METAR/SPECI Reporting Changes for Snow Pellets (GS) and Hail (GR)
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Winter Precipitation Liquid–Ice Phase Transitions Revealed with Polarimetric Radar and 2DVD Observations in Central Oklahoma
MAY 2017 B U K O V CICETAL. 1345 Winter Precipitation Liquid–Ice Phase Transitions Revealed with Polarimetric Radar and 2DVD Observations in Central Oklahoma PETAR BUKOVCIC ´ NOAA/National Severe Storms Laboratory, and Cooperative Institute for Mesoscale Meteorological Studies, and School of Meteorology, and Advanced Radar Research Center, University of Oklahoma, Norman, Oklahoma DUSAN ZRNIC´ NOAA/National Severe Storms Laboratory, Norman, Oklahoma GUIFU ZHANG School of Meteorology, and Advanced Radar Research Center, University of Oklahoma, Norman, Oklahoma (Manuscript received 30 June 2016, in final form 8 November 2016) ABSTRACT Observations and analysis of an ice–liquid phase precipitation event, collected with an S-band polarimetric KOUN radar and a two-dimensional video disdrometer (2DVD) in central Oklahoma on 20 January 2007, are presented. Using the disdrometer measurements, precipitation is classified either as ice pellets or rain/freezing rain. The disdrometer observations showed fast-falling and slow-falling particles of similar size. The vast majority (.99%) were fast falling with observed velocities close to those of raindrops with similar sizes. In contrast to the smaller particles (,1 mm in diameter), bigger ice pellets (.1.5 mm) were relatively easy to distinguish because their shapes differ from the raindrops. The ice pellets were challenging to detect by looking at conventional polarimetric radar data because of the localized and patchy nature of the ice phase and their occurrence close to the ground. Previously published findings referred to cases in which ice pellet areas were centered on the radar location and showed a ringlike structure of enhanced differential reflectivity ZDR and reduced copolar correlation coefficient rhv and horizontal reflectivity ZH in PPI images. -
Downloaded 10/01/21 08:52 PM UTC 186 WEATHER and FORECASTING VOLUME 16
FEBRUARY 2001 NOTES AND CORRESPONDENCE 185 Further Investigation of a Physically Based, Nondimensional Parameter for Discriminating between Locations of Freezing Rain and Ice Pellets ROBERT M. RAUBER,LARRY S. OLTHOFF, AND MOHAN K. RAMAMURTHY Department of Atmospheric Sciences, University of Illinois at Urbana±Champaign, Urbana, Illinois KENNETH E. KUNKEL Midwestern Climate Center, Illinois State Water Survey, Champaign, Illinois 9 December 1999 and 16 August 2000 ABSTRACT The general applicability of an isonomogram developed by Czys and coauthors to diagnose the position of the geographic boundary between freezing precipitation (freezing rain or freezing drizzle) and ice pellets (sleet or snow grains) was tested using a 25-yr sounding database consisting of 1051 soundings, 581 where stations were reporting freezing drizzle, 391 reporting freezing rain, and 79 reporting ice pellets. Of the 1051 soundings, only 306 clearly had an environmental temperature and moisture pro®le corresponding to that assumed for the isonomogram. This pro®le consisted of a three-layer atmosphere with 1) a cold cloud layer aloft that is a source of ice particles, 2) a midlevel layer where the temperature exceeds 08C and ice particles melt, and 3) a surface layer where T , 08C. The remaining soundings did not conform to the pro®le either because 1) the freezing precipitation was associated with the warm rain process or 2) the ice pellets formed due to riming rather than melting and refreezing. For soundings conforming to the pro®le, the isonomogram showed little diagnostic skill. Freezing rain or freezing drizzle occurred about 50% of the time that ice pellets were expected. -
Lesson 6 Weather: Collecting Data GRADE 3-5 BACKGROUND Meteorologists Collect Weather Data Daily to Make Forecasts
