November 5, 2018

Nighttime Severe Thunderstorms and Tornadoes Are Likely Tonight in the South



The Storm Prediction Center has issued a tornado watch for portions of Louisiana and Mississippi as a dangerous nocturnal severe weather outbreak gets underway. An enhanced risk for severe thunderstorms—a three out of five on the scale that measures the threat for severe weather—is in place tonight for the Mid-South. Severe weather, especially tornadoes, are extremely dangerous after dark because you can't see and many people start tuning out the weather as they head off to bed.

The situation tonight is a classic setup for severe weather in November. A developing low-pressure system over the Midwest is dragging a cold front across the southern states. In fact, you could apply just about everything I wrote about last Wednesday's risk for severe weather to today's risk, just moving all the locations a bit to the north and east. Warm, unstable air ahead of the cold front will foster the development of thunderstorms, and wind shear ahead of the storm system will allow the individual thunderstorms to turn severe.

All modes of severe weather are possible, including damaging straight-line winds, large hail, and tornadoes.



The Storm Prediction Center has issued a 10% risk for significant tornadoes across much of Mississippi and central Tennessee. The black hatching indicates the area where the environment is capable of support tornadoes that could be strong or long-lived. Tornadoes are most likely in discrete (individual) thunderstorms that pop up ahead of the main lines of thunderstorms that develop along the cold front pushing into the region.

The threat for damaging winds is greatest in the line (or lines) of storms as they organize ahead of the cold front tonight. However, tornadoes are also possible in those lines of storms. Just like we saw last week a bit farther to the southwest, we could see little kinks develop along the leading edge of the lines of thunderstorms. These rotating kinks can lead to tornadoes that develop quickly, sometimes with little or no lead time before it hits.

The storms will move from west to east through the nighttime hours, reaching the Appalachian Mountains by early Tuesday morning. The line will regenerate on the eastern side of the mountains by Tuesday afternoon, bringing the risk for severe weather to parts of the southeast and Mid-Atlantic during the day tomorrow. If you haven't voted yet, it's a good idea to vote early so the weather doesn't affect your ability to cast your ballot.

Severe weather is dangerous anytime, but storms pose a greater threat to life in the cold months and even more so again after dark. Many people want to see a tornado coming at them before they act. On top of the many, many reasons that's a bad idea, the least of which is the fact that you can't see tornadoes after dark. What's worse is that the tornadoes in a setup like this are likely to be rain-wrapped, adding an additional shroud to the tornadoes that makes it impossible to see them even when they're backlit by lightning.

Make sure the emergency weather alerts are activated on your phone. I know quite a few people who tried to disable them in the lead-up to last month's nationwide test of the Emergency Alert System. There are people alive today only because they acted when the Wireless Emergency Alerts pushed a tornado warning to their smartphones. If you don't have a smartphone or live in an area with a bad signal, keep a television or radio on when you go to sleep so you have a chance to hear warnings when they're issued. Do not rely on tornado sirens for severe weather alerts. I know your parents and grandparents swore by them, but these systems are aging, they're not designed to be heard indoors, and (ironically) they're unreliable during a storm.


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October 31, 2018

Some Strong Tornadoes Are Possible Tonight in Louisiana and Mississippi


A potent storm system moving through the southern United States today will trigger severe thunderstorms as the evening hours wear on. The environment ahead of the low-pressure system will allow some of those thunderstorms to spawn tornadoes, a few of which could be strong or long-tracked. Any threat for severe weather is a big deal at night, but especially today due to people going out for Halloween.



I wrote about the broader weather setup over at my blog on Forbes early this morning. A low-pressure system developing over the central south will trigger severe thunderstorms in the warm, unstable air over the stretch of land between central Texas and Mississippi. As we see so many times during severe weather, the threat will occur in two stages. The most dangerous storms are the discrete cells that form in the unstable airmass over eastern Texas, Louisiana, and Mississippi this evening and tonight. A line of thunderstorms will follow soon after as the cold front pushes into the region. The threat for severe weather will cease once the cold front moves through.

A tornado watch was in effect across eastern Texas and parts of Oklahoma, Arkansas, and Louisiana as of the publication of this post. Some tornadic storms are already popping up west of Houston. This activity will increase and spread east as the evening wears on.

