From NOT A LOT OF PEOPLE KNOW THAT

By Paul Homewood

 It seems we get a storm or flood of the century nearly every year!

Melissa may well be the most powerful hurricane to hit Jamaica in recent times. But is this significant in itself?

Jamaica is a relatively tiny speck in the Caribbean. Hurricanes barrel across the Caribbean every year. What are the odds of a Cat 5 one making a direct hit on Jamaica? Most would just bypass the island.

So, let’s take a dispassionate look at the facts.

First, and most importantly of all, the death toll in Jamaica at the moment stands at four. This will likely increase over the next few days but is a remarkably low number at this stage.

Secondly, there is no evidence at all that Melissa made landfall with winds of 185 mph, something which has been widely reported across the media as fact. Let me repeat – NO EVIDENCE AT ALL.

Let me explain.

The claim is derived from wind speeds estimated from hurricane hunter aircraft data sometime prior to 11.00 AM EDT. Sustained winds were calculated at 160 kts, or 184 mph.

The previous advisory was six hours earlier, so the aircraft data would have been collected sometime during that six-hour period.

Melissa made landfall at 1.00 PM, at least two hours after the aircraft data had been collected, when Melissa would still have been maybe 50 miles or more out at sea. However, there were no further measurements during that time, or at landfall itself. Therefore, the figure of 185 mph was retained as the official “landfall speed”:

Hurricanes invariably weaken as they near land, because the sea becomes shallower and the coastline interferes with atmospheric airflow.

The satellite data confirms this weakening, and shows that even before landfall winds were lower than claimed at 155 kts, 178 mph.

What the windspeeds actually were at landfall, we simply do not know. Nobody measured them. This may sound like I am splitting hairs, but this is, of course, precisely the situation we would have been in prior to the satellite/hurricane hunter era began forty years or so ago. That is why we simply cannot directly compare today’s hurricanes with those of the past.

To put windspeeds into perspective, the highest sustained speed recorded was from Hurricane Allen in 1980, which measured 190 mph.

How does Melissa match up historically? I recently came across this NOAA study from 1983, long before hurricanes were looked at through the lens of global warming.

Was Melissa any worse than Galveston? Or Okechobee? Or the Great Miami hurricane which wiped out Miami in 1926.

Or the strongest US hurricane of the lot, the Labor Day storm in 1935? Or the second most powerful, Camille in 1969?

These, of course, are purely US hurricanes. Many more more wreaked havoc across the Caribbean and elsewhere. The worst of all was the Great Hurricane of 1780, which is estimated to killed 27500 dead in Martinique, Barbados and elsewhere. This is an astonishing number by any account. Winds have since been estimated at over 200 mph.

A closer look at Camille exemplifies well just how observation methods have changed over the years.

In 1969, satellite technology was pretty much useless as far as monitoring hurricanes were concerned, other than for tracking purposes. Hurricane hunter aircraft tended to be pot luck as well, unable to fly inside hurricanes for hours on end in order to find the peak winds, which they routinely do nowadays.

The official report stated that hurricane hunters had estimated sustained winds of 190 mph, based on dropsonde data. But this was ten hours before landfall and no further flights were made.

The official data for Camille states that winds at landfall were 175 mph. These were derived from two land based recordings of barometric pressure, both of which were close to the eyewall and both instruments were inspected later and confirmed as reliable.

Comparing Camille and Melissa then is comparing chalk and cheese. Wind speeds for the former are accurate at landfall but Melissa’s are not at landfall at all but 50 or so miles out at sea, when they would have been higher.

Whatever the wind speeds were, there can be mistaking the devastation wrought in August 1969, as the before and after photos of the Richelieu Apartment block show:

Let me be clear. I am not in any way trying to minimise how powerful and damaging Melissa was. It was a terrible storm and a historic one.

But it is a sad fact of life that hurricanes like Melissa have always brought death and destruction to the Caribbean, Gulf and Atlantic coasts of America, and they always will.