by Keith L. Seitter, CCM, AMS Executive Director

This week we join many other scientific publishers celebrating Peer Review Week to highlight the importance of high-quality peer review in the scientific process. The process of peer reviewing research results has been an indispensable component of the modern scientific enterprise: when scientists talk about having reached a consensus in some area of research, they mean that there is a consensus in the peer-reviewed literature. This week gives us an opportunity to focus on the importance of peer review while also recognizing the dedication of researchers around the world who make considerable commitments of time to ensure its continued success while usually receiving little or no explicit credit for those contributions.

When a researcher submits a manuscript presenting research results to a high-quality journal like those AMS publishes, the editor of the journal selects several experts in relevant specialties to review of the manuscript. These experts make sure the author(s) have carried out their experiments, observations, and/or analysis following sound practices and that their conclusions can be justified from the data and analysis they have provided. In their reviews, these experts identify weaknesses or flaws in experimental design or reasoning and suggest additional research and analysis that might be required, as well as other ways to improve the paper.

The editor collects these peer reviews and determines if the manuscript can be made suitable for publication. If the science is flawed and the paper cannot be made acceptable with a reasonable amount of additional work, the paper is rejected. More than one in three manuscripts submitted to AMS journals are rejected. The editor’s decision is provided to the authors, along with the full set of reviews with the names of the reviewers removed (unless the reviewer chooses otherwise), along with the editor’s decision. If the paper has not been rejected, the authors follow the guidance of the editors and reviewers to revise the paper, which then may face additional peer review under the editor’s direction. If the paper can reach the point that the editor is satisfied with the quality of the work, the manuscript is accepted for publication.

Peer review, even when implemented in the rigorous manner used by AMS, is not perfect, of course. Occasionally important research is initially rejected in peer review, or fundamentally incorrect research survives peer review to publication only to be shown later to be incorrect. Peer review done well, however, greatly reduces the chance of publication of poor or incorrect science, and experience has shown that overall the process is extremely successful. That is why scientists depend virtually exclusively on results presented in rigorously peer-reviewed journals and why major scientific assessments—like the reports from the Intergovernmental Panel on Climate Change (IPCC)—rely on peer-reviewed literature from well-established, high-quality journals like those published by AMS.

Astute readers will have noticed that I refer to “high quality journals” multiple times above. It is important to make that distinction because there are journals vying for authors’ papers (and the income they provide) that do not put the time or expense into doing peer review with the rigor employed by the AMS journals. Authors, and the scientific enterprise itself, are best served by those journals that invest the resources needed to do the peer review to the highest standards. AMS journals enjoy membership in the elite group of such high quality journals that serve the atmospheric and related sciences.

Let me close with note of appreciation for those who maintain the very high standards of peer review for the AMS journals.  While the professional staff at AMS does a wonderful job of ensuring smooth and expedient reviews, as part of a positive author experience that is among the best in scientific publishing, it is the volunteers who serve as chief editors, editors, associate editors, and reviewers who dedicate the time and energy to maintain the AMS journals as world-class publications. And the reviewers especially deserve credit given that their efforts are, by design, mostly done anonymously for the collective good of science. All of us owe these dedicated individuals our thanks.

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2018’s devastating Hurricane Michael struck the Florida panhandle at Mexico Beach and Tyndall Air Force Base in October at Category 5 intensity with 160 mph winds, the National Hurricane Center announced Friday. That’s 5 mph higher than Michael’s wind estimate of 155 mph at the time of landfall.

GOES-16 Pseudo-color image or Hurricane Michael at 1730 UTC October 10, 2018. (Courtesy: NOAA NESDIS)
GOES-16 Pseudo-color image or Hurricane Michael at 1730 UTC October 10, 2018. (Image courtesy: NOAA NESDIS)

 

In its post-storm tropical cyclone report, released the same day, NHC stated it culled an abundance of wind data measurements not available in real-time to add the 5 mph to Michael’s wind intensity. The data came from aircraft reconnaissance, ground observations, satellite intensity estimates, surface pressures, and Doppler radar velocities from Eglin Air Force Base and the NWS in Tallahassee. The report goes in-depth with the data, explaining the observations and identifying those that were believable—a 152 knot (175 mph) aircraft wind measurement at 8,000 feet in the southeast eyewall that yields a surface wind of 137 knots (158 mph)—versus those that were suspect—a 152 knot (175 mph) surface wind measured by the stepped frequency microwave radiometer (SFMR) instrument aboard a different aircraft, deemed too high based on experience with such intense winds in hurricanes Irma, Jose, and Maria in 2017.

