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Friday, July 26, 2019

Paris Set Their All-Time Hottest Temperature This Week. Is it Climate Change? No.

By Chris Martz | July 26, 2019



 It's summer, temperatures are hot － sometimes record hot － and as usual, climate alarmism reaches record highs, and climate activists have a field day with it by fear mongering rather than reasoning with facts and data. Every week, various weather events end up getting caught in the spokes of the wheel of climate; it's an endless cycle. Rinse, wash, repeat. This time, it's the [second] European heatwave.

A Bit of Historical Perspective

While countries like the Netherlands, Germany, and Belgium have recorded their hottest temperatures on record this week, Paris's record high of 108.7°F (42.6°C) on Thursday, July 25 made international headlines and consequently sparked climate insanity.¹

The graph below (Figure 1) shows the maximum temperature in Paris, France for each year since 1900.² As indicated by the red trendline, there has been a noticeable increase in the annual maximum temperature in Paris over the long run, however, the trend is not alarming.

 Paris's previous hottest temperature record stood for nearly 72 years.³ On July 28, 1947, the city reached 104.7°F (40.4°C).³ Paris's high of 108.7°F (42.6°C) on Thursday broke the old record by 4°F (2.2°C), which is an incredible feat by any stretch of the imagination. To break an all-time temperature record by 4°F in summer, let alone tie it, is extremely difficult to do, even with global warming. 
Figure 1. Paris, France annual maximum temperature since 1900.
The 1947 heatwave was an incredible one in Europe and it's forever stitched in the memories of elders. 

 In Paris, the heatwave lasted for 12 days (July 22 through August 2) with highs consistently at or above 90°F (32.2°C).³ Two days were at or above 100°F (37.8°C), and four were at or above 95°F (35°C).³

 What really stuck out to me when comparing maximum temperatures this summer with 1947 is that maximum temperatures seem to trace those of 1947 (Figure 2). It's quite interesting and odd.
Figure 2. Paris, France daily maximum temperature for the summer of 1947 and 2019.
Is Climate Change to Blame?

 Like most scientists, I agree that climate change － both natural fluctuations or man-made forcings like land use and urbanization － should cause weather patterns and the intensity and/or frequency of extreme weather or weather-related events to change. 

 It's indeed possible that the warmer atmosphere today as compared to the 1980s may have made this heatwave slightly more intense. However, nobody knows for sure because heatwaves have always occurred; some are just worse than others. It's summer.

 While this heatwave is the latest poster child for the "ecological breakdown," there is a natural explanation for this heatwave, as with all other weather events.

 There's been a persistent weather pattern that's causing this bake fest. A large area of high pressure is stationed over Europe and an area of low pressure is situated off of the coast of Ireland.⁴ The wind flow around the pressure centers are drawing in air from the south, which is blowing hot, Saharan air into Europe (Figure 3).⁴ This natural process occurs with or without 415 parts per million (ppm) of carbon dioxide in the atmosphere.
Figure 3. European surface map. - Met Office.
The air over France at the time of Paris's record high was relatively dry (Figure 4), and as all weather hobbyists or meteorologists should know, dry air heats up faster than saturated air. Had the dew points (and thus relative humidity) been higher Thursday afternoon, the record high may not have been set!
Figure 4. 2-meter relative humidity in France. - weathermodels.com.
It's also worth pointing out that Paris, like any other large city, is a massive urban heat island (UHI). 

 When land is developed, urban infrastructure takes place of land that was once covered with vegetation like grass and particularly forests.⁵ Development limits the amount of plant transpiration (evaporation that cools plant leaves and air temperatures).⁵ Buildings like factories, skyscrapers, houses, and shops, not to mention automobiles and dark urban infrastructure like roads and black roofs absorb and retain more heat than grassy surfaces or forested areas.⁵ 

 All of the heat generated by these objects and surfaces make its way into the atmosphere above the city adding supplemental heat that's not natural.⁵

 I've seen some Tweets from a few meteorologists and other people who claim that the UHI is only or mostly effective at night. 

 While there is some truth to that (as most of the warming seen in the U.S., for instance, is with overnight temperatures), NOAA has created maps from various U.S. cities of both high and low temperatures.⁶ The map below (Figure 5) is of Baltimore, Maryland's 3:00 p.m. afternoon temperature on August 29, 2018.⁶ Notice how the city is noticeably warmer than its more rural surroundings, even in the afternoon! I know this from personal experience because I live in Northern Virginia, not too far from Baltimore and Washington, D.C. 
Figure 5. Baltimore, MD UHI effect.