Source: COD 


The above chart shows the crossover between winds at the 850mb level (the red barbs, around 5,000 ft) and the 500mb level (the blue barbs, around 18,000 ft). The wide angle of the crossover between lower-level and upper-level winds across eastern Texas, Louisiana, and Mississippi, is a sign that storms that form there may turn into supercells capable of producing tornadoes, damaging winds, and large hail. Damaging winds are the greatest threat from any lines of storms that develop.



This afternoon's update from the Storm Prediction Center paints parts of eastern Texas, Louisiana, and southwestern Mississippi under a 10% risk for tornadoes. The 10% risk zone includes Houston, Shreveport, Baton Rouge, and Jackson. A 10% risk doesn't seem like much, but that's pretty high all things considered. The black hatching on the map above is where forecasters believe the environment is favorable enough for some of those tornadoes to be strong and have long tracks.

Tornadoes at night are dangerous no matter what, but it's even worse when the nocturnal tornadoes occur in late October—when a lot of people don't necessarily expect tornadoes—and when people will be out trick-or-treating or attending Halloween parties. The risk for severe weather will transition shift toward the northern Gulf Coast on Thursday and move through the rest of the southeast on Friday.

Please pay close attention to weather radar and listen for watches and warnings through the evening and overnight hours. Make sure emergency weather alerts on your phone are activated in case a tornado warning is issued when you're asleep.


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October 27, 2018

Fighting Conspiracy Theories Is a Matter of National Security

I'm not shocked that the accused mail bomber, a Florida man who allegedly sent more than a dozen live explosives to prominent politicians, actors, and a news organization, shared posts about the chemtrail conspiracy theory on his social media pages. It doesn't take much for someone who believes in seemingly-silly conspiracy theories to fall for harder conspiracies that can completely warp their perception of reality. That's a dangerous prospect when the person falling down the rabbit hole may lash out based on the posts they read and videos they watch.

The chemtrail conspiracy theory insists that the trails of condensed water vapor (called "contrails") left behind by the jet exhaust of high-flying airplanes are really a mixture of dangerous chemicals intentionally sprayed into the atmosphere to control the weather or make us sick. The conspiracy theory came to prominence in the 1990s at the height of talk radio and spread like wildfire as social media came into existence. There are millions of websites, forums, YouTube videos, and pages on Twitter and Facebook that work every day to try to convince people to buy into this outlandish bastardization of physics and meteorology.

It's silly, of course. Anyone who paid attention during science lessons in elementary school—or, you know, breathed outdoors when it was cold—understands the basic concept of condensation. The hot, moist jet exhaust of high-flying aircraft can condense into a thin, wispy cirrus cloud if the atmosphere is cold and moist enough. These condensation trails can linger for hours and eventually cover the entire sky if it's cold enough and there's enough moisture at flight level, or the trails can immediately dissipate (or not form at all) if it's too dry or warm. Contrails can even form at ground level in frigid parts of the world like Siberia and Antarctica.

Conspiracy theorists would like you to believe that basic physical and meteorological principles are bunk and that the clouds are really a nefarious government plot to unleash chaos on the world. If you're uninitiated to the world of weather conspiracy theories, that's actually one of the tamer theories, coming in behind the folks who believe that antennas in Alaska and Doppler weather radar dishes can create and control destructive storms with precision that allows them to destroy entire towns and even individual homes. (If that was possible, Iraq would be tornado alley and Raytheon would own a controlling stake in The Weather Channel.)

I've written quite a bit about these theories in the past—in fact, I wrote a post much like this one back in 2014. While it's fun to make fun of the silliness of it all, I really do believe in combating nonsense with good science. My anti-conspiracy messaging was effective. For years, I was a frequent target of the ire of popular conspiracy theorists looking to hold their ground. My name showed up on lists of "disinformation government shills" or whatever term they chose to use to make me sound like I was a well-paid CIA agent for writing about things like elementary science.

Protecting the integrity of science is important; however, debunking conspiracy theories like chemtrails plays another important role. People used to ask me why I went to such lengths to debunk such a silly conspiracy theory. They usually said that my bringing attention to these theories could actually lead people to believe in them. My argument goes the other way: if we don't fight back against the nonsense, people who consume false research and start believing in little conspiracy theories like chemtrails will ultimately start down a dark path of believing in bigger and more destructive stuff.