Lesson 6 Weather: Collecting Data GRADE 3-5 BACKGROUND Meteorologists collect weather data daily to make forecasts. With the aid of high altitude weather balloons, weather equipment and gauges, satellites, and computers, accurate daily forecasts can be made. Collecting weather data in just one location and making a forecast requires a great deal of skill. Since air travels from one location to another, it is helpful to know what the approaching weather will be. In this investigation, the students will collect data for two weeks. At this time they will start seeing patterns in each of the areas. They can predict what the weather will be like the next day and for the next few days. They will also write if their predictions were correct from the previous day. Collecting the data for this lesson can be done instead of collecting the data separately in lesson 1-4. BASIC LESSON Objective(s) Students will be able to… Collect data for two weeks and use the information to detect patterns and predict weather around their location. State Science Content Standard(s) Standard 4. Students through the inquiry process, demonstrate knowledge of the composition, structures, processes and interactions of Earth's systems and other objects in space. A. 4.4 Observe and describe the water cycle and the local weather and demonstrate how weather conditions are measured. A. Record temperature B. Display data on a graph C. Interpret trends and patterns of data D. Identify and explain the use of a barometer, weather vane, and anemometer E. Collect, record and chart data from each weather instrument F. -
AMOFSG/10-Sod 19/6/13
AMOFSG/10-SoD 19/6/13 AERODROME METEOROLOGICAL OBSERVATION AND FORECAST STUDY GROUP (AMOFSG) TENTH MEETING Montréal, 17 to 19 June 2013 SUMMARY OF DISCUSSIONS 1. HISTORICAL 1.1 The tenth meeting of the Aerodrome Meteorological Observation and Forecast Study Group (AMOFSG) was held at the Headquarters of the International Civil Aviation Organization (ICAO) in Montréal, Canada, 17 to 19 June 2013. 1.2 The meeting was opened by Mr. Greg Brock, Chief of the Meteorology Section of the Air Navigation Bureau of ICAO, who extended a warm welcome to all the participants. Mr. Brock emphasized that this tenth meeting of the AMOFSG was likely to be the last of the group prior to the convening of an ICAO Meteorology (MET) Divisional Meeting in July 2014, to be held in part conjointly with the Fifteenth Session of the World Meteorological Organization (WMO) Commission for Aeronautical Meteorology (CAeM-XV). For this reason, Mr. Brock underlined the need for the group to work efficiently during its three days of deliberations, with a strong emphasis placed on determining whether proposals arising from each of the topics to be addressed were of sufficient maturity so as to reduce or eliminate entirely the need for significant further work and/or a meeting ahead of the MET Divisional Meeting. 1.3 The names and contact details of the participants are listed in Appendix A . Mr. Bill Maynard was elected Chairman of the meeting. The meeting was served by the Acting Secretary of the AMOFSG, Mr. Greg Brock, Chief, Meteorology Section. 1.4 The meeting considered the following agenda items: Agenda Item 1: Opening of the meeting; Agenda Item 2: Election of Chairman; Agenda Item 3: Adoption of working arrangements; Agenda Item 4: Adoption of the agenda; (41 pages) AMOFSG.10.SoD.en.docx AMOFSG/10-SoD - 2 - Agenda Item 5: Aerodrome observations; Agenda Item 6: Forecasting at the aerodrome and in the terminal area and ATIS requirements; Agenda Item 7: Deliverables; Agenda Item 8: Any other business; and Agenda Item 9: Closure of the meeting. -
Soaring Weather
Chapter 16 SOARING WEATHER While horse racing may be the "Sport of Kings," of the craft depends on the weather and the skill soaring may be considered the "King of Sports." of the pilot. Forward thrust comes from gliding Soaring bears the relationship to flying that sailing downward relative to the air the same as thrust bears to power boating. Soaring has made notable is developed in a power-off glide by a conven contributions to meteorology. For example, soar tional aircraft. Therefore, to gain or maintain ing pilots have probed thunderstorms and moun altitude, the soaring pilot must rely on upward tain waves with findings that have made flying motion of the air. safer for all pilots. However, soaring is primarily To a sailplane pilot, "lift" means the rate of recreational. climb he can achieve in an up-current, while "sink" A sailplane must have auxiliary power to be denotes his rate of descent in a downdraft or in come airborne such as a winch, a ground tow, or neutral air. "Zero sink" means that upward cur a tow by a powered aircraft. Once the sailcraft is rents are just strong enough to enable him to hold airborne and the tow cable released, performance altitude but not to climb. Sailplanes are highly 171 r efficient machines; a sink rate of a mere 2 feet per second. There is no point in trying to soar until second provides an airspeed of about 40 knots, and weather conditions favor vertical speeds greater a sink rate of 6 feet per second gives an airspeed than the minimum sink rate of the aircraft. -
