Saturday, August 27, 2011

Hurricane Irene Forecasts and Their Hurricanes Versus Our Hurricanes

The media is hitting Hurricane Irene really hard and some descriptions are going too far: "historical storm", "storm of the century", etc.  Folks, this a category 1 storm with sustained winds of 85 mph.  Serious, but not catastrophic.  We are already seeing local authorities overreact--like NYC cutting off bus and subway service at noon EDT.  At that time the winds at NY's Kennedy Airport were 8 miles per hour and there are only a few showers around.   The strong stuff will not happen until tonight, so why cripple people's ability to move around and for coastal people to evacuate?  Overreaction stemming from massive complaints about poor snow removal last winter?

A key reason for my field to improve forecasts is to reduce the overwarnings and overreactions--which undermine confidence in forecasts, resulting in calls of "crying wolf" and lessening public reaction when truly threatening situations are imminent.    Many of us worry about situations such as the SE tornadoes when forecasts are very good, but many people still die.  And more limited and surgical warning save money.  Big money.  The trouble, of course, is that the media loves to overhype storms...really good for viewership.

For those of us on the West Coast it is good to keep some perspective on storms.  We don't have tropical hurricanes, but our big storms are the equal of all but the strongest hurricanes. Take Irene..fairly large hurricane with sustained winds of 85 mph and a central pressure of 952 hPa (mb).  Here is a nice image of it:


Lets compare to our Dec 12, 1995 windstorm.  Here is an image:


Ours is just as big if not bigger.   Maximum winds?  Here is a nice analysis by storm-maven Wolf Read:

Gust to well over 100 mph on the coast!  Certainly, the winds from this storm are in the same league or greater than Irene.  Central pressure of our storm--953 hPa...virtually the same as Irene.  The 1995 storm is nothing compared to the 1962 Columbus Day Storm.
And the waves from our big storms generally eclipse those of the East Coast varieties.

A major difference between our storms and East Coast hurricanes is the coverage--for many reasons the WeatherChannel and East Coast media give relatively short shrift to our storms. 

But hurricanes do bring heavy rains and flooding, which is generally limited for our big windstorms.  The reason--hurricanes are tropical systems depending on warm water and the release of heat by condensation of water vapor.  Our storms derive their energies mainly from another source:  horizontal variations in temperature.  And the coastal areas of the east coast are more vulnerable to storm surges and coastal flooding--the biggest threats of hurricanes.








No comments:

Post a Comment