Believing in conspiracy theories makes it harder for someone to discern objective truth in the world. One conspiracy theory often leads to another, and pretty soon that person is open to believing everything they read, no matter how detached from reality the theory is. Once someone believes that the thunderstorm currently raging over their apartment may have been created by the government—and even worse, possibly created specifically to target them—all bets are off when it comes to how they view the world. After all, if they're spraying clouds of sickness in the sky or generating a thunderstorm over someone's house, what else are they capable of? Who's pulling the strings? Who's next on the hit list?

It's tempting to tell people to just ignore the crazy ramblings of random no-names and even to brush off those with millions of followers. But online conspiracy theories don't exist in a vacuum. There are real people behind those keyboards. A real person walked into a pizza joint in Washington D.C. and opened fire because of false information he read online. Real people regularly harass the real parents of the real children who died in the real massacre at Sandy Hook Elementary School because of conspiracy theories they read on Facebook and watched on YouTube convinced them that it was all an act.

Once you're convinced that the world around you is a stage play controlled by a handful of evil people, it doesn't take much fiery rhetoric or bombastic vitriol (hello, Mr. President!) to cause someone to flip out over how scary the world is and try to do something to break the perceived cycle of control and deception. That can manifest itself in scary ways when the person trying to break the system finally snaps and decides to pick up a gun and go to a baseball field or assemble and mail a dozen live explosive devices to former presidents and cabinet members.

The world becomes vastly more dangerous as people become farther untethered from a basic plane of reality. The crazier things become, the crazier people will act. Weather exists as a way for nature to balance itself out. An enormous hurricane over the Atlantic Ocean exists to redistribute heat from the tropics to the poles. Political tension that grows without end will only serve to encourage people already on the edge to engage a severely misguided attempt to correct the world back to the balance they believe should exist—and the world they believe we live in is dramatically different from the way things really are.

When you see a conspiracy theory online—no matter how insignificant—don't let it go unchecked. A fact check may fall on closed eyes, but when we stop defending science, when we let simple facts like the size of a crowd or what someone said on tape become a subjective free-for-all that's up for debate, when we let conspiracy theories rule the internet without anything there to greet curious searchers with an alternative to the bunk they're consuming, we're waving the white flag and conceding the fight to preserve reality. This stuff is too important. The internet is a real place that's run and read by real people who can make decisions that have real-world consequences based on the things they read and see online. It's time we start acting like it.


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October 26, 2018

Can't Stand the Gloomy Weather in the Southeast? Blame Cold Air Damming.

Happy CAD season! Today is the first installment of many gray, soggy days that will cast a shroud of gloom over the southeastern United States through next spring. Cold air damming (CAD) is a frequent phenomenon east of the Appalachian Mountains during the chilly months, and it's something that—despite how common it is—you never quite get used to when you live around these parts.

Cold air damming is one of those great weather terms that doesn't leave much to the imagination. It describes exactly what's going on. The atmosphere is a fluid. Cold air is denser than warm air, so it tends to stay close to the surface. When easterly or northeasterly winds blow cool air across the Mid-Atlantic and Carolinas, the cooler air gets dammed up on the eastern side of the Appalachians because it's too dense to simply flow up and over the ridges. The cold air pools up east of the mountains and leads to chilly, dreary days like we're experiencing today.

Other parts of the country can experience cold air damming—especially in Montana along the eastern base of the Rocky Mountains—but the region between north-central Georgia and the Mid-Atlantic is where this type of weather is most common and most prominent.

Today's bout of cold air damming is about as classic as it gets. Northeasterly winds are blowing chilly air across the Piedmont as a result of high pressure near New Jersey and a developing low-pressure system entering Georgia. That area of low pressure will grow into a full-fledged nor'easter this weekend, bringing heavy rain and gusty winds to the Mid-Atlantic and Northeast. Some of the wind gusts could reach 60 MPH in coastal parts of New Jersey and New York.

The weather on cold air damming days is usually harmless—today, it's just heavy rain with temperatures in the 40s—but it can have significant impacts depending on the overall setup that led to the event. The most common feature is the unshakable gloominess that can blanket the southeast from Atlanta through the Washington D.C. area. Areas to the south could have a warm, sunny day, and even communities just on the other side of the Appalachian Mountains could see temperatures as much as 20-30°F warmer than towns stuck in the pool of cold air. Locations stuck under the wedge of cold air, however, remain chilly and socked under a thick deck of clouds—sometimes even thick fog—until the wind shifts direction and begins to scour away the cold air.

