RENO — Dynamic, changing weather patterns and variables are some of the challenges anyone deals with in forecasting the weather in northern Nevada. Those who work at the local National Weather Service (NWS) office face this on a daily basis.

“The weather here is very unique; there’s things that go on that don’t happen anywhere else in the country,” said Rhett Milne, a warning coordination meteorologist. “The Sierra Nevada mountains create havoc on weather systems.”

Milne works as a liaison between the NWS and local emergency managers and officials. If any of them spot hazardous conditions heading toward the area, Milne contacts the county and local police so they can prepare for it.

When making predictions by looking at weather systems coming from the west, Milne said, strong storms hitting the Sierras can be torn apart, leaving little to reach the Reno-Sparks area due to a shadowing effect on the lee (downwind) side of the mountains.

“It’s not necessarily the wind as it is what we would call stability,” Milne said. “When the atmosphere is very stable all that precipitation falls out on the windward side up to the crest of the Sierra.”

Then air is ducted down, which warms and dries it. However, east of the northern Nevada area it can lift, cool and regain precipitation.

A good example is this week’s storm that dumped snow on the west side of the mountains, then left the Truckee Meadows almost untouched while areas east of Reno-Sparks, including Fernley and Fallon, experienced rain showers.

The local NWS office is responsible for a large area from the crest of the Sierra Nevadas to the Oregon border, south towards Mono County, Calif. and east across Pershing and Churchill counties.

“Our main function is issuing forecasts but what we’re really after are warnings and advisories,” Milne said. “We issue winter storm warnings, severe thunderstorm warnings, flash flood warnings, all kinds of products that keep the public safe and help prevent loss of property and damage.”

Milne, who is in management, acts as a liaison for the agency’s customers. When threatening weather is approaching, and time is short, he’ll use e-mails or phone calls to alert local officials responsible for public safety or, in the case of severe weather, activate the Emergency Alert System that uses both radio and TV broadcasts to warn the public.

A warning of this type will be called into Wayne Seidel, the head of Sparks Public Works Department. Depending on the situation, assistant city manager Steve Driscoll could be involved and may activate the city’s Emergency Management Team.

This would set in motion preparations by department heads, as well as the police and fire departments to take steps necessary to minimize property loss and to protect lives.

Normally any forecast begins with a look upstream across the Pacific Ocean — a challenge in itself.

Milne explained that the Pacific is considered a data void since, except for an occasional observation from either a ship or airliner, there aren’t any sensors keeping track of the weather.

“A lot of times when we’re forecasting a storm seven or eight days out, it might be over China,” he said. “And that’s such a big challenge to us because, when we get it wrong, people say, ‘Hey, you guys are idiots; how can you get it wrong?’ ”

These days, satellite imagery, radar and computer models assist the meteorologists.

“And computer models are fancy supercomputers that take a snapshot of the atmosphere then simulate it in time to see how the weather is expected to behave,” Milne said. “So we rely heavily on them to guide us as to what’s going to happen. But there’s a lot of uncertainty by the time it gets over the Pacific to us.”

The area’s microclimates are another variable that has an effect on the weather.

“Just in the area we forecast for, there are over 50 mountain ranges and each drainage, each lake, each valley all have something different going on and they’re all unique,” Milne said. “So, everything we do here is microclimates and the best forecasters are the ones that get a really good grasp of what those are doing and, I’ll be honest, it’s not an easy place to forecast here.”

As a result, the meteorologists in the Reno office are constantly working to improve the products they offer.

Asked what sets the National Weather Service apart from the TV and Internet weather outlets, Milne said, “The biggest difference is that we’re paid by the taxpayer and we’re here solely to keep people safe and to provide information to help businesses, commerce, firefighters. So we’re always doing research to improve as we live in your backyard and we know about the microclimates.”

Regarding weathermen on TV, he said, “I can’t speak specifically for each TV person but we put our forecasts out there and it’s up to each one if they use it. Any way you slice it, the TV people are using our forecasts in some fashion.”

Milne showed two computer models that predicted this week’s weather in the Truckee Meadows. One, the United States model, turned out to correctly predict the weather while the European model showed the area would have two storms back to back. The U.S. model said there would be a storm Sunday and Monday, which quickly transformed into a spring-like weather, but the European model indicated that there would have been a second storm by Wednesday and Thursday.

“That’s the tough part of our job to figure out if it’s correct and if it isn’t correct, what’s wrong with it and what’s really going to happen,” Milne said.

There are about 20 different models and the challenge for meteorologists is that one might be better than another at certain times, and that’s where experience comes in.

“The computers can still be wrong and that’s why there’s still need for human interpretation,” Milne said. “No matter how high-tech and computer-driven the information is, it still comes down to a person deciding what the forecast will be and that will be based on experience with this area and its variables.”

Milne also mentioned that meteorology is a great field to work in, but those considering it should concentrate on math, physics, chemistry and computer classes. They also need to work on their communication skills, an important part of producing a good, understandable forecast.

For those interested in the local NWS forecasts, its Web site is www.weather.gov/reno.

In the menu are satellite imagery and radar, as well an area where the forecast is talked about and explained.

“In the discussion section on our Web site we can actually talk about the uncertainty to the forecast and why we put out it out,” he said. “And this is updated at least twice a day.”

Milne concluded by saying people should consider all the variables the northern Nevada area has and realize that any forecast will vary depending on their location.

He also added that the station is manned 24/7 and forecasts are continually updated because “the weather never stops.”