The upgrade makes Michael only the fourth Category 5 hurricane to hit the United States, joining a small, elite group of monster landfalling storms that include Hurricane Andrew (1992, 165 mph winds), Hurricane Camille (1969, 175 mph winds), and the Labor Day Hurricane (1935, 185 mph winds). Andrew plowed into South Florida, Camille landed on the Mississippi coast, and the Labor Day Hurricane devastated the Florida Keys.

A realty building destroyed by Hurricane Michael's winds on the east of Panama City, Florida.
A realty building destroyed by Hurricane Michael’s winds on the east side of Panama City, Florida.
(Photo courtesy: Chris Cappella [AMS])

Hurricane Michael roared ashore on October 10 as the strongest hurricane on record to strike the Florida Panhandle, with a storm surge around 14 feet above ground level, destroying Mexico Beach and much of Tyndall AFB, while tearing apart homes and businesses in Callaway, just inland, as well as in the eastern side of Panama City. Sixteen people died directly from the hurricane due to storm surge flooding and the intense winds, which blew down entire forests in the panhandle and destroyed crops across southern Georgia. Wind damage extended into the Carolinas.

Very few surface observations of the hurricane’s intense winds were made at landfall. The highest gust was 139 mph measured by an anemometer at Tyndall AFB before it failed. Two coastal monitoring program towers measured 129 mph and 125 mph, substantially lower than the upgraded wind speed at landfall. One of the towers was knocked over before the peak winds struck, and the other was outside the hurricane’s core. NHC notes that the sites “were likely not optimally located to sample the maximum winds, which is typical during landfalling hurricanes.”

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The largest biographical study to date of TV meteorologists shows some disturbing disadvantages for women in the profession.  You can hear Alexandra Cranford, the author of that study, discuss the study on the latest episode of our podcast, AMS on the Air.

Cranford, who is an AMS Certified Broadcaster with WWL-TV in New Orleans, made an exhaustive survey of online information for more than 2,000 weathercasters. She focused on the relation between her colleagues’ professional status and education. The results, which formed the basis of her BAMS article, show women meteorologists have made gains on local TV, yet are not proportionately well represented in the most prominent and prized positions on local stations.

For example, women are much more likely to be on TV during daytime, mornings, and weekends, than on prime time slots:

CranfordChart

And they are far less likely to be chief meteorologist for their station:

CranfordChart2

In the podcast interview, she speculates on some of the reasons for these findings.

Perhaps when a hiring manager is interviewing a man versus a woman as a weathercaster, they are looking at slightly different criteria….Another thing is, maybe women are choosing for some reason…perhaps to work maybe weekends and mornings. Maybe women are staying away from those chief positions for some reason. I have no idea if this is the case—I’m just throwing out ideas here—but…possibly due to family reasons or personal preference. That could maybe be another thing.

Also, women may choose to exit the industry earlier in their careers, so that leaves a pool of mainly older, more experienced, mainly males to fill those chief spots, which are typically filled by an older, more experienced person.

And then, one of the reviewers of my study brought my attention to the effect that all of us think about—but how much of a real effect might it have?—the effects of criticisms of consultants and social media and so forth. We all know about the internet trolls. Anyone who works as a TV weathercaster, I’m sure has gotten emails from viewers….That’s a very real thing too. There is research that suggests maybe that’s a bit worse for females versus males. Maybe that can play a role as well.

Listen to the whole interview on the AMS website or on your favorite podcast app.

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Wow! It’s World Water Day, as observed by the United Nations. Pretty much everything AMS is about has to do with water—from raindrops to atmospheric rivers to thunderstorms and hurricanes on to ocean currents and groundwater.

Which is why this concluding paragraph from the AMS Policy Program’s recently released study, “Toward an Integrated Approach to Water,” hit home and hits hard for us.

