Pub Date : 2019-08-06DOI: 10.15191/nwajom.2019.0710
Gail M. Weaver, N. Smith, E. Berndt, Kristopher White, J. Dostalek, B. Zavodsky
At high latitudes in winter, the atmosphere at flight levels used by passenger and cargo aircraft can reach temperatures cold enough to restrict the flow of jet fuel from the fuel tanks to the engine, due either to water freezing in the fuel or the fuel itself freezing. Currently, aviation forecasters rely on a combination of aircraft reports, pilot reports, a sparse network of radiosondes, and global model fieldsfor identifying and characterizing Cold Air Aloft (CAA) events. More atmospheric data are needed to improve forecasts of CAA placement and timing, and satellite observations can help fill the gap. In particular, products derived from the NOAA-Unique Combined Atmospheric Processing System (NUCAPS) can be utilized by National Weather Service (NWS) forecasters to assist in the production of aviation hazard products. NUCAPS combines measurements from infrared and microwave sounding instruments on polar-orbiting satellites to retrieve atmospheric profiles of temperature and moisture in the high latitudes. NWS forecasters have real-time access to NUCAPS soundings via the Advanced Weather Interactive Processing System-II (AWIPS-II). The Joint Polar Satellite System Sounding Applications Initiative created Gridded NUCAPS in order to view soundings as isobaric surfaces or vertical cross sections in AWIPS-II. The Cooperative Institute for Research in the Atmosphere (CIRA) developed a web-based product for displaying satellite-derived CAA information. This paper describes how the AWIPS-II and CIRA displays of satellite sounding observations augment aviation forecasting activities in Alaska using two specific CAA cases from the 2016–2017 and 2017–2018 winter seasons.
{"title":"Addressing the Cold Air Aloft Aviation Challenge with Satellite Sounding Observations","authors":"Gail M. Weaver, N. Smith, E. Berndt, Kristopher White, J. Dostalek, B. Zavodsky","doi":"10.15191/nwajom.2019.0710","DOIUrl":"https://doi.org/10.15191/nwajom.2019.0710","url":null,"abstract":"At high latitudes in winter, the atmosphere at flight levels used by passenger and cargo aircraft can reach temperatures cold enough to restrict the flow of jet fuel from the fuel tanks to the engine, due either to water freezing in the fuel or the fuel itself freezing. Currently, aviation forecasters rely on a combination of aircraft reports, pilot reports, a sparse network of radiosondes, and global model fieldsfor identifying and characterizing Cold Air Aloft (CAA) events. More atmospheric data are needed to improve forecasts of CAA placement and timing, and satellite observations can help fill the gap. In particular, products derived from the NOAA-Unique Combined Atmospheric Processing System (NUCAPS) can be utilized by National Weather Service (NWS) forecasters to assist in the production of aviation hazard products. NUCAPS combines measurements from infrared and microwave sounding instruments on polar-orbiting satellites to retrieve atmospheric profiles of temperature and moisture in the high latitudes. NWS forecasters have real-time access to NUCAPS soundings via the Advanced Weather Interactive Processing System-II (AWIPS-II). The Joint Polar Satellite System Sounding Applications Initiative created Gridded NUCAPS in order to view soundings as isobaric surfaces or vertical cross sections in AWIPS-II. The Cooperative Institute for Research in the Atmosphere (CIRA) developed a web-based product for displaying satellite-derived CAA information. This paper describes how the AWIPS-II and CIRA displays of satellite sounding observations augment aviation forecasting activities in Alaska using two specific CAA cases from the 2016–2017 and 2017–2018 winter seasons.","PeriodicalId":44039,"journal":{"name":"Journal of Operational Meteorology","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2019-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42540640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-10DOI: 10.15191/nwajom.2019.0709
J. Gibbs, Barry R. Bowers
Significant tornadoes (EF2+) make up a very small percentage of the total United States tornado events, but produce the overwhelming majority of tornado fatalities. Identifying significant tornado events in a shortfused warning environment has been a particular focus of the United States National Weather Service’s severe weather program in recent years, with the goal of reducing the loss of life from significant events to the greatest extent possible. This study aims to further this effort by identifying and quantifying the skill of key signals present in Weather Service Radar-1998 Doppler velocity data in the minutes prior to the onset of significant tornado damage. When separated by storm mode, several radar velocity signals are identified that show operationally useful skill in differentiating between significant and weak/nontornadic events in supercells—with lead time. The highest skill scores are achieved by combining maximum volumetric rotational speed and depth of the storm’s mesocyclone, as well as the overall change in rotational speed in the final minutes prior to the onset of significant damage. Very little, if any, predictive skill was found when only the lowest elevation scan was considered, including more frequent supplementary scans in between full volumetric scans. The same signals that showed noteworthy skill for supercells failed to discriminate between significant and weak/nontornadic events in quasi-linear convective Systems and bow echo/mesoscale convective vortex events.
