Dwight Silverman

The SCW Q&A: Heading inland, hurricanes vs. winter, AI models, pool evaporation, late storm tracks

In the September Q&A, even though we think Texas’ hurricane season is in our rear-view mirror, many of the queries we tackle this month are hurricane related. Oh, except for the one about humidity and swimming pool water!

Got questions you’d like us to consider for next month? Reply in the comments below, or use the Contact link on the blog’s home page.

Q, As I get older, and having been through Ike and Beryl in Pearland, I’m becoming much less willing to endure another major storm so close to the coast. If a Cat 4 or 5 were to hit somewhere near Freeport or Galveston, would living somewhere like Magnolia or Katy really offer much more protection than Pearland? After Beryl, we drove to Dallas and saw downed trees all the way through Madisonville, about halfway there.

A. You know, I had similar thoughts as we rode out Beryl in League City. It was an unpleasant experience. (Personal note: I’m very much not a storm chaser. I appreciate the video and images they capture, but I like my storms far away, thank you). I used to think that I would stay in place for a Category 1 or Category 2 hurricane, but with the wildly swaying trees during Beryl, I’m not sure any more.

As for what you’ve asked, there is no question that Magnolia (especially) or Katy would on average be less susceptible to impacts from wind than areas closer to the coast, including Pearland. However, much depends on the strength of the hurricane, the angle at which it strikes the coast, and the speed at which it moves inland. Let’s look at a reasonably good wind gust forecast for Beryl:

Wind gust forecast for Beryl shortly before landfall. (Weather Bell)

This is not exactly what happened, but it’s pretty close, and it is illustrative of what I want to talk about. Specifically, note how important the track, and proximity to the core, is for the strongest winds. Whereas some areas of Galveston County near the water experienced gusts well below that of hurricane force, areas north of Montgomery County, including San Jacinto County, were vulnerable to hurricane force gusts. This is more than 100 miles from the coast.

The bottom line here is that there are a lot of variables. In general, however, the further you live from the coast, the lower the odds that you’ll experience significant wind damage from a hurricane. But that doesn’t mean the odds are zero.

– Eric

Q: (Are) there any historical trends or data to predict a ‘strong’ winter weather (e.g. extremely cold) based upon the low hurricane season activity relevant to Houston? As well as broader US implications? Given our weather patterns are tied together, highs dragging hurricanes and lows pushing them.

A: So the simple answer is no, there is no consistent way to use hurricane season as a gauge for the upcoming winter. We also hear a lot of people say “Well we had a hurricane, so we’re getting snow this winter!” Back in 2021, I wrote a section in our winter outlook, specifically for Houston that showed, historically, a hurricane strike on Houston doesn’t mean anything really and that the odds of snow in a normal winter were pretty much identical to the odds of snow in a post-hurricane winter.

But in a broader sense, a weather company (WDT, which I believe is now part of DTN) published a post a few years back to correlate Accumulated Cyclone Energy (ACE) to winter temps, which found nearly no correlation. The atmosphere is complicated and singular weather events like hurricanes, whether frequent or infrequent are unlikely to have an appreciable impact on an entire season’s worth of weather 3-4 months later.

I will say, there has been some work done to try to quantify this at a hemispheric scale, and there have been some results. A professor at Florida State has done good work on this. So I think there may be something we will eventually be able to gather from all this, but it’s unlikely to be due to one ocean basin’s activity.

– Matt

Q. Love your content. I’m curious, the models you cite [during hurricane coverage] sound like the same ones we’ve been using. Are AI models in development? I wonder if we can dump them all into AI and see what it thinks…

A1. This is the first year that we’ve really begun to use AI models as tools for hurricane forecasting. (If you’re curious how they work, compared to traditional physics-based models, I wrote a longer article here). We’re going to need to get to the end of the hurricane season to know precisely how well they worked. At that point there will be some comprehensive studies done to calculate how well AI-based models handled hurricane tracks in comparison to physics-based models. But my sense is that, for a new product, they’re surprisingly useful. They’re another tool in the arsenal that we look at every day. Matt may have some thoughts about this as well.