Water is simultaneously a resource and a threat. It is centrally important to every aspect of socioeconomic wellbeing and water becomes a hazard when there is too much, too little, or if the quality is poor. The ever-changing, increasingly human influenced water regime is characterized by localized, uncontrolled, intermittent, and sometimes huge flows of water (fresh and salt) across coastal zones, urban and rural areas, transportation infrastructure, agricultural resources, and through waterways. Earth observations and science provide critical environmental intelligence that help us determine when there is too much water, too little, or of the wrong quality. Services help us manage risks and realize opportunities that environmental intelligence makes possible. Decision-making with respect to water, as with all societal choices, has the greatest chance to benefit people when grounded in the best available knowledge & understanding.

Uncontrolled..intermittent…huge…too much…too little…An unflinching assessment from Paul Higgins, Yael Seid-Green, Andy Miller, and Annalise Blum. Read the whole report here and take in the full flow of interrelated issues that we, as an AMS community, must grasp in knowing and dealing with Earth’s ways.

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In the pages of scientific history, one often hears too much silence. A science–especially meteorology–is built by women who are rarely, if ever, remembered, let alone credited.

So maybe on this International Women’s Day, and more broadly, for Women’s History Month, let’s look back in the pages of history at the dedication to meteorology that women have always shown. Consider the dedication to a very essence of science—observation—shown in this item tucked into the January 1929 BAMS:

MRS. MORGAN IS POINT BARROW OBSERVER

When the Weather Bureau announced in the fall that radio weather reports were beginning to come in from our northernmost station, Point Barrow, Alaska, at latitude 71°…nobody would have guessed that the observer at this coldest and most inaccessible station, 450 miles north of other radio weather outposts, is a young woman, Mrs. Beverly A. Morgan, wife of the Army Signal Corps radio operator at the trading post there. …Mrs. Morgan and her husband live in the most primitive surroundings with only a few score people within hundreds of miles. Their only communication with the outside world, with the exception of their radio, will be a steamer once and sometimes twice a year. Occasionally even this powerful icebreaker is unable to penetrate to the post for months after her scheduled arrival. Shortage of food and other supplies has often caused serious handicap at the station, necessitating rationing of food. The temperature averages 19° F. below zero during the coldest winter months, and has been known to reach 55° below zero. Despite these hardships, Mrs. Morgan has pledged herself to make the routine observations twice a day regardless of weather, storms, sickness or other conditions. Many of the instruments require considerable mechanical attention and Mrs. Morgan is performing these duties in addition to her work as observer. The arduous observing is of great importance to cold wave forecasting in the United States, for Charles L. Mitchell, chief forecaster of the U. S. Weather Bureau in Washington, D. C., has found, by studies of reports for earlier years received by mail from this station and others, that the great invasions of cold air that sweep over much of the North American continent come in most frequently off the Arctic Ocean north of Alaska and are first observed at Point Barrow. Thus the reports from Mrs. Morgan will probably give us warnings of the approach of cold periods in winter some days earlier than heretofore.

And let’s listen to the commitment of one Mrs. Ross Morgan, a noted Weather Bureau Cooperative Observer, as recorded in her address to an AMS meeting in Nashville, Tennessee, later published in the January 1928 BAMS:

DUTIES AND EXPERIENCES OF A COOPERATIVE OBSERVER

By MRS. ROSS WOODS, Cooperative Observer, Palmetto, Tenn.

For years it has been my desire to have a convention of the weather observers of our state, that I might meet my fellow cooperatives and exchange experiences with them, but such a convention up to this time has not seemed feasible.

But now two mighty luminaries in the scientific world are in conjunction and with their combined attractive force, are drawing all the earth, great and small, toward them. The American Meteorological Society, for the first time in its history, and the American Association for the Advancement of Science, for the second time in its history, are met in our capital city. Truly opportunity is at the high tide of the spring tide and my erstwhile dream for years of too little importance to warrant fulfillment, is now a reality.

And now that I have the opportunity to speak, my heart fills so with emotion the words are choked back and with Tennyson I cry, “And I would that I could utter the thoughts that arise in me.” That little latticed shed, or instrument shelter, in the yard back home does not seem to me to house mere instruments of wood and metal. Those instruments are a part of my family and as dear to me as some cherished heirloom to another. And why shouldn’t I love them when I recall the days that used to be?….

At first I loved them because of my father, later for their own sake or shall I say because through association with my own babies they became almost like one of the children. For more than twenty-two years they have stood in my yard with the pride of their thirty-eight years of unbroken record which…had stood until last summer I was absent for ten days and not even the most insistent S.O.S. could secure a substitute.

