Who Exactly Can You Trust with Weather Forecasts?
Being a National Weather Service (NWS) meteorologist in Wyoming can be a humbling experience. The numerous basins, mountain ranges and microclimates make day-to-day weather forecasting a continual challenge. The rapid advancement of technology – from smart phones to tablets to more and faster access points – has led to a demand for accurate point forecasts for every nook and cranny.
Part of the humbling experience is hearing from friends and neighbors about how we could miss the snow forecast by two inches. How come the low was 31 degrees instead of 34? The wind sure seemed stronger than what you forecasted!
So, how is it that the inexact science of meteorology makes forecasting the next week so difficult, yet one of the more frequent questions we hear is, “What kind of winter are we going to have?” Really? You will trust the person who cannot forecast next Tuesday’s high temperature accurately with giving you an accurate long-range outlook through the winter? One thing is for sure – despite our shortcomings, at least people seem to find us trustworthy!
With all seriousness, the science of long-range forecasting has certainly improved over the last 10 to 20 years. Computing power has allowed for more and faster calculations that allow scientists to ingest greater amounts of data into the complicated process of climate prediction. Factors such as global circulations, trends as compared with climate averages, soil moisture conditions and an ensemble of forecast models are all part of the process of seasonal forecasting.
Just how tough is it to produce accurate long-term forecasts? Just take a look at the stark difference between 2011 and 2012 in Wyoming. The 2010-11 winter saw mountain snowpack in Wyoming river basins far exceed the 30-year climate normal and, in the case of the North Platte Basin, even exceed all-time record high snowpack values. Reservoirs across the state were filled to the brim, many rivers ran stronger than ever, and it seemed the drought was over.
Mother Nature, however, was quick to remind us who really calls the shots. The 2012 water year was the third driest over 119 years of record. And, the critical period of March through September 2012 went down as the driest stretch for those months over the same 119 years. The difference between these two seasons underscores how highly variable long-term, and even month-to-month, weather patterns can be. Combine the totals over these two years, and it was close to “average.”
The NWS Climate Prediction Center (CPC) in College Park, Md., specializes in long-range forecasting. The center issues weekly, monthly and seasonal outlooks using these data and model forecasts to determine long-term trends. At times the earth-atmosphere system provides strong clues as to what may happen over the coming months. One such clue is the El Niño/Southern Oscillation (ENSO) index, commonly referred to using the terms El Niño or La Niña.
The ENSO uses sea-surface temperatures in the equatorial Pacific Ocean to try and determine winter weather patterns across North America. During an El Niño winter, the general pattern is for warmer conditions across the northern tier of the U.S. with cool and wet conditions across the south. The opposite is typically the case during a La Niña episode. The current Pacific Ocean temperatures continue to indicate ENSO neutral conditions through the upcoming winter and into spring 2014. This means there is no trend toward El Niño or La Niña conditions, which, if there were, would provide more confidence in the North American winter forecast.
So what does all this mean for Wyoming? Well, this will sound just like what you would expect from a meteorologist. Right now the official CPC forecast, which can be found at cpc.ncep.noaa.gov, shows an equal chance of having near average, above-average or below-average temperatures this winter. Flip a coin! There is no strong tie to give confidence to how global circulations will evolve. Forecast uncertainty is high across the northern Rockies and the Pacific Northwest.
Over the past few months, however, the Wyoming winter forecast has trended from an expected warmer-than-average winter to one that will be more “average.” In fact, some of the model forecasts are trending toward a near to below-normal temperature forecast for the Wyoming winter. The wet soil conditions this fall are probably one reason why. September and October certainly provided a significant boost to soil moisture content heading into the winter months. Many areas east of the Continental Divide saw 200 to 500 percent of normal precipitation for that two-month period.
The snowfall outlook for December and January is a little more favorable. The active fall jet stream pattern that brought an earlier start to winter is expected to prevail. Accordingly, the CPC forecast shows a better chance of above-normal snowfall across Wyoming, especially the northwest quadrant of the state, through January. How about the critical spring months? You guessed it – the trend is toward an equal chance of above- or below-normal snowfall. It should be noted that long-term snow forecasts are generally less reliable than those of temperature.
Given that much uncertainty exists across Wyoming this winter, your best bet for assisting you around the farm or ranch will be to stay in touch with the seven day forecast provided by your local NWS office. We encourage you to visit us at weather.gov, or on your smart phone, mobile.weather.gov. We are also active on social media, specifically Facebook, Twitter and YouTube. These media enable you to share your reports, photos and thoughts with us and have helped the NWS reach out in new ways.
Without internet access? Please call us toll-free anytime and speak directly with a forecaster. The two NWS offices located in Wyoming are in Cheyenne, at 800-269-6220, and Riverton, at 800-211-1448, and are staffed 24 hours a day. We routinely field questions about snowfall and travel forecasts, wind forecasts for spring burning and rain forecasts during the haying season. So, give us a try and see if we can assist you. Come on, you can trust us, can’t you?
Chris Jones is a meteorologist with the National Weather Service in Riverton. He travels across western and central Wyoming working with agencies to prepare for hazardous weather and to give presentations to schools and civic groups. Please contact Chris at 307-857-3898 ext. 726 if you are interested in scheduling a meteorologist to speak with your organization or club.