– Eric

A2: I will add that specifically for this year’s Gulf storms, the European AI model (the AIFS) has done astoundingly well. It has locked in early on and has tended to front-run the other model guidance in the right direction. In my day to day with it, I have also found it to occasionally have some skill in snuffing out risks to the forecast, such as a cooldown in mid-summer. Perfect? No. Useful? I believe so. The AI suite will get a good test this winter of how reliable they are at picking out cold snaps or snowstorm risks in the Midwest/Northeast. But they are firmly in my toolkit daily now. –

–Matt

Q: This may have an obvious, easy answer but why am I constantly filling up the pool in the hot HUMID summer? I would figure dry air would sop up pool water (moisture) quickly but not so much air already saturated with water.

A: This is an interesting question, and your assumption is correct: More humid air tends to reduce evaporation of water in a pool. So the question then becomes, what’s going on?

One possible reason could be exposure to sun. If it’s in a lot of sun with limited tree coverage, even in high humidity, you’ll still deal with evaporation. Another possible explanation could be the very dry stretch we went through in August. The spigot shut off for an extended time, which probably didn’t help. Beyond those two explanations, there may be something else afoot! Probably something to monitor for pool maintenance folks, just in case!

–Matt

Hurricane Francine as approached the northern Gulf Coast on Sept. 11. (NOAA)

Q. I’ve noticed that many major hurricanes in the Gulf of Mexico during September and October tend to impact Louisiana and Florida more than Texas. I’m curious about the reasons behind this pattern. For example, does it have anything to do with the position of the Bermuda High or seasonal changes in weather patterns? Additionally, is it common for hurricanes to stop hitting Texas after mid-September, or are there historical exceptions?

A. I noticed this phenomenon nearly 20 years ago, and did a little research to figure out that after the date of September 24 the historical odds of a hurricane striking the state of Texas are about 1-in-50. So every year, around this date, I write something to the extent that the Texas hurricane season is pretty much over. (Here’s this year’s post). At some point I’ll probably be embarrassingly wrong about this, but generally, if we get to September 24 and things look quiet, it’s a fairly safe bet that we’re done with the threat of hurricanes. And I am talking about hurricanes—the odds of a tropical storm or depression are higher.

There are sound reasons why this is. Generally, as we get toward the end of September, the upper air pattern starts to change as the jet stream begins to move southward. This provides a generally eastward steering flow that we don’t see in August or earlier in September. A good indicator of this is when we start to get our first cool fronts (we’ve already had two this month). The big risk here, of course, is that the Caribbean Sea and Gulf of Mexico are still plenty warm in October to support hurricanes, so the threat is there. It’s just that, meteorologically speaking, it’s difficult for these storms to track westward into Texas. That’s not a taunt, mind you.

–Eric

The SCW Q&A: Storming back home; tropical funnels; summer patterns; radar oddities; ‘cane clusters.

Man, will you look at the calendar! August’s almost done with us, but we are not done with it, which means it’s time for our monthly Space City Weather Q&A.

And yeah, we know, there wasn’t an installment in July. We have no excuses, other than to say that July was . . . a little busy.

Anyway, we’re reporting for duty now. On with your questions!

And don’t forget to to feed this beast: Post questions for future Q&A’s in the comments here, or use the Contact link below the blog’s header.

Q. If you were on summer vacation, at what time would you come back if there was something tropical-ish heading for Houston?

A. First, a word on my own plans for summer vacation. I try to never take them in August or September, because that’s the time I’m most concerned about when it comes to tropical weather and Houston. And when I travel in June or July, I definitely bring a laptop.

As for returning in the face of tropical weather, it’s really a difficult question because there are so many variables. Are you returning to prepare your house, only to evacuate again? Are you returning to prepare and hunker down? Are you most concerned about, wind, surge, or inland rainfall? That said, the fundamental question I would want to answer is how long you need to make whatever preparations you want to make before the storm hits. If it is 24 hours, then I would return no fewer than 24 hours before the onset of tropical conditions.

The National Hurricane Center has a useful tool for this you can use during active systems. This product offers a forecast for “earliest reasonable arrival” of tropical storm force winds. (The image below shows the forecast for Beryl, issued on the morning of Saturday July 6, for example). Essentially, this is a good guide to when final preparations for an impending storm should be made. We sometimes publish them on Space City Weather for this very purpose.

–Eric

Example of “earliest reasonable arrival time” of tropical storm winds during Beryl. (National Hurricaen Center)

Q. On Sunday, July 21, in a special weather statement for areas east of Houston, the statement talked about the risk of tropical funnel clouds. What are these and why is there a special weather statement for them vs. a tornado watch?

