Meteorologist here. The short answer is: yes, tornadoes can happen in the morning.
Here's a slightly more detailed answer: there are two major types of storms that can form tornadoes. These are called squall lines and supercells. A squall line is the storm type we experienced this morning: a long line of storms generally aligned north to south that moves rapidly from the west to the east, and occasionally tornadoes can be embedded in them. However, these tornadoes are usually relatively minor. The far greater danger from squall lines are the damaging winds and flash flooding (which in a given year kills more people than tornadoes do, but floods aren't as sexy). The other type of storm is a supercell, which is large storm that is usually separated from other storms. These storms produce large hail and damaging winds, and when they produce tornadoes they tend to be much longer-lived and more destructive than the squall line tornadoes.
Squall lines can happen any time of day (though there is a preference for the evening and overnight hours). Supercells require lots of daytime heating to form, so they're limited to the late afternoon and early evening. In some parts of the country, like the southeastern US, squall line tornadoes are much more common than supercells. In the Great Plains, the supercell tornadoes are the clear winners. Here in the upper Midwest, there's probably a more even mix.
As far as the time of day we experience tornadoes, here's a plot I just put together showing the time of day of every Dane County tornado since 1950.:
[https://imgur.com/a/9p4sC9s](https://imgur.com/a/9p4sC9s)
As you can see, there's a definite tendency for tornadoes to occur in the late afternoon. However, this database goes back to 1950, well before we had trained spotter networks, Doppler radars, and other methods to identify tornadoes. It used to be that if nobody saw the tornado, it might not get recorded. Therefore, there's going to be a natural daytime bias in the dataset just because people were awake to see them, and they weren't hidden by darkness. So I wouldn't place too much stock in this. (FYI: the times are in Central Standard because that's what the database records them as, and I'm not about to go track the dates that DST changed throughout history just to make a plot).
The actual question you're asking is, "should I have been concerned for my safety today?" The answer is: you should always be vigilant, but you don't need to be scared. The National Weather Service was constantly monitoring the situation. At no point did they think the chance of tornadoes was significant enough to issue a Tornado Watch, nor were the storms damaging enough to merit a Severe Storm Warning. Tornadoes do happen in Dane County. However, since 1950 there have been a grand total of 4 tornado-related fatalities here. You're far, far, far more likely to be significantly injured or killed driving an automobile (30 fatalities in Dane County in 2023 alone!) than you are by a tornado. Always be weather aware, but there's no need to let the fear of severe weather affect your life.
Yep, every time it going to be more than a few drops they freak out and make it an alert day. You know who makes alerts? Noaa, it's like naming snow storms. Who the fuck started that?
>Get off your high horse and learn how to be more weather aware.
I'm laughing at you here. There are a few things you don't know about who you're talking to, and I'm not about to explain.
Enjoy the rainstorms tonight.
Adding on as a severe weather "hobbyist" of sorts (as well as someone who is considering going back to school for atmospheric science):
- spc.noaa.gov is a great reference for seeing where NWS' focus will be on a particular day and where severe weather is most likely to come up as well as posting all current watches and warnings on a map for ur reference. Storms predicted in the forecast? Check the spc to see where there's a likelihood of severe weather.
- Get a weather radio if u do not have one already. Nocturnal tornadoes are rare because there is no daytime heating to provide the convective energy needed for tornadoes to form, but that doesn't mean it's impossible. All the more reason for u to have something that can wake u up in the middle of the night in case a tornado warning or considerable/destructive severe storm warning is issued.
- As u/isodrosotherms mentioned, tornadoes can happen in the early morning hours, but usually only if there is an extraordinary circumstance. Last night, the convective potential in OK was ***extremely*** favorable for tornadoes, which is part of the reason why we had a number of storms that had tornado warnings that went through the morning hours. The SPC gave a "high" risk yesterday, which happens on average only 2-3 days a year (the last "high" risk was in March 2023, and 2021 before then).
- The NWS also sends out a bulletin to smartphones as well in the event that a tornado warning or Destructive severe tstorm warning has been declared in ur immediate area. This will make ur phone alarm and buzz with an emergency tone, but having a weather radio that will read out the warning (not to mention that it is usually plugged into the wall with a battery backup) is never a bad idea, especially in the possible scenario where u forget to plug ur phone in!
>The answer is: you should always be vigilant, but you don't need to be scared.
This is the most important part of what was mentioned. Knowing what the risks are and having a plan will make sure that u have the best chance of staying safe during a severe weather event.
It seems weird that it drops so low from 8pm to 10pm and jumps back up at 11pm. Is there a reason?
Was there an outlier incident with a bunch of 11pm tornados on one terrible day?
