An Analysis of 2016-2018 Tornadoes and National Weather Service Tornado Warnings across the contiguous United States

Previous work has considered tornado occurrence with respect to radar data, both WSR-88D and mobile research radars, and a few studies have examined techniques to potentially improve tornado warning performance. To date, though, there has been little work focusing on systematic, large-sample evaluation of National Weather Service (NWS) tornado warnings with respect to radar-observable quantities and the near-storm environment. In this work, three full years (2016–2018) of NWS tornado warnings across the contiguous United States were examined, in conjunction with supporting data in the few minutes preceding warning issuance, or tornado formation in the case of missed events. The investigation herein examines WSR-88D and Storm Prediction Center (SPC) mesoanalysis data associated with these tornado warnings with comparisons made to the current Warning Decision Training Division (WDTD) guidance.Combining low-level rotational velocity and the significant tornado parameter (STP), as used in prior work, shows promise as a means to estimate tornado warning performance, as well as relative changes in performance as criteria thresholds vary. For example, low-level rotational velocity peaking in excess of 30 kt (15 m s−1), in a near-storm environment which is not prohibitive for tornadoes (STP > 0), results in an increased probability of detection and reduced false alarms compared to observed NWS tornado warning metrics. Tornado warning false alarms can also be reduced through limiting warnings with weak (<30 kt), broad (>1nm) circulations in a poor (STP=0) environment, careful elimination of velocity data artifacts like sidelobe contamination, and through greater scrutiny of human-based tornado reports in otherwise questionable scenarios.

National Weather Service Data Needs for Short-Term Forecasts and the Role of Unmanned Aircraft in Filling the Gap: Results from a Nationwide Survey

Inclusion of unmanned aircraft systems (UAS) into the weather surveillance network has the potential to improve short-term (< 1 day) weather forecasts through direct integration of UAS-collected data into the forecast process and assimilation into numerical weather prediction models. However, one of the primary means by which the value of any new sensing platform can be assessed is through consultation with principal stakeholders. National Weather Service (NWS) forecasters are principal stakeholders responsible for the issuance of short-term forecasts. The purpose of the work presented here is to use results from a survey of 630 NWS forecasters to assess critical data gaps that impact short-term forecast accuracy, and explore the potential role of UAS in filling these gaps.NWS forecasters view winter precipitation, icing, flood, lake-effect/enhanced snow, turbulence, and waves as the phenomena principally impacted by data gaps. Of the ten high-priority weather-related characteristics that need to be observed to fill critical data gaps, seven are either measures of precipitation or related to precipitation-producing phenomena. The three most important UAS capabilities/characteristics required for useful data for weather forecasting are real- or near-real-time data, the ability to integrate UAS data with additional data gathered by other systems, and UASs equipped with cameras to verify forecasts and monitor weather. Of the three operation modes offered for forecasters to consider, targeted surveillance is considered to be the most important compared to fixed site profiling or transects between fixed sites.

The state of weather, water and climate services in the U.S. and strategic challenges for the next decade: the perspective from the American Meteorological Society and U.S. National Weather Service

&lt;p&gt;This keynote presentation will discuss several key applications and operational systems in the U.S. National Weather Service (NWS) and how they fit in with the broader mission of providing science-based weather, water and climate services to the nation. In addition, the future evolution of the National Centers for Environmental Prediction&amp;#160;(NCEP) and NWS will be discussed as it relates to future goals and priorities related to people, science, technology, operational concepts and practices, and partnerships between government/public sector, the private sector, and academia. Also, in his role as the current President of the American Meteorological Society (AMS), Dr. Farrar will address the theme for the 2022 AMS annual meeting, &quot;Environmental Security: weather, water and climate for a more secure world&quot;, which will explore the national and human security impacts from extreme weather and climate events and intersections with health, energy, food, and water security.&lt;/p&gt;

The National Weather Service-North Carolina State University Internship Course: Impacts and Success over a Generation

Nearly 100 North Carolina State University students have participated in a unique, highly structured internship course conducted by the National Weather Service Forecast Office in Raleigh, NC. Here, we explore the impact that this course has had on their professional development and career trajectories. The course has now been running for 17 years, and this paper provides an update on how the course has changed over time, including an evolution of the interview process to participate in the course, the number of students enrolled each semester has systematically been lowered to allow for more individual attention, and additional experiences outside of the WFO have been added. There are benefits for the students, with about half of the students now employed by the NWS, and nearly universal praise for how the course impacted their career progression. The university benefits from the course because the course serves as a compelling selling point for the MEAS department when recruiting students and the department also ensures that the curriculum is adequately preparing potential students for the job market. Finally, the NWS gains by creating a pool of potential employees that will require less spin-up time if hired, and graduates of the NCSU program have gone on to be involved with similar student volunteer programs at their respective offices once hired.