A. This is a good question. It’s a phenomenon we see frequently in Southeast Texas but not one we really talk a lot about. Tropical funnel clouds form typically when it’s humid and breezy. Why do they form? Funnel clouds form by similar processes both within supercell thunderstorms (which can produce tornadoes) and in these more benign tropical environments. With breezy, humid conditions, you can get a setup with a little bit of wind shear, especially near the coast, where wind direction may change with height. This can lead to some “spin” in the atmosphere, or what we call vorticity. As that vorticity gets stretched out a bit vertically, you get faster spin. And as that happens, you can get a funnel cloud.

So why are these benign? The process by which these funnel clouds form is much slower than the process by which supercell thunderstorms can produce funnel clouds and subsequently tornadoes. Additionally, they usually dissipate after a few minutes. Very few of these funnel clouds ever reach the ground, producing a tornado, and even if they were to do so, the tornado would likely cause minimal, minor damage. So they’re more likely to just get noted as a curiosity more than anything else. Because the process is slow to evolve and quick to dissipate, it doesn’t warrant a watch or warning.

–Matt

Q. My mom says she can remember back 10 or 20 years ago that Houston would normally get thunderstorms every day in the summer. Today it seems like long periods of no rain in the summer is the new normal. Has the weather pattern changed in the past 10 years? Or is it is just a lot drier where we live now (near Addicks Reservoir) than it is over downtown?

A. As best I can tell the patterns of summer rainfall have not really changed all that much in Houston, during the summer, over the last couple of decades. (That’s in contrast to temperatures, which have gone up strikingly, particularly at night). We have always been subject to prolonged periods of summertime high pressure during which there is no rainfall. Sometimes, as in last summer, these highs persist for months on end. This year, the high pressure pattern did not emerge until early August, in which case it hung around until the last week of the month.

Basic schematic for a sea breeze. (NOAA)

In June, July, and August, when we are on the periphery of a high pressure system, Houston summers are like the ones your mom described. This is due to the sea breeze, a pattern in which the land heats up faster than the Gulf of Mexico. This typically happens during the late morning or afternoon hours, and the rising air over land forms clouds a few thousand feet up at the lifting condensation level. This can then lead to the development of showers and thunderstorms. Some summers, particularly the ones your mom remembers, can see this type of pattern persist for weeks.

–Eric

Q. I saw a (radar) effect I can only describe as a rain “splash” or “bubble”. This is a ring of what appears to be very light rain, that starts centered on a newly forming cell and expands in all directions, rather quickly, before eventually dissipating. It appears like a two-dimensional cross section of a bubble inflating, or the expanding wave one might see after tossing a pebble into still water. Are you familiar with this phenomenon?

A. This is good opportunity for us to explain some common features you may see on weather radar that aren’t specifically precipitation. When you look at radar and you see what looks like a bunch of “noise,” as if there’s a bunch of light precipitation, we call this ground clutter.

An example of a radar image with a couple actual showers and a whole lot of ground clutter (birds, bugs, bats, etc.) from this past weekend. (RadarScope)

Ground clutter can literally be anything other than precipitation: Birds, bugs, bats, etc. can all make it up. You see it at every radar site. After awhile, you learn to disregard it. Radar can also pick up wind turbines.

Wind turbines as seen around Corpus Christi. (RadarScope)

These can be a bit of a headache when you look at radar, but again, after awhile they sort of just become background noise to a seasoned user. I noted ground clutter above. How about bat colonies heading out for a night of snacking?

Bat colonies emerging across Central Texas after sunset, while light rain showers work south to north between Houston and San Antonio. (RadarScope)

Similar to bats at sunset, you can see birds emerging from slumber during the morning, a phenomenon that looks like something is literally exploding on radar. These are just enormous flocks of birds taking off for the day from various locations. We call these “roost rings.”

Roost rings on radar from July 17th, as large flocks of birds spread out in all directions after sunrise. (RadarScope)

Then, I think we get to what this reader asked about. If you look at this radar loop from July 17th in the afternoon, you can see numerous showers and thunderstorms over the Houston area generally propagating westward.

