Blog

54 Articles

Weather Blog

True signs of an early spring

Posted on

About two weeks ago, I reminded you not to trust a randomly chosen rodent pulled from his den and asked for a weather forecast. I stand by what I said. However, I am currently seeing true signs of an early spring in the real world and in computer models.

snake

A grumpy, little snake the author met on a trail at Falls Lake.

Last weekend, I made the most of our gorgeous, warmer-than-normal weather and area state parks, and hiked on Saturday and Sunday. Given that it was barely mid-February, I was not being wary of animals that you typically see in the warmer months, and I almost stepped on a grumpy, little snake. I startled him. He startled me. We took a good, long look at each other, I snapped a slightly blurry picture with my phone while catching my breath, and then we both went our separate ways. Happily, neither of us was any worse for the encounter.

The daffodils in the yard will be blooming by next week, the forsythia is showing its yellow blossoms, and the pear tree is starting to bud. These are all signs of spring, and they are on the early side for central North Carolina. Still, it wouldn’t be the first time that flowers bloomed early and then we managed to eke out one last winter storm if that were to happen.

With that thought in mind, I took a look at one of the longer-range forecast models this morning. Over the next 16 days, it appears that our temperatures will stay mostly above normal. At this point in the year, our average highs are in the mid 50s and our average lows are in the mid 30s. Our weather tomorrow and Thursday will be a little below average, but this weekend we’ll watch those temperatures creep back up into the low 70s.

I don’t know about you, but I don’t mind a little warmth one bit. Of course, I don’t hide the fact that I am a warm weather lover at heart.

I also took a look at the Climate Prediction Center’s website, and they are also showing above average chances for warmer-than-normal temperatures for the foreseeable future. Does that mean that there is no way we won’t get a stray winter storm? Not really. It only takes one cold day and the right conditions aligning to create an icy mess.

According to the State Climate Office of North Carolina, the latest day on record where there was at least a trace of snowfall in Louisburg (Wake Forest’s closest climate reporting station) was March 28th in 1947. Our average last day of snowfall is actually February 7, so the numbers are on our side at this point if you like to play the averages.

CPC map

The Climate Prediction Center’s map showing above average chances for warmer-than-normal temperatures over the next three to four weeks.

Weather Blog

Did global warming cause that storm?

Posted on

You might recall claims over the recent decades that global warming could increase the number of extreme weather events such as tornado outbreaks, major hurricanes, heavy flooding, and lengthy droughts. While few meteorologists would point to one specific event and claim anthropogenic — meaning human-caused — global warming contributed to its severity, somehow the media still made the claim that extreme convective events such as F-5 tornadoes would happen more often and be far more destructive as the earth continued to warm.

The reality is that scientists are still unable to quantatively prove that link between global warming and extreme events on the scale of severe thunderstorms, tornadoes, and even subtropical cyclones. The link to the longer duration events is almost as weak according to some studies. However, it does appear that long-term drought and single-day, extreme rain events are among the few things that may be directly connected to a warmer climate.

A study called “Attribution of Extreme Weather Events in the Context of Climate Change,” published last year included this statement:

Confidence in attribution analyses of specific extreme events is highest for extreme heat and cold events, followed by hydrological drought and heavy precipitation. There is little or no confidence in the attribution of severe convective storms and extratropical cyclones.

I will admit that I didn’t spend the $79 to buy the paperback version of the report, but instead I read a climate scientist’s summary of the report with the conclusion’s key points quoted directly. Forgive me. I’m on a tight budget.

Also, I would like to point out the word “confidence” in that statement. There is still some level of uncertainty, but you can have uncertainty and still have a higher level of confidence about some things over others.

Take a look at 2016. NASA reported it was the warmest year on record and the third record-setting year in a row. Yet, NOAA’S Storm Prediction Center produced the infographic below showing lower than normal severe weather reports and watches across the United States. By our standards, it was a pretty quiet year overall for thunderstorms.