Radar Derived Rainfall and Rain Gauge Measurements at SRS
Radar Derived Rainfall and Rain Gauge Measurements at SRS A. M. Rivera-Giboyeaux February 2020 SRNL-STI-2019-00644, Revision 0 SRNL-STI-2019-00644 Revision 0 DISCLAIMER This work was prepared under an agreement with and funded by the U.S. Government. Neither the U.S. Government or its employees, nor any of its contractors, subcontractors or their employees, makes any express or implied: 1. warranty or assumes any legal liability for the accuracy, completeness, or for the use or results of such use of any information, product, or process disclosed; or 2. representation that such use or results of such use would not infringe privately owned rights; or 3. endorsement or recommendation of any specifically identified commercial product, process, or service. Any views and opinions of authors expressed in this work do not necessarily state or reflect those of the United States Government, or its contractors, or subcontractors. Printed in the United States of America Prepared for U.S. Department of Energy ii SRNL-STI-2019-00644 Revision 0 Keywords: Rainfall, Radar, Rain Gauge, Measurements Retention: Permanent Radar Derived Rainfall and Rain Gauge Measurements at SRS A. M. Rivera-Giboyeaux February 2020 Prepared for the U.S. Department of Energy under contract number DE-AC09-08SR22470. iii SRNL-STI-2019-00644 Revision 0 REVIEWS AND APPROVALS AUTHORS: ______________________________________________________________________________ A. M. Rivera-Giboyeaux, Atmospheric Technologies Group, SRNL Date TECHNICAL REVIEW: ______________________________________________________________________________ S. Weinbeck, Atmospheric Technologies Group, SRNL. Reviewed per E7 2.60 Date APPROVAL: ______________________________________________________________________________ C.H. Hunter, Manager Date Atmospheric Technologies Group iv SRNL-STI-2019-00644 Revision 0 EXECUTIVE SUMMARY Over the years rainfall data for the Savannah River Site has been obtained from ground level measurements made by rain gauges. -
The Error Is the Feature: How to Forecast Lightning Using a Model Prediction Error [Applied Data Science Track, Category Evidential]
The Error is the Feature: How to Forecast Lightning using a Model Prediction Error [Applied Data Science Track, Category Evidential] Christian Schön Jens Dittrich Richard Müller Saarland Informatics Campus Saarland Informatics Campus German Meteorological Service Big Data Analytics Group Big Data Analytics Group Offenbach, Germany ABSTRACT ACM Reference Format: Despite the progress within the last decades, weather forecasting Christian Schön, Jens Dittrich, and Richard Müller. 2019. The Error is the is still a challenging and computationally expensive task. Current Feature: How to Forecast Lightning using a Model Prediction Error: [Ap- plied Data Science Track, Category Evidential]. In Proceedings of 25th ACM satellite-based approaches to predict thunderstorms are usually SIGKDD Conference on Knowledge Discovery and Data Mining (KDD ’19). based on the analysis of the observed brightness temperatures in ACM, New York, NY, USA, 10 pages. different spectral channels and emit a warning if a critical threshold is reached. Recent progress in data science however demonstrates 1 INTRODUCTION that machine learning can be successfully applied to many research fields in science, especially in areas dealing with large datasets. Weather forecasting is a very complex and challenging task requir- We therefore present a new approach to the problem of predicting ing extremely complex models running on large supercomputers. thunderstorms based on machine learning. The core idea of our Besides delivering forecasts for variables such as the temperature, work is to use the error of two-dimensional optical flow algorithms one key task for meteorological services is the detection and pre- applied to images of meteorological satellites as a feature for ma- diction of severe weather conditions. -
News and Notes
