Strong algorithms for strong storms

In the aftermath of a major winter storm, meteorologist Barry Lynn claims to have a better way to predict the weather

The snow-covered rooftops of Jerusalem's Nachlaot neighborhood (photo credit: Nati Shohat/Flash90)
The snow-covered rooftops of Jerusalem's Nachlaot neighborhood (photo credit: Nati Shohat/Flash90)

In the aftermath of last weekend’s might winter storm and with thousands of Israelis still without power, politicians, pundits, and the head of the Israel Electric Corporation were pointing fingers at each other Saturday night over the country’s sluggish response. Meanwhile, State Comptroller Yosef Shapira said he would look into the alleged failures and assess the country’s preparedness for future storms.

Another group who didn’t get the job done is the weather forecasters of the Israel Meteorological Service, whose predictions, according to Barry Lynn of Weather-It-Is, were less accurate than the ones he released on his own website. “On Wednesday, the Meteorological Service said that there would be snow late Thursday, and said nothing about Friday. And they only talked about the major Friday storm on Thursday.”

Compare that, Lynn said, to the predictions he made. On his discussion (blog) page, Lynn predicted the arrival of the monster storm Israel just went through a full week before it began. “Another shot of cold winter air will arrive early next week, and bring another bout of rain,” Lynn wrote on December 5. “Then, all eyes will turn to the storm that could sweep down from the north and then amplify a larger and ferocious storm just off the Mediterranean coast. Our ensemble is showing a 50% chance of this happening from mid-week onwards, and the storm could potentially last several days.”

Speaking to The Times of Israel, Lynn said he was the only one to predict the blizzard-by-Israeli-standards. “On Wednesday morning, we sent a message to our clients saying that between 50 and 100 centimeters of snow could be expected in Jerusalem and environs.”

Lynn’s site also customizes the forecast for dozens of specific towns and cities in Israel. While the official forecast predicts temperature and precipitation by region (southern Negev, northern Negev, coastal plain, etc.), Lynn supplies daily forecasts not just for Jerusalem, Tel Aviv, and Haifa, but also for their suburbs — e.g., Mevasseret Zion, Rishon Lezion, and Nesher — as well as for far-flung kibbutzim and development towns in the north and south, as well as for West Bank settlements.

It’s all about the forecast model, said Lynn. “We use the Weather Research and Forecasting Model, which allows for very accurate predictions based on observed weather patterns.”

Barry Lynn (Photo credit: Courtesy)
Barry Lynn (Photo credit: Courtesy)

First developed in 2006, the model has been significantly improved over the past two years as more information about weather patterns has been added to it, enabling more accurate predictions, Lynn said. The model, which was sponsored by the National Oceanic and Atmospheric Administration and the National Center for Atmospheric Research, with help from dozens of other organizations, is also crowd-sourced, taking criticism and suggestions from users to make improvements.

“Because of the model’s improved resolution, we can predict the weather based on an area of 1.2 kilometers for the same-day forecast,” said Lynn, meaning that the algorithms he employs to analyze the WRF model can predict the weather in specific areas as small as 1.2 kilometers square. “The weather is different everywhere, and by crunching the numbers and observing the patterns in an area, we can come up with a very accurate prediction.”

For his three-day forecast, Lynn said, the algorithms can provide an accurate forecast for up to 12 square kilometers. Other models (such as the one used by the IMS, he said) are less accurate, “able to provide a forecast for a 50-square kilometer area.”

Lynn did not speculate on why the IMS used the model developed by the European Centre for Medium-Range Weather Forecasts (ECMWF), which he feels is less accurate than the WRF model. Requests for comments by the IMS went unanswered.

“It’s more than the model, though,” said Lynn. “You have to know how to mine the model for the data,” and that’s where his technology comes in. “We use a cluster of dozens of computers that work together to analyze the data.”

The results, he said, speak for themselves, “as they did this past week.”

Of course, predicting the weather is as much art as it is science, and there will always be changes that the forecaster cannot foresee. In some areas, accumulations predicted by Lynn turned out to be dustings, while other areas got more snow than he expected. “We are not prophets, which is why every forecast issued by all weather professionals mentions the chances of an event happening. The nature of weather is that some unusual development will compromise your forecast. You will almost never see a forecast that predicts a 100% chance of something happening,” Lynn said.

Lynn’s Weather It Is Israel web site includes general forecasts for dozens of towns and cities around the country are available for free. In addition, Lynn has a premium service for farmers, hoteliers, firefighters, and utility companies, among many others. “For example, we do work on behalf of a tourist organization in Eilat, and we have predicted anomalous weather events there accurately, such as rainstorms and floods.” Lynn also does work on behalf of firefighting organizations in Israel and other countries, producing forecasts on where conditions are ripe for brush fires, enabling firefighters to prepare appropriately.

And preparation is what predicting the weather is all about, said Lynn.

“The weather prediction business has always been popular, but there is greater demand now than there has been, because of concern over global climate change. Governments and individuals are less sure of what to expect, so the need for accurate forecasts is greater than ever, and that’s what we strive to do.”

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