My Conclusion

 While it's incredible that Paris exceeded their record high on Thursday, it's important that we look not only at trends, but also give a bit of perspective. 

 One can not make a preconceived notion on one daily temperature measurement. 

 You have to first look at whether or not a record temperature occurred in an urban area, then see what the upper air pattern is doing, and lastly look at trends and previous years with similar atmospheric conditions.

 Skeptics who use cold and snow as evidence that global warming is a hoax are always reminded by climate activists that weather and climate are vastly different, and they'd be correct. 

 So, why then do activists blame a single record high temperature, let alone a summer heatwave on climate change? That I can not answer. It seems to me that it's "do as I say, not as I do."

The bottom line is this: heatwaves happen, it's summer, and it's hot.
REFERENCES

 [1] Leister, Eric. "Paris breaks all-time high temperature as deadly heat wave grips Europe." AccuWeather. July 25, 2019. Accessed July 26, 2019. https://www.accuweather.com/en/weather-news/scorching-heat-produces-all-time-record-highs-in-belgium-netherlands-as-western-europe-swelters-under-heat-wave/70008886.

 [2] "Annual Maximum of Monthly Maximum of Daily Maximum Temperature." KNMI Climate Explorer. Accessed July 26, 2019. http://climexp.knmi.nl/data/xgdcnFR000007150_max12_anom_max1_anom.dat.

 [3] "Maximum Temperature PARIS/LE BOURGET." KNMI Climate Explorer. Accessed July 26, 2019. http://climexp.knmi.nl/data/xgdcnFR000007150.dat.

 [4] "Surface pressure charts." Met Office. July 26, 2019. Accessed July 26, 2019. https://www.metoffice.gov.uk/weather/maps-and-charts/surface-pressure.

 [5] "Satellites Pinpoint Drivers of Urban Heat Islands in the Northeast." NASA. Accessed July 26, 2019. https://www.nasa.gov/topics/earth/features/heat-island-sprawl.html.

 [6] Herring, David. "Citizen Scientists take to the streets to map the hottest places in ten U.S. cities." NOAA Climate.gov. July 24, 2019. Accessed July 26, 2019. https://www.climate.gov/news-features/features/citizen-scientists-take-streets-map-hottest-places-ten-us-cities.
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Saturday, July 20, 2019

Heat Wave Hysteria? The Truth Shall Set You Free

By Chris Martz | July 20, 2019


We've made it to mid-July and we are just now having our first major heat wave of the season here in the United States. 

A massive ridge of high pressure has built in over the southeast, which is dominating weather conditions almost everywhere east of the Rockies (Figure 1).¹

Figure 1. NOAA NWS surface analysis for July 19, 2019.
The National Weather Service has issued Heat Advisories, Excessive Heat Watches, and Excessive Heat Warnings, from Nebraska to New Jersey as temperatures soar well into the 90s (scattered 100s are possible too) through Sunday (Figure 2).

Figure 2. Weather alerts for Friday, July 19.
When high pressure systems like this move over an area, air is pulled down towards the surface whereby it's compressed, increasing the temperature.²

The longer the "heat dome" remains over an area, the temperature generally becomes hotter with each passing day until the high either moves away or weakens.² This is because there is little mixing of air which would otherwise prevent heat accumulation at the surface. 

The large amount of sinking motion prevents low pressure systems from moving into areas dominated by high pressure while also inhibiting convection and cloud development in much of the area dominated by high pressure.² As a result, the ground becomes dry due to a lack of precipitation, which can enhance the temperature. The air can also become dry, unless water vapor is trapped underneath the "heat dome," like it is currently. This excess water vapor in and of itself causes other issues like the heat index to soar well into the 100s.

Due to a lack of clouds, the sunlight can feel penalizing.² This buildup of heat at the surface is known as a "heat wave," and they generally last anywhere from three to seven days, although some last longer.

Heat waves like this are typical of summer and from personal forecasting experience, they generally occur two to three times per year. This natural process used to be called "weather," but in 2019, like everything that goes wrong, it's climate change.

Unlike more recent weather or weather-related events, heat waves are actually not new to being blamed on global warming. However, the amount of heat wave hysteria among the public has increased significantly in recent years.