Cold air damming can have major implications on precipitation type when temperatures are hovering around the freezing mark. The wedge of cold air at the surface can lead to sleet or freezing rain when precipitation moves into the area, creating a travel nightmare in areas that aren't used to wintry precipitation or where the ice wasn't particularly well-forecast.

We probably won't have to deal with the winter weather aspect of cold air damming anytime soon. Today's weather is a dreary preview of what we can expect as we head deeper into the fall. Whenever you can't stand that winter-like gloom looming over the southeast or Mid-Atlantic, just look to the west and blame the mountains.


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Unusually Dry Pacific Northwest on Track to See Much-Needed Rainfall, But Not Enough

We don't really get the chance to talk about rain out west these days. A recurring story across much of the past...well, several years...is that the west is thirsty for any drop of water it can wring from the sky while areas east of the Rocky Mountains have more rain than they can handle. Fortunately, the Pacific Northwest is in the midst of a much-needed rainy spell, but the region is also grappling with a hefty rainfall deficit, and it'll take more than a couple of days of rain to make a dent in the region's drought.


NOAA's latest precipitation analysis really tells the tale of this year's weather patterns. The above map shows the departure from normal precipitation since January 1. The departure from normal is measured in inches. Vast swaths of land east of the Rockies have seen feet more rain than they typically see through the end of October—isolated pockets of North Carolina have seen more than 100" of rain this year—while the West Coast between northern California and Washington stands out for having fallen more than a foot below normal in rainfall so far this year.

Thursday's update of the U.S. Drought Monitor shows drought conditions overspreading almost everyone along and west of the Continental Divide. The very worst drought conditions exist over the Four Corners region, but parts of the Pacific Northwest—especially in Oregon—continue to slip into deeper levels of drought. Conditions have actually improved somewhat in northwestern Washington, where some areas have managed to escape drought over the past month or so.


We have the chance to erase some of those rainfall deficits over the next couple of days. Several rounds of rain will move ashore in the Pacific Northwest through early next week, bringing a general swath of 3-5" of rain to western Washington. The highest totals will fall in the mountains, where the highest elevations will see some precip fall as snow, while the Weather Prediction Center predicts about 3" of rain around the Puget Sound in the coming days.

Long-range models continue to show waves of rain moving across western Washington over the next week or so. While this will help erase some of that steep precipitation deficit in some areas, it won't do much to ameliorate the worsening drought in Oregon. The Climate Prediction Center's latest precipitation forecast for the next three months shows heightened chances of below-average rainfall in interior parts of Washington and Oregon, while equal chances for above- or below-normal precipitation exist along the coast.


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October 19, 2018

Texas' Lake Travis Approaches Record Levels as Heavy Rain Continues

It's been pretty calm across most of the United States for the past week, a far cry from what we've experienced for...well, the entire year up until now. Hurricane Michael is out of the picture, the raging Santa Ana winds in southern California have calmed down, and the rest of us only see the occasional passing shower, if that. The only active weather in the United States right now is a persistent slog of heavy rain over Texas, and the persistent slog of rain for days on end is leading to some pretty big flooding problems.

Parts of Texas have recorded more than a foot of rain over the past week. The heaviest rains have fallen in the central part of the state. Much of that rain fell in a short period of time, and much of it fell across the Colorado River watershed.

The surge of water into the Colorado River led to a significant rise in Lake Travis, northwest of Austin that's created by the Mansfield Dam. Water levels in the lake have exceeded major flood stage, and the pool is just six feet shy of its record high of 710 feet. The excess water in Lake Travis is flooding surrounding communities. Water levels are so high that officials may have to open all eight flood gates on the dam, something they've never had to do before.