Keep in mind that the SPC’s purview is hail, high wind, and tornadoes, all of which move thunderstorms up the scale from garden-variety to severe. Flooding and hurricanes are covered by the Weather Prediction Center and the National Hurricane Center, respectively, so they are not included in the SPC’s infographic.

My point is to change the perspective of people who still quote those old media suppositions and speculations that global warming will bring more convective storms, bigger tornadoes, and more devastation and destruction from severe weather. Climate change may contribute to some event types and not others, so making a blanket statement regarding all types of weather becoming increasingly worse is dubious at best.

SPC graphic

Storm Prediction Center’s 2016 Severe Storm Summary Infographic

Weather Blog

Happy Arbitrary Adorable, Small Animal Day

Posted on

Groundhog Day is February 2, every year. The spring equinox is on March 20, a little more than six weeks later. The season of winter is about three months – or 12 weeks – long. If you’re good at math, you probably already see my point, but humor me, please.

Centuries ago, Germans decided to pick a day halfway into the winter and an adorable, small animal to which they ascribed some level of intelligence, and watch it come out of its den to see whether or not it saw its shadow on that day every year. Why they didn’t just look for their own shadows, I have no idea. Regardless, that tradition was carried across the Atlantic to Pennsylvania. Instead of a hedgehog as in Germany, the settlers found groundhogs in Penn’s woods. Thus, we have Groundhog Day in the United States instead of Hedgehog Day. Personally, I think hedgehogs are a little cuter, but nobody asked me.

Phil

Punxsutawney Phil. Photo Credit: Christian Science Monitor.
Does he look trustworthy to you?

If the rodent of your choice sees his shadow on February 2, the interpretation is that we will have six more weeks of winter. If he does not, then expect an early spring, or so the folklore goes. Apparently, rodents have alarm clocks and calendars in those little dens of theirs. They wake up every second day of February for the sole purpose of checking the weather. Obsessive little creatures, aren’t they?

Of course, if they really wanted to be technical, they’d let themselves sleep in. If they really counted weeks, they’d see that astronomical spring would start in about six weeks anyway.

As a meteorologist and a person who really doesn’t enjoy cold weather, I prefer to use the climatological start of spring, which is March 1. It doesn’t make the winter any shorter since climatological winter starts on December 1. While everyone is counting their six weeks after Groundhog (or Hedgehog) Day, I only have four weeks more. So, you see, you don’t just have the option of what critter to stalk, you have the option of which version of season measurement to use.

No matter how you measure it – whatever arbitrary day you pick for hopefully logical reasons – does the first day of spring automatically bring warmth and blossoming flowers? Hardly.

If you choose March 1, in central North Carolina, you actually have a decent chance of seeing an ice storm that day. If you choose March 20, the day could be toasty or it could be pretty chilly.  Our record coldest low temperature on March 20 in Raleigh was 22 degrees Fahrenheit in 1923. Our record warmest low temperature was 65 degrees in 1948, and that year also holds the record for the warmest high temperature of 88 degrees. The coldest high temperature in Raleigh for the date was recorded in 1981 at 41 degrees.

In case you’re wondering, Punxsutawney Phil, the most famous and long-lived of all forecasting groundhogs, saw his shadow in 1923, 1948 and 1981.

Why do meteorologists have a problem with Groundhog Day really? My reason is simple: I doubt anyone has held Phil, or our local rodent Sir Walter Wally, accountable for his missed forecasts they way they hold us accountable for ours.

Weather Blog

Take your politics out of my science

Posted on

Until a few months ago, most of you had never heard of me unless you were regular readers of the big daily paper in Raleigh. You probably don’t know that I have been against making climate science a political issue for years.

I can understand why some think public policy is necessary for the purpose of cleaning up the environment, but I am a free market believer. When green technology is affordable and widely available, we can educate the public about it’s benefits, and it will eventually become more widely used. For a real-life example, see solar energy.

I can also accept the argument that rules and laws can be used to force development of such technology. Although, I think engineers focused on environmental concerns would develop it anyway because it is the right thing to do.