Severe Weather Warnings: impact of an event vs. impact of a warning.

&lt;p&gt;The most important question a national weather service should ask itself in connection with its warning task is: &quot;Do our warnings contribute to reducing the impact of extreme weather events?&quot;. A perfect impact forecast of an extreme weather event does not necessarily contribute to reduce the impact of the event. Even the most perfect warning, whether based on physical thresholds or on potential impact, is not a guarantee for a reduction of the impact of the warned extreme event. Only If the warning reaches the recipient in time, is understood and action is taken, is there a chance that the impact can be reduced, which means that the warning unfolds an impact. Therefore, if we want the recipient to understand the warnings and to know what action to take, we have to know what his needs are.&lt;/p&gt;&lt;p&gt;In this contribution we describe a method (&amp;#8220;Jobs to be done&amp;#8221;) with which we investigated the needs of the authorities in terms of severe weather warnings in Switzerland and we will present the results of this investigation. This method focuses our attention on those processes that are important to the authorities but unsatisfactorily fulfilled. Once isolated, we engage our experts in cooperation with the authorities to find optimal and innovative solutions through design thinking workshops. In the Swiss federal structure, the warning chain extends over all levels of the governance structure: the severe weather warnings are issued at federal level and transmitted to the Cantons, these can decide to add local information, particularly concerning impact, and transmit them to the communities and the population. In our investigation, we concentrated on the administrative authorities and on the cantonal coordination bodies of the fire brigades. The aim of this study is to find indications for optimising the warnings, in terms of content, representation and also distribution.&lt;/p&gt;&lt;p&gt;The investigation started in January 2021 with a series of interviews with seven natural hazard experts and six fire inspectors of different Cantons. Currently (April 2021) we are running two surveys in all Cantons and in June we plan two workshops with representatives of the Cantons and of the fire brigades together with collaborators of the National Weather Service MeteoSwiss (forecasters, developers and key accounts).&amp;#160;&lt;/p&gt;

User Engagement in Developing Use-Inspired Glacial Lake Outburst Flood Decision Support Tools in Juneau and the Kenai Peninsula, Alaska

Glacial lake outburst floods (GLOFs) significantly affect downstream communities in Alaska. Notably, GLOFs originating from Suicide Basin, adjacent to Mendenhall Glacier, have impacted populated areas in Juneau, Alaska since 2011. On the Kenai Peninsula, records of GLOFs from Snow Glacier date as far back as 1949, affecting downstream communities and infrastructure along the Kenai and Snow river systems. The US National Weather Service, US Geological Survey, and University of Alaska Southeast (for Suicide Basin) provide informational products to aid the public in monitoring both glacial dammed lakes as well as the ensuing GLOFs. This 2 year study (2018–2019) analyzed how communities affected by the aforementioned GLOFs utilize these various products. The participants in this project represented a variety of different sectors and backgrounds to capture a diverse set of perspectives and insights, including those of homeowners, emergency responders, tour operators, and staff at federal and state agencies. In addition, feedback and suggestions were collected from interviewees to facilitate improvements or modifications by the relevant entities to make the informational products more usable. Findings from this study were also used to inform changes to the US National Weather Service monitoring websites for both Suicide Basin and Snow Glacier. This paper’s findings on GLOF information use are relevant for other GLOF-affected communities, from both an information user and information developer perspective.

An Hourly Climatology of Operational MRMS MESH-Diagnosed Severe and Significant Hail with Comparisons to Storm Data Hail Reports

The multi-radar/multi-sensor (MRMS) system generates an operational suite of derived products in the NationalWeather Service useful for real-time monitoring of severe convective weather. One such product generated byMRMSis the maximum estimated size of hail (MESH) that estimates hail size based on the radar reflectivity properties of a storm above the environmental 0 °C level. The MRMS MESH product is commonly used across the National Weather Service (NWS), including the Storm Prediction Center (SPC), to diagnose the expected hail size in thunderstorms. Previous work has explored the relationship between the MRMS MESH product and severe hail (≥ 25.4 mm or 1 in.) reported at the ground. This work provides an hourly climatology of severe MRMS MESH across the contiguous U.S. from 2012–2019, including an analysis of how the MESH climatology differs from the severe hail reports climatology. Results suggest that the MESH can provide beneficial hail risk information in areas where population density is low. Evidence shows that the MESH can provide potentially beneficial information about severe hail occurrence during the night in locations that are climatologically favored for upscale convective growth and elevated convection. These findings have important implications for the use of MESH as a verification dataset for SPC probabilistic hail forecasts as well as severe weather watch decisions in areas of higher hail risk but low population density.