Showers and thunderstorms firing up, weakening, and redeveloping to the west from July 17th. (RadarScope)

To the untrained eye, this is a chaotic mess of storminess. But if you look closer, the radar can actually tell you what’s happening here. Let’s zoom into Sugar Land and Greatwood down into Fort Bend County.

Outflow boundaries colliding to produce new thunderstorms southwest of Sugar Land. (RadarScope)

If you look right above and on the right side of what I circled on the loop above, you can see what looks like a “line” of green on the radar. We call these outflow boundaries or gust fronts. When we get thunderstorms, sometimes a cool breeze or cool gust of wind will move in before it starts raining. That’s what we call outflow, and you’re literally feeling the rain-cooled air come in ahead of the rain itself. In this case, outflow from the storms east of Greatwood, closer to Pearland was pushing west. Near Greatwood, it ran into another outflow boundary that was lifting northwest from storms down in Brazoria County. As the two boundaries collided, a new storm formed right over Highway 59/I-69, flared up and then weakened.

Such outflow boundaries are common in our area in summer. Sometimes, you’ll see what looks like outflow lifting north from the Gulf of Mexico. That’s the sea breeze, and once one storm pops on a hot day, it can create an effect of boundary collisions all over the place in erratic fashion. This explains why so often you’ll get a quick inch of rain whereas your neighbor 5 blocks away gets next to nothing. I liken it to atmospheric bumper cars: Pure chaos.

Anyway, now when you look at radar, maybe you’ll be able to detect some cool features too!

-Matt

Q. Do hurricanes come in clusters in certain parts of the Gulf and Atlantic? Several years ago, it seemed like Florida and the lower East Coast were getting slammed over and over. Then for a while the upper Gulf Coast was the big target. Is this faulty memory, or does this actually happen? And is it maybe the Texas coast’s turn?

A. The simple answer is: Yes, that can happen. Look back at 2020 when it seemed as if every storm had its mind set on Louisiana. But we can look back at some other seasons and see this concept in action. Let’s take 1995 for example.

The 1995 hurricane season was active but also highly clustered. (NOAA)

In 1995, there were 19 total storms. Many ended up in the Atlantic, clipping the Caribbean islands or just wandering out to sea. There was a secondary cluster of storms in the Gulf, particularly near the Florida Panhandle. 2010 was another season like that, where we had lots of storms clustered into two distinct areas. The first was out at sea as in 1995. But the second was focused on Central America and Mexico. But then you get seasons like 2017, where anyone and everyone was in play for hits from storms.

The reasons are tough to explain in a simple Q&A, but in general: The weather pattern in summertime can be semi-permanent. In other words, the Bermuda high over the Atlantic can sit in place for weeks at a time. Like we experienced last summer, high pressure can sit over Texas for weeks at a time. When patterns like this happen, it can sort of lead the atmosphere to produce a more common outcome. Those features help steer storms, so when they don’t move, most storms will follow generally similar tracks. Each year is a blank slate, though various climatological cycles can possibly predispose a series of seasons to a more common outcome (see the 1950s on the East Coast of the U.S.).

So does that mean anything for this year? Our weather pattern this summer has been a little more chaotic, though it has firmed up some in the last month, trending more toward stagnant over Texas. That would theoretically put the East Coast or western Atlantic in play, not so much the western Gulf. And we’ve seen Ernesto (Bermuda) and Debby (Florida) do just that. Will that hold through October? No clue truthfully. But it would be nice for us to say Beryl was it for this year.

-Matt

The Space City Weather app now has AccuWeather data and a prettier splash screen

If you’ve been paying attention to what happens on your iPhone, iPad, Mac or Android devices, you know that a new version of our app recently dropped and is in the wild. As is our wont, when the summer comes – and yeah, there’s no denying it IS summer – it’s time for a major update for the Space City Weather app.

Over the past couple of years, we’ve added features that users have asked for most: dark mode, a better tablet/desktop layout, current conditions for more area neighborhoods and cities. This year, we’ve chosen to focus on behind-the-scenes aspects, as we’re pretty happy with app as a whole.

The Space City Weather app, as seen on a Mac that uses Apple Silicon chips, in dark mode. Sweet! (Screenshot)

One of the issues we’ve addressed is the reliability of the data for forecasts and conditions. In past versions, these have come directly from the National Weather Service, which has an Application Programming Interface (API) available for free. But the flow isn’t 100 percent reliable, which is why you may have seen blanks where numbers should be, or in some cases old data.

