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Weather Blog

Will planting more trees stop global warming?

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I have always preferred to exercise outside. I walk on the sidewalks and greenways and hike in the woods. The fresh air and nature’s music – the sounds of the wind through the trees, the birds, running water, etc. – keep me grounded and happy.

Reedy Creek

Trees line a muddy Reedy Creek running through Umstead State Park in Raleigh, NC.

This weekend while walking with my friend at Umstead State Park, I heard a loud, unmistakable popping and cracking, and I looked to our right just in time to see an old, dead tree come crashing down. Believe it or not, that was the second time in a year we have witnessed a tree fall in the woods. If we see one more, I might start to think it has something to do with us.

That moment was a reminder that trees don’t live forever. It was also just part of a thread of tree-themed conversation items that has run through my life in the last month. A larger part is a question I have been asked a few times in recent weeks: will planting more trees stop global warming?

The answer seems simple. After all, we learned in grade school that trees turn carbon dioxide into oxygen, right? Unfortunately, the issue is really not simple at all.

I don’t claim to be a forestry expert or a climatologist. I’m an operational and broadcast type of meteorologist. Still, that doesn’t mean I don’t enjoy reading and researching answers to questions like this one. Over the last couple of days, I have done just that, and trying to find a succinct answer has lead me down rabbit hole after rabbit hole.

It seems – like so many other aspects of weather, climate, environment, and nature – not only is the answer complicated, but all the things we need to consider to be able to answer it are not necessarily completely understood.

If you ask the Arbor Day Foundation, planting trees fights climate change. Period. Its website even tells you which side of your house to plant trees for the biggest benefit if your goal is an energy-efficient home. It says that neighborhoods with tree-lined streets are several degrees cooler than neighborhoods without, and it lists other reasons to plant trees. Of course, what else would you expect from an organization with the goal of planting trees?

An article by Thinkprogress titled “Reforestation Doesn’t Fight Climate Change Unless It’s Done Right,” inspires a bit more deep thought on the subject. The author points out that while reforestation is generally a good idea, planting in the wrong places may actually do more harm than good.  For example, planting more trees in areas that tend to have a good deal of snow such as Canada’s boreal forests, will decrease the earth’s albedo, which is a measure of a planet’s reflectivity. Snow reflects more of the sun’s radiation – earth’s largest source of heat – back to space than trees do. Decreasing the amount of solar radiation reflected would lead to more warming.

An article on Eos, the news website of the American Geophysical Union, makes the same point and talks about afforestation, which is planting forests where none have existed. There’s another interesting idea that has its own pros and cons and if undertaken, must be done so in an intelligent, thoughtful, and well-researched manner. One point to consider is the trees planted should be native to the area and helpful in creating and protecting biodiversity.

One last article that I read was from the International Union for Conservation of Nature. By looking at three case studies in the American Northwest, it explains a little further how reforestation isn’t just about planting trees. I’ll admit, there isn’t much about climate change in this one, but it was interesting nonetheless.

NASA is currently assimilating satellite data into computer models to show how carbon dioxide moves in the atmosphere and changes seasonally. The better those models are, the better we will understand where the carbon dioxide in the atmosphere comes from and goes to, and in the long run, that may help determine just how much planting the right kinds of trees in the right places might help mitigate a warming climate.


I really do suggest reading the following linked articles if you want more detail.

Arbor Day Foundation

Think Progress

American Geophysical Union

International Union for Conservation of Nature

NASA carbon cycle video and story

Weather Blog

Long wait to see weather heroes worth it

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Hundreds of people of all ages stood for hours in a line queued around and inside the General Aviation Terminal at RDU International Airport Wednesday afternoon. Looking at it and listening to the chatter of the people in it, I was reminded of waiting to experience a popular ride at Disney World on a high traffic day. The afternoon heat combined with concrete helped create that memory as well, but RDU had something Disney would never offer — free bottles of water being handed out by Red Cross volunteers and RDU police officers.

Like Disney, with the exception of a few grumpy toddlers, everyone was in good spirits and quite friendly. Unlike Disney, we weren’t in line for a thrill ride in a theme park. Instead, we were patiently waiting to meet service men and women who get to live the ultimate thrill ride every year – the NOAA Hurricane Hunters!