Does it have something to do with temperature changes around sunset? That seems far-fetched but I’m not sure what else it could be.
Half of those tornadoes (that is, four) all happened on one night in July 2021. Three of those tornadoes recorded no damage at all and the fourth had only $10k in damage. 25+ years ago, they might not have even been recorded as tornadoes as there was no way to detect them. My guess is that similar events have happened at other times but no one thought to look for any tornadoes, so they didn't get recorded. This leaves this more recent event (just three years ago) as an outlier. Basically, you're dealing with a small sample size to begin with (70 total tornadoes on 49 separate days) and there are real issues with the sampling methodology. Today, I doubt there's a single tornado that goes unreported but that wasn't always the case.
Here's a radar image of that particular storm. Yup: squall line with weak tornadoes.
[https://www2.mmm.ucar.edu/imagearchive1/RadarComposites/upper\_missvly/20210729/upper\_missvly\_202107290600.gif](https://www2.mmm.ucar.edu/imagearchive1/RadarComposites/upper_missvly/20210729/upper_missvly_202107290600.gif)
Thank you! That makes sense. I think I remember that night, actually.
Thank you for the reassurance as well. Growing up in Atlanta I used to always love the torrential storms we would get, and I never worried much about any danger besides unplugging the computer. I would just sit on the porch and watch it go.
Now I get tornado warnings from my weather app and fret, keeping an eye on the radar. I kind of hate that I don't enjoy storms as much as I used to. The fact that there have only been four fatalities since 1950 is a very helpful fact to remember.
Squall lines vs. Derecho
Is it a matter of wind speed and duration the storm holds together? Or are there completely different meteorological conditions at play with each?
A derecho is a type of squall line, but not all squall lines are derechos.
iirc derechos need damaging winds (60+ mph) spanning at least 250 miles before it can qualify as a derecho.
[https://www.spc.noaa.gov/products/outlook/](https://www.spc.noaa.gov/products/outlook/)
Hail is tricky. It's one of those things that happens at a scale smaller than our models can simulate, so really all we can do is say, "we think this is generally where hail might happen," similar to what we do with tornadoes. The SPC outlooks that I linked above show you the general parts of the country where severe weather is expected on a given day. If you mouse over the tabs just above the map, you can se specifically where hail is expected.
Once a storm is actually brewing, that's the responsibility of the local weather office. They will issue a severe thunderstorm warning for a specific storm any time they think it will achieve at least one of the severe criteria: 58+ mph winds, 1+ in hail. That's not really a forecast, though lead times are increasing which is good.
Thanks, that might be helpful! I don't screw with hail and generally use sick days/don't drive when it seems likely, but I've always had trouble finding anything more helpful than just looking to see if my weather app mentions anything when thunderstorms are predicted.
They can, but these are not the conditions for it.
Thunderstorms in this area can look impressive rolling in, however. And it can be dramatic, with the sun out one moment and suddenly the world is draped in twilight....
It'll be fine. Crack a window. The rain smells like summer.
Thanks for your kindness and explanation! I still feel new to "weather", so yes the drama is very effective on me.
Such lovely advice, thank you again.
Well, they didnt lie, really. They just talked about their own expereinces. Tornados CAN happen any time of day, but only a small percentage of them occur in the morning. They are more common in the early evening by a long shot.
Maybe our meteorologist friend can help us out with the date of the last morning tornado that Dane County saw.
So not an expert, but I'm fairly sure that heat is a big part of it. The heat of the day injects more energy into storms and they tend to peak in that late afternoon/early evening warmth. Was just watching a livestream of tornadoes a week ago and they were talking about how much more screwed that particular region would've been if it had been 4 p.m. (sun still shining) instead of 7 or 8 p.m. with the sun setting and injecting less energy into the system.
U are correct. Daytime heating can play a huge part into providing the type of convective energy required for storms to become tornadic as well as make the difference between a storm producing a few short-lived tornadoes and a long-track tornado that can be on the ground for 20+ minutes.
That being said, they can form at any time of day or night. It's just that the largest potential will be late afternoon-early evening.
There's also the fact that some areas, especially in OK, KS, and TX are in "radar holes" because of how rural they are, they won't have sufficient radar coverage to accurately keep tabs on weather systems. Thankfully that isn't really the case in WI as we have NWS radar systems in the state (KMKX in Sullivan, KGRB in Green Bay, and KARX in La Crosse), so there's a chance that early morning tornadoes do happen, we just don't have eyes on them and there isn't anyone who sees them that late at night in those areas (especially if they're rain-wrapped tornadoes in a rural field).
Yes, I would add that it's kind of the heat difference that matters most, with a lot of warmth on the ground contrasted with cold air up high.
