# Whats up with the hurricanes in mexico?

1. Sep 20, 2014

### MathAmateur

While we live far enough north and inland that the hurricanes only have given us a lot of rain (LOTS of rain). I am wondering why after years of no storms, why suddenly we get 3 in 3 weeks? Is this random? Or is there something special about the eastern Pacific Ocean this year? Has anyone else experienced serial hurricanes like this?

2. Sep 20, 2014

### D H

Staff Emeritus
Mid-September is the peak of the hurricane season Atlantic and eastern Pacific.

3. Sep 20, 2014

### FactChecker

I wouldn't rule out that there might be some reason. But I should point out that a uniform random behavior will often show more clustering than people expect. So it often looks like something must be causing clustering when it is really just the natural clustering of a uniform random behavior.

4. Sep 20, 2014

### D H

Staff Emeritus
The distribution of tropical storms is not uniform, not even close. The clustering around mid-September is very real.

5. Sep 20, 2014

### FactChecker

Right. But the OP asked about having several in one month but none for several prior years. That implies none in the same month for several prior years. So even after seasonal adjustment, the OP has a valid question. My point is that after all the known effects are compensated for, it is hard to distinguish natural random clustering from clustering due to some other cause. Statistical tests must be applied.

Last edited: Sep 20, 2014
6. Sep 20, 2014

### D H

Staff Emeritus
Not really. The number of hurricanes in January and February is essentially zero. If you saw three back-to-back hurricanes in late January / early February you would have to wonder whether something weird was happening. Seeing three back-to-back hurricanes hitting Baja California in September is something different. It's well within the statistical norm.

7. Sep 20, 2014

### FactChecker

You are just eyeballing the statistics. My point was that there is more natural random clustering than people expect. They think there is a cause where there isn't one. It supports what you were saying. However, if all three hurricanes started the same place and followed the same path, I bet there is a common contributing cause. That would be significantly less likely in a uniformly random process.

Last edited: Sep 20, 2014
8. Sep 23, 2014

### berylman

There is a minimum threshold sea surface temperature for hurricanes of about 26-27 C. You also need low vertical wind shear--that means that the wind doesn't change much in speed or direction in going from the surface upward. What we have this year is ocean temperatures in the Eastern Pacific that are much warmer than normal. The wind shear has been favorable and consequently the number of storms is quite a bit above average, and the storms have been stronger than average. That means you're more likely to have 3 in 3 weeks than in a normal year. To affect Mexico, you also need the steering currents (mid-atmosphere winds) to bring the storms toward Mexico. Earlier in the season storms that form will typically meander vaguely off toward Hawaii in the easterlies. Typically once it gets to be September/October the steering currents will bring storms back toward North America, and that is what has been happening.

So this is not really a random phenomenon like, say, the disintegrations of multiple radioactive atoms in a particular time interval, since both the formation of a hurricane and that the hurricane was steered toward Mexico mean that the likelihood of the same event happening again is greater than what the long term mean what give.

9. Sep 25, 2014

### MathAmateur

Thank-you for your good information. Things have settled down and we are back to just our usual thunderstorms.