With the exception of a few broadcast meteorologists, very few weather geeks receive the recognition and heroic welcome that these guys do. Part of it is the excitement of meeting the select few who pilot planes that fly through the eye wall of hurricanes, the specialists who drop meteorological instruments into the storms, and the mechanics that keep the planes in top condition for their important missions. The other part is the fact that they bring the planes for the public to see up close and in person.

I would never profess being an aviation geek. I am not even a fan of flying; although, I am a fan of traveling to far-off places and that often requires boarding a plane. Thinking about the job the Hurricane Hunters do from the perspective of someone who suffers motion sickness creates an even greater element of awe for them. I heard them asked by several people whether they have ever been ill during a mission, and all said “no.” Impressive.

big plane

From outside the terminal, a glimpse of the big plane hinted at just how big it really was.

For being the rock stars of the military and scientific research worlds, they were very approachable and friendly. They seemed to enjoy chatting about their lives and careers with perfect strangers.  A few even walked up and down the line soliciting questions from those patiently awaiting their chance to see the inside of the big plane.

Pilot Shannon Hailes stopped to chat with my section of line on the tarmac and offered to have his photo taken with us. I opted to just have him in the picture (the album is posted on my Facebook page), and asked him a few questions about his career and why he chose to be a Hurricane Hunter. Hailes told us that he has been in the Air Force since 1991 and used to fly combat missions. This week is his 26th anniversary of active duty. He chose to join the Hurricane Hunters for three reasons: they are based close to his home in Mississippi, he gets to help people by providing necessary data used to improve hurricane forecasts, and he was “tired of getting shot at.” We thanked him for his service — past and present — as he moved down the line.

After nearly two hours of waiting, I finally got to see the inside of the big plane, which is a WC-130J that has a few customizations specific to its mission including a radiometer pod on the left wing and two external fuel tanks that give it a longer flight range. I was impressed despite not really knowing much about planes. I could see where the crew sits, and I could see where the weather equipment lives. That is really all I wanted to see.

More interestingly to me was meeting the man whose job it is to deploy Dropsondes from the big plane. His name was Chris Beckvar, and he was inside the big plane answering questions. He told us that he has been doing it for six years. He used to be a carpenter and wanted to do something different. He enjoys helping to get information about the storm to the National Hurricane Center so that our Hurricane forecasts can be more accurate. Beckvar explained that he deploys 12 to 14 Dropsondes on a mission, three of four of which are deployed while flying through the eye wall, inside the eye, and back through the eye wall. They also drop the instruments outside of the hurricane in areas around it to find the steering currents to help forecast the direction of the storm.

I could probably spend all day writing more about the experience, but I have other work to do. Feel free to look at the album of photos from the afternoon on my professional Facebook page. For now, I will leave you with a few final thoughts:

  • If you have the chance to see the Hurricane Hunters in person, take it, but bring your patience. The experience is truly worth the wait.
  • While some of the day focused on educating school children, the real goal was to educate the public about this special group’s important mission.
  • The next time you hear or read a hurricane forecast, remember the brave people who fly through and around those storms in order to collect data that is absolutely necessary to making that forecast.

A few links for more information on the NOAA Hurricane Hunters: (Dropsonde information) (Like them!)

Weather Blog

Things that make you say “ugh”

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Most weather forecasters like a good challenge. When you live in the Piedmont of North Carolina, challenges abound.

We have the mountains, foothills, and ocean. We have all four seasons — sometimes all in one week, as the joke goes. Our latitude and our geography both play a role in our weather for better or worse.

This week, our challenge is a stationary front. The boundary between cool air and warm air is just draped across the state from northwest to southeast creating a headache for meteorologists who are trying to publish forecasts for the Triangle area — yours truly included.

forecast high temp map

The NAM model’s forecast high temperatures across the country for Thursday, May 10, 2017

I think I said “ugh” at least 10 times this morning while writing the forecast for the Wake Forest Weekly and the Butner-Creedmoor News. While the towns aren’t very far apart, the forecast could be quite different in a case like the one we have this week. I settled on similar expected temperatures for both, but reality could play out differently than the virtual computer models are showing.

