From the time they first left the comfort of dry land, seafarers have sought to understand the mysterious and unpredictable ways of weather. And although meteorology has long since evolved from lore to science, its still a mystery to many of us, so we seek the guidance of those who study it professionally.
| Ralph Naranjo|
| NOAA meteorologist Joe Sienkiewicz reviews the latest weatherfaxes.* * *|
| To meteorologists, the challenge of accurately predicting weather that lies in the offing is their daily bread, and because of the broad impact weather has on our daily activities, governments employ many of them. The U.S. National Oceanographic and Atmospheric Administration (NOAA) is probably the worlds largest body analyzing and predicting weather. And few of those who sail the worlds oceans and benefit directly from the work of NOAAs Ocean Prediction Center (OPC, formerly the Marine Prediction Center) would deny that the agency is an example of their tax dollars well spent.
Over the past decade, huge strides forward in electronics and data-processing technology have aided the quest for a better understanding of the atmosphere, and the OPC has employed these advances to produce significant results in the form of more reliable long-range forecasts. The team of OPC meteorologists stationed at the Camp Springs, Maryland, NOAA Science Center continuously fields a stream of data from buoys, weather stations, computer models, satellites, and ships at sea and massages it into a variety of forecast products that provide mariners with reliable short- , medium- , and long-range looks at the weather that lies ahead. Computer technology has revolutionized the meteorologists tradecraft, but it has yet to replace human decision making. Rather, its enhanced the humans capability.
Todays forecaster has a digital toolbox filled with data-crunching programs that offer a big picture as well as small snapshots of whats going on from the sea surface to the roof of the atmosphere. This increase in detail makes possible more accurate and specific forecasts, to the benefit of those preparing to put to sea as well as those already at sea.
During a recent visit to the OPC headquarters, I noticed how equipment and working methods had changed over the decade that had passed since I was there last. Then, forecasters had far fewer computers, and most were bent over large desks drawing isobars on paper charts by hand. Today, there are two or three monitors on every desk, and at the touch of a key, an analyst can access a wide range of data. At one station, I watched a forecaster review a screen full of ship reports color-coded to reveal specific characteristics. Special software allowed the user to quickly reference the reliability of any reporting ship and even highlighted questionable data. (Japanese mariners currently get the highest marks for reliable and valid reporting.)
Joe Sienkiewicz is the OPCs Science and Operations Officer and acting chief of the Ocean Applications Branch. “My branch is very small,” says Joe, “but basically supports the operations through computer development, training, and extending the science. Its a challenge.” Joe brings more to bear on his job than just the scientific theories behind meteorology. His passion finds its roots in youthful days spent dinghy sailing while growing up in New England and working as a teenager at Bostons Community Sailing Center.
From messing around in small boats, he moved on to competitive intercollegiate sailing at SUNY Maritime College in Throggs Neck, New York, where he studied meteorology and oceanography. There, the legendary summer calms and heat-bred super-cell thunderstorms of western Long Island Sound offered dramatic practical studies. Understanding thunderstorm behavior held the same practical appeal for Joe as did the knowledge he had gleaned as a youth regarding the line between rain and snow–an important issue to a snow-shoveling boy growing up in Boston.
While he was studying meteorological theory, Joe could watch, outside the classroom window, how a normally tranquil, pond-still Long Island Sound could transform, in just a few short minutes, into a heaving maelstrom. “I quickly learned,” says Joe, “that a shelf cloud with greenish color is a sure sign of a severe thunderstorm.”
This early fascination with the dynamics of the atmosphere and the implications it held for small-boat sailors and commercial mariners alike was further elevated when, as a newly minted merchant-marine deck officer, Joe shipped out as the mate on a tug plying the coastal waters of the northeastern United States. He quickly began to note the effects of the change in seasons on predominant weather systems. He observed repetitive trends that played out like the refrain of a familiar song, and he soon grew more and more interested in the details behind the forecasts that he was using as a professional mariner.
These early seafaring experiences formed within him a deep respect for weather anomalies and stimulated his curiosity regarding what was really going on up there in the atmosphere. He took the logical next step: graduate school and a masters degree in meteorology from the University of Washington.
Lee Chesneau is a marine forecaster at OPC, but he has another role in which he acts as both a good friend and staunch advocate for those who venture offshore. Lee is responsible for public and customer relations at OPC, and hes the departments best-known face and voice.
I first met Lee vicariously through his signature on numerous weatherfax forecasts I used during a passage to Bermuda and on a gale-strewn transatlantic voyage. His name stuck in my mind because of the accuracy with which he forecast, and thus prepared me for, the lumps and bumps along my route. On several occasions, I and my crew of U.S. Naval Academy midshipmen felt we were no more than an offshore buoy validating the model-reading and analytical skills of forecaster Chesneau, who we were certain was in a warmer, drier place than we were. Meeting him a couple of years later gave me a chance to thank him and the team at OPC for all the valuable information they provide to mariners of all stripes.
Lee is a graduate of the University of Wisconsin and a former U.S. Navy officer. During a naval career that, between active and reserve stints, spanned 21 years, he earned such qualifications as officer of the deck and meteorological officer. He served most of his sea time aboard aircraft carriers, and he was recalled for Desert Storm.