The National Weather Service has flood characterizations for every major waterway in the country, detailing the kind of flooding you can expect once water levels reach a certain point. Here are the characterizations for flooding on Lake Travis:

714 Flow reaches and goes uncontrolled over the emergency spillway over Mansfield Dam at Lake Travis. Hundreds of homes around Lake Travis flood, many with water well over their roofs or in the second floor level.
710 Hundreds of homes around Lake Travis at Graveyard Point at Lakeway flood with water well over some roofs and into the second floor of lower homes.
705 Disastrous residential flooding of hundreds of homes occurs around Lake Travis at Graveyard Point at Lakeway, many with water over their roofs in up to 17 feet of water.
700 Many homes flood at Graveyard Point at Lakeway on Lake Travis, some with water to their roofs in up to twelve feet of water.
695 Lowest temporary and mobile homes in Graveyard Point at Lakeway on Lake Travis have up to seven feet of water in them.
691 The lowest permanent homes at Graveyard Point at Lakeway on Lake Travis flood. Several temporary homes are in several feet of water.
688 Lowest temporary and mobile homes at Graveyard Point at Lakeway on Lake Travis flood.
685 The lowest temporary and mobile homes at Lakeway at Graveyard Point on Lake Travis are threatened.

The lake is just a few inches shy of the level at which "disastrous residential flooding" is possible, and any further rise in water levels will have a significant impact on surrounding communities.

The region isn't hurting for rain anymore. Drought conditions that existed across large parts of Texas for the past year vanished with the onset of heavy rains over the past month. Only small pockets of drought conditions remain over parts of Texas that largely avoided the recent rains.

Heavy rain will continue across parts of the southern Plains through Saturday, and the greatest chances for heavy rain over the next week will be confined to southern Texas and the Gulf Coast.


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October 12, 2018

A Look at Tropical Storm Michael's Unexpectedly Intense Winds in Central N.C.

More than a million people in North Carolina and Virginia are without power this evening as energy crews try to repair the damage caused by Tropical Storm Michael's passage on Thursday. The Piedmont region was particularly hard hit, unexpectedly experiencing high-end tropical storm conditions for more than an hour during the height of the storm. I live in Rockingham County, North Carolina, one of the hardest-hit areas and a county that saw nearly 70% of its residents lose power during the worst of the storm.

Nasty conditions were in the forecast for central North Carolina for days before the storm. The main risk was always going to be flooding from heavy rain, which we saw in abundance. Tropical storm warnings were in effect for many inland locations to reflect the risk for high winds during the storm, but the warnings were mostly confined eastern parts of the state in the lead-up to the storm on Thursday and only expanded westward on Thursday morning.



The storm here in Rockingham County was relatively tame for most of the day. It poured all day. The winds picked up a bit in the early afternoon hours as the center of Tropical Storm Michael drew closer to the area. I even tweeted a video of the heavy rain and breezy conditions to make note of how well the winds were behaving despite the heavy rain and our proximity to the center of the storm.

That didn't last long.


I was in the living room around 3:00 PM when I heard a loud thunk on the roof. I turned around to look out the window and saw a cloud of leaves and debris swirling over our apartment building. I got away from the window in time to see the trees twisting and bending like I'd never seen during any of the awful storms we've had in the past. The sound of the wind was horrendous, made even worse by the howling whistle coming through the cracks in the windows and front door.

The wind grew stronger as the minutes wore on, at first in buffeting gusts but eventually settling into a steady, constant roar. Shingles and window shutters peeled off of our apartment buildings. The blizzard of leaves and branches and occasional roofing debris and building material whizzed by the window and over the roof. The power flickered on and off for a while before finally giving out about 30 minutes into the ordeal. The wind finally started to calm down after almost an hour.

I had to go back and piece together a timeline to make sure my perception of time wasn't biased by my anxiety. It really did last about an hour. The strongest winds began right around 3:00 PM. I first tweeted about the kicking winds at 3:02 PM. The National Weather Service issued a severe thunderstorm warning about ten minutes after the damaging winds started, alerting Rockingham and Caswell Counties, as well as several counties in Virginia, of the potential for damaging winds of up to 70 MPH. The Storm Prediction Center received a report of a possible tornado in Reidsville at 3:20 PM. A tornado warning was issued at 3:42 PM for more areas of rotation spotted on radar. I noted that the wind had finally died down around 4:00 PM.

Nearly 70% of Rockingham County's 50,000 electric customers lost power at the height of the storm, and more than half still had no power by midnight the following day. The entire City of Danville, Virginia, lost power for the night after the storm. Many counties in central parts of North Carolina and Virginia saw more than half of their residents lose power as a result of the intense winds on Thursday afternoon, according to PowerOutage.US.