The map above shows one model’s forecast high temperatures for Thursday. The northeastern corner of North Carolina could have high temperatures in the 50s, while the southern portion of the state might see a high in the upper 80s. That’s a 30 degree temperature spread over just one state!

Any little waver in that frontal boundary could make a huge change in the forecast. If it moves a little to the north, we could see warmer temperatures. If it moves a little to the south, it could be much cooler.

Disturbances in the atmosphere are riding along the boundary from northwest to southeast bringing rain and the chance for strong to severe storms over the next couple of days as well. The timing of those showers and storms changes a little with each model run, so a forecaster really has to play it safe and just say “chance of showers and storms” for the whole 24-hour period.


Quantitative Precipitation Forecast map for May 10 – May 15, 2017

The amount of precipitation each location receives over the next few days also depends upon the position of the front. The QPF (Quantitative Precipitation Forecast) map shows a pretty wide range from south to north. The southern tip of the state may only receive a quarter of an inch while the northeastern corner  of North Carolina could get nearly two inches.

Happily, the last disturbance and the frontal boundary will finally exit late Saturday as a low pressure system develops off the Atlantic Coast and moves toward New England, leaving us sunshine and a chance to warm up and dry out on Sunday.

Weather Blog

Severe storm forecasts are improving, but could be better.

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With the system that brought us rain Monday night, there were 215 filtered reports of severe winds (58+ mph) from South Carolina up to the New York/Canada border, as well as seven tornado touchdowns and three hail reports. You could say that our area dodged a bullet since all of the storm reports in North Carolina happened in the western Piedmont.

SPC storm reports

Storm Prediction Center’s map of Monday’s filtered storm reports

Improvements in our computer models over recent years have made forecasting severe weather days in advance possible. As with any weather forecast, the resolution improves as the time period gets closer. In other words, there is some confidence several days out about the timing and geographic area of an event. There is usually more confidence with each model run closing in on the event — two days out, one day out, within hours, etc.

If you watch the progression of the models’ output, you will see slight changes in space and time with each run. It’s normal, and it’s why the forecast for Friday published on Tuesday afternoon may look different from the forecast for Friday published on Thursday afternoon.

Metorologists have many computer model options available to use when forecasting. The most popular three include the GFS, which is a long-range model with course resolution used to see up to 16 days out. The NAM-HIRES is used to forecast for a period within 3 days. The RAP and HRRR are used for forecasting within hours. As the time gets closer, the resolution for the models gets finer.

There is also more reliable initial data and fewer assumptions with the higher resolution models. Imagine looking 16 days into the future and trying to predict what the stock market will do. A lot can change in 16 days. Politicians can make rash decisions, gas pipelines can develop leaks, iconic corporations can announce massive layoffs or take-overs, or a natural disaster could bring transportation to a complete stop. Any one of those things can change the economic forecast.

The same is true for weather forecasting. We can look two-plus weeks out and see what we think may happen giving what is happening around the globe right now combined with mathematical theory and basic assumptions, but there are likely smaller details that we are not taking into account because we don’t see them yet. At one week closer to the date, we can see more details and have more confidence in the way things are shaping up. By the time the date is tomorrow, we have a pretty good idea of what will happen, where it will happen, and when it will happen. Still, occasionally, we don’t get it exactly right, but by the day of the event, we’re pretty sure we know what’s going on.

Going back to Monday’s system:

On Friday, we could tell there would be thunderstorms on the east coast on Monday, and that it would likely be during the second half of the twenty-four hour period. By Sunday, we could see the ingredients for severe weather lining up from northern North Carolina all the way to the Canadian border with New York. By Monday morning, we could tell that the rain should hit the Triangle late in the evening and clear by early morning. By Monday afternoon we could tell that the tornado threat would remain north of the Virginia/North Carolina border, but there was still the potential for severe level winds across North Carolina.

That’s pretty good considering how far the science of meteorology has come in the last century! Still, as with all technology, there is room for improvement.