It is in this writing that I have three simple and valid points that destroy the hype on heat waves, like the current one.



Reason #1: Equal, But Opposite

While everyone is fixated on the heat wave, they ignore the unusual cold that's nearby (Figure 3). As all weather forecasters should know, "for every action, there's an equal and opposite reaction." In other words, for every place that there's warm anomalies, there are places with cool anomalies; it's nature's balancing act.

Figure 3. GFS 2-meter temperature anomalies for the U.S. on Friday July 19, 2019. - weathermodels.com.
Climate activists seem to ignore the fact that nature tries to find a balance. If they took note of equilibrium, they wouldn't be fretting over this heat wave, simply because there's  reasonably cool temperatures relative to average out west to balance it all out in the total picture. 

Another thing that really annoys me with these people is that they get anxious because the weather is not "normal," and by normal they mean climatologically "normal." 

Most people, even those who aren't fascinated by the weather like me, understand that "normal" weather rarely happens. It's usually one extreme or the other; hot or cold, warm or cool. These extremes for a single location for a single day end up averaging out numerically for a daily average over the course of 30 years. It's highly unlikely that a daily temperature average of the high and low are going to stack up near the 30-year normal. It just doesn't happen.

Figure 3 above shows the 2-meter temperature anomalies for Friday, July 19. Figure 4 below shows the same thing, but I adjusted the contrast of the image in order to separate the most extreme color differences, or in this case, the temperatures based on the color key to the right. 

It's time for a vision test. 

It looks like to me that there's pretty much an equal balance between extreme heat and extreme cold relative to average on the map (warmth dominates slightly with positive anomalies east of Hudson Bay), so nobody can reasonably make the argument that the warmth outweighs the cold.

Figure 4. GFS 2-meter temperature anomalies for the U.S. on Friday, July 19, 2019 (contrast adjusted). - weathermodels.com.



Reason #2: Some Historical Perspective

Most people are just too lazy to do a little bit of research. It's a simple cold, hard fact. And for this, they believe everything they hear from journalists and politicians, both of which aren't trained as scientists. This is quite dumbfounding considering we have the internet right at our fingertips.

According to the Fourth U.S. National Climate Assessment, the average duration of warm spells (heat waves) has declined from around eleven days during the 1930s to 6.5 days during the 2000s (Figure 5).³ In other words, the average duration of heat waves have declined by nearly 41% since the 1930s.

Figure 5. Warm spell duration. - U.S. Fourth National Climate Assessment.
In addition, the average maximum temperature during any given heat wave has also declined in the U.S. from 101°F in the 1930s to 99°F since the 1980s (Figure 6).³

Figure 6. Average warmest temperature each year. - U.S. Fourth National Climate Assessment.
The 1930s remains the warmest decade in U.S. history. It also had some of the hottest summers that the country has ever seen since records began.

The map below (Figure 7) shows the decade in which each U.S. state (also includes Guam, Puerto Rico, the U.S. Virgin Islands, and Washington, D.C.) initially set their current hottest temperature in the record books, and as you can see, there's an overwhelming number that are colored dark red (almost brown), which indicate the 1930s.⁴

Figure 7. Decade in which each U.S. state and territory initially recorded its hottest temperature.
In fact, 19 (38%) of the 50 U.S. states (I realize Alaska and Hawaii weren't states until 1959) initially recorded their (current standing) hottest temperatures in the 1930s. 22 states (44%) either set or tied their hottest temperatures in the 1930s (Figure 8).

Figure 8. Each U.S. state that set or tied its hottest temperature in the 1930s.
If we had heat like that of the 1930s (click this link to see U.S. heat extremes), people would be screaming "climate doomsday" at ten times the levels they are currently!



Reason #3: Weather ≠ Climate

With most climate activists － especially those who are not trained or degreed scientists － it's "do as I say, not as I do." 

They get triggered if a skeptic uses a record low temperature or record snowfall as proof that global warming is a hoax, and claim "weather and climate are not the same," or that "climate is global, weather is not," then turn around and use a single localized heat wave as evidence of a "climate catastrophe." 



In conclusion...

Using single weather events as evidence that global warming is either a hoax or is a crisis is completely dishonest and two-faced. I have seen too many certain people do it for both reasons, and its usually to try to pass legislation. 