{"title":"Techniques and Thresholds of Significance for Using WSR-88D Velocity Data to Anticipate Significant Tornadoes","authors":"J. Gibbs, Barry R. Bowers","doi":"10.15191/nwajom.2019.0709","DOIUrl":"https://doi.org/10.15191/nwajom.2019.0709","url":null,"abstract":"Significant tornadoes (EF2+) make up a very small percentage of the total United States tornado events, but produce the overwhelming majority of tornado fatalities. Identifying significant tornado events in a shortfused warning environment has been a particular focus of the United States National Weather Service’s severe weather program in recent years, with the goal of reducing the loss of life from significant events to the greatest extent possible. This study aims to further this effort by identifying and quantifying the skill of key signals present in Weather Service Radar-1998 Doppler velocity data in the minutes prior to the onset of significant tornado damage. When separated by storm mode, several radar velocity signals are identified that show operationally useful skill in differentiating between significant and weak/nontornadic events in supercells—with lead time. The highest skill scores are achieved by combining maximum volumetric rotational speed and depth of the storm’s mesocyclone, as well as the overall change in rotational speed in the final minutes prior to the onset of significant damage. Very little, if any, predictive skill was found when only the lowest elevation scan was considered, including more frequent supplementary scans in between full volumetric scans. The same signals that showed noteworthy skill for supercells failed to discriminate between significant and weak/nontornadic events in quasi-linear convective Systems and bow echo/mesoscale convective vortex events.","PeriodicalId":44039,"journal":{"name":"Journal of Operational Meteorology","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2019-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47035791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-09DOI: 10.15191/nwajom.2019.0708
Todd A. Murphy, Cynthia K. Palmer, Chad Entremont, James D. Lamb
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.
{"title":"Early Operational Successes of the University of Louisiana Monroe’s Polarimetric S-band Doppler Radar","authors":"Todd A. Murphy, Cynthia K. Palmer, Chad Entremont, James D. Lamb","doi":"10.15191/nwajom.2019.0708","DOIUrl":"https://doi.org/10.15191/nwajom.2019.0708","url":null,"abstract":"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.","PeriodicalId":44039,"journal":{"name":"Journal of Operational Meteorology","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2019-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44250416","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-03DOI: 10.15191/nwajom.2019.0707
G. Stano, Matthew R. Smith, C. Schultz
The launch of the Geostationary Lightning Mapper (GLM) aboard Geostationary Operational Environmental Satellite-R/S (GOES-16/17), provides new opportunities to support lightning safety, such as the 30-min hazard (“stoplight”) safety product developed by the National Aeronautics and Space Administration’s Short-term Prediction Research and Transition Center. This product plots the spatial extent where lightning occurred over the past 30 min and color codes the data in 10-min bins. Using GLM’s mapping of the spatial footprint of individual flashes, the product identifies when temporal rules for lightning safety have been met based on the needs of decision-support partners [commercial airlines, 10 min; United States Air Force (USAF) 45th Weather Squadron, 20 min; emergency management (EMA)/National Weather Service (NWS), 30 min]. The effort was guided by EMA partners requesting a product that quickly shows the location and age of lightning observations in an easy-to-interpret visualization. Analysis of lightning safety rules of thumb were performed in the framework of the GLM stoplight product to determine the number of times each of the partner criteria would be violated using an Eulerian-based approach simulating an integrated decision support point of view. The temporal criteria for commercial airlines, USAF, and EMA/NWS were violated 9.5%, 3.5%, and 1.4% of the time within this sample, respectively. Examples are provided to show the GLM 30-min hazard product in linear convection, multicellular convection, and electrified snowfall events. Illustrations also demonstrate how this GLM safety product and ground-based, lightning-location systems can work in tandem to maximize lightning safety protocols.