The problem I have with politicizing science of any kind, but especially climate, is that the public policy pendulum can swing two ways. In one direction, the scientists have free reign and the ever-ready ear of top officials. In the other direction, the scientists lose credibility and the hope of advancing knowledge in the way in which they are accustomed.  For decades, the pendulum was on the upswing, helping the growth of the Environmental Protection Agency because the people in high office didn’t question the actions of the agency. While its actions are for the betterment of the environment, and I have no doubt nearly everyone working within the EPA believe in its cause, some would say it did so to the detriment of businesses.

So now we have a pro-business president, looking at a political* entity and saying it’s too big and makes economic progress too difficult for certain industries. Now the pendulum is swinging in the opposite direction, and the EPA is reportedly on media lock-down. Do I agree with the actions of the president as they are being reported in news and social media? No. I have friends at the EPA who are concerned for their science and, as importantly, their livelihoods. I would not wish that feeling on anyone.

That being said, I can see how we got here, and making climate change a political issue is a big part of it.

global temp map

Global temperature anomalies averaged from 2012 through 2016 in degrees Celsius. Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio. Data provided by Robert B. Schmunk (NASA/GSFC GISS).

The earth is warming. The climate is changing. Let me just get those statements out of the way before anyone lumps me into the category of “climate denier” because it’s easier to stereotype than it is to read someone’s thoughts open-mindedly.

However, there are still legitimate scientists with higher degrees, peer-reviewed research, and all sorts of credentials out there, who still aren’t 100% convinced that carbon dioxide is the only cause. It may be a big contributor, or a small contributor, but it may not be the only cause.

Should we clean up the air? Yes. Should we reduce greenhouse gas emissions? Sure. Should we take care of the environment so that we leave something nice and clean for future generations? Of course! But to say that all scientists agree that CO2 is the culprit and that public policy – not just nationally, but globally – should focus only on that is a very narrow-minded point of view, as well as untrue.

My guess is that President Trump has realized that the popular claim of total agreement among scientists is untrue and decided that the lie needs to stop. My guess (since I haven’t talked to him myself) is that he is stereotyping in the other direction, thinking that if you’re not a climate denier, you’re a liar. There’s very little gray area allowed when something gets politicized in such a polarizing way as climate change has over the last few decades, and that is the reason I have always said that we should take politics out of science.**

Honest scientists who are searching for the truth behind the symptoms of climate change are being shut down. The first who were silenced were the ones who questioned the popular theories. The last are those who hold to the popular theories. No true scientist should ever be silenced because of unpopular ideas. If they stick to the scientific method and find differing results, those results should be reviewed and there should be attempts at replication, not blind acceptance.

Science is not a popularity contest. Politics is.

 

*Political here is defined as “of or relating to the state, government, the body politic, public administration, policy-making, etc .”
**One definition of science is the systematic study of the nature and behavior of the material and physical universe, based on observation, experiment, and measurement, and the formulation of laws to describe these facts in general terms.

Weather Blog

Tornadoes in January are rare, but not unheard of.

Posted on

This weekend was a rough one for the Southeast United States from Louisiana to Florida, as I’m sure you have already heard. Severe thunderstorms ripped across the Deep South and Gulf Coast from Saturday morning through late last night leaving a path of devastation in their wakes. So far, 29 tornadoes have been confirmed, and the storms are being blamed for at least 20 deaths.

The question I received today was just how rare are tornadoes in January? The answer is that they are somewhat rare, but they do happen. In fact, when they occur on January 22, it is more likely to be across Mississippi, Alabama, and a portion of southern Tennessee than anywhere else.

SPC TOR Map

Storm Prediction Center’s Tornado Probabilities map for January 22

The Storm Prediction Center, part of the National Oceanic and Atmospheric Administration, does more than just predict severe weather – they keep records of it as well. The two maps to the right show the probabilities of tornadoes and the probabilities of significant tornadoes for January 22. The records used to create the maps are from 1982-2011, so this weekend’s storms are not yet part of the count.

