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Curtis R. Alexander

Affiliation/Employer
Federal
Partner Affiliation
gsl
Publon ID

Publications

Corresponding Articles: 32

Curtis R. Alexander authored and/or contributed to the following articles/publications.

Progress in NOAA hourly-updated model forecasting for renewable energy guidance

NOAA has made rapid progress in the last year toward improved hourly-updated model forecasts over the lower 48 United States, significant to meet requirements for guidance for 20-150m wind and solar forecasts. This progress includes an improved version of the 3km High-Resolution Rapid Refresh (HRRR), now covering this entire CONUS domain, with b...

Curtis R. Alexander

Using VIIRS fire radiative power data to simulate biomass burning emissions, plume rise and smoke transport in a real-time air quality modeling system

Curtis R. Alexander
Institution National Oceanic and Atmospheric Administration - NOAA

Exploring Convection - Allowing Model Evaluation Strategies for Severe Local Storms Using the Finite-Volume Cubed-Sphere (FV3) Model Core

Verification methods for convection-allowing models (CAMs) should consider the finescale spatial and temporal detail provided by CAMs, and including both neighborhood and object-based methods can account for displaced features that may still provide useful information. This work explores both contingency table–based verification techniques and o...

Curtis R. Alexander
Institution National Oceanic and Atmospheric Administration - NOAA

Improvements to Lake-Effect Snow Forecasts Using a One-Way Air–Lake Model Coupling Approach

Lake-effect convective snowstorms frequently produce high-impact, hazardous winter weather conditions downwind of the North American Great Lakes. During lake-effect snow events, the lake surfaces can cool rapidly, and in some cases, notable development of ice cover occurs. Such rapid changes in the lake-surface conditions are not accounted for i...

Curtis R. Alexander
Institution National Oceanic and Atmospheric Administration - NOAA

Addressing a Warm/Dry Bias over Central North America with Improved Boundary Layer and Land Surface Physics and Data Assimilation

Representing shallow cumulus in numerical weather prediction and climate models is a significant challenge. Misrepresenting these subgrid-scale clouds can result in large errors in the downwelling shortwave radiative flux at surface, resulting in large errors in the surface temperature that results in feedbacks into the accuracy of the thermodyn...

Curtis R. Alexander
Institution National Oceanic and Atmospheric Administration - NOAA

Assimilating Differential Reflectivity Columns into the High-Resolution Rapid Refresh Using Latent Heating Forcing

The High Resolution Rapid Refresh (HRRR) assimilates radar reflectivity information in order to skillfully forecast convection. This assimilation is done using an empirical relationship between reflectivity and latent heat release from hydrometeor condensation and freezing to update the temperature tendency field. The temperature tendency field ...

Curtis R. Alexander
Institution National Oceanic and Atmospheric Administration - NOAA

Application of the High-Resolution Rapid Refresh (HRRR) to the Bay Area Advanced Quantitative Precipitation Information Project

The Bay Area Flood Protection Association has just recently begun funding the Physical Sciences Division and Global Systems Division (GSD) of NOAA’s Earth System Research Lab (NOAA-ESRL), as well as the NOAA Cooperative Institute for Research in the Atmosphere (CIRA), to design and build a specialized nowcast / forecast system for the 9 Californ...

Curtis R. Alexander
Institution National Oceanic and Atmospheric Administration - NOAA

A Progress Report on the Development of the High-Resolution Rapid Refresh Ensemble

The High-Resolution Rapid Refresh Ensemble (HRRRE) is a 36-member ensemble analysis system with 9 forecast members that utilizes the Advanced Research version of the Weather Research and Forecasting (ARW-WRF) dynamic core and the physics suite from the operational Rapid Refresh/High-Resolution Rapid Refresh deterministic modeling system. A goal ...

Curtis R. Alexander
Institutions National Center for Atmospheric Research - NCAR National Oceanic and Atmospheric Administration - NOAA

A Features-Based Assessment of the Evolution of Warm Season Precipitation Forecasts from the HRRR Model over Three Years of Development

The High Resolution Rapid Refresh (HRRR) model has been the National Weather Service’s (NWS) operational rapid update model since 2014. The HRRR has undergone continual development, including updates to the Weather Research and Forecasting (WRF) Model core, the data assimilation system, and the various physics packages in order to better represe...

