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Long Range Weather Forecasting Is Difficult Even With Sophisticated Data


Predicting weather further out than five to seven days is a difficult task. At the same time NOAA, the National Oceanic and Atmospheric Administration along with the Old Farmer’s Almanac does it anyway and this winter according to these predictions is shaping up to be dryer and milder than normal for northern Utah. KPCW talked with a resident water expert about the science of predicting the weather. Carolyn Murray has this:
NOAA Hydrologist, Brian McInerny says the Farmers Almanac has their own methods to predict weather and NOAA uses climate modeling but both systems don’t have great track records.

“Both would be equally bad and that’s the truth on these forecasts. We can do weather forecasts about seven days but after that it falls apart pretty quick. So, when you really look into how we do it, computing time and the amount of data you can collect for a long term weather forecast, it falls apart after seven days.”

McInerny says the experts who do this type of forecasting debate all the time about the usefulness of doing long range forecasts.

“The ability to quantify the atmosphere that far out is so difficult, they’re continually trying to find correlations between sea surface temperatures and different parts of the oceans and long-range weather forecasts. I think Universities are trying to use satellite data, historical satellite data to see if there is correlation somewhere and they’re coming up short.”

McInerny says modeling the atmosphere has limited accuracy because there are so many events, like smoke, convection, sea ice, that are hard to quantify.

He says the CO2 levels are changing the atmosphere and that’s changing weather patterns and temperatures.

“CO 2 levels that used to be a 250 parts per million and are now at 410 parts per million. It’s the highest it’s been in 200 million years. So, now you have a new atmosphere, how do you model that? The night time lows are not as cold as it used to be. That’s where you see it stand out in the data that we are getting warmer all the time. You can see it. You can sit out in your backyard now and not need a jacket and a long time ago, you were kind of freezing.

Winter sports enthusiasts often pay attention to the frequently used terms El Nino (warming) and La Nina (cooling) of the south pacific equatorial region. Northern Utah falls right in the middle of the Pacific Northwest region and the Desert Southwest.

“There is a signal in there that when you get El Nino, you get a little more snow in the Wasatch. From 2012 to 2016, high pressure dominated the west. Think about a rotating wheel that’s going around clock-wise and when the jet stream comes off the pacific, it hits that wheel and gets shunted north into Canada. 2017 came along and the high pressure shrunk down and it went down to Mexico and the door was open and we had 41 atmospheric river events…what we used to call the Pineapple Express. There was so much snow. Three to 400 percent here in Utah during December and January had 300 % and if you remember, that was a great ski year. Then we went back to high pressure last year.”

McInerny says Scientists can’t say what causes the shifts in weather because the temperatures are going up and the increases have a compounding affect that supercharges the atmosphere.

“Because it is so complex, it is so dynamic, you look at a warming atmosphere, for every degrees c (Celsius) you raise the moisture in the atmosphere by seven percent. So the weather makes it more extreme and even more difficult to forecast.

He says there are some indicators that help them predict weather, but that data isn’t available this far out.

“And the meteorologists look at the pattern roughly sometime in late October and if you have cold air that’s pooling up near Siberia and Alaska and those northern areas,  then you have a better shot at looking at an intense storm activity for the next month or two.

In October of 2016, they saw a cold pool of Siberian air that ended up bringing a lot of moisture into northern Utah in December and January

The monsoon storms have been infrequent but severe this summer. This pattern, McInerny says, will continue as the climate warms.

“When the storm intensity did get here, it was pretty ferocious. And we had debris flows and flooding in St. George all within a three-day period and then we go back to high pressure. That’s what we are going to see more of in the future. Extended periods of high pressure followed by very intense weather, very intense thunder storms, a lot of flooding a lot of debris flows and then we’re going to have an additional fire threat as we continue to warm.”

Senior Hydrologist with NOAA, Brian McInerny is a frequent guest on KPCW.


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