The public knows who their local radio and TV meteorologists are, but who feeds critical weather information to airports, hospitals, ski resorts and local DPWs?

A growing number of forecasting companies are providing key weather information that saves private industry billions of dollars annually. From aviation to rum production, meteorologists have the answers that business needs to avoid weather-related losses.

Meteorologist Rob Carolan started Hometown Forecast Services in Nashua in 2001 with six radio station clients. That list has grown nationally to 60. Weather is big business. There’s more high pressure to getting the forecast right than you might think.

Q. Where are your radio stations located?

A. Well, we have about 60 radio stations. They’re located here in New England as well as across the country as far west as California. Also the Caribbean – Jamaica, Virgin Islands and Puerto Rico. In New Hampshire, we have stations on the seacoast, central New Hampshire, NHPR, as well as occasionally doing some work for stations that just want information concerning severe weather.

Q. So you are heard all over the country.

A. A good example is at 8:45 a.m. I’m live in Boston. Five minutes later, I’m live in Jamestown, S.D. Three minutes after that, I’m live in the Virgin Islands in St. Croix. Then I’m out in San Francisco 10 minutes later. For me , a game. I have to know where I am; I have to sound like I’m local, pronouncing names (of communities) correctly. After doing it for almost 30 years, it’s become second nature.

Q. Those local listeners think you live there?

A. That’s right. Exactly. I’ll listen to the air personalities and hear what they’re talking about locally and throw that back into the forecast, and it starts to sound like you live there. That’s the radio magic side of things.

Q. Talk about how weather events cost private industry billions every year.

A. In the summer season, it might be that we’re dealing with high winds, downed power lines, the potential that a facility such as Manchester-Boston Regional Airport may have to contend with flights that have to be diverted from other airports. Also, we deal with a lot of the cities and towns across New Hampshire that are interested from a DPW standpoint whether or not they’re going to have to send crews out clean up debris after a storm. Are they going to have areas where they have power outages due to downed trees? Are they going to have storm drain issues? Are they going to have flooding? Do they have events taking place?

In the winter, it’s a completely different kind of forecasting. We want to let them know whether or not they can keep their schools open, when they have to start plowing, how much snow they’re going to get. Are they going to get ice? Will there be issues with trees to bring down power lines.

From an operational perspective, there’s Dartmouth-Hitchcock Medical Center, the largest employer in northern New England. They actually have a rush hour at 5 in the morning when they change shifts with 30 acres of parking lot. We help them maintain those lots so they’re cleared so staff and patients can get in.

When we started working with the airport they said to us, ‘We never close. You need to understand that.’ We’ve briefed their airport when Air Force One is coming in. We’ve made sure they do what they’ve promised they’d do and act as the first point of diversion from Logan in Boston and for Albany, N.Y.

Q. What was it like forecasting Superstorm Sandy for clients in late October, 2012?

A. That was a scary storm. It was a weekend when the models started to forecast about 10 days out. One of the guys called me at home and said, “You gotta look at the European model. It looks like the end of the world.”

I, to be honest, had never seen anything like that on a weather chart. It actually scared me to look at that and say, “If that happens, there’s going to be huge ramifications.” So we watched it for the next three days, and still seven days out the European model was forecasting this storm. So we made a decision as a group that we were going to contact all our clients ahead of time and let them know about the potential.

I told Bloomberg Radio, “I’m afraid the subway tunnels are going to flood. I’m concerned about the Holland and Lincoln tunnels. I remember them saying to me, “You can’t be serious.” And I said, “There is not a storm surge wall at Battery Park. It’s going to come up over the Battery and spread through the southern part of New York City, if the models are right.” And they were.

We began doing updates on Sandy seven days out until after it ended, trying to provide the best possible coverage for our clients

Q. Do certain industries that rely on visitors ever lean on you to put out a forecast that would be more likely to get people out of the house?

