What I just learned by watching Loco 4....

[MWmetalhead]

Sandra Ali evidently thinks "a half century" is 500 years in length!

I do realize brain farts are prone to happen periodically on live TV, of course.

[SteveS]

It was actually Garagiola that mentioned the half century. She was referring to Paul Gross' earlier description at 6:03 of it being a 500 year event.

[Rate This]

That 500 year event took a liking to my car… got caught out in it last night after taking the cat into the emergency vet… glad I always keep a spare car… it was only about 3 feet of water but enough that it came up about 8 inches into the car from underneath.

[Mega Hertz]

It's the radical left MSM Dems and a conspiracy to make everyone think a half century is 500 years. Facts. Look it up. Antifa. Wake up. It's Biden and the LEFT making it rain like this to make PRESIDENT TRUMP look bad.
ABCBSNBDNAIOMDKSKSMNDSBAK.

[MWmetalhead]

Well, Paul Gross is a complete moron then, if that is indeed what he said and meant. I didn't see that part of the newscast. 6 inches of rain is not a "500 year event." Some portions of Metro Detroit saw similar rainfall amounts in August 2014. Areas west of Big Rapids saw 7 inches of rain in 24 hours in early October 2019. I guess he didn't want to let an opportunity to exaggerate / over-sensationalize go to waste.

Sorry to hear about your car, Rate This. That sucks.

I felt bad for Andrew Humphrey last night. WXYZ and Fox 2 both had team coverage (two meteorologists) during the Livingston County tornado warning last night. Andrew - who had been working since the crack of dawn - was left to do coverage all by himself, including running all the graphics, from the look of things.

[SteveS]

Paul was referring to the 6.8 inches of rain received at Comerica Park in 24 hours and how that much in 24 hours is statistically a 500 year event.



In the graphic after that he mentioned how four to seven inches of rain is the liquid equivalent of forty to seventy inches of snow.

[MWmetalhead]

On the first point, he is simply wrong. Weather records in Detroit only date back to the 1870s, and some areas saw similar rainfall just seven years ago! There is no legitimate research he can cite to support the "500 year" claim. In other words, he is spreading FAKE NEWS.

On his second point, he is making an absurd comparison. Very warm air is capable of holding far more moisture than cold air. The amount of atmospheric "forcing" required to wring out 40 to 70 inches of snow at a 10:1 ratio at temps, say, in the 20s is far higher than the amount necessary to wring out 4 to 7 inches of rain with temps in the 70s.

Paul is overdramatizing the significance of the event and is full of shit. Much of the flooding in Detroit was manmade due to inoperative storm drain pumps. Where pumps were fully functional, flooding was minimal away from creeks and streams.

Government mouth pieces in some instances are blaming mother nature perhaps in an effort to ward off lawsuits arising from their willful neglect of infrastructure, which in some neighborhoods has led to repeated basement flooding episodes.

[Mega Hertz]

MW, we didn't get jack shit in the Brighton area. I even got the notice on my phone for the Livingston county tornado warning. I was in Ann Arbor when my girlfriend called and said the sirens were going off. They went downstairs and, as I was on my way home, it didn't even start raining until I got to Silver Lake Road on 23. It rained for a little while and then stopped. Heavy rain started up again around 11. But as far as tornadoes and severe storms...nothing.

[MotorCityRadioFreak]

MW, we didn't get jack shit in the Brighton area. I even got the notice on my phone for the Livingston county tornado warning. I was in Ann Arbor when my girlfriend called and said the sirens were going off. They went downstairs and, as I was on my way home, it didn't even start raining until I got to Silver Lake Road on 23. It rained for a little while and then stopped. Heavy rain started up again around 11. But as far as tornadoes and severe storms...nothing.

A funnel cloud was spotted near M59 and US 23 as well as further south by I-96 near Latson Road. So, there was something, and the storm was moving northeast which is why it missed Brighton.

[MWmetalhead]

The precipitation did dissipate quickly - especially on the southern end of the system - once the precip reached US-23.

The clowns on TV were preaching late last week about how the entire weekend would be a washout. At my house, I received only a few hundredths of an inch of rain after sunrise yesterday, absolutely zero rain last night, and today has been party cloudy the entire day so far.

Any precip across SE Michigan today should be isolated to scattered in nature and should not last very long.

Precip organization and totals for tomorrow also shouldn't be very impressive.

[innate-in-you]

Paul was referring to the 6.8 inches of rain received at Comerica Park in 24 hours and how that much in 24 hours is statistically a 500 year event.