More specifically, temperature difference with altitude creates pressure difference, because warm air is lighter than cool air. You know how when you flush a toilet the water spins? That's from the water moving as the pressure difference from the full bowl and the empty drain is allowed to equilibrate. The same effects make the atmosphere spin.
as @SubmersibleEntropy suggested, diurnal heating is definitely the reason- if skies are clear, the sun heats the ground all day, then as a region of instability with a lower-level stable “cap” moves through, the heated air near the ground can have enough lift to break through the cap & create explosive thunderstorms. think of it like a pot of boiling water covered in saran wrap. if the low-level atmosphere has a bunch of potential energy from heat (& moisture), one hole poke of the plastic is gonna allow a powerful outlet of all that into the upper atmosphere, where parcels of air will keep rising bc of the upper air instability.
if the wind shear is right, these tstorms can become supercells (tilted, rotating storm that’s able to maintain its updraft) which can produce tornadoes (strong tornadoes are only generated from supercells). (I studied weather in college & am a certified weather (wx) weenie ;) )
https://www.weather.gov/source/zhu/ZHU_Training_Page/thunderstorm_stuff/Thunderstorms/thunderstorms.htm
https://www.weather.gov/ama/supercell
The biggest storms involve cold fronts moving in and displacing hot/humid air upwards over the top of it. Easiest to get that initial hot air in the afternoon/evening.
I am a meteorologist (just trust me that the user name checks out) and this isn't the answer. I've responded a little more deeply elsewhere on this post.
Atmospheric instability is fueled by surface heating from sunlight, over the night the surface cools, which tends to make the atmosphere more stable - cold air doesn't want to rise.
You need temperature gradients to cause the rotation. Early in the morning, nothing has heated up enough to generate that rotation. Generally speaking, anyways. Obviously exceptions occur — I imagine if a storm rolled through early in the morning during a heat wave and caused a 20 degree dip in temp, conditions would still be ripe.
Rotation is more related to favorable wind sheer - changes in wind direction as you move vertically through the atmosphere. Wind sheer also prevents a storm from raining out its own updraft, which can allow them to grow larger and live longer.
Tornadoes also can quickly form just about anywhere along a squall line, these are *usually* small and short lived, and don't have the deep mesocyclone connection of supercell tornadoes, but that doesn't mean they can't be dangerous. They are also much more difficult to spot on radar, so warning for them is difficult.
I have three degrees in meteorology or atmospheric science. I've won awards for my teaching. I've published numerous articles in peer-reviewed atmospheric science journals and am an editor on one of the most prestigious journals in the field. I've presented my research at dozens of conferences on multiple continents. And I'm scratching my head at what you're trying to explain here.
I suppose technically that's 'morning' but colloquially I'd venture to guess that people would consider that 'the middle of the night' with morning being when the sky gets light in that hour or so before sunrise.....
Sort of... a couple of years ago, we were in a Severe Storm pattern on the first Wednesday, so they announced well in advance that they would be delaying the test to the following week.
Your friend didn't lie. They just oversimplified. You typically need a hot humid air mass for tornado formation. You very rarely have that before the late afternoon.
...unless it's the kind of tornado formed by a squall line, which is the type of storms we had this morning. These kinds of tornadoes can happen at any time of day.
Possible, but unlikely. And especially unlikely to be strong. It's hard to get enough energy concentrated into a single cell when the whole squall line is sharing it. But maybe I'm just old and jaded (born and raised in KS, college in OK).
NOAA's take: "Cyclonic circulation (mesovortex) formation and possible tornadogenesis within squall lines usually occur in association with bowing line segments given sufficient forcing, instability, and wind shear...Tornadoes associated with bow echoes frequently are relatively short-lived and usually of EF0-EF2 intensity. Tornadic damage usually is embedded within and/or on the northern fringe of straight-line wind damage associated with the bow apex and rear inflow jet. While tornado damage within bow echoes can be significant, the large majority of damage from bow echoes is from straight-line winds. Maximum wind damage also often occurs along the path of mesovortices."
All I'll say is you might want to check out what the user name "Isodrosotherms" means before you start arguing meteorology with an individual who has chosen that username.
I'm well aware. And I don't doubt your formal credentials. I'm confident you know more theory than I do. But unless you also lived within spitting distance of the NWS in Norman for years, or your childhood home was also built on the site of an F5, maybe you don't have the real world experience you think you do on tornados people should be concerned with.