In other words, this entire movement has become a political thing and not one about science. It's clear as day, and if you can't see that, then you're on your own. 

In the end, the truth shall set you free.



REFERENCES

[1] "Current Surface Maps." National Weather Service. July 19, 2019. Accessed July 19, 2019. https://www.weather.gov/oun/sfcmaps.

[2] McLeod, Jamie. "What Causes a Heat Wave?" Farmers Almanac. Accessed July 19, 2019. https://www.farmersalmanac.com/what-causes-a-heat-wave-10912.

[3] "Chapter 6: Temperature Changes in the United States." CSSR. 2017. Accessed July 19, 2019. https://science2017.globalchange.gov/chapter/6/.

[4] "U.S. state temperature extremes." Wikipedia. July 18, 2019. Accessed July 19, 2019. https://en.wikipedia.org/wiki/U.S._state_temperature_extremes.
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Development likely within the next few days in the East Pacific

While there are currently no tropical systems across the Eastern Pacific, development is likely within the next few days.

A cluster of thunderstorms associated with a tropical wave and a disorganized low pressure area is currently centered several hundred miles to the south-southwest of the southern tip of Baja California. This disturbance will be moving into an area of low wind shear and warm waters, which is conducive for further organization and development. A tropical depression or storm is likely to form within the next few days. This system will continue to track off to the northwest and not threaten any important landmasses.

In the Central Pacific, we are watching a disorganized cluster of showers and thunderstorms centered well to the south of Hawaii. This area of disturbed weather is currently around 600 miles south of the Big Island. There is a small chance this area could develop and organize further over the next several days.

By AccuWeather Senior Meteorologist Adam Douty and updated by Senior Meteorologist Dan Pydynowski

NHC E. Pacific Activity


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Tuesday, July 16, 2019

East Coast Braces for Typical Summer Heat Wave

By Chris Martz | July 16, 2019



 Well, it's that time of year again, which means that it's only a matter of time before a heat wave grips a part of the country. Unfortunately, the hour class has run out and one is knocking on the doorstep.

 As you can see in the map below (Figure 1), a ridge of high pressure is building in over the Mid-Atlantic, Midwest, and Northeast this week and will strengthen as we progress into the weekend.
Figure 1. GFS model - weathermodels.com.
While the heat wave will get progressively worse throughout the course of the week as the heat dome strengthens its grip, the weekend looks to be a "bake fest" (Figures 2 and 3). Highs across the lower Plains and up and down the eastern seaboard will be closing in on the 100° mark Friday, Saturday, and Sunday. 
Figure 2. NWS forecast high temperatures, Saturday - weathermodels.com.
Figure 3. NWS forecast high temperatures, Sunday - weathermodels.com
While I don't think many places will tie or break daily or monthly, records are certainly not out of the question. Some models, like the GFS and European, have been astonishingly aggressive with forecast highs, but I think there's more to be desired. I believe the models are overdoing the heat, but we shall see where the chips fall in the forthcoming days.

 Relief will be on the order for next week, as an upper level trough ushers in some cooler air for the east coast.
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Sunday, July 14, 2019

Is Climate Change to Blame for Hurricane Barry?

By Chris Martz | July 15, 2019



 As a future meteorologist, the weather is something I truly enjoy. If you ask any meteorologist that I have met, or if you ask anyone who personally knows me, they'd tell you the same thing. I always think of the weather as being the current prevailing and/or forecasted atmospheric conditions that may be good or bad depending upon my preference.

 Here lately, it seems like politicians have either been confusing weather and climate, or they are just weaponizing the weather to carry out their political agendas, and unfortunately, I think the latter is more likely to be the case.

Every week, various weather events are being used as evidence of the "climate crisis." In fact, over the last two weeks alone, four specific weather events have been used as evidence of our impending doom and gloom; the European heat wave, the Guadalajara hailstorm, the flooding in D.C., and most recently, Hurricane Barry, which made landfall in Louisiana on Saturday, July 13 (Figure 1).
Figure 1. July 2019 climate crisis events.
I have already written articles explaining why the Mexico hailstorm and flooding in D.C. are not signs of the so called "ecological breakdown" (I avoided writing one for the European heat wave due to a lack of time, information, and confusion on whether or not the record was official at the time). This article is focused on Hurricane Barry, which made landfall this past Saturday in Louisiana as a weak Category 1 hurricane.
As usual, people who have their facts backwards are using Barry as the latest "poster child" for climate change. Because people these days believe everything they hear or see on social media without taking five minutes to fact-check, they are succumbed into this dangerous way of thinking, that's politically motivated. 

