Are Storms Getting More Intense Over the Pacific Northwest?

It is rare to have a week go by without a local media outlet doing a story suggesting that storms are getting worse in our area, with global warming being the suggested cause.  For example, last month KING-5 ran a story saying exactly that (see image), quoting from a representative of  the National Conservancy.

And this is not the only example of claims that Northwest storms are strengthening.

The sad thing is that these claims of increased storms in our region are simply not true, contradicted by the both observations and the peer-reviewed literature.   The "experts" quoted are often representatives of well-meaning, but poorly informed, advocacy groups.

All too often, the media is failing to do their homework in checking out the veracity of these claims.    So let's do the homework for them!  Let's look at key observations to see if there are any trends in storminess in our region.

First, what about winds?   With the help of UW's Neal Johnson, we have found the maximum winds observed each year at a number of Northwest locations.  Below you will find the plots of annual maximum winds for Astoria and Seattle-Tacoma Airport ... the others are very similar.  There is absolutely no evidence of an upward trend in wind speeds.  In fact, there seems to be a decrease at Seattle-Tacoma Airport.

To really ensure we got the story right, we next found the lowest pressures observed each year at various stations.   The lower the pressure, the stronger storms are in general, so if storms were getting more intense we would expect to see a drop in extreme pressures each year.

Below are the extreme low pressures observed each year for Astoria and Seattle-Tacoma Airport.  Do you see a trend?  I don't.  No hint that storms are getting more intense around here.  You might even come to the opposite conclusion from the pressures at Seattle-Tacoma Airport, that storminess is decreasing.

Are storms getting stronger around here?  The results above do NOT support that conclusion.  And there is a lot of corroboration for doubting the increase.  For example, the comprehensive analysis of Northwest windstorms by Wolf Read (information here) clearly shows that the strongest windstorms on record occurred in 1962 (Columbus Day Storm), with the other big ones in 1880, 1921, 1934,  and 1951.  There is NO evidence that storms are getting more powerful in the Northwest from his work.

Recently, an article in Science Magazine suggested that precipitation/flooding in our mountains are decreasing due to a weakened jet stream approaching the region (see below).  Weakened jet streams would suggest weaker storms, since the wind and temperature gradients associated with the jet stream provides the energy for midlatitude storms.

You can tell I am a bit frustrated by the incessant claims that global warming is already having a big influence on storms and adverse weather here in the Northwest.   

Neither observational evidence nor theory supports such claims. 

Global warming is a very serious issue and later in this century the effects will probably be profound for many regions.  For us, the largest impact will probably be a serious decline in snow pack and the ending of skiing at Snoqualmie Pass.  But exaggerating current impacts when observations and the science say otherwise will only lessen the credibility of the scientific community.  Environmental advocacy groups mean well, but they must understand that crying wolf is not a useful approach in the long run.  And media folks need to vet the claims better.