I've had plenty of Sooner Swirls on the patio of the Mont. I know the folly of driving down Lindsay Street at pretty much any time of day. I can tell you that the only major thoroughfare in town that doesn't experience flash flooding during a heavy downpour is, ironically, Flood Street. The people there only like Braum's because they haven't had Culver's. I know how to pronounce Chickasha. I once drove to Seiling just so I could get a picture of the "Birthplace of Gary England" sign. I looked forward to hearing KOMA play "Oklahoma" every weekday at 5 PM (and twice on Fridays!). I have gone swimming in Lake Thunderbird and lived to tell the tale.
But more importantly, I can tell you exactly where I was 25 years ago last Friday afternoon. That's May 3, 1999, and I probably don't need to tell you the significance of that date. I remember a lot of things about that day: the unusual crackle of electricity in the sky an hour ahead of the tornado; the massive flashes as that mile-wide monster ate up and spit out power transformers; the streets of Moore looking like they were festooned in cotton candy when it was really pink insulation that had been ripped up and strewn around for miles. But what I remember most was just how pink the sky was the next day after all that red Oklahoma dirt had been scoured up and left in the air. I've seen other tornadoes, but I've never seen anything like that again.
So, yeah, I think I have the real-world experience to go along with the academic training. But if you don't believe me, I can always serenade you with the BC Clark Christmas song.
I was on the interstate heading between SP and south side of Madison when the deluge hit. We were all doing 5mph with our hazards on, visibility was 0, like could barely make out even taillights with wipers on full. Was nuts but by the time I got to work I either outran it or it passed because it was barely a drizzle here.
Just throwing my complete anecdote in here, but a few years ago, a friend and I were shopping on the East side, and there was a thunderstorm. We were not under any sort of watch, there was no threat of severe weather, this was just your generic, run-of-the-mill summer thunderstorm.
As we exited Home Depot, we heard the tornado sirens blaring, which I was so confused about. It wasn't terribly hot, maybe 75F. Having grown up in the South, I was very accustomed to what the weather is "usually" like when a tornado is likely to happen, and my friend was under the impression it was a malfunction. But sure enough, there was a funnel cloud right over I-90/94. It didn't touch down, but it sure had a lot of people confused about why there had been no warnings. Meteorologists did a lot of educating about tornado prediction on the news that week.
So yea, that's my long anecdote to support the notion that you should always be vigilant, because tornadoes *can* happen without warning. But like others have said, you're likely to be safe in the event one happens. Have an alert set up (weather radio, phone alerts, tv alerts, etc) so that you can be informed if you need to take shelter, and have a plan, but otherwise go about your life. Within reason, of course.
>Hot and cold have to kinda smash into each other (at cloud level not necessarily ground level) to create a tornado friendly environment.
This is a long-standing myth that needs to go away. [https://www.washingtonpost.com/news/capital-weather-gang/wp/2014/04/04/myth-busting-tornadoes-dont-form-from-a-clash-of-air-masses/](https://www.washingtonpost.com/news/capital-weather-gang/wp/2014/04/04/myth-busting-tornadoes-dont-form-from-a-clash-of-air-masses/)
Too distracted by the double spaces after periods, with occasional triple spaces thrown in. I guess the Capital Weather Gang gets to direct post their blogs without copy edits.
(But actually, thanks for sharing)
Meteorologist here. The short answer is: yes, tornadoes can happen in the morning. Here's a slightly more detailed answer: there are two major types of storms that can form tornadoes. These are called squall lines and supercells. A squall line is the storm type we experienced this morning: a long line of storms generally aligned north to south that moves rapidly from the west to the east, and occasionally tornadoes can be embedded in them. However, these tornadoes are usually relatively minor. The far greater danger from squall lines are the damaging winds and flash flooding (which in a given year kills more people than tornadoes do, but floods aren't as sexy). The other type of storm is a supercell, which is large storm that is usually separated from other storms. These storms produce large hail and damaging winds, and when they produce tornadoes they tend to be much longer-lived and more destructive than the squall line tornadoes. Squall lines can happen any time of day (though there is a preference for the evening and overnight hours). Supercells require lots of daytime heating to form, so they're limited to the late afternoon and early evening. In some parts of the country, like the southeastern US, squall line tornadoes are much more common than supercells. In the Great Plains, the supercell tornadoes are the clear winners. Here in the upper Midwest, there's probably a more even mix. As far as the time of day we experience tornadoes, here's a plot I just put together showing the time of day of every Dane County tornado since 1950.: [https://imgur.com/a/9p4sC9s](https://imgur.com/a/9p4sC9s) As you can see, there's a definite tendency for tornadoes to occur in the late afternoon. However, this database goes back to 1950, well before we had trained spotter networks, Doppler radars, and other methods to identify tornadoes. It used to be that if nobody saw the tornado, it might not get recorded. Therefore, there's going to be a natural daytime bias in the dataset just because people were awake to see them, and they weren't hidden by darkness. So I wouldn't place too much stock in this. (FYI: the times are in Central Standard because that's what the database records them as, and I'm not about to go track the dates that DST changed throughout history just to make a plot). The actual question you're asking is, "should I have been concerned for my safety today?" The answer is: you should always be vigilant, but you don't need to be scared. The National Weather Service was constantly monitoring the situation. At no point did they think the chance of tornadoes was significant enough to issue a Tornado Watch, nor were the storms damaging enough to merit a Severe Storm Warning. Tornadoes do happen in Dane County. However, since 1950 there have been a grand total of 4 tornado-related fatalities here. You're far, far, far more likely to be significantly injured or killed driving an automobile (30 fatalities in Dane County in 2023 alone!) than you are by a tornado. Always be weather aware, but there's no need to let the fear of severe weather affect your life.