 Because some mainstream journalists (not all of them, there are good journalists out there) and many politicians are bombarding the public with hysterical nonsense about the weather day in and day out, people have been having anxiety and panic attacks because of even the most ordinary weather events, thinking that they are signs of human-induced climate change, when in fact they are not.

 Whenever one extreme event is over with, the "climate crisis" moves somewhere else as the narrative shifts. It's not stationary.

 I've created two interactive graphs which are shown below. 

 The first graph shows the number of landfalling hurricanes in Louisiana by year since 1851.

 (Both graphs are interactive. You can hover your mouse over the blue columns to see the year and the number of landfalling hurricanes corresponding to the year.)


As you can see by the graph above, there has been literally no trend in the number of hurricanes making landfall in Louisiana since record keeping began for the Atlantic basin (which includes the Gulf of Mexico and the Caribbean) in 1851. The most hurricanes to make landfall in Louisiana within a single season were three strikes, set in both 1860 and 1985.

 The next interactive graph (below) shows the number of Louisiana hurricanes by decade since the 1850s.



As you can see by the red trendline in the graph above, there has been an insignificant decease in the number of landfalling hurricanes per decade in Louisiana.

 (You can access the data yourself on the National Hurricane Center data archive.) 

 Dozens of news articles such as this one and this one have surfaced, not to mention politicians, claiming that hurricanes, Barry included － and last year, Florence － are going to occur more frequently and cause more flooding in the future as the planet warms. Some articles were written prior to the storm being named by the National Hurricane Center, and others were written pre-maturely, i.e. before landfall.

 Their scientific explanation roots itself in the very fact that a warmer atmosphere can hold more moisture, in addition to the fact that the amount of available moisture in the air increases as sea surface temperatures rise. Furthermore, climate activists make the case that hurricanes are starting to move more slowly as a result of a lessened temperature gradient between the poles and tropics (polar amplification) which slow the winds that move tropical cyclones, and as a result, dump out more rain on any given area impacted by a landfall.¹
The problem with attributing [at the very least Gulf of Mexico] hurricanes on climate change is that the sea surface temperatures in the Gulf have seen very little change since 1900. A little outdated I know, but recent sea surface temperatures in the Gulf are actually a little bit cooler than they were during the 1930s and 1940s (Figure 2).² 
Figure 2. Monthly Gulf of Mexico sea surface temperature anomalies from HADSST2 from 1900 to 2011. - Bob Tisdale.
But here's what they don't tell you. 

 Tropical cyclones require many more ingredients to develop than warm sea surface temperatures － preferably at or over 80°F. The Gulf of Mexico's sea surface temperatures are plenty warm enough every year to produce hurricanes of any size and/or intensity. 

 Most tropical cyclones can be traced back to tropical waves or cyclonic circulations that originally formed off of the coast of Africa － or elsewhere. Such disturbances are pre-existing conditions and may intensify into an organized circulation that is sustained by warm sea surface temperatures. 

 If tropical storm systems, like hurricanes or tropical storms run into wind shear, the storm will fall apart as it becomes tilted vertically, which consequently draws in dry air, suppressing convection.³

 Wind shear is generally higher in the Atlantic basin during El Niño events, when there's warmer than average sea surface temperatures in the Equatorial Pacific.³ During La Niña events, wind shear in the Atlantic, Caribbean, and Gulf tends to be lower. Both 2005 and 2017 were La Niña years (Figure 3), and were very hyperactive seasons in the Atlantic.⁴ 
Figure 3. La Nina years.
With El Niño fading currently (Figure 4),⁵ I'm actually a bit concerned that we might see an uptick in tropical development in the Atlantic, Caribbean, and Gulf of Mexico in the coming weeks and months.
Figure 4. CDAS Nino 3.4 time series.
A result of the Pacific Decadal Oscillation (PDO) undergoing a phase change into its warm mode in the late 1970s, is more El Niño events.⁶ Because of this, higher wind shear in the Atlantic basin likely contributed to the record "11-year hurricane drought" in the United States lasting from 2006 through 2016 (in between the active seasons of 2005 and 2017), when there were no major hurricane strikes (Category 3+) in the Continental United States.