For example, Monday morning’s outlook for severe weather that evening showed more of the state having the potential for severe, damaging winds. By the time the storms reached the Triangle, the wind threat had greatly diminished, so narrowing down that geographic area  farther in advance is a potential improvement in our forecasting.

Why would that help? Any advances in our accuracy helps meteorologists’ credibility when we predict severe weather days in advance. Higher reliability gives the public more reason to prepare ahead of time to protect life and property when a threat exists. Perception being reality — if you buy into that idea — means that we have to change the public’s view of how trustworthy a weather forecast is. The best way to do that is to continue to improve the technology we use every day.

Weather Blog

Heavy rain caused localized flooding

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The sun is shining! After the amount of rain that has fallen across the area since Saturday, it will take a while to dry things out across the state. While this particular rain event wasn’t historic or record-breaking, it was serious and damaging to many low-lying spots around the Triangle.

satellite image

Satellite image of low pressure circulating over North Carolina the morning of April 25, 2017

I was asked what caused such massive amounts of precipitation over the last few days, and here is the simple, short-term answer: Saturday through Sunday, we saw a frontal system pass bringing the first round of rain. Almost right on its heels, a slow-moving low pressure system that developed over the Deep South arrived and creeped across North Carolina. Drawing moisture from the ocean, it had a large amount available to dump on much of the state.

This isn’t the first time a situation like this has occurred, and it won’t be the last. In fact, we should probably be grateful that it’s not January — at least, those of us who aren’t fans of snow. Instead of snow drifts, we are dealing with the aftermath of localized flooding. Maybe that’s not much better, but the higher elevations recover and get back to business quicker after a heavy rain than after a heavy snow. The lower elevations may take a bit more time.

One infamous low-lying area in Wake County is Crabtree Creek near Highway 70/Glenwood Avenue, which is home to Crabtree Valley Mall. Anyone who has lived around here for any length of time knows that when we see four-plus inches of rain fall in a short period, Crabtree Valley is probably going to flood.

Crabtree Creek water level

Graph of water level of Crabtree Creek at Highway 70 in Raleigh during April 22-24 extreme rain event

The mall opened in 1972, and the first historic peak discharge listed at the Crabtree Creek and Highway 70 gauge operated by the U.S. Geological Survey is listed as June 29, 1973. I found it odd that the next peak flow listed wasn’t until 1996, so I inquired about the history of that station.

According to Doug Smith at the USGS Raleigh office, that gauging station “was operated as a partial record site and a few flow measurements were made at the site beginning in 1972. There were no continuous data collected at that site before February 1988.” There have been at least 10 flood-level or above-peak stream flow events at that gauge since September 6, 1996 (Hurricane Fran).

What contributes to Crabtree’s flooding issues? First and most obviously is that it is a low point in the geography of Raleigh. Second, the amount of urban development surrounding it has grown exponentially over the decades. The more impervious the surfaces created around the creek, the faster precipitation flows directly into the creek leading to faster water level rise and flash flooding. Concrete, asphalt, and buildings surrounding a creek with very little open green space and absorbant soil to slow the flow are a major cause of Crabtree Valley’s troubles.

Another potential factor there and elsewhere is storm drain blockages. When you see areas that don’t often flood, or those that do, flood more quickly, it’s quite possible that nearby storm drains are unable to do their jobs. Storm drains should divert the flow of water away from roads and into locations where the water can safely collect and eventually disperse. Precipitation that falls too fast for the storm drains to do their jobs is a possibility, but another is blockages caused by debris and litter. A simple rule of living with storm drains: don’t put anything down there except storm water. That water flows to streams which flow to rivers which flow to the ocean. Those drains need to be kept clean for that reason at the very least.

Some people would attribute rain events like this one to climate change, and they might be partially right. I have written here before about studies that point to a warming climate as a cause for extreme rain events. Below are links to a couple of relatively recent stories about two such studies. There is no question that climate models predict dramatic warming and related weather events such as heavy single-day rainfall, prolonged drought, and temperature extremes. I would be remiss if I did not acknowledge the documented questions about the accuracy of the climate models and such predictions and their potential fallacies.