346 BULLETIN AMERICAN METEOROLOGICAL SOCIETY NEWS AND NOTES Air Force Scientists Develop Technique The feasibility of dissipating supercooled clouds by for Cutting Holes in "Cold" Clouds seeding with dry-ice was recognized many years ago. Airborne equipment, previously developed to do this, A new technique for creating holes in supercooled cloud crushed large blocks of dry-ice into particles suitable for layers has been developed by Air Force Cambridge Re- seeding purposes. search Laboratories scientists. During recent flight tests This equipment had two particular limitations. First, using this technique, holes more than 3 miles wide were these machines produced about half powdered dry-ice created in supercooled clouds. which evaporated immediately upon dispersal from the Major James F. Church, project scientist in AFCRL's aircraft and was wasted. Second, the logistical problem Meteorological Research Laboratory is directing research of supplying enough dry-ice where needed and the high on the dissipation of supercooled stratiform clouds. The evaporational losses suffered during storage until used, program is under the technical management of the Air severely limited the utility of this technique. Force System Command's Electronic Systems Division. The Cloudbuster makes ice pellets by passing liquid The principal objective of this research is to provide C02 through an expansion nozzle and then compacting Air Force cargo and transport pilots with an economical the solid dry-ice powder, which is then formed, into proper capability to seed supercooled clouds with dry-ice pellets, size. The Cloudbuster has been designed with the capa- made on the aircraft and dispersed at will, to create bility of making different-sized pellets at the touch of a sizable holes in such cloud decks. -
6.4 the Warning Time for Cloud-To-Ground Lightning in Isolated, Ordinary Thunderstorms Over Houston, Texas
6.4 THE WARNING TIME FOR CLOUD-TO-GROUND LIGHTNING IN ISOLATED, ORDINARY THUNDERSTORMS OVER HOUSTON, TEXAS Nathan C. Clements and Richard E. Orville Texas A&M University, College Station, Texas 1. INTRODUCTION shear and buoyancy, with small magnitudes of vertical wind shear likely to produce ordinary, convective Lightning is a natural but destructive phenomenon storms. Weisman and Klemp (1986) describe the short- that affects various locations on the earth’s surface lived single cell storm as the most basic convective every year. Uman (1968) defines lightning as a self- storm. Therefore, this ordinary convective storm type will propagating atmospheric electrical discharge that results be the focus of this study. from the accumulation of positive and negative space charge, typically occurring within convective clouds. This 1.2 THUNDERSTORM CHARGE STRUCTURE electrical discharge can occur in two basic ways: cloud flashes and ground flashes (MacGorman and Rust The primary source of lightning is electric charge 1998, p. 83). The latter affects human activity, property separated in a cloud type known as a cumulonimbus and life. Curran et al. (2000) find that lightning is ranked (Cb) (Uman 1987). Interactions between different types second behind flash and river flooding as causing the of hydrometeors within a cloud are thought to carry or most deaths from any weather-related event in the transfer charges, thus creating net charge regions United States. From 1959 to 1994, there was an throughout a thunderstorm. Charge separation can average of 87 deaths per year from lightning. Curran et either come about by inductive mechanisms (i.e. al. also rank the state of Texas as third in the number of requires an electric field to induce charge on the surface fatalities from 1959 to 1994, behind Florida at number of the hydrometeor) or non-inductive mechanisms (i.e. -
COOP Observer Manual (1).Pdf
National Weather Service WFO Mount Holly, NJ Cooperative Observation Program Observer Manual Updated: October 3, 2020 Table of Contents 1. Taking Observations a. Rainfall/Liquid Equivalent Precipitation i. Rainfall 1. Standard 8” Rain Gauge 2. Plastic 4” Rain Gauge ii. Snowfall/Frozen Precipitation Liquid Equivalent 1. Standard 8” Rain Gauge 2. Plastic 4” Rain Gauge b. Snowfall c. Snow Depth d. Maximum and Minimum Temperatures (if equipped) i. Digital Maximum/Minimum Sensor with Nimbus Display ii. Cotton Region Shelter with Liquid-in-Glass Thermometers 2. Reporting Observations a. WxCoder b. Things to Remember 1 1. Taking Observations Measuring precipitation is one of the most basic and useful forms of weather observations. It is important to note that observations will vary based on the type of precipitation that is expected to occur. If any frozen precipitation is forecast, it is important to remove the funnel top and inner tube from your gauge before precipitation begins. This will prevent damage to the equipment and ensure the most accurate measurements possible. Note that the inner tube of the rain gauge only holds a certain amount of precipitation until it begins to overflow into the outer can. If rain falls, but is not measurable inside of the gauge, this should be reported as a Trace (T) of rainfall. This includes sprinkles/drizzle and occurrences where there is some liquid in the inner tube, but it is not measurable on the measuring stick. During the cold season (generally November through early April), we recommend that observers leave their snowboards outside at all times, if possible. -