Curtis R. Alexander
Institution National Oceanic and Atmospheric Administration - NOAA

Stratiform Cloud-Hydrometeor Assimilation for HRRR and RAP Model Short-Range Weather Prediction

Accurate cloud and precipitation forecasts are a fundamental component of short-range data assimilation/model prediction systems such as the NOAA 3-km High-Resolution Rapid Refresh (HRRR) or the 13-km Rapid Refresh (RAP). To reduce cloud and precipitation spinup problems, a nonvariational assimilation technique for stratiform clouds was develope...

Curtis R. Alexander
Institution National Oceanic and Atmospheric Administration - NOAA

Recommendations for Developing Useful and Usable Convection-Allowing Model Ensemble Information for NWS Forecasters

U.S. National Weather Service (NWS) forecasters assess and communicate hazardous weather risks, including the likelihood of a threat and its impacts. Convection-allowing model (CAM) ensembles offer potential to aid forecasting by depicting atmospheric outcomes, including associated uncertainties, at the refined space and time scales at which haz...

Curtis R. Alexander
Institutions National Center for Atmospheric Research - NCAR National Oceanic and Atmospheric Administration - NOAA

Initial Development and Testing of a Convection-Allowing Model Scorecard

Evaluation of numerical weather prediction (NWP) is critical for both forecasters and researchers. Through such evaluation, forecasters can understand the strengths and weaknesses of NWP guidance, and researchers can work to improve NWP models. However, evaluating high-resolution convection-allowing models (CAMs) requires unique verification met...

Curtis R. Alexander
Institutions National Center for Atmospheric Research - NCAR National Oceanic and Atmospheric Administration - NOAA

Stochastically Perturbed Parameterizations in a HRRR-Based Ensemble

A stochastically perturbed parameterization (SPP) approach that spatially and temporally perturbs parameters and variables in the Mellor-Yamada-Nakanishi-Niino planetary boundary layer scheme (PBL) and introduces initialization perturbations to soil moisture in the Rapid Update Cycle land surface model was developed within the High Resolution Ra...

Curtis R. Alexander
Institutions National Center for Atmospheric Research - NCAR National Oceanic and Atmospheric Administration - NOAA

The Community Leveraged Unified Ensemble (CLUE) in the 2016 NOAA/Hazardous Weather Testbed Spring Forecasting Experiment

One primary goal of annual Spring Forecasting Experiments (SFEs), which are coorganized by NOAA’s National Severe Storms Laboratory and Storm Prediction Center and conducted in the National Oceanic and Atmospheric Administration’s (NOAA) Hazardous Weather Testbed, is documenting performance characteristics of experimental, convection-allowing mo...

Curtis R. Alexander
Institution National Oceanic and Atmospheric Administration - NOAA

Survey of data assimilation methods for convective-scale numerical weather prediction at operational centres

Data assimilation (DA) methods for convective-scale numerical weather prediction at operational centres are surveyed. The operational methods include variational methods (3D-Var and 4D-Var), ensemble methods (LETKF) and hybrids between variational and ensemble methods (3DEnVar and 4DEnVar). At several operational centres, other assimilation algo...

Curtis R. Alexander
Institution National Oceanic and Atmospheric Administration - NOAA

Object-Based Verification of a Prototype Warn-on-Forecast System

An object-based verification methodology for the NSSL Experimental Warn-on-Forecast System for ensembles (NEWS-e) has been developed and applied to 32 cases between December 2015 and June 2017. NEWS-e forecast objects of composite reflectivity and 30-min updraft helicity swaths are matched to corresponding reflectivity and rotation track objects...

Curtis R. Alexander
Institution National Oceanic and Atmospheric Administration - NOAA

Methods for Comparing Simulated and Observed Satellite Infrared Brightness Temperatures and What Do They Tell Us?