Whether flooding is caused by poor choices in urban development, blocked storm drains, slow moving low pressure systems, or climate change, we need do what we can to mitigate the risk. There are some things we have no control over such as the weather. Other things we have pretty good control over include storm drains and choosing to use pervious materials in and around urban development. Considering storm water runoff when deciding where to build both residential and commercial developments can help avoid issues like those faced by our neighbors along Crabtree Creek in Raleigh.

We can’t go back in time and rethink where to put that mall, but we can avoid repeating that developer’s mistake.


Additonal reading not included in the hyperlinks above:

“Study finds more extreme storms ahead for California”

“Extreme downpours could increase fivefold across parts of the U.S.”

Weather Blog

Wow! What happened with that forecast?

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My print forecast in the Wake Weekly made a lot of sense on Wednesday morning when I wrote it. I thought I might have been a little optimistic about Sunday’s forecast high in the mid to upper 70s. I know my personal bias is caused by my preference for warmer temperatures. However, I didn’t expect my forecast and that of the models I used for it on Wednesday morning to be so drastically different from reality.

The forecast for Saturday was for partly to mostly cloudy skies, a high in the upper 70s, and a chance for showers and thunderstorms with the possibilty that a few storms could be strong to severe. It looked to me like the cold front and its rain would approach early Saturday evening and bring those storms with it.

rain total map

Map of the 24-hour rain totals over central North Carolina from 8am, April 23, to 8am, April 24, 2017 courtesy of the National Weather Service Raleigh Office.

What happened Saturday was a bit surprising – the front stalled in Virginia, the sun shone here, and the temperature at RDU International Airport reached 87 degrees! I doubt anyone was too angry over a sunnier reality on a Saturday filled with outdoor events across the area. I know I wasn’t. Well, I was not thrilled that the forecast busted, but I was happy with the nicer weather.

The severe weather Saturday evening was mostly constrained to just north of the Virgina border where the stalled frontal boundary sat. By the time it started moving south, the atmosphere had cooled and lost its instability, which led to more rain and less thunder.

My forecast busted on the cool side yesterday. I had predicted a rainy day, but the rain and the winds from the east kept the temperature 20 degrees cooler than it looked like it would be several days before.

As I beat myself up a bit over the way my printed forecast did not verify, a friend pointed out to me, “Most people don’t expect weather people to be right. They just want some guidance on what to expect for the next few days.” He told me that he appreciated my personal need to be accurate, but he didn’t think accuracy was all that expected.

While I appreciate his sympathetic thoughs, I disagree. Accuracy should be expected. Maybe not on a weekend like this recent one — when the speed of a cold front’s movements ultimately determined the temperatures over two days and there was not a huge amount of confidence in the models three days in advance — but it should be expected.

Meteorologists’ accuracy over the long term is what gains the public’s trust. Without that trust, we can’t expect them to take us seriously when we forecast a chance for severe weather or a winter storm or a hurricane making landfall several days out. While most of the time we are actually right, it’s those times that we are not that the public seems to recall most. It’s human nature, and it is something we have to work hard to overcome — both as forecasters and as humans.

The best way for a forecaster to improve is to spend time picking apart a forecast that didn’t verify and figuring out what happened. Sometimes, there is not much to blame other than the very models we rely on to make the forecasts. Other times, we can see trends in hindsight that we should have recognized in advance. So, that is why this morning, I asked myself the question that I expected to receive from my readers. “What happened with the forecast?”

Weather Blog

Seeing a storm from many angles highlights technology

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GOES-16, also known as GOES-R, is the satellite that was launched in November of last year, and although it is still in the testing phase, it is already showing exciting images. “GOES” stands for Geostationary Operational Environmental Satellite. GOES-16 is one of many satellites, as the number implies, tasked with orbiting the earth and transmitting information about the atmosphere for severe weather tracking, space weather monitoring, and weather forecasting and research.

SPC Storm Reports

Storm Prediction Center Preliminary Reports from April 14, 2017 including Dimmit, TX, tornado sightings.

So far, we have seen some pretty impressive, high resolution images from the new satellite. On Friday, for example, it captured the development and lifespan of a storm that originated on the border between New Mexico and Texas that spawned multiple tornadoes.