{"title":"Development and Evaluation of the GLM Stoplight Product for Lightning Safety","authors":"G. Stano, Matthew R. Smith, C. Schultz","doi":"10.15191/nwajom.2019.0707","DOIUrl":"https://doi.org/10.15191/nwajom.2019.0707","url":null,"abstract":"The launch of the Geostationary Lightning Mapper (GLM) aboard Geostationary Operational Environmental Satellite-R/S (GOES-16/17), provides new opportunities to support lightning safety, such as the 30-min hazard (“stoplight”) safety product developed by the National Aeronautics and Space Administration’s Short-term Prediction Research and Transition Center. This product plots the spatial extent where lightning occurred over the past 30 min and color codes the data in 10-min bins. Using GLM’s mapping of the spatial footprint of individual flashes, the product identifies when temporal rules for lightning safety have been met based on the needs of decision-support partners [commercial airlines, 10 min; United States Air Force (USAF) 45th Weather Squadron, 20 min; emergency management (EMA)/National Weather Service (NWS), 30 min]. The effort was guided by EMA partners requesting a product that quickly shows the location and age of lightning observations in an easy-to-interpret visualization. Analysis of lightning safety rules of thumb were performed in the framework of the GLM stoplight product to determine the number of times each of the partner criteria would be violated using an Eulerian-based approach simulating an integrated decision support point of view. The temporal criteria for commercial airlines, USAF, and EMA/NWS were violated 9.5%, 3.5%, and 1.4% of the time within this sample, respectively. Examples are provided to show the GLM 30-min hazard product in linear convection, multicellular convection, and electrified snowfall events. Illustrations also demonstrate how this GLM safety product and ground-based, lightning-location systems can work in tandem to maximize lightning safety protocols.","PeriodicalId":44039,"journal":{"name":"Journal of Operational Meteorology","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2019-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43348224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-06-19DOI: 10.15191/nwajom.2019.0705
A. Raghavendra, S. Milrad
A new coupled dynamic and thermodynamic metric is developed based on the Eady Moist Baroclinic Growth Rate (EMBGR), to discriminate between left-of-track (LOT) and right-of-track (ROT) precipitation distributions in transitioning tropical cyclones (TCs). LOT events pose a major flood risk even when a TC tracks along a coastline or just offshore, as flash flooding can occur hundreds of kilometers inland from the cyclone center. The EMBGR can improve human-produced quantitative precipitation forecasts (QPF) because it is dependent on relatively well-forecast large-scale mass fields. The ability of the EMBGR to identify precipitation distribution is first explored in a case study of TC Matthew (2016), using reanalysis and numerical model forecasts. Subsequently, a composite analysis of 36 years (1979–2014) of United States landfalling TCs using reanalysis data shows that the EMBGR is an effective discriminator between LOT and ROT distributions. The utility of the EMBGR is quantified using a pattern correlation analysis for both TC Matthew and the composites. Finally, a conceptual schematic is developed for LOT cases so that forecasters can most effectively utilize the EMBGR to improve human QPF skill during transitioning TCs.