The Tornado Probabilities map shows that from eastern Texas through southwestern Tennessee over to southwestern Georgia and in central Florida, there is a 0.20% probability that a tornado will occur on January 22.

If you were a betting person and I told you that a horse had a 0.20% chance of winning a race, would you bet on it? My guess is that you would not, unless you just really loved that particular horse. While chances are slim the horse would defeat all the others in the field, there is still a very slight chance that it will win, and if it does, the world would take notice.

SPC SIG TOR MAP

SPC’s Significant Tornado Probabilities Map for January 22

On the Significant Tornado Probabilities map, the probability of a tornado with an EF-2+ rating on the Enhanced Fujita Scale are even smaller over that area – less than 0.10%. Now you’re betting on a blind horse, but as long as it’s in the race, winning is possible.

This weekend, the blind not-so-thoroughbred beat the odds. All of the ingredients for a major severe storm outbreak with significant tornadoes came together in late January with sorrowful and devastating effects. It happened in the one area we suspected it would based on our historical data, but that doesn’t make it any easier to deal with for those people affected.

Weather Blog

Weather is complicated

Posted on

As I sit staring out the window yesterday at persistent, gray clouds – the results of cold air damming, I reflect upon just how complex weather really is. Don’t get me wrong, I think about the topic almost daily, but this afternoon, it’s heavy on my mind.

Often I am asked why our weather is like this or why the storm did that, and my answer tends to be either too short or too long for the person who is inquiring. It’s too short when I give the most obvious explanation such as “because we had a cold front pass through.” It’s too long when I go into the details of the many ingredients required to setup the situation in question.

Sadly, there seems to rarely be a correct length of answer. How I answer should really depend on how well the person asking actually understands the different dynamics at play. Unless I know that person well, I am usually unsure how weather savvy he is. So, I tend to keep my responses short and may come across as curt. If he asks for more detail, I suddenly offer too much information and come off as a know-it-all.

Venn diagram

Things we know and don’t know Venn diagram visual aid

Believe me. I do not know it all. No person does, and I wish more people were willing to admit it. One of the most useful lessons I have ever learned was when I was told about 15 years ago that there are the things we know, the things we know that we don’t know, and the things that we don’t know that we don’t know. You may have to reread that last part twice. It’s not a typo, I promise, and most of the universe fits into that third set of “things.”

The thought will keep you humble, but before I go too far on a philosophical tangent, let’s return to the weather.

The word “complicated” means “composed of interconnected parts” or “difficult to analyze, understand, or explain,” according to Dictionary.com. That word perfectly describes the weather. Today’s clouds aren’t just caused by humidity or warm air rising as they might be on a more spring-like day. Today’s clouds are caused by high pressure to our northeast, light winds coming from the Atlantic, and the mountains blocking those winds, forcing the cold air they bring to collect at the surface in a dome-like structure stretching across the Piedmont. Cold air sinks, and in this case, literally dams up against the mountains and traps us in this grey, cloudy, chilly day.

For this type of weather pattern to break, something has to change in the atmosphere to our northeast and/or to our west.  That high pressure system either needs to move along, or a frontal system from the west needs to bring in warmer air. Usually, what really happens is some combination of both because it is literally all connected.

Where does the high pressure system go, and the warmer air come from? How did they get there in the first place. What does a butterfly flapping it’s wings in the Indian Ocean have to do with anything? Well, I’m not sure if the butterfly has a huge effect, but our weather is determined, at least in part, by global patterns, waves, and oscillations across the planet.

While we may have a pretty good handle on the basics of weather forecasting at this point – at least it is enough to make some pretty accurate predictions in the short term, there is still an unknown amount of things we still need to learn. Truly, I don’t know how much we still don’t know – nobody does, but I do know that the entire goal of science is to constantly discover new information about the world around us. If we make the assumption that we know it all – even about a single topic, science stalls, so we have to keep an open mind, read different perspectives and studies, and do our best not to shut down to differing viewpoints no matter how much dissonance it causes us.