After his release from the U.S. Navy, he retired as a lieutenant commander and went to work for Oceanroutes Inc. as a route analyst for commercial shipping. This three-pronged perspective on marine-weather information makes him an effective communicator, not only on how forecasts are prepared but also on how sailors can best act upon the information the forecasts contain.
The Forecasters’ Day
Lee took me to the morning meeting at which the OPC team plans the day’s strategy. One of the biggest challenges forecasters at the OPC face is determining which of the systems making their ways toward the Pacific Northwest or up the coast of the Eastern Seaboard will erupt into full-blown storms.
That December day, the meeting opened with a group discussion of an intensifying 970-millibar low that had imploded on its way up the U.S. East Coast and was about to lash out at the Canadian Maritimes with 90-knot sustained winds, promising potential disaster to any vessel in its track. It was a great time to get a feel for atmospheric dynamics and all that goes into predicting how they might change.
Computer models provide baseline meteorological information, but such a massive array of atmospheric variables influences the development of each weather system that their output must often be filtered by forecasters. Its not unusual to find significant disparity among different models–as many as eight models of different national origins may be consulted at any one time.
During the morning meeting, these differences are discussed and other data are layered on top of the model output. Ship reports still play a vital role in corroborating computer-generated forecasts, while buoy data and sea-state reports from satellite radar imagery lend real-time feedback to the computers guesses. Meanwhile, satellite radar images help the meteorologists to validate a forecast; these images correlate sea-surface texture with wind strength and direction and thus assess, in real time, the wind and sea conditions associated with specific weather events.
Lee Chesneau explained to me the importance of the forecasters role in tweaking a models output. The OPC meteorologists are familiar enough with the various computer models to use experience and intuition to weight the output of each under differing conditions. Any mariner who uses the OPC forecasts gets the benefit of the forecasters opinions based on all this information thats shared at the morning meeting. “GRIB files carry raw data thats normally weighted and interpreted by a forecaster,” Chesneau says. “Using the information in its raw state can introduce unanticipated forecast errors.”
In some situations, one model will predict weak development of a front while another promises a real gear-buster. The long-range model is the hardest for the meteorologist to evaluate. Even todays sophisticated computerized modeling programs arent able to deal with the vast number of dynamic variables involved, and under certain scenarios, a computer model will miscue and develop a forecast thats well off the mark. This can be disconcerting–or worse–for the sailor who, having downloaded a GRIB file of raw model data as his sole input for weather information, expects the forecast 5- to 10-knot wind but finds himself in a sustained 20-knot sea breeze. A skilled weather forecaster will know under what conditions such a situations is likely to occur, even if the model overlooks subtle local influences.
With forecasters checking predictions against real-time wind and sea reports from an array of coastal and offshore stationary and drift buoys, model tweaking has risen to a fine art. Trend analysis from such a forecast/feedback loop also helps programmers improve future models and lessen the effect of inaccurately weighting variables. As time goes on, forecast models will become even more reliable, but for now, the OPC forecast is a blend of man and machine.
Last spring, Joe Sienkiewicz gave attendees at the Safety at Sea Seminar at the U.S. Naval Academy a poignant overview of the most effective ways to use Ocean Prediction Center forecast material to make good passagemaking decisions. He packed his presentation with a lot of firsthand been-there/done-that wisdom that helped to convey what its like to encounter a gale at sea or be overtaken by a short-lived but violent squall line. He offered advice from the perspective of one whos both sailed to Bermuda and done sea time on a variety of commercial vessels.
Lee also teaches weather awareness and how to best use OPC forecast products at Safety at Sea Seminars, boat shows, and other training venues. His easygoing nature and enthusiasm for teaching are infectious, and by the time his lecture is over, the audience has gained important insights into basic weather systems, how they can intrude on cruising plans, and the best ways to cope with the wind and sea conditions that they pose.
While they acknowledge the skill and expertise of weather consultants who sell customized forecast services to commercial as well as recreational sailors, both Joe and Lee emphasize how important it is for sailors to understand the telltale signs of changing weather and to learn how to analyze forecasts.
“Surface weatherfax charts produced by the Ocean Prediction Center show the movement of fronts and lows as well as their intensity. Learn to recognize danger signals such as stacked isobars,” says Chesneau, “and youll have a free source of highly reliable weather information.”
Chesneau and Sienkiewiczs message to sailors is that through training and the study of basic meteorology, you can improve your understanding of professionally prepared forecasts. You can then blend your own local weather observations into the prediction. This knowledge will keep you weather aware and responsive whether anchored in a remote harbor or gunkholing among the cays of some off-the-beaten-path archipelago. Youll be able to amplify the broadcast forecast by adding to the mix the implications of your barometer readings and local cloud cover. Before long, youll start consciously matching your own observations with the scenarios scrolling out of the weatherfax printer aboard your boat.
And because weather is a continuum, any serious sailor will continue the process at home, watching the current weather evolve on a computer screen or even on a TV tuned to the Weather Channel, observing trends that may impact a cruise planned for the coming weeks. Joe Sienkiewicz and Lee Chesneau would offer their encouragement, because part of their mission is to help all sailors understand, and then get the best use from, the forecasts generated by the staff at the OPC.
Ralph Naranjo is Cruising Worlds technical editor.