{"title":"A New Metric to Diagnose Precipitation Distribution in Transitioning Tropical Cyclones","authors":"A. Raghavendra, S. Milrad","doi":"10.15191/nwajom.2019.0705","DOIUrl":"https://doi.org/10.15191/nwajom.2019.0705","url":null,"abstract":"A new coupled dynamic and thermodynamic metric is developed based on the Eady Moist Baroclinic Growth Rate (EMBGR), to discriminate between left-of-track (LOT) and right-of-track (ROT) precipitation distributions in transitioning tropical cyclones (TCs). LOT events pose a major flood risk even when a TC tracks along a coastline or just offshore, as flash flooding can occur hundreds of kilometers inland from the cyclone center. The EMBGR can improve human-produced quantitative precipitation forecasts (QPF) because it is dependent on relatively well-forecast large-scale mass fields. The ability of the EMBGR to identify precipitation distribution is first explored in a case study of TC Matthew (2016), using reanalysis and numerical model forecasts. Subsequently, a composite analysis of 36 years (1979–2014) of United States landfalling TCs using reanalysis data shows that the EMBGR is an effective discriminator between LOT and ROT distributions. The utility of the EMBGR is quantified using a pattern correlation analysis for both TC Matthew and the composites. Finally, a conceptual schematic is developed for LOT cases so that forecasters can most effectively utilize the EMBGR to improve human QPF skill during transitioning TCs.","PeriodicalId":44039,"journal":{"name":"Journal of Operational Meteorology","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2019-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41747326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-06-19DOI: 10.15191/nwajom.2019.0706
J. Garner, William C. Iwasko, Matthew Kidwell, Karleisa Rogacheski, Ryan P. Aylward, Jason Anderson
National Weather Service (NWS) forecasters across the west coast of the United States often deal with cool season hail showers that produce hazardous driving conditions. These small hail events, with diameters averaging 5.8 mm, occur with cold upper troughs that support weak instability favorable for low-topped convection and reflectivity values averaging 48 dBZ. The public generally assumes that heavy snow is common across west coast mountains, while heavy rain prevails near sea level. However, motorists can be caught offguard when wet, relatively warm low elevation roadways suddenly transition to icy hail-covered conditions. Thus, west coast small hail events represent an opportunity for the NWS to provide tailored messaging that can modify public perceptions and optimize outcomes. This research examines environments supportive of accumulating small hail over the western United States during the period 2008–2018, and supplements the environmental analysis with a summary of enhanced impact-based decision support techniques used to alert NWS partners and the general public.
{"title":"Cool Season Small Hail over the West Coast of the United States: Environments, Hazards, and Decision Support","authors":"J. Garner, William C. Iwasko, Matthew Kidwell, Karleisa Rogacheski, Ryan P. Aylward, Jason Anderson","doi":"10.15191/nwajom.2019.0706","DOIUrl":"https://doi.org/10.15191/nwajom.2019.0706","url":null,"abstract":"National Weather Service (NWS) forecasters across the west coast of the United States often deal with cool season hail showers that produce hazardous driving conditions. These small hail events, with diameters averaging 5.8 mm, occur with cold upper troughs that support weak instability favorable for low-topped convection and reflectivity values averaging 48 dBZ. The public generally assumes that heavy snow is common across west coast mountains, while heavy rain prevails near sea level. However, motorists can be caught offguard when wet, relatively warm low elevation roadways suddenly transition to icy hail-covered conditions. Thus, west coast small hail events represent an opportunity for the NWS to provide tailored messaging that can modify public perceptions and optimize outcomes. This research examines environments supportive of accumulating small hail over the western United States during the period 2008–2018, and supplements the environmental analysis with a summary of enhanced impact-based decision support techniques used to alert NWS partners and the general public.","PeriodicalId":44039,"journal":{"name":"Journal of Operational Meteorology","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2019-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45452459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-06-12DOI: 10.15191/nwajom.2019.0704
S. Hodanish, B. J. Vogt, P. Wolyn
Average cloud-to-ground (CG) lightning flash density values for Colorado are analyzed for the 21-yr period 1996–2016. An annual mean map and monthly mean maps of flash density provide insight into the thunderstorm/lightning climatology over the complex physical landscapes of Colorado. Findings include that 1) the Denver convergence/vorticity zone regional circulation influences the CG lightning distribution across the northeastern Colorado region; 2) moisture associated with the North American monsoon increases CG lightning over the entire state, focusing along the southern exposures of the San Juan Mountains; and 3) the highest concentrations of CG lightning occur where moisture, lift, and instability are maximized.
