The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.
The site is secure.
The
https://
ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.
Zoltan Toth authored and/or contributed to the following articles/publications.
High-resolution models that are able to explicitly resolve convection have the potential to greatly aid forecasting for aviation concerns, where thunderstorms can have a huge impact. Current high-confidence thunderstorm forecasts are generally restricted to the range covered by extrapolation of a given thunderstorm complex, which can extend pred...
Sensitivity of Weather Forecasts over North America to Cycling of Initial Conditions
A comparison of several analysis schemes in their ability to diagnose boundaries
There have been a number of recent additions and changes to analysis schemes available or potentially available to operational forecasters. The Local Analysis and Prediction System (LAPS) has been available on AWIPS at 10 km horizontal grid resolution since the late 1980s, but is now run at some National Weather Service (NWS) Weather Forecast Of...
Although numerical models continue to advance with increasing horizontal grid resolution sufficient to begin to resolve convective storms, convective initiation remains a difficult short-term forecast problem. And determining whether the convection that does initiate will produce a severe storm with the development of a non-supercell tornado is ...
Development of a New Precipitation Dataset for Model Downscaling and Bias Correction
Bias correction and downscaling of forecast products, such as temperature and wind, of the NCEP Global Ensemble Forecasting System (GEFS) and the North America Ensemble Forecasting System (NAEFS) have demonstrated benefit in improving the forecast. The application of the same procedure to precipitation is hindered by the lack of a satisfying pre...
Some Characteristics of GEFS Stochastic Perturbations
A Stochastic Perturbation Scheme (SPS) will be implemented into the Global Ensemble Forecast System (GEFS) at the National Centers for Environmental Predictions (NCEP) in 2009. The scheme represents the uncertainty associated with the forecast model itself by adding stochastic terms, known as Stochastic Perturbations (SP), to the tendencies of a...
Pseudo-precipitation: a continuous variable for statistical post-processing
Some of the atmospheric processes leading to the formation of precipitation are highly nonlinear. This is reflected in the spatially and temporally discontinuous and highly variable nature of precipitation. Discontinuity and nonlinearity have their challenges not only in numerical modeling in terms of difficulties in tangent linear and adjoint m...
A Twenty-First-Century California Observing Network for Monitoring Extreme Weather Events
During Northern Hemisphere winters, the West Coast of North America is battered by extratropical storms. The impact of these storms is of paramount concern to California, where aging water supply and flood protection infrastructures are challenged by increased standards for urban flood protection, an unusually variable weather regime, and projec...
Institution National Oceanic and Atmospheric Administration - NOAA
Visualization, Evaluation, and Improvement of nwp-based Cloud Analyses and Forecasts
From its synoptic-scale origins, Numerical Weather Prediction (NWP) expanded to address both larger (coupled global climate system) and finer scale (nowcasting) forecasting. In particular, great strides have been made in the use of radar and other observations for the initialization of convective systems in their precipitating phase. This led...
Partition of Forecast Error into Positional and Structural Components
Weather manifests in spatiotemporally coherent structures. Weather forecasts hence are affected by both positional and structural or amplitude errors. This has been long recognized by practicing forecasters (cf., e.g., Tropical Cyclone track and intensity errors). Despite the emergence in recent decades of various objective methods for the diagn...
Institution National Oceanic and Atmospheric Administration - NOAA
Solar radiation is the ultimate source of energy flowing through the atmosphere; it fuels all atmospheric motions. The visible-wavelength range of solar radiation represents a significant contribution to the earth's energy budget, and visible light is a vital indicator for the composition and thermodynamic processes of the atmosphere from the sm...
Institution National Oceanic and Atmospheric Administration - NOAA
On the Prospects for Improved Tropical Cyclone Track Forecasts
The success story of Numerical Weather Prediction is often illustrated with the dramatic decrease of errors in tropical cyclone track forecasts over the past decades. In a recent essay, Landsea and Cangialosi (2018), however, note a diminishing trend in the reduction of perceived positional error (PPE, difference between forecast and observed po...
Institution National Oceanic and Atmospheric Administration - NOAA
A New Measure of Ensemble Central Tendency
Ensemble prediction is a widely used tool in weather forecasting. In particular, the arithmetic mean (AM) of ensemble members is used to filter out unpredictable features from a forecast. AM is a pointwise statistical concept, providing the best sample-based estimate of the expected value of any single variable. The atmosphere, however, is a mul...
Institution National Oceanic and Atmospheric Administration - NOAA
Partition of analysis and forecast error variance into growing and decaying components
Due to the scarcity of and errors in observations, direct measurements of errors in numerical weather prediction (NWP) analyses and forecasts with respect to nature (i.e. “true” error) are lacking. Peña and Toth (2014) introduced an inverse method called SAFE?I where true errors are (a) theoretically assumed to follow exponential error growth, a...
Institution National Oceanic and Atmospheric Administration - NOAA
Self-Correction of Soil Moisture Ocean Salinity (SMOS) Soil Moisture Dry Bias
Satellites produce global monitoring data, while field measurements are made at a local station over the land. Due to difference in scale, it has been a challenge how to define and correct the satellite retrieval biases. Although the relative approach of cumulative distribution functions (CDF) matching compares a long-term climatology of referen...
Institution National Oceanic and Atmospheric Administration - NOAA
Instabilities play a critical role in understanding atmospheric predictability and improving weather forecasting. The bred vectors (BVs) are dynamically evolved and flow-dependent nonlinear perturbations, indicating the most unstable modes of the underlying flow. Especially over smaller areas, however, BVs with different initial seeds may to som...
