Experiment fills critical gap in weather forecasting

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Across the Southeastern United States, the atmosphere has decided to send a first glimpse of what it can actually cook up in terms of summer heat, as record temperatures hit triple digits in parts of Florida, Georgia and South Carolina. The record heat was related to a wavy pattern of the jet stream, as an abnormal high pressure was over the southeast and an abnormal low pressure resided over the southwest, causing temperatures to be colder than average. In between, the Great Plains experienced day after day severe storms and tornadoes as the pressure pattern barely changed for several days. Credit: NOAA

Scientists working on the next frontier in weather forecasting hope that weather conditions in 3 to 4 weeks will soon be as available as the seven-day forecast. Having this type of weather information, called sub-seasonal forecasts, in the hands of the public and emergency managers can provide the critical time needed to prepare for natural hazards like heat waves or the next polar vortex. .

Scientists like Professor Ben Kirtman of the Rosenstiel School of Marine and Atmospheric School at the University of Miami (UM) and Assistant Professor Kathleen Pegion of George Mason University are leading the way in filling this critical gap in the forecasting system meteorological thanks to the SubX project. SubX, short for The Subseasonal Experiment, is an operations research project to provide better sub-seasonal forecasts to the National Weather Service.

“Sub-seasonal forecasts are the most difficult time to predict,” said Kirtman, professor of atmospheric sciences and director of the NOAA Cooperative Institute for Marine and Atmospheric Studies (CIMAS). “The hardest part is taking all the observations and putting them into the model.”

SubX bridges the gap between weather forecasting and forecasting seasonal conditions, which is driven by slowly changing ocean conditions like sea surface temperatures and soil moisture and climate system variability that operate on scales several weeks time. To reach the sub-seasonal scale, scientists need information about conditions that affect global weather, such as large-scale convective anomalies such as the Madden-Julian Oscillation in the tropical Indian Ocean, in their computer models.

UM experiment fills critical gap in weather forecasting

As of July 4 and for several days, temperatures across Alaska were 20 to 30 degrees above average in some places. In Anchorage, highs reached 80 ° F for a record six consecutive days, doubling the previous record. And three of those days have broken or equaled the previous all-time record. The high average temperature from June 27 to July 8 was nearly 81 ° F, 5.5 ° F higher than the previous 12-day high. Credit: NOAA

“The public SubX database is making 3-4 week forecasts available now and providing researchers with the data infrastructure to study how to make them even better in the future,” Pegion said.

SubX has already shown great promise for weather forecasting. He accurately predicted the amount of precipitation from Hurricane Michael – about 50mm, the July 4 heat wave in Alaska where temperatures reached over 90 degrees Fahrenheit – 20 to 30 degrees above average at some places – and the polar vortex that hit the Midwest. from the United States and eastern Canada in late January and killed 22 people.

For Kirtman and his team, the power to make these predictions requires the ability to calculate and store a large amount of data. This means that they rely heavily on the computational capacity of the UM Center for Computational Science (CCS) to handle the complex calculations required for their models. CCS resources are essential for Kirtman and Pegion to meet the on-time, real-time, and all-time deadlines required for SubX to be successful.

SubX’s publicly available database contains 17 years of historical forecasting (1999-2015) and over 18 months of real-time forecasts for use by the research community and the National Weather Service.

As Kirtman and his research team pointed out in an October 2019 article in the journal of the American Meteorological Society BAMS, “Early warning of heat waves, extreme cold, torrential rains, sudden droughts or other weather hazards up to 4 weeks into the future could help reduce risk and prepare for disasters, potentially preserving life and resources. Less extreme, but no less important and reliable probabilistic predictions of the potential for hotter, colder, wetter or drier conditions a few weeks in advance are valuable for routine planning and resource management.


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More information:
Kathy Pegion et al, The Subseasonal Experiment (SubX): A Multimodel Subseasonal Prediction Experiment, Bulletin of the American Meteorological Society (2019). DOI: 10.1175 / BAMS-D-18-0270.1

Provided by the University of Miami


Quote: Experiment fills critical gap in weather forecast (2019, December 7) retrieved September 17, 2021 from https://phys.org/news/2019-12-critical-gap-weather.html

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