In the spirit of “you get what you pay for,” we have opened our checkbook and signed a deal with AccuWeather to provide us with current conditions data. We are still relying on the NWS for weather alerts and the detailed forecast discussions that appear when you tap the bell icon at the bottom of any SCW app screen. The NWS also still powers our area radar display.

We’ve also changed the way the app behaves when data for one of the 12 areas we cover is unavailable. The app will pick up the feed for the next nearest reporting station, so you’ll have local data on which to rely.

In addition, we’ve updated the opening screens of the app you see when it launches to better match the nifty new banner on the SCW blog. These so-called splash screens include branding for our sponsor, Reliant. If you’ve got both iOS and Android devices, you may notice these screens look different. That’s due to limitations on newer versions of Android. Regardless, both Space City Weather and its sponsor get to shine when the app fires up.

The new SCW opening splash screen as seen on an iPhone, left, and on newer Android devices. Androids running an operating system older than version 12 display the iOS-style screen. Blame Google.

There are other tweaks and bug fixes. If you have not downloaded the latest app, go grab the newest versions from from the Apple App Store or Google Play.

If you encounter issues, it’s a good idea to uninstall, then reinstall, the latest version. If you’re still in distress, email us at [email protected] and give us as much detail as you can as to what you’re seeing, as well as the version of your device’s operating system, the version of the device and the version of the app (found at the bottom of the Settings screen). A future release of the app will include a bug-report button in settings that will automagically give us these details. Watch for it!

And as always, there are no trackers or ads in the SCW app. It’s pure, sweet weather information, with Eric and Matt’s insightful and easy-to-understand explanations. We’re here for you, wherever you are.

And a big thanks to our developer, Hussain Abbasi, whose hard work and good humor has made the process a breeze.

Want to know what a storm is likely to do where you are? Dig into your phone’s weather app

In brief: We’re happy to have Dwight Silverman, a longtime Houston tech journalist who is working with us behind the scenes, contribute this post on how to find hyper-local forecast information from the powerful computer in your pocket. Dwight explores some features and data in your phone’s weather apps you may not know existed.

Whenever a storm is bearing down on the Houston area, Eric and Matt are swamped with questions about conditions at individual readers’ locations. They have time to answer a few of them, but given what needs to be done and the volume of work they face, they can’t respond to all of these queries.

But there’s good news: Often, the answers you seek can be found in the palm of your hand.

Nearly everyone carries a smartphone, and many weather apps that are included with them can give you a lot more detail than just the current temperature and rain chances. Some let you drill deep into the metrics you want to know most about a major storm – wind speed and precipitation. Want to know what peak wind gusts will be when a storm is forecast to be nearest you? Or how much rain is expected to fall near you? There is, indeed, an app for that. They’re not perfect, and they don’t do a great job with uncertainty in forecasts, but they offer a solid approximation of what to expect.

This post is not intended to be a manual for weather apps, but rather to shed some light on features you may not realize are there, or are hidden a few layers deep in an app’s design. There are many third party weather apps out there, and I am not going to try to cover them all. But I will offer tips for some of the better one, and those that are included on your phone.

Space City Weather

You may have heard that we have our very own, free app? It’s true, and it’s available for both Apple products (iPhones, iPads, Macs) and Android devices. The app is primarily designed to give you quick access to Eric’s and Matt’s posts, current conditions, hourly and daily forecasts for a week out, as well as radar for any of 12 cities in our region. But one thing you may not realize is that it includes detailed, up-to-date National Weather Service forecasts and advisories on storms and hazardous conditions.

The lower right hand icon on the Space City Weather app home page takes you to the National Weather Service forecasts and current alerts.

Open the SCW app, tap the bell icon in the lower right corner of the screen to get to the Active Alerters as well as short- and long-term advisories. There are also discussions of aviation and marine weather as you scroll down. (Note: The aviation section will NOT tell if your flight has been canceled! Check with your airline, and keep an eye on the FAA’s airport status website.)

Apple Weather

After Apple bought the popular Dark Sky app, it soon redesigned the app that came with iPhones, iPads and Macs to incorporate the former’s hyperlocal forecast features. It will give you details about conditions – both current and future – at relatively precise locations.