On the satellite loop, you can see the overshooting tops of the tornadic supercell — the parts of the cloud that push through the tropopause and up into the stratosphere — showing an extremely potent updraft around which the tornadoes form.

Combining the satellite imagery with radar returns and ground confirmation from Skywarn spotters and storm chasers, meteorologists knew exactly what they were dealing with in that storm. The ability to see a thunderstorm from three different angles in real time is invaluable and amazing. Think about the advances in technology required in the last century for us to be able to track a severe thunderstorm from space, from a stationary point on the ground miles away, and to live-stream a chase feed from an automobile on the internet!

Instead of hearing about a tornado after the damage has been done, we are able to forecast a severe weather outbreak days in advance, warn that a storm may produce a tornado before it does, and confirm a tornado is on the ground at the moment it is witnessed touching down.

If you want to see two of the angles of this particular storm and geek out a bit like I did, check out the Satellite Liaison Blog from GOES-R and JPSS and then search Youtube for the Dimmitt, Texas, April 14, 2017 tornado. A word of warning before viewing chaser videos, sometime the language can be a bit much for children. (Imagine what you might say at the moment you see a tornado touch down.)

Weather Blog

Tornadoes and manufactured homes: an unfortunate combination

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In response to my blog post about tornadoes and sociology shared on Facebook a few weeks ago, Pamela P. said:

When it comes to tornados, I always wish we had sirens. But because that’s not feasible, at the very least they should be installed in every trailer park, along with a storm cellar. Most people of a certain income can be warned through news, social media, cell phones, radio, etc. However, those who live in the flimsiest of housing have the most to fear (trailer parks are always decimated in a tornado), and they are also the hardest to warn. They may not have access to any of the devices mentioned above, and they have a higher chance of not speaking English. Why not pass a law requiring a siren and a storm shelter in every trailer park? Those are just my thoughts. Thanks!

destroyed mobile home

National Weather Service photo: Mobile home in Henry County, Alabama, was flipped and destroyed by an EF-1 tornado while residents took shelter in a near by home.

I agree, Pamela! I have always thought sirens and storm shelters should be required for manufactured housing communities. Truly, I wish there were a safer option in affordable housing for those who live there. Manufactured homes are unsafe in tornadoes, and as importantly, they are unsafe in high-speed straight-line winds as well because they roll easily. So, severe thunderstorms with 70 to 80 mph winds can be just as dangerous to people who live in mobile homes.

A weak tornado of the Enhanced Fujita Scale category of one (EF-1) with 86 to 110 mph winds can push mobile homes off their foundations or completely overturn them. An EF-2 with winds of 111 to 135 mph can demolish one completely. In contrast, an EF-1 tornado would damage roofs of frame houses, and an EF-2 could tear roofs completely off, yet the majority of the structures would still remain intact — assuming they were built sturdily and to code.

So far this year, of the 27 fatalities caused by tornadoes, 17 have been in manufactured houses, seven have been in stick-built houses, two have been outside, and one was inside a vehicle. These numbers are tragic and far too high to begin with, and when you think about how having a reliable hyperlocal warning system and safe, sturdy shelter may have helped save even a couple of them, the situation is even sadder.

Now, I am not saying that I know the situation in each fatality location. Maybe the people received the warnings and chose not to act upon them — that does happen sometimes. Typically though, I choose to believe that when given an urgent, timely warning, if there is a safe place to go, people will wisely opt to shelter there.

Weather Blog

Whispers, marches, and science

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I’m not marching for science on April 22. I think it’s a waste of time, energy, and somewhat hypocrytical.

March meme

Meme posted on the Facebook page “March for Science” on March 31, 2017

The Facebook page “March for Science” posted the meme to the right. “Science is unbound by borders, working at its best when ideas flow freely among peoples and nations,” is a beautiful thought, but it’s not reality, and President Trump is not to blame for that fact. The squelching of scientific free speech came long before he took office, and it came from within the scientific community itself.

Let me comment on one issue I am aware of personally, although I’m sure it is just one of many — the issue of the mythological climate consensus. (Oh, I’m in trouble now, aren’t I?)

