Over the weekend, the volcanic island of Hunga Tonga-Hunga Ha’apai erupted in the south Pacific. People as far away as Alaska heard the sound. Here in Indiana, we did not. But we were able to detect the shock wave from the explosion as a rapid pressure change.
Graph of barometric pressure at my house showing an abrupt rise and fall in pressure as the shock wave passed on Saturday morning.
In fact, you can watch it cross the continental US by plotting the pressure changes, as Daryl Herzmann did.
15 minute pressure altimeter change via ASOS NWS/MADIS 5 minute interval data. Shows the shockwave from the #Tongaeruption , feel free to use as you wish. pic.twitter.com/P31Aq1SYku
A little after midnight, the pressure wave came around from the other side of the globe. Alerted to this possibility by Daniel Dawson, I grabbed the graph from my weather station again.
Graph of barometric pressure at my house showing an slight rise and dramatic fall in pressure as the shock wave passed again on Sunday morning.
Edited 17 January 2022 at 3pm EST to say the pressure wave came from the other direction, not around again. Thanks to Shelley Melchior for the correction.
A couple of friends independently directed me to a recent forecast discussion from Peachtree (Atlanta). Forecaster Kyle Thiem embraced his inner poet when he wrote the long-term discussion entirely in haiku. (Full disclosure: I didn’t count syllables to verify.) The discussion is now forever enshrined in the Forecast Discussion Hall of Fame.
On Friday, I was looking at the radar and I thought “gee, that storm a few miles away from me looks like it might have a little bit of rotation.” I talked myself out of it. This means, of course, that it produced two tornadoes an 18 minute drive from my house. On Saturday when I saw some storms getting their spin on in central Illinois, I refused to be fooled again. So I woke my girlfriend from a nap and we got in the car heading toward Paxton.
As we pulled into Hoopeston, I had a choice to make. There were some cells popping up from Paxton to Mahomet that looked interesting but not particularly spinny. The main squall line was meh except further north. I had to pick an option. My risks were basically “nothing happens” to the south or “stuff happens but you can’t see it” to the north. Given the choices, I decided to engage to the south.
Storm 1
Screen shot of radar reflectivity (top) and storm relative velocity (bottom) from KILX at 4:24 PM CDT.
Screen shot of radar reflectivity (top) and storm relative velocity (bottom) from KILX at 4:43 PM CDT. The circled storm was the first one I targeted after getting into Illinois.
We turned down IL 1 toward Rossville. I figured we’d cut west from there to get under the storms. Unfortunately, the storms were speeding up, and I quickly decided that staying near IL 9 was the better option. We took a county road back north and made it all the way to IL 9 when we encountered a flooded roadway. With John Fausett in mind, we turned around (and didn’t drown) after driving about half a mile in reverse. We picked the next county road west and went north.
The storm was near Rankin at this point and it seemed to be showing some signs of rotation. We stopped to watch it for a few minutes and saw some lowerings, but there was no spinning.
View to the north of the first storm. Taken at 5:14 PM CDT just south of IL 9 from N 1300 E Road.
Lowerings from the first storm. Taken at 5:17 PM CDT about 1 mile northwest of Hoopeston. View is to the north-northwest.
Screen shot of radar reflectivity (top) and storm relative velocity (bottom) from KILX at 5:26 PM CDT. Location and direction of view as given on the image.
View of the second storm from the first storm position. Taken at 5:28 PM CDT. View is to the southwest.
After a few minutes, it was time to reposition again. The storm had become uninteresting, so I decided to follow it’s friend slightly to the south. From our position looking southwest, it looked pretty nice.
Storm 2
We dropped south a bit to meet it and then followed east and a little north to watch it further. At that point, we were a little east of Wellington. The lowering maybe showed a little bit of weak rotation, but it was never obvious. After a few minutes, it became an mess.
Lowering from the second storm. Taken at 5:35 PM CDT from about 2 miles north of Hoopeston. View is to the northwest.
Screen shot of radar reflectivity (top) and storm relative velocity (bottom) from KILX at 5:38 PM CDT. Location and direction of view as given on the image.
Lowering from the second storm. Taken at 5:50 PM CDT from about 2 miles east of Wellington. View is to the northwest.
Lowering from the second storm. Taken at 5:51 PM CDT from about 2 miles east of Wellington. View is to the northwest.
