National Weather Service Operations Research Articles

Innovations in Winter Storm Forecasting and Decision Support Services

Abstract Winter storms are disruptive to society and the economy, and they often cause significant injuries and deaths. Innovations in winter storm forecasting have occurred across the value chain over the past two decades, from physical understanding, to observations, to model forecasts, to postprocessing, to forecaster knowledge and interpretation, to products and services, and ultimately to decision support. These innovations enable more accurate and consistent forecasts, which are increasingly being translated into actionable information for decision-makers. This paper reviews the current state of winter storm forecasting in the context of the U.S. National Weather Service operations and describes a potential future state. Given predictability limitations, a key challenge of winter storm forecasting has been characterizing uncertainty and communicating the forecast in ways that are understandable and useful to decision-makers. To address this challenge, particular focus is placed on establishing a probabilistic framework, with probabilistic hazard information serving as a foundation for winter storm decision support services. The framework is guided by social science research to ensure effective communication of risk to meet users’ needs. Solutions to gaps impeding progress in winter storm forecasting are highlighted, including better understanding of mesoscale phenomenon, the need for better ensemble calibration, a rigorous and consistent database of observed impacts, and linking multiparameter probabilities (e.g., probability of intense snowfall rates at rush hour) with users’ information needs and decisions.

The Extreme Precipitation Forecast Table: improving situational awareness when heavy rain is a threat

A collaborative team of Science and Operations Officers from the National Weather Service (NWS) Weather Forecast Offices (WFOs), hydrologists from the Lower Mississippi River Forecast Center (LMRFC), and management from the Weather Prediction Center (WPC) worked together to develop and transition a tool into NWS operations called the Extreme Precipitation Forecast Table (EPFT). The EPFT was designed to help NWS forecasters improve their situational awareness (SA) when heavy rainfall threatens their county warning area. The EPFT compares Quantitative Precipitation Forecasts (QPF) to Average Recurrence Intervals (ARIs) from the NOAA Atlas-14 to alert forecasters to the potential for climatologically significant and extreme rainfall. A counterpart to the EPFT, called the Extreme Precipitation Assessment Table (EPAT), compares observed precipitation (i.e., Quantitative Precipitation Estimates [QPE]) to inform forecasters as to the climatological significance of impactful rain events. This paper presents cases demonstrating the usefulness of the EPFT and EPAT in helping forecasters improve their SA in real-time operational settings when heavy rain was a threat.

Early Operational Successes of the University of Louisiana Monroe’s Polarimetric S-band Doppler Radar

In October 2016, the University of Louisiana Monroe (ULM) began operating a polarimetric S-band Doppler weather radar to help close the low-level radar coverage gap across northern Louisiana by increasing the quantity of data sampled below 3.0 km AGL. Data are delivered in near-real time to local National Weather Service (NWS) Weather Forecast Offices to help meteorologists accomplish their mission of protecting life and property. The inclusion of ULM radar data into NWS operations has led to improved detection of severe and hazardous weather across northern Louisiana. This paper details how the ULM radar has been incorporated into NWS operations, the improvement in operational radar coverage, and the challenges of using a non-NWS radar in the NWS operational setting.

Forecaster Evaluations of High Temporal Satellite Imagery for the GOES-R Era at the NWS Operations Proving Ground

AbstractBetween February and April of 2015, the National Weather Service (NWS) Operations Proving Ground (OPG) facilitated an evaluation of the usefulness of 1-min satellite imagery for NWS operations in the Geostationary Operational Environmental Satellite-R (GOES-R) series era. The overarching goal of the evaluation was to provide quantitative and qualitative guidance to NWS management, including the regional NWS Scientific Services division chiefs, on how satellite imagery with a refresh rate of 1 min impacts NWS forecaster decision-making. During the simulations, forecasters evaluated 1- and 5-min satellite imagery while completing tasks ranging from aviation forecasting and wildfire decision support services to monitoring where convective initiation would occur and integrating the imagery into the convective warning decision-making process. Feedback was gathered to assess if the satellite imagery had influence on forecaster decision-making, if the satellite imagery provided them with more confidence in making those decisions, if forecasters could assimilate the data into operational practices, and if there were adverse impacts on forecaster workload. Forecasters overwhelmingly were of the opinion that 1-min satellite imagery improved their ability and increased their confidence to make effective forecast and warning decisions. The majority of participants expressed that they were able to internally assimilate the imagery with ease. However, feedback gathered when forecasters were asked how useful and easy the imagery was to use in convective warning operations was mixed. Some forecasters expressed difficulty integrating both satellite imagery and radar data while issuing convective warnings. Others felt that with ample training and experience the imagery would be invaluable in warning operations.