The pursuit of science is the pursuit of knowledge by observation, creation of hypotheses, testing of hypotheses, more observation, and tweaking of hypotheses, etc. It is a cyclical process. Only when a hypothesis has been tested over and over in ways that are replicable and it is strenthened by replication can that hypothesis graduate to status of theory. Even theories can eventually be proven incorrect.

Somehow the idea that climate change is caused by an increase in carbon dioxide in the atmosphere has been elevated beyond theory to some new belief system that is not allowed to be questioned. Anyone who proposes an alternate hypothesis or questions the quality of the data and experiments gets blacklisted, name-called, and pushed to the back of the bus, or worse, pushed off the bus altogether — figuratively speaking, of course. How is this behavior by other scientists exemplary a free exchange of ideas?

Many of us who are willing to look into potential alternative causes of climate change speak quietly amongst ourselves in hushed tones because we fear the kind of vehement judgement that our more outspoken counterparts have faced. One example is Judith Curry who testified in front of the House Science Committee on March 29. Here is the link to her oral comments in her own words. If you weren’t aware that some scientists question the consensus, reading her statement might prove quite enlightening.

Personally, I like to read everything I can find about alternative explanations to most super-popular theories because I am proud to be a scientist in the truest sense of the word. I like to keep an open mind, and it would be wonderful if those of us who do could speak above a whisper when we meet.

Weather Blog

Radar images are just snapshots in time

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As I prepared for work this morning, I glanced at the radar and saw a number of signs in a single image that let me know I could be in for a rough commute. The screen, a snapshot of which is to the right, showed that a gust front had just passed my part of North Raleigh, a heavy rain shower was moving toward my house, and a large area of rain was heading into the Triangle.

radar image

A screenshot of the radar image at 6:19 A.M. on Tuesday, March 28, 2017.

I set my phone with its radar app back down and rushed to get out the door before that heavy rainshower hit, but it never did. The shower dissapated, or rained itself out, before it made it to my neighborhood. The large blob of rain behind it developed holes and weakened into lighter showers. The next time I looked at the radar, about 20 minutes after the first, I saw a very different situation. That’s how it goes with the radar.

Any time someone asks me if it’s raining, I follow my answer with the obligatory “right now,” because a radar image is just a snapshot in time. Just like any photograph, it shows the situation at that moment whether that be rain, hail, high winds, rotating winds, or nothing at all.

Doppler radars take four to six minutes to complete a full scan, so the image takes four to six minutes to update. A lot can happen between updates. Tornadoes can form, hail can fall, rain can begin, snow can end, etc. What you see at that moment is what the radar saw in the last sweep.

Radar is a tool for nowcasting and very short-term forecasting at best — a highly important and effective tool. Without radar, we would be utterly dependent upon people on the ground reporting tornadoes, and by the time those reports were disseminated and the public was alerted, the damage would already be done. It wasn’t long ago when that was the case –merely decades.

With Doppler radar, we can see velocity signatures that indicate rotation in storms before a funnel even develops. Our warning time for most storms has greatly improved, and tornado warnings for long-lived, slow-moving storms may even be 45 minutes to an hour in advance of the storm’s arrival at a point on the map. That’s pretty impressive when you think about it!

What about those moments when storms are forming faster than the radar can keep up? Those are the times when it is extremely important to take it upon yourself to pay attention to weather watches and warnings and to look at the sky. Your own eyes on the horizon are invaluable to your safety. If you see a rotating wall cloud, green clouds, lightning, or the effects of strong winds, don’t wait for a warning to be issued. Take shelter.

A rotating wall cloud is a lowering of the cloud base that is rotating around a vertical axis, and it is a sign that a storm could produce a tornado at any moment. Greenish-tinted clouds tend to signal that there could be hail or very large raindrops inside. Lightning is a danger if thunder is close enough to be heard. Strong winds can kick up debris and do as much damage as a weak tornado. All of these things could develop quickly, and being weather aware could be the one thing that saves your life. It sounds rather dramatic, but it’s true.

As we head into one of our busiest storm seasons of the year, practice safe weather watching. Watch the radar and look at the sky to stay truly weather aware.