It's a fair argument to make － and I would generally agree － that natural variations in Earth's climate, changes potentially caused by man like land use, or some combination of the two could alter the intensity and/or frequency of weather patterns and extreme events like heat waves, tornadoes, wildfires, and tropical cyclones. However, the notion that a warming climate － caused by whatever reason － worsens such events is not supported by observational data. 

 In fact, numerous studies and scientific reports have tried finding a linkage between recent human-induced climate change and tropical cyclones, and results have been inconclusive on the matter. 

For instance, the IPCC openly admitted in their 2013 report that tropical cyclones can not be blamed on climate change. In IPCC AR5 (2013), they stated:
"Globally, there is low confidence in attribution of changes in tropical cyclone activity to human influence. This is due to insufficient observational evidence, lack of physical understanding of the links between anthropogenic drivers of climate and tropical cyclone activity, and the low level of agreement between studies as to the relative importance of internal variability, and anthropogenic and natural forcings."
The National Academy of Sciences (NAS) also says that there is low confidence in attributing tropical cyclones on anthropogenic climate change (Figure 5).⁷
Figure 5. Climate change and extreme weather. - National Academy of Sciences (NAS).
So, why are people blaming hurricanes on man-made climate change? It's because they have no clue what they're talking about and are not interested in facts. It's that simple.

 To blame or link extreme, life-threatening weather events, like hurricanes on man-made climate change while the storm is ongoing, is USELESS information to those who may be in the storm's path. The last thing they, or forecasters like me are worried about is whether or not increases in a trace, odorless gas in the atmosphere slightly worsened a storm headed their way. 

 It's one thing for someone to link a single extreme weather event to climate change after the event is all said and done with, assessments are made, and statistics are looked over. It's another to write articles pre-maturely and assume things based on scientific illiteracy.
REFERENCES

 [1] Skilling, Tom. "Why do some hurricanes move slowly?" WGN-TV | Chicago's Very Own source for breaking news, weather sports and entertainment. July 8, 2017. Accessed July 14, 2019. https://wgntv.com/2018/07/08/why-do-some-hurricanes-move-slowly/.

 [2] Tisdale, Bob. "Are Gulf of Mexico Sea Surface Temperature Anomalies Near to Record Levels?" Bob Tisdale - Climate Observations. April 30, 2011. Accessed July 14, 2019. https://bobtisdale.wordpress.com/2011/04/30/are-gulf-of-mexico-sea-surface-temperature-anomalies-near-to-record-levels/.

 [3] Sosnowski, Alex. What is wind shear and how does it impact hurricanes, other tropical cyclones?" AccuWeather. Accessed July 14, 2019. https://www.accuweather.com/en/weather-news/what-is-wind-shear-and-how-does-it-impact-hurricanes-other-tropical-cyclones/70007871.

 [4] Null, Jan. "El Niño and La Niña Years and Intensities." Golden Gate Weather Service Accessed July 14, 2019. https://ggweather.com/enso/oni.htm.

 [5] Cowan, Levi. "CDAS Niño 3.4 Index." Tropical Tidbits. Accessed July 14, 2019. https://tropicaltidbits.com/analysis/ocean/nino34.png.

 [6] D'Aleo, Joseph. "Ocean Multi-Decadal Changes and Temperatures." Accessed July 14, 2019. http://icecap.us/docs/change/OceanMultidecadalCyclesTemps.pdf.

[7] "Climate Change and Extreme Weather." Penn State Department of Meteorology and Atmospheric Science. Accessed July 14, 2019. https://www.e-education.psu.edu/meteo3/l10_p9.html.
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Monday, July 8, 2019

Something's Rotten in D.C., and It Isn't Those Rain Totals

By Chris Martz | July 9, 2019



It seems as if every day, there's someone linking ordinary and not-so-ordinary weather events to the "climate crisis." Dare I say that we should actually do a little fact-checking first. 
"Nope, we know the answer already. Climate change causes all weather events, big and small, normal and rare."

 Yet, while my italicized quote is supposed to be funny, that kind of mentality has embedded itself into our reality. 