Institution National Oceanic and Atmospheric Administration - NOAA
Spatially extended estimates of analysis and short-range forecast error variances
Accurate estimates of ‘true’ error variance between Numerical Weather Prediction (NWP) analyses and forecasts and the ‘reality’ interpolated to a NWP model grid (Analysis and true Forecast Error Variance, hereafter AFEV) are critical for successful data assimilation and ensemble forecasting applications. Peña and Toth (2014, PT14) introduced a S...
Institution National Oceanic and Atmospheric Administration - NOAA
THORPEX Research and the Science of Prediction
The Observing System Research and Predictability Experiment (THORPEX) was a 10-yr, international research program organized by the World Meteorological Organization’s World Weather Research Program. THORPEX was motivated by the need to accelerate the rate of improvement in the accuracy of 1-day to 2-week forecasts of high-impact weather for the ...
Institution National Oceanic and Atmospheric Administration - NOAA
Ensemble forecasts are developed to assess and convey uncertainty in weather forecasts. Unfortunately, ensemble prediction systems (EPS) usually underestimate uncertainty and thus are statistically not reliable. In this study, we apply the Bayesian Processor of Ensemble (BPE), which is an extension of the statistical post-processing method of Ba...
Institution National Oceanic and Atmospheric Administration - NOAA
Chapter 2 - Weather Forecasting: What Sets the Forecast Skill Horizon?
Determinism (a unique dependence of future states on the current state) makes weather forecasts possible, while chaos (the sensitivity of such dependence on minor details of the initial state) strictly bounds predictability. In particular, the predictability of the spatiotemporal position of finer-scale weather features is lost first, while the ...
Two widely used precipitation analyses are the Climate Prediction Center (CPC) unified global daily gauge analysis and Stage IV analysis based on quantitative precipitation estimate with multisensor observations. The former is based on gauge records with a uniform quality control across the entire domain and thus bears more confidence, but provi...
Institution National Oceanic and Atmospheric Administration - NOAA
Ensemble transform sensitivity method for adaptive observations
The Ensemble Transform (ET) method has been shown to be useful in providing guidance for adaptive observation deployment. It predicts forecast error variance reduction for each possible deployment using its corresponding transformation matrix in an ensemble subspace. In this paper, a new ET-based sensitivity (ETS) method, which calculates the gr...
Institution National Oceanic and Atmospheric Administration - NOAA
Estimation of Analysis and Forecast Error Variances
Accurate estimates of error variances in numerical analyses and forecasts (i.e. difference between analysis or forecast fields and nature on the resolved scales) are critical for the evaluation of forecasting systems, the tuning of data assimilation (DA) systems and the proper initialisation of ensemble forecasts. Errors in observations and the ...
Institution National Oceanic and Atmospheric Administration - NOAA
Major Operational Ensemble Prediction Systems (EPS) and the Future of EPS
Since the early 1990s, ensemble methods have been increasingly used to address predictability issues, and provide estimates of forecast uncertainties, e.g., in the form of a range of forecast scenarii or of probabilities of occurrence of weather events. Although there is an overall agreement on the main objectives of ensemble-based, probabilisti...
Institution National Oceanic and Atmospheric Administration - NOAA
Overview of Weather and Climate Systems
Weather and climate phenomena develop as part of the coupled ocean-atmosphere-land-ice system. To understand the nature of the coupled system and its constituent processes, as well as the basis for and the limits of their predictability, some important concepts are reviewed, including determinism, chaotic error growth, and linear as well as nonl...
The end of 2014 marked the conclusion of The Observing System Research and Predictability Experiment (THORPEX), a 10-year research and development program organized under the World Meteorological Organization (WMO)/World Weather Research Programme (WWRP) and designed to accelerate improvements in the accuracy and use of 1-day to 2-week numerical...
Institution National Oceanic and Atmospheric Administration - NOAA
Pseudo-Precipitation: A Continuous Precipitation Variable
The discontinuous and highly nonlinear nature of precipitation makes its statistical manipulation, like the reduction of bias in quantitative precipitation forecasts (QPF) or probabilistic QPF (PQPF) problematic. To ease the statistical post-processing of precipitation, a new continuous variable, pseudo-precipitation (PP) is introduced. Pseudo- ...
Institution National Oceanic and Atmospheric Administration - NOAA
The accurate and timely depiction of the state of the atmosphere on multiple scales is critical to enhance forecaster situational awareness and to initialize very short-range numerical forecasts in support of nowcasting activities. The Local Analysis and Prediction System (LAPS) of the Earth System Research Laboratory (ESRL)/Global Systems Divis...
Institution National Oceanic and Atmospheric Administration - NOAA
Community Data Assimilation Research and Development
The quality of Numerical Weather Predictions (NWP) critically depends on the choice of initial conditions. In the US alone, a number of major Data Assimilation (DA) systems have been developed to provide estimates of the state of the atmosphere to initialize NWP forecasts. While these schemes contain state-of-the-art algorithms (i.e., the scient...
Institution National Oceanic and Atmospheric Administration - NOAA
STATISTICAL POST-PROCESSING OF 1–14 DAY PRECIPITATION FORECASTS FOR TAIWAN
The predictability of precipitation is limited due to the important role finer scale processes play. However, demand for medium- (3–10 days) and extended-range (10–30 days) precipitation forecasts by agriculture, forestry, livestock, and water resource management users has grown significantly. In this study, a statistical post-processing techniq...
Institution National Oceanic and Atmospheric Administration - NOAA
Initial-Value vs. Model-Induced Forecast Error: A New Perspective
Numerical models of the atmosphere are based on the best theory available. Understandably, the theoretical assessment of errors induced by the use of such models is confounding. Without clear theoretical guidance, the experimental separation of the model-induced part of the total forecast error is also challenging. In this study, the forecast er...