Meteorologists face dilemma during AZ monsoon

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The Arizona monsoon is "the hardest kind of forecasting that you can possibly do." (Source: 3TV) The Arizona monsoon is "the hardest kind of forecasting that you can possibly do." (Source: 3TV)
PHOENIX (3TV/CBS 5) -

Arizona during the monsoon can be one of the most challenging areas for which to forecast weather. An important tool meteorologists use to track storms is being thrown for a loop this time of the year.

"The monsoon time is where meteorologists earn our bucks because it's the hardest kind of forecasting that you can possibly do," said Randy Cerveny, a professor of geographical sciences at Arizona State University.

Cerveny, author of "Weather's Greatest Mysteries Solved!," knows the important role special computer programs called weather models play in predicting the weather.

"In order to understand how temperature and wind and pressure all change, you can write those as mathematical equations," he explained. "A weather model is simply the massive equations that are used to find out what will happen to the weather."

There is an array of models that research institutions have created, and every day, the 3TV Forecasters time out when storms are going to hit your neighborhood using models depicted in Futurecast.

While these models can be incredibly accurate most of the year, they don't handle the monsoon very well.

"One of the biggest problems we have with weather models has to do with the fact that in order to get them to run, you actually have to have information to start with," Cerveny said.

That information comes from weather observation sites like the National Weather Service office in Phoenix, where things like temperatures, winds and dew points are measured. But these weather sites are few and far between.

"Our ability to forecast is only as good as what we can currently observe in terms of our weather," Cerveny said. "If we wanted to have great models, what we would need to do is to have weather stations on every block. We don't have anything close to that."

Unlike large cold fronts that swing in from the west and can cover large areas measured by multiple observation stations, Arizona's monsoon storms are convective and very small in size. 

"They're based off of surface heating, and surface heating can be very localized," Cerveny explained. "Some parts of the Valley can heat up more than others, and that may be a part of the Valley where we get some more buildups, and the other part of the Valley doesn't."

What's more, the models can't read surface heating very well, which sometimes means surprise rain showers or perhaps no rain at all when the models suggested an active monsoon day. 

But, these forecasting models continue to improve with time.

"Back 400 years ago, if you made a forecast, you were burned at the stake," Cerveny said. "So, we've come a long way, but we're not perfect."

Forecasting models are expected to be more accurate when we start tracking winter storms later this year.

BE PREPARED: MonsoonWatch 360

AROUND AZ: 3TV 360 Camera Network

WEATHER: Your forecast

Copyright 2015 KTVK (KPHO Broadcasting Corporation). All rights reserved.

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