How very, very often, I have the pleasure of showing a visitor or newcomer the maximum and the minimum thermometers, how they keep their register till I set them, explain the way to measure the rain, of keeping a daily record and noting the direction of the wind and character of the day, all of which must be made out once a month and sent to the Weather Bureau at Nashville. Usually this information calls forth words of appreciation and commendation, but there are some who are wont to ask, “Why do you do all this for nothing?” The easiest reply is: the compensation the Government could allow for this work would be small yet there are many incompetent and irresponsible persons, who would take it for the price, small though it be. But the truest and best reason is deep within my heart and could not be understood by a disinterested listener.

In fancy I stand before the instrument, not at the time I set the thermometer and make my daily record, but this is the hour before bedtime and this is my observation; above me is the sky “that beautiful parchment on which the sun and moon keep their diary….I see it “sometimes gentle, sometimes capricious, sometimes awful, never the same for two moments together, almost human in its passions, almost spiritual in its tenderness, almost divine in its infinity,” and I am glad I am numbered even though in a humble way among those who scan the sky.

Yes, we will remind readers of the exploits of the first woman to earn a Ph.D. in atmospheric sciences, the late Joanne Simpson who also served as AMS president (for example, today is a good day to listen to Carol Lipschultz’s biographical presentation on Dr. Simpson, here). And we will remember the story of Ann Louise Beck, who earned her Master’s degree in our science in 1922 while being instrumental in pioneering the use of the Norwegian cyclone model in weather analysis and forecasting in the United States. Her review paper on what she learned from her fellowship year in Bergen was probably the introduction to modern scientific forecasting for many American meteorologists in her day.

But lets remember that despite the all-too-often silence of history, women have long been a pillar of meteorology. Because of course they were, even if the journals are mostly silent.

In Dr. Simpson’s words, when she accepted the AMS Rossby Research Medal in January 1983.

Women meteorologists can now stand on their own, without defensiveness—and soon without, I hope, the prefix “woman ” preceding “meteorologist.” They no longer need, want, nor should expect special treatment or attention. For this alone I’m very glad I’ve survived to this day. My receiving this wonderful, encouraging—though simultaneously humbling—recognition is not an anomaly, but on the contrary, is a harbinger. It says—loudly and clearly—to that increasing number of younger women contributing to our science that each of you can expect an opportunity comparable to that of your male colleagues to receive the recognition that you earn. I am confident, in fact, if I am accorded a normal life span, that I will be here to cheer for the next several of you when one of these great honors comes your way.

 

 

 

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Most of us can barely imagine the experience AMS Fellow Ada Monzón went through to warn–and then come to the aid of–her fellow citizens in Puerto Rico during Hurricane Maria of 2017. On the latest episode of our podcast, AMS on the Air, the award-winning broadcast meteorologist for WIPR-TV tells BAMS Senior Editor Chris Cappella,

With Maria, I was really scared. All of us have special circumstances right?…in our families. My mother is, almost, all the time in bed and my cousins are sick. They have to be with me; I have to contend with my problems, right? Because I was working. So you have to consider all these factors in all the decisions and all of the things are going through your head while maintaining the right attitude and being calm for the benefit of the rest of the island.

AMS_on_the_air_logoListen from the AMS website or your favorite podcast app as Monzón talks in depth about the personal and professional challenges of the hurricane–and a situation that in many varieties AMS members eventually must face: Warning your own neighbors, communities, and audiences of impending disaster as its bears down on your own families and homes.

Then check out her keynote to the 2019 AMS Student Conference in Phoenix this January. Monzón explains how she turned the storm she calls “hell” into a “transformative experience” for herself and for her renowned science education museum programs for Puerto Ricans.

 

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by Mona Behl, Georgia Sea Grant

Guru-shishya parampara is a centuries-old tradition in India that fosters a thoughtful exchange of ideas, expertise, and friendship between a guru (teacher) and shishya (student). The relationship between a guru and a shishya is an emotional, spiritual, and intellectual friendship built on the foundation of trust, respect and commitment.