A. We call it forecasting chamber of commerce weather. That’s some of the things we’ve done for some of our radio clients in New Hampshire, particularly ones that are on the Seacoast, where we’ll do a beach and boating forecast. We might say, “Hey it looks like a great weekend to go out…” With clients in the winter, they always wanted us to say, “Rain’s not going to affect conditions on the slopes.” I really have a hard time doing that. When it’s 55 degrees and it’s raining, conditions are not as good on the slopes when it’s 32 and snowing. We’ve been pushed toward that sometimes. We can do it better and more effectively in the summer months than winter months unless it is a snowy winter like we had two years ago.

Q. Which other New Hampshire industries do you provide forecasts for?

A. We deal with clients as small as lawyers who are looking for forensic meteorology, which is completely different. We’re not forecasting ahead, we’re going back and looking back at weather events that occurred and then seeing if there’s some kind of impact the weather had on the claim that their clients may be making as either the plaintiff or defense.

We’re currently working on a case right now where we’re able to prove that weather conditions developed that the plaintiff said developed even though they’re not visible in any other pictures that were taken at the scene.

Q. How does New Hampshire’s topography and geography add challenges to creating a forecast here?

A. You know, I have forecasted for every state in the country, including Alaska and Hawaii, and New England, by far, is the worst because of our proximity to the Atlantic, so we’re close to a source of moisture, our proximity to the Gulf of Mexico, a source of very moist warm air, cold Canadian air masses, air masses coming from the west. All kinds of crazy things.

Topographically, there are the Monadnocks and White Mountains. If we have a southeast wind over the White Mountains, the areas in the northern parts of the state don’t get snow, but the southern part of the state gets buried. It’s a very challenging place. It keeps us on our toes and makes us better forecasters.

Q. What’s the ratio of human instinct to empirical evidence when constructing a forecast?

A. I kind of say this is like alchemy. It’s magic. It’s intuition. Experience is huge. I think that’s what sets us apart as a business.

Our forecasting staff has over 100 years of forecasting experience in this part of the country. Either you can do this do or you can’t. And it’s learning to look outside the box, not only being able to interpret the models but figuring out which models are right more often than not.

It’s the trend in the data. Our philosophy behind the forecast is we work as a group not as an individual. You find that when you look at forecasts statistically, consensus is the best. Everybody puts their input in; you come up with a forecast together and use that joint experience to come up with a solution

Q. Is that approach used for TV weather casting?

A. With TV, they’re trying to bring the viewer back to watch more commercials, so it’s the end-of-the-world situation. For us, we’re trying to save our clients money, so it doesn’t do me any good if I say, “Hey, guys! There’s going to be an 18-inch snowstorm” and they get two inches. They just spent tens of thousands of dollars on overtime. But when I say to them, “Hey, look Manchester Airport, your ground temperature is 38 degrees. The air temperature’s going to be 32; I don’t think we’re going to have freezing rain on the runways. To treat each runway costs $16,000, so we save them a tremendous amount of money by making that call.

Our job is to save them money. What bothers me is that my business is viewed as an expense. No, it’s not. We’re here to make sure our contract pays for itself not once but multiple times over, so that you have money to spend on other things. For radio stations, we hope we do such a good job that it brings sponsorships.

Q. Does it eat away at you when a forecast you send out at 6 a.m. is clearly not happening? How do you alert clients about the change?

A. We have contacts between emails, cellphone, Twitter, whatever. We get in contact with the clients and let them know the forecast is off track now and need to bring it up to date. We’re carefully watching the forecast here 24/7/365 and know how to get the data out. It’s a stressful job. We’re so concerned about getting the forecast right. Summer is easy for us. We seriously sweat the winter.

Q. Forecasting weather continues to improve, thanks largely to technology. Are we approaching the day when we can expect 100 percent accuracy?

A. No. This is a very humbling business. I’ll never have a greater critic than my wife because I’ll be away with her on vacation and she’ll say stuff to me like, “You said it was going to be nice today and it’s raining. What the heck happened?” We’ve gotten better, especially in the long range. That’s where I’d say our greatest improvements have been, where 25 years ago it was a crapshoot to say in five or six days what was going to happen. We can really tell you the trend.

But 100 percent accuracy? There’s no way. The atmosphere is too complex. These computer programs run on assumptions and “When you assume, you make an ass out of you and me.”