{"title":"Colorado Lightning Climatology","authors":"S. Hodanish, B. J. Vogt, P. Wolyn","doi":"10.15191/nwajom.2019.0704","DOIUrl":"https://doi.org/10.15191/nwajom.2019.0704","url":null,"abstract":"Average cloud-to-ground (CG) lightning flash density values for Colorado are analyzed for the 21-yr period 1996–2016. An annual mean map and monthly mean maps of flash density provide insight into the thunderstorm/lightning climatology over the complex physical landscapes of Colorado. Findings include that 1) the Denver convergence/vorticity zone regional circulation influences the CG lightning distribution across the northeastern Colorado region; 2) moisture associated with the North American monsoon increases CG\u0000lightning over the entire state, focusing along the southern exposures of the San Juan Mountains; and 3) the highest concentrations of CG lightning occur where moisture, lift, and instability are maximized.","PeriodicalId":44039,"journal":{"name":"Journal of Operational Meteorology","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2019-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48024177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-05-15DOI: 10.15191/NWAJOM.2019.0703
Michael T. Lawson, K. Fuell
The NASA Short-term Prediction Research and Transition (SPoRT) Center has provided National Weather Service (NWS) Alaska Region forecasters with the experimental Daytime Microphysics (DtMicro) red-green-blue (RGB) product to support forecasting aviation hazards (Berndt et al. 2017), which has become an integral tool in the forecast process. On 11 March 2018, a rapidly deepening cyclone entered the Gulf of Alaska and developed gale-force winds and relatively strong convection for late winter, while lowlevel clouds and fog remained in its wake. The multispectral DtMicro RGB (Rosenfeld and Lensky 1998; EUMETSAT User Service Division 2009) provided an efficient product to analyze cloud properties and surface features with improved efficiency compared to single-channel visible or infrared imagery. The DtMicro RGB and 0.64 µm visible images (Fig. 1) show a mature, occluded cyclone over the Gulf of Alaska at 2030 UTC (1230 LST). The DtMicro RGB combines visible and infrared channels related to cloud brightness, particle size, and temperature in order to analyze convective clouds and other cloud and surface features (Table 1; Lensky and Rosenfeld 2008). A limb correction and intercalibration was applied to infrared channels using the technique outlined in Elmer et al. (2016). These adjustments allow for greater consistency across the imager swath and consistency between numerous polar-orbiting satellites. The RGB clearly delineates the back-bent occlusion (dark orange to red), and dry air wrapping into the system, allowing a view of the low to mid-level clouds in the center of the image. Bright orange/yellow combinations over the Alaska panhandle and northwestern Canada are mountain-wave cirrus clouds composed of small ice particles. The magenta cloud features within the dry slot are deeper convective cells, and cyan to yellowgreen cloud features are low-level water clouds. Near Illiamna, the tan to dull green coloring indicates very low stratus and fog, which is not distinguishable from snow cover in the visible imagery.
美国宇航局短期预测研究和过渡(SPoRT)中心为国家气象局(NWS)阿拉斯加地区预预员提供了实验性日间微物理(DtMicro)红绿蓝(RGB)产品，以支持预测航空灾害(Berndt等人，2017)，该产品已成为预测过程中不可或缺的工具。2018年3月11日，一个快速加深的气旋进入阿拉斯加湾，并在冬末形成了大风和相对强对流，而低空云和雾仍在其后。多光谱DtMicro RGB (Rosenfeld and Lensky 1998;EUMETSAT用户服务部(2009年)提供了一种高效的产品来分析云特性和地表特征，与单通道可见光或红外图像相比，效率更高。DtMicro RGB和0.64µm可见光图像(图1)显示了UTC时间2030 (1230 LST)阿拉斯加湾上空一个成熟的闭塞气旋。DtMicro RGB结合了与云亮度、粒径和温度相关的可见光和红外通道，以分析对流云以及其他云和地面特征(表1;Lensky and Rosenfeld 2008)。使用Elmer等人(2016)概述的技术，将肢体校正和互校准应用于红外通道。这些调整使得整个成像仪图像和众多极轨卫星之间的一致性更加一致。RGB清晰地描绘了背向弯曲的遮挡(暗橙色到红色)，干燥的空气包裹在系统中，允许在图像中心看到低空到中层的云。阿拉斯加狭长地带和加拿大西北部的亮橙色/黄色组合是由小冰粒组成的山波卷云。干槽内的洋红色云特征为较深的对流单体，青色至黄绿色云特征为低层水云。在伊利诺伊州附近，黄褐色到暗绿色表示非常低的层和雾，在可见图像中无法与积雪区分开。