On Monday, July 8, Democratic congresswoman Alexandria Ocasio-Cortez (AOC) stated that "Unprecedented flooding is quickly becoming a new normal. Despite that, Republicans are tripling down on fossil fuels w/no plan to transition off them, or make the critical infra investments we need to prep for the climate crisis. Each day of inaction puts more of us in danger."
The irony of her statement － when was the last time a politician actually cared about the people they represent? Okay, okay, I'm going to stick to the science!

 The congresswoman also stated that extreme weather or weather-related events like flooding and wildfires have gotten worse due to the "climate crisis." (I'm using "climate crisis" in order to be more scientifically precise, like The Guardian stated they would do with their articles. That was pure sarcasm).
Her reference to "unprecedented flooding" was fueled off of headlines detailing flooding in the Washington, D.C. area (where I live and forecast the weather). Indeed, she was right in the sense that the flooding on Monday was impressive, but the usual scaremongering tactic of blaming fossil fuel emissions on the event is just plain pseudoscience and superstition, and doesn't root itself in reality.

 According to the National Weather Service office in Sterling, Virginia, official observations from Reagan National Airport indicate that 3.44 inches of rain fell Monday, July 8. This rainfall was not only a record for the date (old record was 2.16 inches from 1958), it was a little over 92% of D.C.'s average July monthly total rainfall of 3.73 inches!
All of this was caused by a complex of slow-moving thunderstorms that rolled through the area Sunday evening and Monday morning (I can confirm since I live in the area). This was not caused by magic CO₂ fairy dust in the atmosphere. 

 Flash floods from thunderstorms generally occur when thunderstorm cells are slow-moving, or when different thunderstorm cells move over the same area over and over again.¹ The severity of a flash flood － in terms of how fast it develops and how high the water levels get － depend upon factors like the duration of the rain, the rainfall intensity and terminal velocity of raindrops, and/or soil moisture.¹ Sunday evening and Monday morning, the storms were slow-moving and rainfall intensity was high. In addition, last year (2018) was the wettest year on record in Washington, D.C. with 66.28 inches of precipitation falling on the city.² 2019 has also been a pretty wet year, with 27.12 inches of rain falling so far.² Thus, soil moisture remains high, and as a result, excess water from rain or runoff can't seep into the ground, creating a higher risk for flash floods.
Figure 1. Total precipitation January - December in Washington, D.C. 1872 - 2018,
So, with that said, does her claim about "unprecedented flooding" in D.C. hold any water? Spoiler alert, it doesn't!

 Before I show the statistics, her statement doesn't even make any sense. If each new flood is "unprecedented," then that's climatologically not "normal." So how can it become normal? Maybe she means that flash/inland/river flooding is the new normal? If so, that's still wrong. Two strikes in a row AOC, the third is OUT.

 Washington, D.C. has a long history of flash flood events, river flooding, and heavy rainfall events, most of which are not even noteworthy because they happen so often, especially the during spring and summer as daytime heating and high dew points act as "trigger mechanisms" to initiate thunderstorm development in the afternoon hours.


Heavy Rainfall Events

 Meteorologist Kevin Williams of Rochester, New York made note that of the top ten heaviest 24-hour rainfalls in D.C., only two of the ten have occurred this century. Of the eight heaviest 24-hour rainfalls to be officially recorded in D.C. during the 20th century, seven of them occurred prior to 1975, and five occurred prior to 1970. 
So, obviously, heavy rainfall events in D.C. are not a new thing. What about actual floods?

Some Select Flash Floods & River Flooding in D.C. 

David Birch, a friend of mine and a well-known solar researcher in the climate community sent me this link Monday afternoon, which has a list and description of some of Washington, D.C.'s largest flood events in memory.

 So, let's break it down.

 1. The "Great Fresh Flood" of May 1771 was devastating to the Virginia colony and Washington, D.C. area.³ ⁴ The Virginia Gazette reported, "...From the mountains, to the Falls, the low Grounds have been swept of almost every Thing valuable; and the Soil is so much injured that it is thought not to be of Half its former Value, and a great Part is entirely ruined...³

 2. On June 2, 1889 the Potomac River crested 12.5 feet above flood stage. Many streets, including Pennsylvania Avenue were flooded (Figure 2).⁴
Figure 2. Pennsylvania Avenue flooded on June 2, 1889 in Washington, D.C. Photo credit: Library of Congress.
3. The Flood of March 17-19, 1936 was one of Northern Virginia's, Maryland's, and D.C.'s worst natural disasters in history.⁵ This flood is often noted as the "Record Flood of 1936," "Great Potomac Flood," or the "St. Patrick's Day Flood of 1936."⁵

 March of 1936 was pretty warm in Washington, D.C., averaging 3.5°F above normal for the month, despite frequent drastic temperature swings from the 40s to the 70s and back.²

 Most of Eastern West Virginia, Northern Virginia, and Maryland had received their entire March monthly average rainfall by mid-month.⁵ While most of the rainfall events were relatively small, the high frequency of them that March allowed stream water levels to increase. 