I got the opportunity to reflect on guru-shishya parampara during a panel discussion led by the AMS Board for Early Career Professionals. The session – “The Early Career Leadership Academy: Beyond Leadership to Mentorship” — aimed to reflect on the 2018 AMS Early Career Leadership Academy (ECLA), address leadership issues in the workplace and provide mentorship to students and early career individuals. Facilitated by my dear friend and colleague, Brad Johnson, the panel discussion featured Chris Vagasky from Vaisala, Kimberly Wood from Mississippi State University, and Alan Sealls from WKRG-TV. Brad, Chris, and Kim are all alumni of the inaugural class of 2018 AMS ECLA. What follows is a brief summary of what I learned from the panel discussion, and I hope it encourages you to consider applying for the 2019 AMS ECLA–the deadline is coming up fast.

Mentorship is friendship. Over time, this relationship develops organically. You may not realize the role that mentors have played in your life until several years later, when you reflect on your experiences and think about the people who have guided you, supported you, and rooted for you, all along.

Mentors come into our lives in various relationships. Some mentors are individuals who are more experienced and have more knowledge than you. Others are colleagues who may be at the same career stage as you. Parents, teachers, siblings, and even friends could all be mentors. Sometimes mentorship can be established in a structured manner. It needn’t be sought only from individuals who enjoy a high-profile career or are well established. Everybody has something valuable to offer. At any stage of your career, you are both a mentor and mentee.

Communication is the key to a good mentoring relationship. Assessing the effectiveness and impact of communication in a mentorship is equally important. An effective mentor gives wise counsel, and the mentee feels comfortable speaking on issues that may be sensitive. Shared vulnerability between two individuals nurtures trust and builds honest mentoring relationships. However, being vulnerable also means taking a risk of harm, which you need to acknowledge and understand. You also need to know when to walk away from that relationship.

Mentoring is a skill that can be developed over time through practice, participation, and partnership. Many individuals who wish to be mentors are confronted with imposter syndrome. Overcoming the imposter syndrome might entail developing a network of peers and colleagues who are able to provide validation, guidance, and support, when needed. If you feel like an imposter, chances are that others in your situation feel the same way.

It is also important to acknowledge the benefits of being a novice in mentorship and recognize opportunities presented by failure. Confronting failure and acknowledging that you don’t know everything isn’t proof that you are worthless. It is an opportunity to grow. Cultivating a mindset of learning instead of performance allows you to view your limitations as growth opportunities thereby catalyzing self-improvement. Extending opportunities to others so that they too can learn and grow builds confidence and generates greater benefits for society.

Mentorship is a doorway to complete transformation for both the guru and shishya. Done right, mentoring can benefit both: you get a chance to share your experiences, learn about challenges and opportunities that you aren’t aware of, and uncover ways of doing things differently.

ECLA is designed to be a transformative peer-to-peer mentoring experience for early career leaders in weather, water, and climate science professions. As a result of the Academy, ECLA alumni have been able to take calculated risks in their lives, connect with colleagues in similar career phases, and acquire affective skills that are usually not taught in traditional academic setting. Most importantly, ECLA participants have been able to build deep and meaningful relationships with a diverse group of peers who support and advocate for one another, lead their organizations through uncertain times, and inspire change.

Mentoring changed my life for the better and I sincerely wish that it transforms your life too. Please consider applying for the a place in the next AMS Early Leadership Academy. The application deadline is 8 March 2019; the Academy, including regular webinars, begins in April and leads to a meeting at Stone Mountain, Georgia, on 24-26 July. From there, the program continues onward with guru-shishya parampara.

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by Margaret Mooney, CIMSS

NOAA’s Cooperative Institute for Meteorological Satellite Studies (CIMSS) in Madison Wisconsin is pleased to announce a virtual science fair for students from grades 6-14 applying GOES-16 or GOES-17 data to investigate weather scenarios and natural hazards.

‘Pleased’ is probably too mild of a word to describe our enthusiasm around this project. Madison is after all, the birthplace of satellite meteorology and CIMSS founder Verner Suomi is widely known as the “Father of Satellite Meteorology.”  Recent launches of the GOES-R, NOAA-20 and GOES-S satellites have made our building a very exciting to place to work! Our goal, and motivation, is to share our passion for GOES-R series data as broadly as possible.