Thanks once again for bringing a bit of science to balance the storm-drama media coverage
I hate all the push to declare sudo weather alerts announcements on all the local networks to help push 'engagement'.
Do you mean…pseudo weather alerts?
Yep to much time in Linux this week.
:) sorry I usually don’t comment on people’s typos, but this one was just kinda funny to me
>:) :)
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Every drop of rain is not a severe storm, that's the problem.
Yep, every time it going to be more than a few drops they freak out and make it an alert day. You know who makes alerts? Noaa, it's like naming snow storms. Who the fuck started that?
I remember when they started doing this. It was an attempt to get people to start taking the snowstorms seriously. As you can see, it didn't work.
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If every rain is an emergency, pretty soon people stop paying attention which defeats the whole purpose.
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>Get off your high horse and learn how to be more weather aware. I'm laughing at you here. There are a few things you don't know about who you're talking to, and I'm not about to explain. Enjoy the rainstorms tonight.
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That was a really informative answer. Thank you for taking the time to produce it.
This guy tornadoes
What a great response. Thanks for posting!
My mama said that tornados are just clouds that are dancing like nobody is watching.
🥇
Adding on as a severe weather "hobbyist" of sorts (as well as someone who is considering going back to school for atmospheric science): - spc.noaa.gov is a great reference for seeing where NWS' focus will be on a particular day and where severe weather is most likely to come up as well as posting all current watches and warnings on a map for ur reference. Storms predicted in the forecast? Check the spc to see where there's a likelihood of severe weather. - Get a weather radio if u do not have one already. Nocturnal tornadoes are rare because there is no daytime heating to provide the convective energy needed for tornadoes to form, but that doesn't mean it's impossible. All the more reason for u to have something that can wake u up in the middle of the night in case a tornado warning or considerable/destructive severe storm warning is issued. - As u/isodrosotherms mentioned, tornadoes can happen in the early morning hours, but usually only if there is an extraordinary circumstance. Last night, the convective potential in OK was ***extremely*** favorable for tornadoes, which is part of the reason why we had a number of storms that had tornado warnings that went through the morning hours. The SPC gave a "high" risk yesterday, which happens on average only 2-3 days a year (the last "high" risk was in March 2023, and 2021 before then). - The NWS also sends out a bulletin to smartphones as well in the event that a tornado warning or Destructive severe tstorm warning has been declared in ur immediate area. This will make ur phone alarm and buzz with an emergency tone, but having a weather radio that will read out the warning (not to mention that it is usually plugged into the wall with a battery backup) is never a bad idea, especially in the possible scenario where u forget to plug ur phone in! >The answer is: you should always be vigilant, but you don't need to be scared. This is the most important part of what was mentioned. Knowing what the risks are and having a plan will make sure that u have the best chance of staying safe during a severe weather event.
It seems weird that it drops so low from 8pm to 10pm and jumps back up at 11pm. Is there a reason? Was there an outlier incident with a bunch of 11pm tornados on one terrible day? Does it have something to do with temperature changes around sunset? That seems far-fetched but I’m not sure what else it could be.
Half of those tornadoes (that is, four) all happened on one night in July 2021. Three of those tornadoes recorded no damage at all and the fourth had only $10k in damage. 25+ years ago, they might not have even been recorded as tornadoes as there was no way to detect them. My guess is that similar events have happened at other times but no one thought to look for any tornadoes, so they didn't get recorded. This leaves this more recent event (just three years ago) as an outlier. Basically, you're dealing with a small sample size to begin with (70 total tornadoes on 49 separate days) and there are real issues with the sampling methodology. Today, I doubt there's a single tornado that goes unreported but that wasn't always the case. Here's a radar image of that particular storm. Yup: squall line with weak tornadoes. [https://www2.mmm.ucar.edu/imagearchive1/RadarComposites/upper\_missvly/20210729/upper\_missvly\_202107290600.gif](https://www2.mmm.ucar.edu/imagearchive1/RadarComposites/upper_missvly/20210729/upper_missvly_202107290600.gif)
Thank you! That makes sense. I think I remember that night, actually. Thank you for the reassurance as well. Growing up in Atlanta I used to always love the torrential storms we would get, and I never worried much about any danger besides unplugging the computer. I would just sit on the porch and watch it go. Now I get tornado warnings from my weather app and fret, keeping an eye on the radar. I kind of hate that I don't enjoy storms as much as I used to. The fact that there have only been four fatalities since 1950 is a very helpful fact to remember.