In this study, the utility of dimensioned, neighborhood-based, and object-based forecast verification metrics for cloud verification is assessed using output from the experimental High Resolution Rapid Refresh (HRRRx) model over a 1-day period containing different modes of convection. This is accomplished by comparing observed and simulated Geos...

Curtis R. Alexander

Seasonal Analysis of Cloud Objects in the High-Resolution Rapid Refresh (HRRR) Model Using Object-Based Verification

In this study, object-based verification using the method for object-based diagnostic evaluation (MODE) is used to assess the accuracy of cloud-cover forecasts from the experimental High-Resolution Rapid Refresh (HRRRx) model during the warm and cool seasons. This is accomplished by comparing cloud objects identified by MODE in observed and simu...

Curtis R. Alexander
Institution National Oceanic and Atmospheric Administration - NOAA

GSI Three-Dimensional Ensemble–Variational Hybrid Data Assimilation Using a Global Ensemble for the Regional Rapid Refresh Model

The Rapid Refresh (RAP) is an hourly updated regional meteorological data assimilation/short-range model forecast system running operationally at NOAA/National Centers for Environmental Prediction (NCEP) using the community Gridpoint Statistical Interpolation analysis system (GSI). This paper documents the application of the GSI three-dimensiona...

Curtis R. Alexander
Institutions Earth System Research Laboratory - ESRL National Oceanic and Atmospheric Administration - NOAA

The Weather Research and Forecasting Model: Overview, System Efforts, and Future Directions

Since its initial release in 2000, the Weather Research and Forecasting (WRF) Model has become one of the world’s most widely-used numerical weather prediction models. Designed to serve both research and operational needs, it has grown to offer a spectrum of options and capabilities for a wide range of applications. In addition, it underlies a n...

Curtis R. Alexander
Institutions National Center for Atmospheric Research - NCAR National Oceanic and Atmospheric Administration - NOAA

A North American Hourly Assimilation and Model Forecast Cycle: The Rapid Refresh

The Rapid Refresh (RAP), an hourly-updated assimilation and model forecast system, replaced the Rapid Update Cycle (RUC) as an operational regional analysis and forecast system among the suite of models at the NOAA National Centers for Environmental Prediction (NCEP) in 2012. The need for an effective hourly-updated assimilation and modeling sys...

Curtis R. Alexander
Institution National Oceanic and Atmospheric Administration - NOAA

Ensemble Prediction with the High-Resolution Rapid Refresh (HRRR): Providing Probabilistic Forecasts of Weather Hazards for Aviation

The 13-km Rapid Refresh (RAP) and 3-km convective-allowing High-Resolution Rapid Refresh (HRRR) are hourly updating weather forecast models that use a specially configured version of the Advanced Research WRF (ARW) model and assimilate many novel and most conventional observation types on an hourly basis using Gridpoint Statistical Interpolation...

Curtis R. Alexander
Institution National Oceanic and Atmospheric Administration - NOAA

Expanding the High-Resolution Rapid Refresh (HRRR) from Deterministic to Ensemble Data Assimilation, Forecasts and Post-Processing

The 13-km Rapid Refresh (RAP) and 3-km convective-allowing High-Resolution Rapid Refresh (HRRR) are hourly updating weather forecast models that use a specially configured version of the Advanced Research WRF (ARW) model and assimilate many novel and most conventional observation types on an hourly basis using Gridpoint Statistical Interpolation...

Curtis R. Alexander
Institution National Oceanic and Atmospheric Administration - NOAA

Progress Toward Improved Solar Forecasts in Hourly Updated RAP and HRRR Forecasts

The High-Resolution Rapid Refresh (HRRR) 3km hourly updated model is now being run operationally at NOAA's National Centers for Environmental Prediction (NCEP). A focus on improved cloud/solar forecasts has been central to development of HRRRv2 and HRRRv3 experimental versions, along with the parent 13km Rapid Refresh (RAP). Experimental, advanc...

