Over the past couple months, we've had the pleasure of meeting with several fishing charter and dive boat captains as well as their customers at public festivals and shows. One question we've heard repeatedly is: Is this windy weather unusual for the Keys?
The answer is a resounding yes!
Taking a look at Sand Key from the period 1991 through 2001, we noted that the average sustained wind for the month of April is 12.6 knots. The average peak gust during any hour is 16.4 knots. A typical forecast made for such average conditions would be expressed as "10 TO 15 KNOTS" in one of our coastal waters forecasts. The standard deviation for the sustained wind for April is 5.3 knots, which means that two-thirds (2/3) of observed sustained winds at Sand Key fall within 5.3 knots of the average speed of 12.6 knots, or the range from 7.3 to 17.9 knots. You can view the average wind speeds for Sand Key throughout the year by clicking here.
Unfortunately, it seems our forecasts have had to include much higher values greater than 15 knots the past several months, warranting such headlines as "SMALL CRAFT EXERCISE CAUTION" and "SMALL CRAFT ADVISORY." Once winds reach beyond 15 knots and especially as they climb past 20 knots, significant impacts become felt in the fishing and diving industries.
Why has it been so windy?
While storms can be associated with strong winds, this year's windy weather has been caused by the normally beneficial high pressure system. The high pressure systems that have followed some of our stronger cold fronts have been reluctant to move east into the Atlantic, instead setting up shop across north Florida and the southeast United States. This produces a strong pressure gradient -- the difference in atmospheric pressure at the surface across a distance -- which in turn results in stronger winds.
The average wind speed in the last ten days from April 11 through April 20 was 16.1 knots. What this means is that while such a windy period in April is unusual, it is not unprecedented.
While we are looking at winds, it was noted that we have had our strongest winds out of the northeast to east. From 1991 through 2001, over half of April winds were out of 080 degrees through 130 degrees: an east to southeast wind. While not common, it was noted that the strongest of the strong winds that have occurred in April have been out of the northwest through northeast. This tells us that an unusual, strong cold front has moved through the Keys from time to time.
And lastly, especially as the fish are concerned, Sand Key's seawater temperatures have averaged 77 degrees during April. Recently, we've been 2 to 3 degrees below normal.
What can we look forward to in May?
The average wind speed at Sand Key during May has averaged around 10 knots, with the standard deviation just over 5 knots as it was in April. Therefore, two-thirds (2/3) of the time, expect the winds to range generally between 5 and 15 knots. This slight adjustment downward says that climatology is on the side of the mariner, and that these strong winds will be less frequent and not last as long.
For more information, please visit our National Weather Service Marine Webpage!