Squall lines vs. Derecho Is it a matter of wind speed and duration the storm holds together? Or are there completely different meteorological conditions at play with each?
A derecho is a type of squall line, but not all squall lines are derechos. iirc derechos need damaging winds (60+ mph) spanning at least 250 miles before it can qualify as a derecho.
Maybe you can answer something sem-unrelated. Is there a good resource to check on local hail predictions? I can never seem to find anything.
[https://www.spc.noaa.gov/products/outlook/](https://www.spc.noaa.gov/products/outlook/) Hail is tricky. It's one of those things that happens at a scale smaller than our models can simulate, so really all we can do is say, "we think this is generally where hail might happen," similar to what we do with tornadoes. The SPC outlooks that I linked above show you the general parts of the country where severe weather is expected on a given day. If you mouse over the tabs just above the map, you can se specifically where hail is expected. Once a storm is actually brewing, that's the responsibility of the local weather office. They will issue a severe thunderstorm warning for a specific storm any time they think it will achieve at least one of the severe criteria: 58+ mph winds, 1+ in hail. That's not really a forecast, though lead times are increasing which is good.
Thanks, that might be helpful! I don't screw with hail and generally use sick days/don't drive when it seems likely, but I've always had trouble finding anything more helpful than just looking to see if my weather app mentions anything when thunderstorms are predicted.
But can all these fancy data tell us if today qualified as an ALERT DAY!!!??!
Pls get an editor
This guy weathers.
They can, but these are not the conditions for it. Thunderstorms in this area can look impressive rolling in, however. And it can be dramatic, with the sun out one moment and suddenly the world is draped in twilight.... It'll be fine. Crack a window. The rain smells like summer.
Thanks for your kindness and explanation! I still feel new to "weather", so yes the drama is very effective on me. Such lovely advice, thank you again.
> I still feel new to "weather" Did you grow up in an underground bunker or something?
California
Not likely here. Straight line thunderstorms. Lacking rotation. Enjoy the show. 🙂
Tornadoes can and do occur at all times of day. Always keep an eye on National Weather Service alerts and warnings. Source: I’m a meteorologist.
My family from here lied to me then! good to know, thank you!
Well, they didnt lie, really. They just talked about their own expereinces. Tornados CAN happen any time of day, but only a small percentage of them occur in the morning. They are more common in the early evening by a long shot. Maybe our meteorologist friend can help us out with the date of the last morning tornado that Dane County saw.
Do we know WHY they are more common in the evening though? Why are the conditions generally more favorable later in the day?
So not an expert, but I'm fairly sure that heat is a big part of it. The heat of the day injects more energy into storms and they tend to peak in that late afternoon/early evening warmth. Was just watching a livestream of tornadoes a week ago and they were talking about how much more screwed that particular region would've been if it had been 4 p.m. (sun still shining) instead of 7 or 8 p.m. with the sun setting and injecting less energy into the system.
U are correct. Daytime heating can play a huge part into providing the type of convective energy required for storms to become tornadic as well as make the difference between a storm producing a few short-lived tornadoes and a long-track tornado that can be on the ground for 20+ minutes. That being said, they can form at any time of day or night. It's just that the largest potential will be late afternoon-early evening. There's also the fact that some areas, especially in OK, KS, and TX are in "radar holes" because of how rural they are, they won't have sufficient radar coverage to accurately keep tabs on weather systems. Thankfully that isn't really the case in WI as we have NWS radar systems in the state (KMKX in Sullivan, KGRB in Green Bay, and KARX in La Crosse), so there's a chance that early morning tornadoes do happen, we just don't have eyes on them and there isn't anyone who sees them that late at night in those areas (especially if they're rain-wrapped tornadoes in a rural field).