Manuscript Was Written Jointly by YL, CK, and MZ
A simplified method for the detection of convection using high resolution imagery from GOES-16 Yoonjin Lee1, Christian D. Kummerow1,2, Milija Zupanski2 1Department of Atmospheric Science, Colorado state university, Fort Collins, CO 80521, USA 5 2Cooperative Institute for Research in the Atmosphere, Colorado state university, Fort Collins, CO 80521, USA Correspondence to: Yoonjin Lee ([email protected]) Abstract. The ability to detect convective regions and adding heating in these regions is the most important skill in forecasting severe weather systems. Since radars are most directly related to precipitation and are available in high temporal resolution, their data are often used for both detecting convection and estimating latent heating. However, radar data are limited to land areas, 10 largely in developed nations, and early convection is not detectable from radars until drops become large enough to produce significant echoes. Visible and Infrared sensors on a geostationary satellite can provide data that are more sensitive to small droplets, but they also have shortcomings: their information is almost exclusively from the cloud top. Relatively new geostationary satellites, Geostationary Operational Environmental Satellites-16 and -17 (GOES-16 and GOES-17), along with Himawari-8, can make up for some of this lack of vertical information through the use of very high spatial and temporal 15 resolutions. This study develops two algorithms to detect convection at vertically growing clouds and mature convective clouds using 1-minute GOES-16 Advanced Baseline Imager (ABI) data. Two case studies are used to explain the two methods, followed by results applied to one month of data over the contiguous United States. -
Assessing and Improving Cloud-Height Based Parameterisations of Global Lightning Flash Rate, and Their Impact on Lightning-Produced Nox and Tropospheric Composition
https://doi.org/10.5194/acp-2020-885 Preprint. Discussion started: 2 October 2020 c Author(s) 2020. CC BY 4.0 License. Assessing and improving cloud-height based parameterisations of global lightning flash rate, and their impact on lightning-produced NOx and tropospheric composition 5 Ashok K. Luhar1, Ian E. Galbally1, Matthew T. Woodhouse1, and Nathan Luke Abraham2,3 1CSIRO Oceans and Atmosphere, Aspendale, 3195, Australia 2National Centre for Atmospheric Science, Department of Chemistry, University of Cambridge, Cambridge, UK 3Department of Chemistry, University of Cambridge, Cambridge, UK 10 Correspondence to: Ashok K. Luhar ([email protected]) Abstract. Although lightning-generated oxides of nitrogen (LNOx) account for only approximately 10% of the global NOx source, it has a disproportionately large impact on tropospheric photochemistry due to the conducive conditions in the tropical upper troposphere where lightning is mostly discharged. In most global composition models, lightning flash rates used to calculate LNOx are expressed in terms of convective cloud-top height via the Price and Rind (1992) (PR92) 15 parameterisations for land and ocean. We conduct a critical assessment of flash-rate parameterisations that are based on cloud-top height and validate them within the ACCESS-UKCA global chemistry-climate model using the LIS/OTD satellite data. While the PR92 parameterisation for land yields satisfactory predictions, the oceanic parameterisation underestimates the observed flash-rate density severely, yielding a global average of 0.33 flashes s-1 compared to the observed 9.16 -1 flashes s over the ocean and leading to LNOx being underestimated proportionally. We formulate new/alternative flash-rate 20 parameterisations following Boccippio’s (2002) scaling relationships between thunderstorm electrical generator power and storm geometry coupled with available data.