The end
These storms were basically done (although there was a report of a funnel cloud near Earl Park, IN later). There were some tornado warnings in the line near Villa Grove. After driving through near-zero visibility on the east side of Hoopeston, we went south on IL 1 for a little bit. But after a few minutes, the line looked less interesting and it didn’t seem worth staying out for. Also, the bag of Combos that I ate was not a reasonable dinner.
We managed to beat the line back to Lafayette by 5-10 minutes. For an unplanned chase, I’m okay with how this turned out. I feel like the decisions I made were reasonable, which was not a given considering I haven’t seriously chased in ten-plus years. Missing a photogenic tornado minutes from my house still stings, but I feel good about doing this again in the future.
Well it took approximately forever, but I finally got around to updating the back end tech for my website (post coming soon!). That means I can catch up on a backlog of Forecast Discussion Hall of Fame nominees.
I have added four new entries to the Social Media Foyer: tweets from NWS offices in Atlanta, Paducah, and Pittsburgh, as well as a Facebook post from Nashville. Plus: a Public Information Statement that includes a map, a Santa Claus watch, forecasters in Juneau telling you to go outside, a sweet discussion with no tricks, an “I’m only doing this because I have to”, a not-so-super Mario, and monster wrestling. Because you’ve all been so patient, there’s also a new entry in the ISIXTYFIVE section where he comes to the conclusion that he sucks.
Some of these have been sitting in my inbox since January 2018, so I apologize in being slow to add them. You get what you pay for sometimes.
The National Weather Service (NWS) is collecting public comment on some proposed changes to severe thunderstorm warnings. These changes would add damage threat labels for wind and hail threats. The three tiers are (no label), considerable, and destructive.
Category
Wind
Hail
(no label)
> 60 mph
> 1.0″
Considerable
> 70 mph
> 1.75″
Destructive
> 80 mph
> 2.75″
As part of the proposal, the NWS says, they will recommend that destructive severe thunderstorms trigger a wireless emergency alert (WEA) message. This means most modern cell phones will receive an alert for the highest-end storms. According to an analysis by Joseph Patton, this would apply to just over 1% of severe thunderstorm warnings. (This percentage will vary by time and location.)
I am 100% on board with this proposal. Let’s be honest with ourselves: most people ignore severe thunderstorm warnings. I’ll be the first to admit that I do. Once I’m inside, I’m safe enough without taking extra precautions. But those top-end storms can do damage similar to tornadoes. Being able to distinguish between “get inside” and “get to the basement” severe storms is helpful.
Now I’ve suggested before that tornado and severe thunderstorm warnings should be combined into a single product. I still hold that opinion. Intensity of the threat matters more than the specific mechanics of the threat. But I very much doubt the NWS will implement that idea any time soon. This proposal at least allows for cleaner communication of the most life-threatening thunderstorms.
You can give the NWS your own opinion via online survey before July 30, 2020.
Sporting events — particularly in the spring and summer when they’re generally done outdoors — present a hazard to participants and spectators alike. Thunderstorms can send a bolt of lightning in an instant, which can prove lethal. Part of the danger is that lightning can strike miles away from the storm, which means people who think they aren’t at risk might be very much at risk.
Many leagues and venues have adopted a largely sensible lighting policy. If lightning strikes within a certain radius, the activity is suspended and everyone is sent to shelter. After some amount of time without a strike (often 30 minutes), the activity resumes. This is, as a general concept, good advice.
Of course, it’s not quite as simple as “if you can see it, flee it. If you can hear it, clear it.” That’s the advice given to the public because it’s simple and easy to remember. But it doesn’t always capture the full story.
To give an example, this summer my local baseball team was playing a game as thunderstorms approached the area. A lightning strike occurred within the 10 mile radius defined by the Prospect League (as an aside, I appreciate the fact that they increased it from the 5 miles it used to be). The umpires suspended play late in the game (it was the 8th inning if I recall).
The trouble with this is that the storm was traveling perpendicular to the stadium. The strike that triggered the delay was well away from the storm and just inside the 10 mile radius. Essentially, it was as close as lightning would come. In this case, continuing play would be a safe decision. And it would have meant pitchers could stay warm and the crowd would have stuck around.