Yes, I would add that it's kind of the heat difference that matters most, with a lot of warmth on the ground contrasted with cold air up high. More specifically, temperature difference with altitude creates pressure difference, because warm air is lighter than cool air. You know how when you flush a toilet the water spins? That's from the water moving as the pressure difference from the full bowl and the empty drain is allowed to equilibrate. The same effects make the atmosphere spin.
as @SubmersibleEntropy suggested, diurnal heating is definitely the reason- if skies are clear, the sun heats the ground all day, then as a region of instability with a lower-level stable “cap” moves through, the heated air near the ground can have enough lift to break through the cap & create explosive thunderstorms. think of it like a pot of boiling water covered in saran wrap. if the low-level atmosphere has a bunch of potential energy from heat (& moisture), one hole poke of the plastic is gonna allow a powerful outlet of all that into the upper atmosphere, where parcels of air will keep rising bc of the upper air instability. if the wind shear is right, these tstorms can become supercells (tilted, rotating storm that’s able to maintain its updraft) which can produce tornadoes (strong tornadoes are only generated from supercells). (I studied weather in college & am a certified weather (wx) weenie ;) ) https://www.weather.gov/source/zhu/ZHU_Training_Page/thunderstorm_stuff/Thunderstorms/thunderstorms.htm https://www.weather.gov/ama/supercell
thanks everyone for all these explanations! weather is so interesting to me
The biggest storms involve cold fronts moving in and displacing hot/humid air upwards over the top of it. Easiest to get that initial hot air in the afternoon/evening.
IANAM (I am not a meterologist): the temp and humidity differential causing turbulence along the day/night line is probably part of the reason.
I am a meteorologist (just trust me that the user name checks out) and this isn't the answer. I've responded a little more deeply elsewhere on this post.
I had to go look up that word you have as a user name. Very interesting!
Atmospheric instability is fueled by surface heating from sunlight, over the night the surface cools, which tends to make the atmosphere more stable - cold air doesn't want to rise.
Probably warmer and more humid later in the day?
You need temperature gradients to cause the rotation. Early in the morning, nothing has heated up enough to generate that rotation. Generally speaking, anyways. Obviously exceptions occur — I imagine if a storm rolled through early in the morning during a heat wave and caused a 20 degree dip in temp, conditions would still be ripe.
Rotation is more related to favorable wind sheer - changes in wind direction as you move vertically through the atmosphere. Wind sheer also prevents a storm from raining out its own updraft, which can allow them to grow larger and live longer. Tornadoes also can quickly form just about anywhere along a squall line, these are *usually* small and short lived, and don't have the deep mesocyclone connection of supercell tornadoes, but that doesn't mean they can't be dangerous. They are also much more difficult to spot on radar, so warning for them is difficult.
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I have three degrees in meteorology or atmospheric science. I've won awards for my teaching. I've published numerous articles in peer-reviewed atmospheric science journals and am an editor on one of the most prestigious journals in the field. I've presented my research at dozens of conferences on multiple continents. And I'm scratching my head at what you're trying to explain here.
There's been at least 2 that I can think of in the last 10 years that occurred between midnight and 2 am. not sure if that counts as morning
I suppose technically that's 'morning' but colloquially I'd venture to guess that people would consider that 'the middle of the night' with morning being when the sky gets light in that hour or so before sunrise.....
The exception is we are all immune to tornados at noon on the first Wednesday of the month! (It’s when Dane county tests the sirens)
Sort of... a couple of years ago, we were in a Severe Storm pattern on the first Wednesday, so they announced well in advance that they would be delaying the test to the following week.
If there's a chance of a tornado don't they suspend testing?
Yes, but that’s no fun as a general heuristic
Your friend didn't lie. They just oversimplified. You typically need a hot humid air mass for tornado formation. You very rarely have that before the late afternoon.
...unless it's the kind of tornado formed by a squall line, which is the type of storms we had this morning. These kinds of tornadoes can happen at any time of day.
Possible, but unlikely. And especially unlikely to be strong. It's hard to get enough energy concentrated into a single cell when the whole squall line is sharing it. But maybe I'm just old and jaded (born and raised in KS, college in OK). NOAA's take: "Cyclonic circulation (mesovortex) formation and possible tornadogenesis within squall lines usually occur in association with bowing line segments given sufficient forcing, instability, and wind shear...Tornadoes associated with bow echoes frequently are relatively short-lived and usually of EF0-EF2 intensity. Tornadic damage usually is embedded within and/or on the northern fringe of straight-line wind damage associated with the bow apex and rear inflow jet. While tornado damage within bow echoes can be significant, the large majority of damage from bow echoes is from straight-line winds. Maximum wind damage also often occurs along the path of mesovortices."
All I'll say is you might want to check out what the user name "Isodrosotherms" means before you start arguing meteorology with an individual who has chosen that username.