{"title":"Gulf of Alaska Cyclone in Daytime\u0000Microphysics RGB Imagery","authors":"Michael T. Lawson, K. Fuell","doi":"10.15191/NWAJOM.2019.0703","DOIUrl":"https://doi.org/10.15191/NWAJOM.2019.0703","url":null,"abstract":"The NASA Short-term Prediction Research and Transition (SPoRT) Center has provided National Weather Service (NWS) Alaska Region forecasters with the experimental Daytime Microphysics (DtMicro) red-green-blue (RGB) product to support forecasting aviation hazards (Berndt et al. 2017), which has become an integral tool in the forecast process. On 11 March 2018, a rapidly deepening cyclone entered the Gulf of Alaska and developed gale-force winds and relatively strong convection for late winter, while lowlevel clouds and fog remained in its wake. The multispectral DtMicro RGB (Rosenfeld and Lensky 1998; EUMETSAT User Service Division 2009) provided an efficient product to analyze cloud properties and surface features with improved efficiency compared to single-channel visible or infrared imagery. The DtMicro RGB and 0.64 µm visible images (Fig. 1) show a mature, occluded cyclone over the Gulf of Alaska at 2030 UTC (1230 LST). The DtMicro RGB combines visible and infrared channels related to cloud brightness, particle size, and temperature in order to analyze convective clouds and other cloud and surface features (Table 1; Lensky and Rosenfeld 2008). A limb correction and intercalibration was applied to infrared channels using the technique outlined in Elmer et al. (2016). These adjustments allow for greater consistency across the imager swath and consistency between numerous polar-orbiting satellites. The RGB clearly delineates the back-bent occlusion (dark orange to red), and dry air wrapping into the system, allowing a view of the low to mid-level clouds in the center of \u0000the image. Bright orange/yellow combinations over the Alaska panhandle and northwestern Canada are mountain-wave cirrus clouds composed of small ice particles. The magenta cloud features within the dry slot are deeper convective cells, and cyan to yellowgreen cloud features are low-level water clouds. Near Illiamna, the tan to dull green coloring indicates very low stratus and fog, which is not distinguishable from snow cover in the visible imagery.","PeriodicalId":44039,"journal":{"name":"Journal of Operational Meteorology","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2019-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46503606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-04-16DOI: 10.15191/NWAJOM.2019.0702
R. Megnia, Timothy W. Humphrey, Jared A. Rackley
On 2 April 2017 Louisiana saw one of its largest tornado outbreaks since 1950. The day saw a total of 21 tornadoes, six of which were classified as significant (EF2+). This extreme event resulted in an estimated 4.2 million dollars in damage and two fatalities. A climatology of Louisiana individual tornado days dating back to 1950 ranked this event second for total number of tornadoes (21) in a day and second for number of significant (EF2+) tornadoes (6) in a day. To assess the overall impact of this outbreak, the Destruction Potential Index (DPI) was used to compare both the overall number and strength of tornadoes to previous events. The 2 April 2017 event had the highest DPI for the state of Louisiana since 1950. Comparisons made to tornado days in nearby states in the region also highlight the significance of this event. The synoptic conditions of 2 April 2017 were compared to a 25-member synoptic scale composite of past Louisiana tornado days with six or more tornadoes. The composite highlighted anomalies in synoptic ingredients that contribute to tornado outbreak environments. Most notably, the synoptic structure consisted of a more meridional flow pattern, which allowed for stronger moisture transport, low level shear, deep layer shear, and increased thermal advection. This produced an optimal mesoscale environment with high instability and storm-relative environmental helicity. The meteorological significance of this event with respect to Louisiana stems from the uncommon combination of a high shear/high CAPE near-storm environment in a southern tornado outbreak. The high shear/high CAPE environment largely responsible for the 2 April 2017 Louisiana tornado outbreak is more commonly observed in Great Plains tornado outbreaks.
