black lines show 11 and 14 days per year.

OK, so that’s a look at their fantasy for the 2080s … but how does that compare with historical records?

Figure 6 is the same as Figure 5, but it includes a histogram in red of the number of days per year with more than an inch of rain in the six historical records shown above.

Figure 6. As in Figure 5, but includes the historical data in red.

The CMIP6 projections shown in the CRRAP Findings look nothing at all like the historical data. Historically, there are many more years with less than 11 days with an inch of rain. Not only that, but there are more years with more than 14 days with an inch of rain. In fact, in some years, some of the stations recorded over 25 days with more than an inch of rain.

Conclusions? The future projections in the CRRAP Findings document are far from “life-like”, meaning they bear very little resemblance to actual historical sea level rise and rainfall patterns. If I lived in Philly, I’d just point and laugh … but hey, I was born yesterday, what do I know?

My best wishes to everyone for a life of love and laughter,

w.

PS—Yeah, I’m still suspended from Twitter. They claimed it was because I said:

I see that James Comer is going to “take steps” against the FBI for concealing evidence of Biden corruption.

Steps? Here’s my simple 3-step plan.

1) Fire every single person working for the FBI.

2) Burn the FBI building to the ground.

3) Salt the earth.

w.

I stated here on WUWT that I thought it was not because of that tweet—it was for my views on climate. Some people laughed at that idea, claiming it was just my egotism, that the tweeps didn’t care about my climate views, and that my tweet was “inciting violence”.

But a search on “burn down the FBI” (in quotes) on Twitter finds over a hundred tweets, including these two, from folks that aren’t suspended.

So, if you’re on Twitter, maybe you could tweet to @elonmusk to unsuspend @weschenbach …

And Also: When you comment, I implore you to quote the exact words you are discussing, so we can all be clear on your subject.