One way to reach students is through the spring 2019 virtual science fair, part of “The GOES-R Education Proving Ground” at CIMSS. A key element of this effort, from the get-go, has been a core group of educators working with CIMSS in close coordination NOAA scientists.

GOES proving ground educators

Above: The original GOES-R Education Proving Ground Team from 2014 – from left to right: John Moore, Tim Schmit (NOAA), Margaret Mooney (CIMSS), Vicky Gorman, Peter Dorofy, Craig Phillips, Brian Whittun, Amy Monahan, and Charlotte Besse.

Most of the original teachers have rotated out of the core group. And sadly, Charlotte Besse, a Florida teacher, has since died of cancer – but not before attending the 2016 GOES-R launch with her family in tow!

A major perk for winners of the GOES-16/17 Virtual Science Fair will be official GOES-T launch invites.   Students will also receive $25 gift cards. Teachers coaching the winning teams will garner launch invites (no travel support) and conference travel support to attend and present at the 2020 American Meteorological Society (AMS) Centennial meeting in Boston.

There will be three winning teams: middle school, high school and grades 13/14 (community college or university). GOES-R Educators from five different states will judge the science fair entries. We will be accepting entries between March 1st through May 3rd, 2019. Guidelines, scoring rubrics and other supporting resources are all on-line at http://cimss.ssec.wisc.edu/education/goesr/vsf.

Please share with your favorite educator!

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Flying the Fastest Skies

February 20, 2019 · 0 comments

How fast can an airliner go? Monday night a Virgin Atlantic Boeing 787-9 reached 801 m.p.h. en route from Los Angeles to London. Matthew Cappucci of the Washington Post reported the jet reached this amazing speed—a record for the Boeing 787-9 and probably the highest speed for a non-supersonic commercial flight—while cruising at 35,000 feet over the central Pennsylvania.

Clearly the plane was hurled along by an intense jet streak; Cappucci showed a sounding at 250 mb—a level nearly as high as the plane—that night over Long Island: the jet stream was moving at 231 m.p.h. This is what pushed the aircraft more than 200 m.p.h. beyond its top airspeed. (The plane’s record speed was relative to the ground, not the swiftly moving air around it.) The Post article states that the sounding “sets the record for the fastest 250-millibar wind speed ever recorded over New York and, probably, the country.”

This raises the other question of speed: just how fast can a jet stream go? It turns out the question is not so easy to answer. To find out, we e-mailed an experienced weather records sleuth, Arizona State University’s Randy Cerveny, who is the World Meteorological Organization’s rapporteur of weather and climate extremes. Cerveny replied,

I had set up a WMO committee this past summer to look into that very question—the strongest tropospheric winds (and so the strongest winds recorded on the planet). As we started to look at the data, we found that by far the strongest tropospheric winds are found east of Japan in the Pacific and normally occur right at this time of the year. They are associated with the normal area when polar and subtropical jets merge. The second area of max tropospheric winds are over New Hampshire and has the same thing happen—polar and subtropical jets merge. BUT unfortunately we ran into serious problems with the quality of extreme tropospheric wind measurements. My experts say that right now the quality of the data for those upper air extreme winds is not good enough to support an investigation for global fastest tropospheric winds. So we are not investigating that record until (and if) NCEI and other groups can establish a viable record for an extreme. We have seen data (again, not good to accept) that has winds in excess of 133 m/s or 297 miles per hour. It is likely that some of those values ARE good but we are still quality-controlling the radiosonde extreme dataset.

With that in mind, we dug into the AMS journals archive and found a February 1955 Journal of Meteorology article by Herbert Riehl, F. A. Berry, and H. Maynard detailing research flights into the jet stream over the Mid-Atlantic states. They record one case of a 240-knot jet stream (276 m.p.h.) and another of 210 knots (241 m.p.h.), each representing averages over 28 miles of flight path.

These can’t be counted as definitive—Riehl et al. emphasized the difficulties of their measurement process. And Cerveny emphasizes that, “No measurement that we have seen at extreme values has been judged of sufficient quality to warrant a full evaluation at this time.”

So for now, just sit back and enjoy the flight.

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Hurricanes are classified by the Saffir-Simpson Scale and tornadoes by the Enhanced Fujita Scale, and now atmospheric rivers—those long, transient corridors of water vapor that fuel flooding rain events each winter in the West, especially California—will also be scaled to enhance awareness and bolster prediction.