{"title":"The Historic 2 April 2017 Louisiana Tornado Outbreak","authors":"R. Megnia, Timothy W. Humphrey, Jared A. Rackley","doi":"10.15191/NWAJOM.2019.0702","DOIUrl":"https://doi.org/10.15191/NWAJOM.2019.0702","url":null,"abstract":"On 2 April 2017 Louisiana saw one of its largest tornado outbreaks since 1950. The day saw a total of 21 tornadoes, six of which were classified as significant (EF2+). This extreme event resulted in an estimated 4.2 million dollars in damage and two fatalities. A climatology of Louisiana individual tornado days dating back to 1950 ranked this event second for total number of tornadoes (21) in a day and second for number of significant (EF2+) tornadoes (6) in a day. To assess the overall impact of this outbreak, the Destruction Potential Index (DPI) was used to compare both the overall number and strength of tornadoes to previous events. The 2 April 2017 event had the highest DPI for the state of Louisiana since 1950. Comparisons made to tornado days in nearby states in the region also highlight the significance of this event. The synoptic conditions of 2 April 2017 were compared to a 25-member synoptic scale composite of past Louisiana tornado days with six or more tornadoes. The composite highlighted anomalies in synoptic ingredients that contribute to tornado outbreak environments. Most notably, the synoptic structure consisted of a more meridional flow pattern, which allowed for stronger moisture transport, low level shear, deep layer shear, and increased thermal advection. This produced an optimal mesoscale environment with high instability and storm-relative environmental helicity. The meteorological significance of this event with respect to Louisiana stems from the uncommon combination of a high shear/high CAPE near-storm environment in a southern tornado outbreak. The high shear/high CAPE environment largely responsible for the 2 April 2017 Louisiana tornado outbreak is more commonly observed in Great Plains tornado outbreaks.","PeriodicalId":44039,"journal":{"name":"Journal of Operational Meteorology","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2019-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42252670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-03-21DOI: 10.15191/NWAJOM.2019.0701
P. McNeal, H. Petcovic, N. LaDue, T. Ellis
Understanding which cognitive factors facilitate meteorology skills is important for meteorology training and education. This study investigated aspects of cognition important to successful completion of meteorology tasks typically provided to student meteorologists. With a sample of 81 participants—spanning the range of experience from undergraduate students to professional meteorologists—we administered two spatial thinking tests, a visuospatial working memory test, a concept inventory, and an experience questionnaire. We compared the resulting scores to performance on a series of novice-level meteorology tasks. An analysis of the data suggests that meteorology knowledge along with disembedding skill (the ability to observe and recognize patterns among nonessential information) positively predicts performance on the meteorological tasks. The relationship among meteorology knowledge, disembedding skill, and performance on the meteorology tasks indicates that disembedding is an important predictor of success at both low and high levels of meteorology knowledge. Thus, our results suggest that individuals with heightened ability to identify patterns embedded in distracting background displays may be at an advantage for completing meteorology tasks of the type that we provided.
{"title":"Identifying Significant Cognitive Factors for Practicing and Learning Meteorology","authors":"P. McNeal, H. Petcovic, N. LaDue, T. Ellis","doi":"10.15191/NWAJOM.2019.0701","DOIUrl":"https://doi.org/10.15191/NWAJOM.2019.0701","url":null,"abstract":"Understanding which cognitive factors facilitate meteorology skills is important for meteorology training and education. This study investigated aspects of cognition important to successful completion of meteorology tasks typically provided to student meteorologists. With a sample of 81 participants—spanning the range of experience from undergraduate students to professional meteorologists—we administered two spatial thinking tests, a visuospatial working memory test, a concept inventory, and an experience questionnaire. We compared the resulting scores to performance on a series of novice-level meteorology tasks. An analysis of the data suggests that meteorology knowledge along with disembedding skill (the ability to observe and recognize patterns among nonessential information) positively predicts performance on the meteorological tasks. The relationship among meteorology knowledge, disembedding skill, and performance on the meteorology tasks indicates that disembedding is an important predictor of success at both low and high levels of meteorology knowledge. Thus, our results suggest that individuals with heightened ability to identify patterns embedded in distracting background displays may be at an advantage for completing meteorology tasks of the type that we provided.","PeriodicalId":44039,"journal":{"name":"Journal of Operational Meteorology","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2019-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43295850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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