Weather 101 - 2010 Hurricane Season Outlooks Spell Disaster - or Do They?

Lynda Reymann, who works at Regatta Gifts in Naples, FL, queried me a while back concerning the 2010 outlook for hurricane season. She's only been in Naples a few years and hasn't yet experienced a visit from these potent tropical weather systems. That's actually not surprising. On average, there have only been a handful of such storms to make direct hits on southwest Florida. In fact, since 1900, only 6 major hurricanes (category 3 and above) have struck the southwest Florida Coast. Since 1851, according to NOAA's National Hurricane Center (NHC), only 13 category 3 or greater storms have struck or passed within 75 miles of Lee and Collier counties. This yields about one such storm every 13 years or so.

While she was thinking about the upcoming hurricane season (which starts June 1 and runs through the end of November), she was also quick to note that she was concerned that people were being scared so far in advance of hurricane season. After all, she discussed things with me on April 10. The Colorado State University seasonal hurricane prediction had already been released and updated and was calling for a big season.

Understanding Seasonal Hurricane Forecasts

Reymann also asked about how they make the seasonal forecasts.

I explained to her, much as I am doing here, that a significant number of variables enter into the seasonal predictions, not only the CSU forecasts, but also those of NOAA and now Accu-Weather. The field of prognosticators keying on seasonal hurricane forecasts is growing.

One of the significant elements involves the variability in El Nino - La Nina patterns. El Nino, warmer than average sea surface temperatures off the northwest coast of South America, leads to stronger westerly winds at high altitudes across Mexico, the Caribbean and the tropical North Atlantic. Conversely, La Nina (cold surface waters in the east Pacific) leads to weaker westerly winds at high altitudes. Right now we are transitioning to a La Nina pattern (see SST animation). But westerly winds over the western tropical Atlantic remain strong (Fig. 1).

Warmer sea surface temperatures (SSTs) in the tropical North Atlantic, Caribbean Sea and Gulf of Mexico (even in regional areas) favors an increased risk of tropical storm development. That's because hurricanes thrive on ocean warmth, which leads to warmer air temperatures and higher humidity. These, in turn, enhance thunderstorms, a key component of any hurricane or tropical storm.

According to NOAA scientists, SSTs in the tropical North Atlantic east of Florida are well above average at this time (Fig. 2). This is linked to a decrease in the northeast low-level trade winds (which is linked to the demise of the El Nino pattern). Although historical analogs favor a decrease in this warmth as the hurricane season unfolds, the overall warmth is expected to persist.

Statistical analysis and finding historical analogs play a role, too. And meteorologists are always comparing a current scenario of weather and ocean variables to the growing historical database.

There's much more involved, and you can read about it at the Climate Prediction Center website. But you may need to wear a meteorological mortarboard to understand all of the nuances presented there. In this article, I am just trying to give you the gist of the process.

Given these factors and the fact that last year's hurricane season was such a dud, it is no surprise that CSU, AccuWeather and NOAA are all looking for a more active hurricane season.

But my biggest concern is that NOAA's range of storminess is so broad that it reaches from almost average (based on 1966 - 2009 events) to extreme, almost record-breaking, numbers. This is quite a range of possible outcomes. Obviously, the media has taken the upper limit as the forecast and run with it. This adds to the overall scare factor, even though NOAA has taken great pains to ensure that their forecast does not hint at the number of landfalling storms. The CSU and AccuWeather forecasts, however, do include a landfall estimate.

We can all anticipate that each of the seasonal forecasts will be tweaked as time goes on. That's simply because as more data becomes available, and we approach the onset of and / or get into the event (tropical storm season), any type of weather pattern becomes easier to detect.

Finally, recognize that any seasonal forecast is just a seasonal forecast. NO forecaster is pinpointing that a particular storm will strike a particular locale with a specified wind speed. Rather, forecasts are more general (e.g., 3 hurricanes are expected to strike the U.S., two will be category 3 or stronger).

Consider a season that is expected to have say 15 named storms, but all 15 storms remain at sea. To people in the U.S., the season is a non-event, even though it was active season.

On the other hand, take 1992. This was a rather lackluster year, but Andrew, the lone storm of consequence, struck south Florida to the tune of $25 billion in damages.

Disaster Preparedness

Aside from keeping abreast the latest forecasts and tropical weather outlooks, now is a good time to consider your family preparedness plan. There's plenty of information online at TV station, county emergency management, NHC and other web sites. Many newspapers in coastal communities from Texas to the Northeast distribute hurricane preparedness inserts. There are also hurricane preparedness booklets available at some major hardware stores, grocery stores and other sources.

Recognize that an emergency plan does not necessarily need to encompass every possible contingency associated with hurricanes and tropical storms; but it should be more rigorous, comprehensive and workable than the plans in place at the Deepwater Horizon drilling platform, the Exxon Valdez and other similar events. Recognize that Federal level planning and response has also been deficient.

Your plan should consider your pet(s), an insurance coverage review, evacuation procedures, plans for covering windows (if appropriate), gas for cars, and food, water and medical needs. If you live inland, don't think you are immune. Some storms bring strong winds far inland, some bring twisters and many bring torrential and flood-producing rainfall (especially when the weather system is moving slowly and/or is affecting hilly or flood-prone areas).

Whatever you do, just do it with careful thought and realize the consequences of any decisions or non-decisions you may make.

Oh, and consider having the entire family involved. There's nothing wrong with getting input from the kids. After all, they may just say something that triggers additional thought on your part.

As a case in point, two years when Tropical Storm Fay was threatening southwest Florida, I was out of the country. My wife implemented our plan and relocated about 8 miles further inland. She (and our dog, Pepper) stayed at a friend's house.

Stay tuned. We'll be providing updates as the season unfolds, not just for hurricane impacts in the U.S., but for impacts in Haiti and also any affects such storms may bring to the oil slick area.