I don't like to see the word "unexpected" in weather reporting. Many weather events really aren't unexpected. The folks in harm's way who didn't expect a natural disaster likely weren't listening to forecasts and warnings ahead of the storm. However, I feel comfortable using "unexpectedly" in the headline of this post because the extent of the damaging wind event we experienced was not well-forecast nor was it well-warned in the areas struck by the destructive winds today.

Forecasts regularly mentioned the potential for wind gusts as high as 40 or 50 MPH as the storm passed to our southeast, but what we experienced went well beyond that—for all intents and purposes, parts of the Piedmont in North Carolina and Virginia experienced the winds of a high-end tropical storm for an hour. On top of that, the hardest-hit counties were never placed under a tropical storm warning, and the severe thunderstorm warning for 70 MPH winds wasn't issued until about 10 minutes after the damaging winds started howling.


The National Hurricane Center found Tropical Storm Michael's maximum sustained winds around 50 MPH as the center of the storm passed through North Carolina on Thursday afternoon. The agency analyzed the extent of its tropical storm force winds reaching to the southeast of the center toward the coast.

If that wasn't the bulk of the storm, then what was it?

The windstorm we experienced in north-central North Carolina was more akin to a persistent severe thunderstorm than a full-fledged tropical storm. The winds in a tropical cyclone are driven by the storm's intense pressure gradient. Air rushes in to fill the void left by the low pressure in the middle of the storm, creating the destructive winds in a storm.
Source: Tropical Tidbits

The winds in a tropical cyclone are much stronger just above the surface than they are at the surface. Winds grow stronger with height because they're not limited by the effects of friction. The winds at the 850 millibar level—a few thousand feet above the surface—were blowing as strong as 70 to 80 MPH as Michael moved across North Carolina.

What appears to have happened is that a line of very heavy showers—essentially, thunderstorms without thunder—formed on the northwest side of Tropical Storm Michael's center of circulation as it passed between Greensboro and Raleigh on Thursday afternoon. This enhanced convection was able to mix-down those powerful winds from just a few thousand feet above the surface. The persistent nature of the thunderstorms caused a prolonged period of high-end tropical storm force winds across parts of the Piedmont in North Carolina and Virginia.

The National Weather Service will conduct a survey in Reidsville on Friday to determine if any of the damage was caused by a tornado. I wondered during the storm whether or not we'd been hit by a tornado right when the winds start, but I'd be surprised if the survey crew found that the damage was caused by anything more than straight-line winds. Most of the damage to our apartment complex was superficial—shingles and shutters torn and tossed, torn vinyl siding, tree damage—but there are lots of reports of more serious damage elsewhere around town and around the county.

The seriousness of the destruction along the Gulf Coast dwarfs what we experienced here in central North Carolina, but such intense winds for such a long period of time is a heck of a thing to experience when you're not expecting it.

(Top Image: CIRA/RAMMB)


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October 10, 2018

Here's Why It's So Hard to Verify a Monstrous Hurricane's Maximum Winds

Hurricane Michael made landfall today near Panama City, Florida, with maximum sustained winds of 155 MPH. Its winds were just a few ticks short of a top-of-the-scale category five, but that doesn't matter to the folks in the path of the storm. This hurricane is an unprecedented disaster, and the pain and suffering for residents in the affected areas is only just beginning. The pictures and videos we saw of the damage from extreme winds and storm surge will only get worse as folks in the hardest-hit areas start to check in with the outside world.

As we see with every storm, the folks who come out of the woodwork on social media after every natural disaster are starting to bray their disapproval with the process that goes into recording the strength of the storm. They like to claim that the maximum winds in the storm were really weaker than advertised and its "official" maximum winds were hyped up for ratings, politics, face-saving, or whatever affirms their conspiracy du jour. We're already seeing that trash talk start before the storm surge has even receded on the Florida coast. I normally wouldn't indulge the nonsense so soon after the disaster, but their concern trolling raises a legitimate question:

Why is it so hard to verify the maximum winds of a hurricane?
Source: Tropical Tidbits
Meteorologists have an enormous array of tools available to them to help survey the world around us. You can use advanced satellites, high-resolution Doppler weather radar, a relatively dense network of observing stations on the ground, and even data collected by airplanes, ships, buoys, and oil rigs to collect information about the strength of a hurricane.

