The Five-Day Rule for Weather Prediction

[rangerrebew]

January 06, 2024
The Five-Day Rule for Weather Prediction
When I write this blog, I generally follow a " Five-Day Rule of Weather Prediction" and so should you.

Here is the rule:

Predictions of severe or exciting weather for more than five days out should be considered with caution.   Be VERY careful of hyping forecasts for longer periods.   Be aware of the uncertainty of big events predicted at longer lead times.

I have noticed that some media and popular local amateur sites (on YouTube, X, and other media) regularly break the five-day rule, often hyping events that often never occur. 

Crying wolf like that is not a good thing.

https://cliffmass.blogspot.com/2024/01/the-five-day-rule-for-weather-prediction.html

[catfish1957]

I think there are outfits like Accumweather that dares to go out 15 days, but.......

In the defense of the profession of meteorology, I can give several reasons why this craft never, has never, and will never be an exact science or have any real accuarcy, outside 1, and the very most 2 days.

1.And most around the issue of  randomness.  Watch a 30 day or longer loop of weather and cloud movement.  It is a extreme hodgepoodge of randomness, and these rivers and pools of moisture that have a life of their own.  The Mets do pretty good at a macro level with trending and overall patterns, but....

2. Sticking with the topic of randomness, weather patterns are greatly effected by (1) wobbling on the earth's rotation (frequency and severity), solar flares, and surface environmental factors like smoke, or dust.

3. Throwing the dice.  Most of us in this country live in areas that are impacted summer thermal showers.  Here near the gulf coast, I have seen an example of one summer shower dropping 3 inches of rain on one spot, and not a drop within eyeshoot a 1/4 of a mile away.  The same can be said around lake effect snow squalls.

4. One of my favorite examples is tropical storm modeling and forecasting.  Next hurricane season, take a gander at the 120 hour modeling data. I have seen certain Cape Verde storms have points of expected locale 3000 miles apart. And believe me, more science has been put in these prgnostication tools by far than any other tool in Meteorology.  I'll give you an extreme example here in SE Texas.  Back in 2007, a wave formed off the gulf, maintained strength, and NHC and everyone else thoought a minimal Depression might form and give the area a gully wash, like we see time to time. That was at 4PM.  By 7 am, Cat 1 Humberto was hitting, downing trees and power lines in a swath at the coast to about 35 miles inland.

That is why as even an un-accurate science that this is, the professional mets are very meticulate in explaining that their wares are based on models, percentages, and ranges.  It's only like hacks at the Weather Channel that might give you an idea that they think they know what they are talking about

[jmyrlefuller]

All valid points. And I say this as a meteorologist myself.

I will say this much: the art, and science, of weather forecasting, has improved dramatically the past 20 years. When in the recent past it was unrealistic to have any degree of accuracy around two days, now you have a reasonable general idea of what can happen in two WEEKS. Sometimes three.

But the key word here is "general." Any amateur influencer taking the kind of guidance that's out there to hype up fear is putting WAY too much faith in the tools at our disposal. They're great tools, don't get me wrong. But, for all the reasons the OP and @catfish1957 mentioned, imprecise—and forever will be imprecise.

Think of a forecast model like AI. In fact, many of the same principles are at play. They're both computer models, one based on the atmosphere, the other on human language. They have a tremendous amount of information at their disposal... but the more they are expected to extrapolate, the worse and worse they get. And whether we like it or not, the idea of us being able to monitor every cubic foot of the atmosphere is always going to be unfeasible, especially given how much is dictated by non-atmospheric process (e.g. human behavior) that can't be modeled with any degree of accuracy. It's like the butterfly effect: one guy changes his mind, the dominoes fall in all directions.

[jmyrlefuller]

To wit: no responsible meteorologist is going to do what amateur hype artists seem to do every day.

[Cyber Liberty]

One good-sized volcanic eruption throws the whole endeavor out of whack.

[catfish1957]

To wit: no responsible meteorologist is going to do what amateur hype artists seem to do every day.

 

Thank Goodness for every Jim Catore and Mike Bettis there are a 1000 NOAA, NWS and NHC workers who do their job well without fanfare.