Analysis of the 15 June 2013 isolated extreme rainfall event in Springfield, Missouri

An isolated extreme rainfall event occurred across portions of the Springfield, Missouri, area on 15 June 2013, causing substantial flooding of several small headwater tributaries of the James River. Heavy, nearly stationary thunderstorm activity developed along an outflow boundary after 1500 UTC. This area of thunderstorms trained over southern Springfield before dissipating around 1845 UTC. Post-event analysis of rainfall amounts indicated both gauge observations and radar-derived estimates exceeding the 100-yr event (1% annual chance equivalent). Local storm reports from the National Weather Service (NWS) forecast office in Springfield were supplemented with additional reports derived from news media and social media. Flash flood nowcasting techniques such as NWS gridded flash flood guidance (GFFG), rainfall average recurrence interval (ARI) estimates, the distributed hydrologic model-threshold frequency (DHM-TF), and the flooded locations and simulated hydrographs (FLASH) project were compared to local storm reports of flash flooding. A timeline of output from each of these techniques was compared to the time of reported flooding to evaluate the usefulness of each tool in the context of NWS operations. It was found that GFFG underestimated the scope of the flash flooding and would not have provided an estimate of flash flood severity. Rainfall ARI estimates, DHM-TF, and FLASH each suggested a significant flash flood event; however, DHM-TF output would have been available too late for forecasters and FLASH output would have provided several areas of false alarms. Rainfall ARI estimates provided the best balance of detecting areas of flash flooding, correctly estimating flash flood severity, and being available in a timely manner to NWS forecasters.

Integration of a Road Surface Model into NWS Operations

Today's winter weather headlines are based on the meteorological strength of an event with the assumption that stronger events produce larger public impacts. In reality, public impacts involve many factors, such as whether or not snow will accumulate on roads and affect traffic. Along with numerous environmental factors, decisions are further complicated by societal factors (e.g., timing of the commute). The National Weather Service (NWS) Strategic Plan calls for increased emphasis on decision support services (DSS) to our partners, especially during high-impact events. However, determining when events will produce high-impact conditions often remains a challenge. While forecasters should be aware of the relevant societal factors, they also need objective tools capable of integrating over the wide range of environmental factors that intersect in producing high-impact weather. This is particularly true in the case of road surface conditions, where complex interactions between temperature, moisture, and the road surface play a key role in determining what hazards might develop during wintry weather. Initial verification suggests that output from the Model of the Environment and Temperature of Roads (METRo) can provide useful information with regard to the timing and severity of hazardous road surface conditions, allowing NWS forecasters to more effectively highlight the impacts associated with impending meteorological events. This information enhances the DSS that the NWS is able to provide to government partners, local emergency management, and the public during high-impact winter weather events.

Images in Weather Forecasting: A Practical Guide for Interpreting Satellite and Radar Imagery

Recent advances in meteorological instrumentation coupled with the ongoing data and infrastructure explosion promise significant improvements in the accuracy of weather forecasts. These advancements, however, increase the knowledge burden on the forecaster. Even relatively simple atmospheric upper air and surface sensors require forecasters to have some basic understanding of the instrumentation if they are to properly interpret the data they provide.With whole careers dedicated to designing and interpreting data from meteorological satellites and radars, forecasters must be proficient users of these data. The new Doppler radars were considered so vital to National Weather Service operations that a massive, organized training program was held for operational forecasters, and applied research was funded to develop quantitative applications. Though satellite data have long been considered vital, training for satellite meteorology and image interpretation has largely been neglected. The education of contemporary meteorologists must cover both technical knowledge of individual data sets as well as the application of those data sets to the science of meteorology. Ideally, courses would utilize any and all available data to illustrate concepts being discussed. Few, if any, textbooks attempt to meet this daunting challenge.

NOAA requests increased funding

At an authorization hearing held June 10, the National Oceanic and Atmospheric Administration submitted a request of $1,924 billion to Congress for fiscal year 1994, an increase of $208 million (12%) over its fiscal 1993 appropriation. Requests for the largest increases are centered in several of the agency's highestprofile programs. They include $440 million (an increase of $72 million from fiscal 1993) for the National Weather Service's Operations and Research Program; $673 million (an increase of $65 million) for the NWS's Systems and Acquisition effort; and $69.9 million (an increase of $23 million) for the Office of Oceanic and Atmospheric Research's Global Climate Change Research Program.

Operational Implications of the “Probability of Precipitation”

Abstract Since the probability of precipitation (PoP) appears in the forecasts of the National Weather Service (NWS), it is important that both the forecaster and user fully grasp the subtleties of the meaning of PoP. A brief review of the theory of PoP is presented. It is shown that although the PoP is defined as the average point probability, the guidelines outlined in the National Weather Service Operations Manual (NWSOM) also make the PoP the expected areal coverage of precipitation across the forecast area.

The national weather service warning system

The National Weather Service (NWS) is the federal agency solely responsible for issuing weather forecasts and warnings of weather hazards. Additional facets of NWS operations that pertain to public safety are dissemination of weather warnings, weather hazard awareness, and the weather preparedness program. These are interrelated to form a successful warning program. NWS field operations encompass many types of atmospheric phenomena, each requiring different action in order to protect life and property. The NWS weather forecast and warning program is of little value if local officials or citizens are unprepared to take necessary precautions. Many deaths and serious injuries that occur due to hazardous weather are preventable. Although the weather-related death toll has decreased significantly since the 1960s, the potential for catastrophic loss of life remains in many areas of the United States. An excellent preparedness/awareness program can minimize the possibility of loss of life.