Okay, so maybe there’s a little tangential thinking here, but I stick to my initial title: Weather is complicated. To say that the universe is complicated would just be too obvious.

 

*Note: This post was actually written Monday afternoon.

Weather Blog

No more snow, right?

Posted on

The sun is peaking through the clouds, and the ice and snow are melting. Feel free to join me in a loud “hooray!” As my mother, a true Yankee, said to me this morning, “The snow is pretty when it first falls, but by the third day, it’s just an ugly mess.”

winter flower

A winter flower covered in snow and ice just off Niki’s front porch.

Now that the temperature has risen above freezing and will stay there for the next week or so, does that mean our winter weather is over?  The question I heard today was, “That was our one big storm, right?”

I have to answer honestly and say probably not, based on the climatology for our area. While meteorologists remind you to be vigilant by saying that it “only takes one storm,” that doesn’t mean you only get one storm per year. In fact, the Triangle area is more likely to see wintry mixes in early February and early March than in early January.

I did take a look at the Climate Prediction Center’s outlook for the next week, two weeks, one month, and three months, and our area does have a better chance than usual to see warmer than average temperatures through the rest of the winter and into early spring. So, maybe this past weekend’s storm was it for us. Maybe.

You see, this is where I have to say that it only takes one storm. While the next three months really could produce warmer than average temperatures overall, there still could be a day or two or three embedded in that time span with another perfect setup for another wintry mess. In fact, the GFS model is showing a possible winter storm taking shape on January 26.

Do I trust long-range models to be accurate that far out? No. Please don’t take that one sentence and run with it as if the next winter storm is a forgone conclusion. My point is that between now and that date, we could see a long stretch of warmer than normal temperatures, and then suddenly have a cold snap and snowfall for a day. Rebounding back to warmer than normal within a day or two afterward would increase our three-month average despite having one more frigid winter storm embedded in those months.

If you’re a snow lover, it may be good news to hear that we could have more this season. If you’re not a snow lover, it may be a bummer. No matter what your preference, if you have lived in Wake Forest for a while, you know that winter typically lasts through early March here regardless of what a rodent may predict in February. I’ll wait a few more weeks before I get on that soap box.

Weather Blog

Snow may be the headline, but cold is the story

Posted on

Snow is in the forecast, and much of North Carolina is under a Winter Storm Warning from this evening through tomorrow evening. Of course, that means everyone is asking meteorologists how much snow we are going to get.  Hardware stores are running out of shovels and ice melt, and there is a run on bread, milk, and sleds across the area. Depending on your feelings about winter weather, you’re either filled with excitement or dread about the possibility of 4-9 inches of the white stuff.

The attention to the precipitation is important, but there is an element of the story that I worry some people are missing: It is about to get bitterly cold by our standards.

If you are planning on being outside this weekend because you’re working or you love the snow or maybe you just have to supervise your children while they are playing in it, keep in mind that our temperatures are not likely to rise above freezing until Monday or Tuesday afternoon.  Add breezy conditions to the cold, and you have some biting wind chills to contend with.

On Saturday, our high will be in the upper 20s with winds at 5-15 miles per hour, gusting to 25 miles per hour at times, creating a wind chill in the lower teens. Sunday won’t be much better with a high near 30 degrees and a breeze in the early part of the day at 5-10 miles per hour, resulting in a possible wind chill in the upper teens.

Many relocated northerners might be used to this, but in these parts, we don’t see over night lows in the single digits and daytime wind chills in the teens very often. It is a different kind of cold that requires layers of warmth and limited time outside.

However you plan to spend this weekend, stay safe and warm, and don’t forget to check on any neighbors that might need assistance due to age or illness.

NOAA Wind Chill Chart

NOAA’s Wind Chill Chart shows what the temperature will feel like based on the actual air temperature and wind speed.

Weather Blog

Snow is in the forecast this weekend

Posted on

As of 11:30 this morning, the National Weather Service had issued a Winter Storm Watch for much of central North Carolina.

