It started as a little wiggle in the trade winds called an easterly wave — they all do. All the great US east coast hurricanes.
This storm didn’t seem to have much future as it encountered hostile upper level winds, but it made it across the Atlantic Ocean intact and became Tropical Storm Matthew as it approached the Caribbean Islands. And then the little storm that could became BIG trouble.
Considering the definition of success from the perspective of the hurricane, the secret to Matthew’s success has been persistence and luck.
The easterly wave that became Matthew persevered across the hostile Atlantic until it reached an area where upper winds were more favorable.
In the Caribbean, conditions were perfect for strengthening: light upper level winds and warm water. The storm became a monster, topping out with winds at 160 miles per hour — category five.
As the steering currents weakened, Matthew eyed his chance to slam the United States. The mountains of Haiti and Cuba, often lethal to a hurricane, stood in the way, but Matthew spotted an opening, the Windward Passage. And his luck held out as he threaded the needle between Haiti and Cuba and emerged only minimally disrupted into the warm waters of the Bahamas.
Yes, the Bahamas are land, but so low that these islands don’t disrupt the circulation of a mature hurricane. There’s enough warm water around the islands to feed the hungry beast, which lives off latent heat of evaporation.
So that’s where we are now. Matthew is a mature storm, diminished to category three by its interaction with Cuba and Haiti but still very dangerous, spinning across the Bahamas, heading for the U.S. – Florida, Georgia, South Carolina, and North Carolina.
Matthew’s Path Of Destruction
Matthew travelled in nearly a straight line across the Atlantic and halfway across the Caribbean. This motion was directed by high pressure to the north which covered most of the Atlantic Ocean. The high split and allowed Matthew to turn sharply to the right and head north to the Windward Passage.
Haiti, still recovering from a powerful earthquake, suffered the most. Confirmed deaths, now in the single digits, will surely rise. Damage is extensive. A population equal to that of the metropolitan New York City area has been displaced.
In The US, Florida Will Take The Worst Of Matthew
Matthew moved into the weakness in the sub-tropical high pressure system to clear Haiti and Cuba and enter the Bahamas.
At this point, the subtropical high strengthened a little and pushed Matthew farther to the west than was previously anticipated.
The new path comes perilously close to the Florida coast, and hurricane warnings are up for much of central and southeast Florida.
Any further change in path to the west could result in landfall, which would bring catastrophic damage.
Expected Effects In Florida
The currently-predicted path of Matthew shows that it will hug the coastline but not cross it. The result is that the center of the storm stays over warm water, so intensity will not be much affected.
On the other hand, the left side of a hurricane, judged from the direction of motion, is normally the weaker side. Hurricane winds now extend about 40 miles from the center, and that is about the distance offshore the eye of the storm is expected to be as it travels parallel to the shore.
Matthew seems to have a penchant for finding the path that is most conducive to a strong storm. The current forecast calls for Matthew to follow the coastline all the way around Florida, Georgia, and the Carolinas. If this is correct, Matthew will maintain hurricane strength and affect an enormous number of people. Evacuations are already underway in several states.
When The Twain Meet
The atmospheric circulation is divided into three segments. The ones that concern us most are the mid-latitude westerlies and the tropical easterlies. These two zones of weather are normally separated by a high pressure system that circles the globe.
Occasionally the divide is breached, sometimes by polar air plunging into the tropics, and sometimes by a tropical cyclone moving into the middle latitudes. The latter occurrence is hard to forecast.
As long as Matthew was under the influence of the subtropical high pressure, its motion was nicely predicted by global forecasting models. Even as it curved into a weakness in the high, the path was well-predicted. But now the storm is moving into the range of mid-latitude westerlies and the picture is not so clear. Until last night, forecasts showed that the hurricane would be picked up by a dip in the jet stream moving east across the US. This scenario would have headed Matthew towards New York and New England. The latest forecasts show the wave in the westerlies bypassing the storm, which could curve out to sea — or could meander around offshore the mid-Atlantic and make another foray toward the coast.
Locations farther north than North Carolina now have a much reduced probability of being influenced by Matthew.
Hazards Of A Hurricane
There is a saying among professional golfers that you drive for show and putt for dough. For a hurricane, an analogous saying would be blow for show, spill to kill. Wind gets the publicity — and causes a lot of property damage — but water kills, particularly by storm surge, but also flooding from rain, especially with a slow-moving hurricane like Matthew.
One Factor That Decreases The Potential For Damage
If there is anything about Matthew that does not maximize its potential for destruction, it’s the timing of its arrival. Coming near the quarter moon means the tides will be at or below their normal range.
The moon is the primary driver of tides, but the sun has about one-quarter as much influence. At quarter moon, the sun and moon are pulling in opposite directions and the tides have a smaller range.
Having said that, the enormous push from 100+ mile per hour winds drives water up beaches and beyond. There are only two words to say to anyone who lives where the ocean has any chance to reach — GET OUT.
*Editorial Note: Thanks to our sharp-eyed readers, who noticed an incorrect reference to the Mediterranean vs. Caribbean in the second section of this article.