 The storm that caused the major flooding was on St. Patrick's day in 1936, when a deepening low in the Carolinas pushed southeast winds and moisture into the region causing intense rainfall.⁵ While most areas in and around the D.C. area saw less than two inches of rain, areas to the west, like the Blue Ridge Mountains received well over four inches of rain in that two day period.⁵ The list below is from the National Weather Service. You can see just how impressive those two-day totals were (Figure 4).
Figure 3. Two-day rainfall totals from the March 1936 storm.
4. The "Record Flood of 1942" unfolded over an eight-day period; October 11-18.⁴ During this event, D.C. picked up over six inches of rain, and floodwaters reached the steps of the Jefferson Memorial (Figure 4).⁴

Figure 4. Jefferson Memorial steps flooded in October 1942 flood.
5. The Flash Flood of August 11, 2001 was one for the books (Figure 5). What's odd about this flash flood event was that it occurred in a narrow band stretching from Warrenton, Virginia to Washington, D.C.⁴ Some storm reports from D.C. and nearby communities noted that upwards of seven inches of rain fell that day.⁴ Reagan National Airport only received 0.92 inch of rain during the event.²
Figure 5. Flash flood of August 11, 2001.



Weather vs. Climate

People like Representative Cortez seem to have a very difficult time grasping the fundamental differences between weather and climate, which is the fact that weather is based on short-term atmospheric conditions and climate is based long-term trends. 

Any individual weather event － regardless of how extreme it is and whether or not it's unprecedented － can simply not be used as evidence for OR against changes in Earth's climate system. The atmosphere － as we know － is very chaotic in nature and any type of extreme weather event is bound to happen at some time or another notwithstanding global average temperature change. 

If you look at the trends in global lower tropospheric temperature since 1979, you'll see that they have undoubtedly gone up, yet we've always had floods (hear that AOC?), we've always had hurricanes, we've always had tornadoes, wildfires, dust-devils, droughts, heat waves, cold waves, thunderstorms, blizzards, and monsoon seasons. While the frequency and/or intensity in such events may or may not alter in either direction due to changes in the climate, because they have always happened, because they're prone to happen, and because there's a lack of sufficient global long-term data, it is extremely difficult and arrogant to pinpoint one weather event as evidence of a "climate crisis."

Flash flood events like the one that occurred on Monday in D.C. are associated with thunderstorms, which are considered "severe convective storms." According to the National Academy of Sciences (NAS), there is very little evidence to link thunderstorms to man-made climate change, global warming, the climate crisis, or ecological breakdown － whichever way you'd like to call it.⁶

Figure 6. Climate change and extreme weather - National Academy of Sciences (NAS).
If I were to sum up this nonsense in one sentence I'd say, "There's something rotten in D.C., and it isn't those rainfall totals, it's clueless politicians."
REFERENCES

[1] "Thunderstorm Hazards - Flash Floods" National Weather Service. Accessed July 9, 2019. https://www.weather.gov/jetstream/flood.

 [2] xmACIS2. Accessed July 9, 2019. https://xmacis.rcc-acis.org/.

 [3] Yeck, Joanne. "The Great Fresh of 1771." Slate River Ramblings... March 13, 2017. Accessed July 9, 2019. https://slateriverramblings.com/2017/03/13/the-great-fresh-of-1771/.

 [4] Ambrose, Kevin. "Floods - Washington Area Floods." WeatherBook.com. Accessed July 9, 2019. https://www.weatherbook.com/flood.html.

 [5] "1936 Flood Retrospective." National Weather Service. Accessed July 9, 2019. https://www.weather.gov/lwx/1936Flood.

[6] "Climate Change and Extreme Weather." Penn State Department of Meteorology and Atmospheric Science. Accessed July 9, 2019. https://www.e-education.psu.edu/meteo3/l10_p9.html.
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