NWS WSW map

The areas under a Winter Storm Watch issued by the National Weather Service as of 11:30 AM, January 5, are highlighted in blue. The storm totals are subject to change.

Wake Forest could see as much as four to six inches of snow, but that amount is still subject to change.  The current forecast track and timing show the storm starting here as rain Friday evening and transitioning to snow Friday night. The temperature is not likely to rise above freezing on Saturday, and precipitation will continue to fall through at least early afternoon.  Actual snowfall totals will depend upon how long that rain to snow transition takes to happen.

Many of the forecast models are showing the freezing line somewhere in the vicinity of the southern part of the Triangle.  If that line shifts northward, we will get more rain – cutting into possible snow accumulation.  If it shifts southward, we will see more snow.

Another factor in snowfall amounts is exactly what path the low pressure center takes. Any waver from the current forecast path and we could see more moisture or less moisture. More moisture could mean more snow.  Less moisture could leave us totally dry all together, but the chances of that happening are increasingly slim with each model run.

In addition to the initial snowfall, black ice will be a lingering hazard.  High temperatures are not expected to get much above freezing on Sunday and Monday.  Any liquid that occurs from daytime melting on the roadway will refreeze quickly.  In shadowy areas, it’s possible that there won’t even be any melting. So, the cold temperatures are important considerations when looking at possible hazards from this storm.

What do you do if you have plans for this weekend?  Stay up to date on the forecasts as the situation unfolds over the next 48 hours.  A Winter Storm Watch means travel is expected to become hazardous. While the State Department of Transportation has been brining the roads since yesterday, if there is enough rain before the transition to snow, some or much of that brine could be washed away. Also, brine does not mean that snow will not accumulate; it just slows the accumulation process.

I can tell you that personally, I have changed my plans for the weekend and expect to be fully hunkered down for the long haul Friday night.

Weather Blog

What low forecast confidence means

Posted on

If you read this morning’s forecast discussion from the Raleigh National Weather Service Office, it actually says that the forecasters have low confidence in the forecast “from Friday night onward.” I noticed because I also have low confidence in the forecast, and I was looking to them for their take on what the models are predicting. Does this mean that we aren’t good at what we do? No, on the contrary, it means that we are good enough to know when to admit that the computer models are giving us contradictory information.

GFS dominant p-type

This map shows the dominant precipitation type for Saturday evening according to this morning’s GFS model run. The GFS is just one model ofseveral that meteorologists consider when making a weather forecast. In this map, blue = snow, purple = sleet, red = freezing rain, and green = rain.

Meteorologists do not look at just one computer model when making a forecast because that would be foolish. There are numerous weather prediction models, and each has its own strengths and weaknesses.

These models are created by taking observations from current weather, trends from those observations, complex mathematical equations, and some basic assumptions about the atmosphere and using high speed computers to calculate the most likely outcomes. The current weather observations and the math equations may be basically the same for each model, but the remainder and the resolution can vary, which is why meteorologists look at each one, study each one, and do their best to understand each one’s strengths and weakness.

When all the models show basically the same potential outcome – in other words, their prediction – it is easy for meteorologists to have high confidence in our forecasts.  When the models vary greatly in their outcomes for the same time period, then we are vexed – sometimes horribly. Those are the times when some forecasters lean on intuition and past experience and others just shake their heads.  Most of us will be intellectually honest with you and say that we are not totally sure what will happen and when.

In the case of this coming weekend, our confidence is low because one model keeps our atmosphere pretty dry until late Saturday while the other has precipitation starting Friday night.  Both have the temperature pretty close to freezing, and that makes deciding whether to mention snow or stick with rain difficult when one degree in either direction makes a huge difference in what type of precipitation will fall.

Until the models start to show some agreement, the smartest thing we can say is that we could see wintry weather this weekend, but we aren’t yet sure when or how much. It’s smart because it’s honest, but honesty doesn’t necessarily sell advertising. Flashy, grocery-run inducing headlines do.