In the graphic after that he mentioned how four to seven inches of rain is the liquid equivalent of forty to seventy inches of snow.

I remember in 1976 or 1977, we had a rainstorm of about the same magnitude.

A lot of basements in the Cadieux/Harper area were flooded.

I picked up a bunch of old radios on trash day, sadly, all of the capacitors in every radio I found were whacked, but I got a lot of tubes.

[Mega Hertz]

MW, we didn't get jack shit in the Brighton area. I even got the notice on my phone for the Livingston county tornado warning. I was in Ann Arbor when my girlfriend called and said the sirens were going off. They went downstairs and, as I was on my way home, it didn't even start raining until I got to Silver Lake Road on 23. It rained for a little while and then stopped. Heavy rain started up again around 11. But as far as tornadoes and severe storms...nothing.

A funnel cloud was spotted near M59 and US 23 as well as further south by I-96 near Latson Road. So, there was something, and the storm was moving northeast which is why it missed Brighton.

No shit!? That is not too terribly far from my house and even closer to my work. See, I've had times where it is downpour at the office, but 5 miles down Grand River, my house is bone dry. Which is even weirder, I had to go to Tractor Supply Co which is a stone's throw from Latson. I just want a good pounding thunderstorm

[jadednihilist]

On the first point, he is simply wrong. Weather records in Detroit only date back to the 1870s, and some areas saw similar rainfall just seven years ago! There is no legitimate research he can cite to support the "500 year" claim. In other words, he is spreading FAKE NEWS.

On his second point, he is making an absurd comparison. Very warm air is capable of holding far more moisture than cold air. The amount of atmospheric "forcing" required to wring out 40 to 70 inches of snow at a 10:1 ratio at temps, say, in the 20s is far higher than the amount necessary to wring out 4 to 7 inches of rain with temps in the 70s.

Paul is overdramatizing the significance of the event and is full of shit. Much of the flooding in Detroit was manmade due to inoperative storm drain pumps. Where pumps were fully functional, flooding was minimal away from creeks and streams.

Government mouth pieces in some instances are blaming mother nature perhaps in an effort to ward off lawsuits arising from their willful neglect of infrastructure, which in some neighborhoods has led to repeated basement flooding episodes.

The assertion that 6 inches of rain within 24 hours being a statistically once in a 500-year event within any given local point is mostly valid, with a caveat I'll add at the end of the post. With any long-term statistics, you can fit data into a distribution function that best fits the data (this is an example for precipitation), and from that fit, you can estimate overall probability and frequency to a high degree of accuracy. Here are a few precip/frequency curves fitted across local stations courtesy of NOAA/NWS's Hydrometeorological Design Studies Center Precipitation Frequency Data Server:

DTW/Metro Airport:


DET/City Airport:


Ann Arbor:


Madison Heights:


Now, these estimates are not exact, computing them within a 90% confidence interval at all of these sites, a 24-hour rainfall totals of about 5 to 8.5" with a median around 6.5" is an event that occurs roughly once every 500 years. If you want to be super generous, 6" of rain within 24 hours across any given point within the metro area falls roughly every 100 through 1000+ years.

Detroit's official climate records dating back to 1874 has a daily maximum of 4.78" that fell on July 31, 1925.

The only assumption that would disrupt this type of frequency analysis is that the local climate is static. That assumption is false as climate is a moving average. NOAA usually does climate analysis on 30-year time scales and the overall local 1991-2020 climate is a bit warmer and wetter than it has been previously. This would imply that extreme precipitation events would occur at a higher frequency than if the climate had been static. Houston has had at least a 100-year extreme precipitation event each of the past 4 years. There are several independent peer-reviewed studies that I'm happy to share that corroborate this trend.

[MWmetalhead]

Many thanks for the detailed and well researched explanation!

Statistical extrapolation is certainly an imperfect method, and your Houston example is an excellent anecdotal case. Extrapolating from 30 year records by using a mathematical equation to predict recurrence of something that might occur once in a lifetime or even less often is especially imperfect once one gets to the extreme end of the scale where few or zero historical observational data points exist.

The other item I'll add is weather records in Detroit, generally speaking, are recorded by calendar day only. If a 6 inch rainfall event occurs within a 24 hour period but crosses Midnight, then that instance (presumably) won't appear when mining past records.

So, while mathematical modeling certainly lends support to Paul Gross's assertion, there are some significant caveats and limitations that should be disclosed.

[jadednihilist]

No problem -- and that is correct re: the caveats, which is true for how you should look at any statistic.