Timothy Delsole

last updated 5/4/2017

Timothy M. Delsole

Professor at George Mason University

4400 University Drive, MSN 2C, Fairfax, Virginia, United States
HQ Phone:
(703) 993-1000

General Information


Co-Chief Editor - Journal of Climate

Senior Research Scientist - Institute of Global Environment and Society


PhDGeorge Mason University

doctorate - applied physics , Harvard University


Global Change Distinguished Postdoctoral Fellow - NASA Goddard Space Flight Center

Recent News  

Task Team 3: AMOC Mechanisms and Predictability | US CLIVAR

Timothy DelSole
George Mason University

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Breaking New Ground in Weather Forecasting | Inside Science

"One of the reasons we can predict averages, like three-month averages, is that when you compute a three-month average you are smoothing out a lot of weather variability that you know you can't predict," said Timothy DelSole, a climate scientist at George Mason University in Fairfax, Virginia and first author on the new study.
"But when you come to two weeks, it's not so clear that that's long enough to average out all of the effects of weather." To test if the week 3-4 forecasts would hold up to scrutiny, DelSole and his colleagues looked at past seasonal forecasts generated between 1999 and 2010 by the Climate Prediction Center, a part of the National Weather Service. DelSole and his colleagues found that winter trends were more predictable than summer trends, and temperature was more predictable than precipitation. For example, 59 percent of the land area in North America showed forecast skill for January temperature, but only 9 percent showed skill for July precipitation. For those land areas that do show skill, the model can give a forecaster at best a slight edge in predicting above or below normal trends, equivalent to predicting a coin flip correctly 67 percent of the time, DelSole said. One reason why the week 3-4 range is tricky is scientists are less sure which atmospheric, oceanic and terrestrial phenomena leave an imprint on the weather at this time scale -- and whether the current weather models can capture the effects of those phenomena accurately enough to make useful predictions. DelSole and his colleagues tested whether the week 3-4 forecast skill they found could be linked to two longer-term weather phenomena: the El Nino-Southern Oscillation, which involves fluctuating water temperatures in the Pacific Ocean and is often tied to seasonal forecast variation, and the Madden-Julian Oscillation, which is a regular buildup of clouds, wind and rain that moves eastward above the Indian and Pacific Oceans, at tropical latitudes. The researchers found that the most predictable components of the winter forecast are related to El Nino. They also linked the Madden-Julian Oscillation to other predictable components of winter precipitation. DelSole emphasized that there could be additional phenomena that help explain the forecasts' skill. The Climate Prediction Center currently releases experimental week 3-4 outlooks based on the same model that DelSole and his team tested.

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An Overviewof the Evidence: A Presentation by Dr. Timothy DelSole, George Mason University Professor in Atmospheric, Oceanic and Earth Sciences.

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