However, this integration has been, umm, less than smooth. For example, last year the app was not loading data, and in other instances it was forecasting rain when there was none. The patient seems to have stabilized lately, but it’s a good idea to double-check what you see in Apple’s Weather app with other sources. (You can find where Apple gets its weather data here.)

That said, the app makes it easy to see forecasts for specifc conditions, particularly wind and precipitation, at your location. On the iPhone, iPad and Mac, it shows you conditions in individual tiles, and tapping any of them takes you to a screen that lets you move forward in time to check the the forecast for a specific condition.

Tapping on any of the tiles in the Apple Weather app gets you more detail, including forecast for specific conditions.

For example, if you scroll down on the iPhone to the Wind or Precipitation tiles and tap one, you’ll get the current conditions for the day in a chart. Scroll to the left to move to the next day, or tap the calendar date near the top.

Traveling and want conditions and forecasts for a different location? Enter the ZIP code in the search field. You can save any of the locations for future use. You’ll also see forecast alerts, warnings and advisories for those locations.

Android devices

Unlike Apple devices, which all have the same detailed Weather app, Android smartphones and tablets use different apps and services, depending on who makes the hardware. For example, Google’s Pixel phones use Google’s own weather service for much of its onscreen information, while Samsung and OnePlus phones will kick you out to a weather website, typically Weather.com.

But there is a general strategy you can use: In the five- or seven-day forecast list, choose the day you want to explore and tap it, then look for the metric – wind or precipitation – for the target location.

On a Google Pixel 6 Pro, tapping the weather widget on the home screen goes to Google’s weather information, and from there you can get to specific forecast metrics.

In the image above, tapping on the weather widget that’s the default on a Pixel phone’s home screen, you’re taken to a general weather page. From there, tap the day for which you want details, and scroll down for wind and precipitation forecasts for that day.

Experiment with the app on your Android phone to find the best route to the information you need.

Next, let’s look at a couple of third-party apps that, while not free for all features, may be well worth buying if you live on the Texas Gulf Coast.

RadarScope

RadarScope is one of the best apps for looking at weather radar data that’s available. It’s a favorite of Eric, Matt and mine, and while there’s a limited-capability free tier, it’s worth the $9.99 annual subscription for the Pro 1 level. (There’s a Pro 2 tier, but most folks will only need Pro 1.) It’s available for Apple devices – and when you pay for it once, you can use it on all Apple products, including the Apple TV 4K streaming box. It’s also available for Android devices, as well as Windows-based PCs.

This is indeed a professional-grade app, giving you access to different kinds of radar technologies and views. Once you unlock one of the Pro tiers, you’ll be able to see the direction storm cells are heading, the location of lightning strikes and local storm and damage reports from the NWS’s crowdsourcing MPing app.

RadarScope shows lots of details about storms on radar, here displaying the initial bands from Tropical Storm Beryl as they move toward Houston on the morning of Sunday, July 7, 2024.

You can pick and choose specific radar stations, both in the United States and abroad, including 13 in Texas. It’s easier to use and navigate on a traditional PC, but still extremely useful on your phone. The help files in the desktop version are helpful, and there’s even a Facebook group you can join to learn from other users.

Windy

Windy is available as a website and an iOS/iPadOS and Android app. As the name implies, its initial focus is on wind conditions, but it’s really a full-featured weather app, with one very interesting features: You can track storms based on computer weather models. Choose the model you want, along with the date and time for a forecast, and it animates the storm on a beautifully rendered map.

Windy lets you choose your weather model, then animates its resulting storm forecast on a map.

From the home screen, press and hold the Home icon. Tap the Basic label at the bottom to see the various forecasting models that are available. Choose one to see the storm at the current location, then scroll through the timeline to see where the storm is expected to be based on that model’s forecast.

While most of Windy’s features are available for free, some – like a 15-day forecast – require a subscription, starting at $2.99 a month up to $29.99 a year. But most folks can get along just fine with the free version.

There are many, many other weather apps and websites that can help you keep track of storm developments, and as I said at the outset this is not meant to be an exhaustive list of resources. (I didn’t even mention one of my favorites, Merry Sky, which was developed for those who miss the look and feel of the old Dark Sky app. Oh, wait, I just did!) If there’s an app you like, feel free to let others know in the comments.