Curtis R. Alexander
Institution National Oceanic and Atmospheric Administration - NOAA

Rap and HRRR Model/Assimilation System Improvements for Aviation Weather Applications: Latest Upgrades and Ongoing Work

An operational upgrade of the RAP and HRRR model systems at NCEP is planned for August 2016. This coordinated upgrade (RAP version 3 and HRRR version 2, RAPv3/HRRRv2) includes many enhancements to the data assimilation, model, and post-processing formulations that result in significant improvements to nearly all forecast aspects, including uppe...

Curtis R. Alexander
Institution National Oceanic and Atmospheric Administration - NOAA

The Influence of Topography on Convective Storm Environments in the Eastern United States as Deduced from the HRRR

Relatively little is known about how topography affects convective storms. The first step toward understanding these effects is to investigate how topography affects storm environments. Unfortunately, the effects of topography on convective environments is not easily observed directly. Instead, we resort to using output from the High-Resolution ...

Curtis R. Alexander
Institution National Oceanic and Atmospheric Administration - NOAA

2020 HFIP R&D Activities Summary: Recent Results and Operational Implementation

This technical report describes the activities and results of the Hurricane Forecast Improvement Program (HFIP) that occurred in 2020. The major development focus remained in building the next generation hurricane model, the Hurricane Analysis and Forecast System (HAFS) within the Unified Forecast System (UFS), primarily for track and intensity ...

Curtis R. Alexander
Institutions Earth System Research Laboratory - ESRL National Oceanic and Atmospheric Administration - NOAA

Overlapping Windows in a Global Hourly Data Assimilation System

The US operational global data assimilation system provides updated analysis and forecast fields every six hours, which is not frequent enough to handle the rapid error growth associated with hurricanes or other storms. This motivates development of an hourly-updating global data assimilation system, but observational data latency can be a barri...

Curtis R. Alexander
Institutions Earth System Research Laboratory - ESRL National Oceanic and Atmospheric Administration - NOAA

Radar Reflectivity-based Model Initialization using Specified Latent Heating (Radar-LHI) within a Diabatic Digital Filter or Pre-forecast Integration

A technique for model initialization using three-dimensional radar reflectivity data has been developed and applied within the NOAA 13-km Rapid Refresh (RAP) and 3-km High-Resolution Rapid Refresh (HRRR) regional forecast systems. This technique enabled the first assimilation of radar reflectivity data for operational NOAA forecast models, criti...

Curtis R. Alexander
Institution National Oceanic and Atmospheric Administration - NOAA

The High-Resolution Rapid Refresh (HRRR): An Hourly Updating Convection-Allowing Forecast Model. Part 1: Motivation and System Description

The High-Resolution Rapid Refresh (HRRR) is a convection-allowing implementation of the Weather Research and Forecasting model (WRF-ARW) with hourly data assimilation that covers the conterminous United States and Alaska and runs in real time at the NOAA National Centers for Environmental Prediction. Implemented operationally at NOAA/NCEP in 201...

Curtis R. Alexander
Institution National Oceanic and Atmospheric Administration - NOAA

The High-Resolution Rapid Refresh (HRRR): An Hourly Updating Convection-Allowing Forecast Model. Part 2: Forecast Performance

The High-Resolution Rapid Refresh (HRRR) is a convection-allowing implementation of the Advanced Weather Research and Forecast model (WRF-ARW) that covers the conterminous United States and Alaska and runs hourly (for CONUS; every three hours for Alaska) in real time at the National Centers for Environmental Prediction. The high-resolution forec...

Curtis R. Alexander
Institution National Oceanic and Atmospheric Administration - NOAA

Verification and Model Configuration Sensitivity of Simulated ABI Radiance Forecasts With the FV3-LAM Model

This study evaluates simulated radiance forecasts from a series of controlled experiments consisting of FV3-LAM forecasts with different configurations of model physics and vertical resolution. The forecasts were produced during the 2020 Hazardous Weather Testbed Spring Forecasting Experiments on the same forecast cases. The evaluation includes ...

Curtis R. Alexander
Institution National Oceanic and Atmospheric Administration - NOAA