When it comes to weather safety, I’d always prefer overcaution to undercaution. But weather is complex, and the simple rules don’t always fit the situation. Sporting events should always leave weather decisions to meteorologists. High-profile near-misses have raised awareness, but it’s still not universal.
Due to a technical error with the forecast submission script. the contest is cancled. I’m not sure I want to invest any more time in fixing this old and busted script, and I have yet to make good on my ten years of “I will rewrite it this winter”, so this may be the end of tropical forecast contests on Funnel Fiasco.
It’s that time of year again! Submit your forecast for mainland landfall by 0000 UTC on 29 August (8pm ET on Wednesday).
Longtime readers of Blog Fiasco know that I have some opinions about how the National Weather Service (NWS) issues and communicates warnings. Just check out the “warning” tag on this site if you’re interested. But it turns out that I have as-yet-unwritten opinions. This post is inspired by a recent tweet from an NWS meteorologist:
Tough to communicate the danger of waterspouts to motorists on long bridges. Can’t issue a TOR because it isn’t land, but an SMW doesn’t trigger WEA. So how do you alert them? Especially dangerous if it’s a mesocyclone tornado and not a fair weather waterspout. https://t.co/ZhcNs2LqCX
I mentioned in a previous post that warning products tend to be technically correct instead of useful, as in the case of the non-hurricane Sandy. This is a fine example. Tornadoes over water are waterspouts and the NWS treats maritime areas (including larger lakes) differently than land areas. The end result is that forecasters are unable to properly communicate threats to the public. This is harmful.
I understand treating land and water areas differently. A storm that is unremarkable on land could be deadly to watercraft. Special marine warnings are usefully distinct. But a tornado warning over water can be useful, too, particularly to folks on land who happen to be downstream. But forecasters aren’t allowed to provide that information because it’s not technically correct.
The National Weather Service is a great agency. The dedicated forecasters are at work around the clock to provide life-saving (and life-enhancing) forecasts and warnings. I just wish it would get out of it’s own way on this issue.
It’s no secret that the Saffir-Simpson scale, used to rate the strength of hurricanes, is inadequate. It is based solely on wind speed, which does a poor job of communicating the potential impacts. I wrote just a few months ago that it’s time to consider retiring it. So when I heard that AccuWeather rolled out a new hurricane scale, you might think I’d be in favor of it.
You would be wrong.
It’s not that I think AccuWeather’s leadership is awful. I do, but that’s not the point here. The AccuWeather RealImpact Scale for Hurricanes does not address the fundamental weakness of the Saffir-Simpson scale because it still produces a single number. That this number is produced from more inputs isn’t novel (the original Saffir-Simpson scale included other aspects of a hurricane threat) nor is it better at explaining the threat. You still need to tell the public why it received a particular rating, and the preparation for wind damage may be different from storm surge may be different from inland flooding.
Not to mention the fact that the scale is opaque. It cannot be reviewed by researchers and meteorologists outside of AccuWeather. There’s no indication that it’s had any input from social scientists and science communication experts to make sure it even accomplishes the stated goal of improving communication to the general public. In short, it’s just AccuWeather acting on its own and pretending there’s value.
After insulting National Weather Service employees by falsely implying that forecasts are degraded during this government shutdown, AccuWeather would do well to shut up for a little bit and work with the meteorological community.
Short answer: yes. Long answer: I’ll let Cliff Mass explain it. But as the 2018 Atlantic hurricane season draws to a close today, I’m more convinced than ever that the Saffir-Simpson scale does us no good.
The categories simply don’t mean much to the average person. Sustained wind speed is only one part of a hurricane’s power, and perhaps not even the most important. Storm surge, rainfall, and wind gusts are all significant contributors to the harm caused by hurricanes. Of course, coastal conditions, population density, and building quality factor into the end impact, too. Particularly inland, a slow-moving but weaker storm could cause more damage (due to flooding) than a stronger storm that spends less time over the area.
Ultimately, as I’ve written in the past, it’s not the meteorology that the public cares about. They want to know what the impact will be and what they should do about it. This means de-emphasizing wind speeds and focusing more on impacts. To its credit, NOAA agencies have put more emphasis on impacts in the last few years, but the weather industry as a whole needs to do a better job of embracing it. It requires a cultural change in the public, too, which may take a generation to settle in.
But there’s no time like the present to start preparing for day. And maybe it’s time to drop the distinction between tropical storm and hurricane watches and warnings, too.