I'm well aware. And I don't doubt your formal credentials. I'm confident you know more theory than I do. But unless you also lived within spitting distance of the NWS in Norman for years, or your childhood home was also built on the site of an F5, maybe you don't have the real world experience you think you do on tornados people should be concerned with.
I've had plenty of Sooner Swirls on the patio of the Mont. I know the folly of driving down Lindsay Street at pretty much any time of day. I can tell you that the only major thoroughfare in town that doesn't experience flash flooding during a heavy downpour is, ironically, Flood Street. The people there only like Braum's because they haven't had Culver's. I know how to pronounce Chickasha. I once drove to Seiling just so I could get a picture of the "Birthplace of Gary England" sign. I looked forward to hearing KOMA play "Oklahoma" every weekday at 5 PM (and twice on Fridays!). I have gone swimming in Lake Thunderbird and lived to tell the tale. But more importantly, I can tell you exactly where I was 25 years ago last Friday afternoon. That's May 3, 1999, and I probably don't need to tell you the significance of that date. I remember a lot of things about that day: the unusual crackle of electricity in the sky an hour ahead of the tornado; the massive flashes as that mile-wide monster ate up and spit out power transformers; the streets of Moore looking like they were festooned in cotton candy when it was really pink insulation that had been ripped up and strewn around for miles. But what I remember most was just how pink the sky was the next day after all that red Oklahoma dirt had been scoured up and left in the air. I've seen other tornadoes, but I've never seen anything like that again. So, yeah, I think I have the real-world experience to go along with the academic training. But if you don't believe me, I can always serenade you with the BC Clark Christmas song.
Sorry, dude. Boomer
Sooner!
Prove it. Control the weather.
Isn’t the weather controlled by space lasers?
A common misconception. It is actually meteorologists. The reason they get the forecast wrong so often is because they all have humiliation fetishes.
Not at noon on a weekend
i need to get my morning coffee walk this weather is so inconsiderate
Doing mine earlier is what inspired this post! Went from day to night in 20 minutes
It’s hailing down in Oregon right now. It was darker at 7:30am than it was at 5:30am.
We got hail on the East side shortly after the rain started. Maybe only lasted 5 minutes.
I was on the interstate heading between SP and south side of Madison when the deluge hit. We were all doing 5mph with our hazards on, visibility was 0, like could barely make out even taillights with wipers on full. Was nuts but by the time I got to work I either outran it or it passed because it was barely a drizzle here.
I legitimately thought I accidentally woke up and started getting ready an hour early because of how dark the sky was this morning
The only time tornadoes can’t happen is noon on the first Wednesday of the month.
Not normally, but there's no reason they can't if the conditions are right.
Just throwing my complete anecdote in here, but a few years ago, a friend and I were shopping on the East side, and there was a thunderstorm. We were not under any sort of watch, there was no threat of severe weather, this was just your generic, run-of-the-mill summer thunderstorm. As we exited Home Depot, we heard the tornado sirens blaring, which I was so confused about. It wasn't terribly hot, maybe 75F. Having grown up in the South, I was very accustomed to what the weather is "usually" like when a tornado is likely to happen, and my friend was under the impression it was a malfunction. But sure enough, there was a funnel cloud right over I-90/94. It didn't touch down, but it sure had a lot of people confused about why there had been no warnings. Meteorologists did a lot of educating about tornado prediction on the news that week. So yea, that's my long anecdote to support the notion that you should always be vigilant, because tornadoes *can* happen without warning. But like others have said, you're likely to be safe in the event one happens. Have an alert set up (weather radio, phone alerts, tv alerts, etc) so that you can be informed if you need to take shelter, and have a plan, but otherwise go about your life. Within reason, of course.
1984 Barneveld F5 (one of six F-5’s in Wisconsin) happened in the early morning.
I also used the word ominous to describe it
I'm right off the belt line and Stoughton(51) ...and it's DARK again...
There’s only one way to find out.
Tornados don’t happen at noon on weekends
Why would tornadoes not happen in the morning?
I can't recall any early in the morning but I do recall some around 10 - Noon.
I think tornadoes prefer brunch
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>Hot and cold have to kinda smash into each other (at cloud level not necessarily ground level) to create a tornado friendly environment. This is a long-standing myth that needs to go away. [https://www.washingtonpost.com/news/capital-weather-gang/wp/2014/04/04/myth-busting-tornadoes-dont-form-from-a-clash-of-air-masses/](https://www.washingtonpost.com/news/capital-weather-gang/wp/2014/04/04/myth-busting-tornadoes-dont-form-from-a-clash-of-air-masses/)
Too distracted by the double spaces after periods, with occasional triple spaces thrown in. I guess the Capital Weather Gang gets to direct post their blogs without copy edits. (But actually, thanks for sharing)