The experts at the National Hurricane Center use all of those methods to determine the intensity of a tropical cyclone leading up to and at the point of landfall. These intensity values are reevaluated at the end of the season to check for accuracy and correct for any mistakes. The above graphic shows data plotted from a reconnaissance aircraft as Michael made landfall on Wednesday afternoon.

While we have all those tools available for analysis, it's hard to directly measure the strongest winds experienced at ground level.

Let's start small by thinking about tornadoes for a second. We can get a decent profile of a tornado based on damage surveys conducted by meteorologists in the days after a storm. Experts surveying the path of a tornado can use damage to structures, vehicles, vegetation, and even the ground itself to estimate the winds in a tornado. We know the EF-5 tornado that tore through Joplin, Missouri, had winds stronger than 200 MPH because, not only did it simply wipe away entire neighborhoods, but it did unfathomable damage like compromising the structure of a five-story hospital and tearing away concrete parking blocks that were staked to the ground with two reinforced steel rods.

We know a whole lot about tornadoes despite the fact that few of them ever directly hit a weather station. The odds of any one tornado directly hitting a weather station are astronomical due to their relatively tiny size. Even in Oklahoma, which is the most tornado-prone region in the world, only four weather stations out of more than a hundred have been struck by tornadoes in the past decade.

Since hurricanes are many hundreds of times larger than tornadoes, any given landfalling storm will hit dozens of weather stations along its path. That gives us a lot of information about a storm as it comes inland, but it doesn't mean that the strongest winds in a storm will hit an unlucky anemometer.

The strongest winds in a hurricane are confined to the eyewall, or the thunderstorms that wrap around the center of circulation. Even though Hurricane Michael had maximum sustained winds of 155 MPH, it doesn't mean that all of the winds in the eyewall were 155 MPH. The peak winds occur in only a very small area of the eyewall, an area that usually only covers a couple of miles of real estate. This maximum is typically located on the right side of the eyewall relative to the forward motion of the hurricane. If the hurricane is moving north, the strongest winds will occur in the eastern eyewall because the winds are flowing in the same direction as the hurricane's forward motion.

It's hard to receive direct ground confirmation of the maximum winds in a hurricane because the maximum winds only encompass a tiny portion of the overall storm, and you would have to get incredibly lucky for that small area to pass directly over a weather station with an anemometer that survives the flying debris and the sheer stress of the wind. Not even during 1992's Hurricane Andrew did a weather station directly sample the storm's maximum winds, despite the category five hurricane's eyewall striking a heavily-populated part of southern Florida, including the National Hurricane Center's own office.


We've seen lots of pictures and videos of horrible damage around Panama City and Panama City Beach this evening. Tyndall Air Force Base, which fell under the northern part of the eyewall and saw sunlight as the eye passed overhead, measured a wind gust of 129 MPH during the worst of the storm. Florida State University's campus in Panama City saw a 116 MPH gust during the passage of the eyewall.

Panama City and Panama City Beach were on the western eyewall. Tyndall Air Force Base was on the northern eyewall. There's so much wind damage in those areas that it looks like a bomb went off.

Here's a look at the damage in Panama City:



Veteran hurricane chaser Josh Morgerman tweeted this evening that he was "literally shocked" at the scope of the damage around Panama City.

But Panama City didn't even see the worst of Hurricane Michael's winds.

However, Mexico Beach did:

 
Pictures and videos from the hardest-hit areas are hard to come by because the power is out and cell phone towers have spotty (or no) service. It'll take a couple of days to get a full idea of the damage inflicted by the hurricane's eastern eyewall.

There were no readily-available weather stations in the eastern eyewall of Hurricane Michael to accurately measure the storm's strongest winds. At least, none that we know of. There could be storm chasers' anemometers or personal weather stations that were located smack in the eastern eyewall that we'll get data from in the coming days and weeks. Meteorologists will be able to use wind damage and storm surge measurements to estimate how strong the winds were as the storm came ashore.

This was an unprecedented hurricane for this part of the country. The Florida Panhandle simply hasn't seen a hurricane this strong since accurate recordkeeping began in 1851. It's going to take a while to account for all the damage. It's likely that people died in the wind and storm surge. It will take years for the area to recover from the storm.

But to say that it wasn't as strong as meteorologists advertised—that they purposely overinflated the numbers—based on a handful of wind reports from the northern and western eyewall is just bunk. It doesn't take direct, observed confirmation of wind speeds to know that this storm was everything they advertised and more.


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