The new AR scale ranks their intensity and potential impacts from 1 to 5 using the categories “weak,” “moderate,” “strong,” “extreme,” and “exceptional,” based on the amount of water vapor they carry and their duration. It is intended to describe the strength of ARs as beneficial to hazardous, aiding water management and flood response.

AR-Scale“The scale recognizes that weak ARs are often mostly beneficial because they can enhance water supply and snow pack, while stronger ARs can become mostly hazardous, for example if they strike an area with conditions that enhance vulnerability, such as [where there are] burn scars, or already wet conditions,” says Marty Ralph and co-authors in a paper appearing in the February 2019 issue of BAMS and posted online as an early release today. “Extended durations can enhance impacts,” he says.

Ralph is director of the Center for Western Water and Weather Extremes (CW3E) at Scripps Institution of Oceanography and a leading authority on atmospheric rivers, which were officially defined by the AMS in 2017. The new scale was created in collaboration with NWS meteorologists Jonathan Rutz and Chris Smallcomb, and several other experts. It marks two decades of intensive field research that involved establishing a network of dozens and dozens of automated weather stations to observe ARs in real time and flying research planes through them as they crashed ashore and up and over the mountainous terrain of California, Oregon, and Washington.

Atmospheric rivers are the source of most of the West Coast’s heaviest rains and floods—roughly 80 percent of levee breaches in California’s Central Valley are associated with landfalling ARs. Research shows that a combination of intense water vapor transport for a long duration over a given area causes the biggest impact. But ARs also are primary contributors to the region’s water supply.

The newly created scale is designed to capture this combination, accounting for both the amount of available water and the duration it is available. It focuses on a period of 24-48 hours as its standard measurement. When an AR lasts in an area fewer than 24 hours it is demoted by one category, and if it persists more than 48 hours, it is promoted by a category. Unlike the operational hurricane scale, which has been criticized for inadequately representing the increased impacts of slower-moving, lower-end hurricanes, duration is a fundamental factor in the AR scale. It also aims to convey the benefits of ARs, not just the hazards.

“It can serve as a focal point for discussion between water managers, emergency response personnel and the research community as these key water supply and flood inducing storms continue to evolve in a changing climate,” says co-author Michael Anderson of the California Department of Water Resources.

The scale ranks ARs in five categories:

  • AR Cat 1 (Weak):  Primarily beneficial. For example, a February 23, 2017, AR hit California, lasted 24 hours at the coast, and produced modest rainfall.
  • AR Cat 2 (Moderate): Mostly beneficial, but also somewhat hazardous. An AR on November 19-20, 2016, hit Northern California, lasted 42 hours at the coast, and produced several inches of rain that helped replenish low reservoirs after a drought.
  • AR Cat 3 (Strong): Balance of beneficial and hazardous. An AR on October 14-15, 2016, lasted 36 hours at the coast, produced 5-10 inches of rain that helped refill reservoirs after a drought, but also caused some rivers to rise to just below flood stage.
  • AR Cat 4 (Extreme): Mostly hazardous, but also beneficial. For example, an AR on January, 8-9, 2017, that persisted for 36 hours produced up to 14 inches of rain in the Sierra Nevada and caused at least a dozen rivers to reach flood stage.
  • AR Cat 5 (Exceptional): Primarily hazardous. For example, a December 29, 1996, to January 2, 1997, AR lasted over 100 hours at the Central California coast. The associated heavy precipitation and runoff caused more than $1 billion in damages.

When AR storms are predicted for the West Coast, the scale rankings will be updated and communicated on the CW3E website and its Twitter handle.

“The launch of the AR Scale marks a significant step in the development of the concept and its application,” Ralph commented in an e-mail to the AMS, “and caused me to reflect back a bit on where it came from. All the people and organizations who’ve contributed. The scientific debate around the subject. The creation of a formal definition for the Glossary of Meteorology. The creation of a 100-station mesonet to monitor them in California. The AR Recon effort underway in a partnership between Scripps and NCEP [now NCEI], and in collaboration with the Navy, NCAR, and ECMWF, as well as others.  A number of papers are already in the works using the scale, and we are hopeful that it will prove useful for the public and for officials who must deal with storms in a large area where scales for hurricanes, tornadoes and nor’easters are not very applicable.”

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