Matt Lanza

In brief: Humidity will inch back up this weekend as we continue with quiet, hot weather. Another cold front may make an attempt to arrive early next week, but whether it brings a big drop in humidity or just a modest one remains to be seen.

On Thursday, the dewpoint at Bush Airport fell to 64° during the peak of our daytime heating. That’s the lowest it’s been since May 19th. While it was plenty hot yesterday, it was at least a bit less humid than we’ve been dealing with. Any break you can muster in the humidity in summer is a good break here in Houston. And we may have some more of it to come.

Today

We’re expecting a very similar day today as we saw Thursday. A few spots will push the upper-90s this afternoon. Humidity will again be low-ish. Walking outside this morning, it doesn’t feel quite as nice as yesterday, but still not terrible for summer. Heat risk today will be minor to moderate across the area.

One side note: Because of so much sunshine, ozone levels will be high today, and there are air quality alerts for ozone posted. So if you struggle with that, be aware that today will be further unpleasant.

Weekend

The humidity will slowly inch back up this weekend. Look for more of our standard 70s dewpoints with daytime highs in the mid-90s. Rain chances look minimal to near zero on Saturday with ample sunshine expected. Sunday stands a slightly better chance of a brief, passing shower, more in the “it can’t be entirely ruled out” range of things. Morning lows should hold in the mid-70s, with slightly steamier morning conditions.

Monday

The forecast gets very difficult here. From a rainfall perspective, we aren’t expecting anything crazy, just a few showers or storms for now. We’ll keep watch. The tricky part comes with determining how much this cold front can punch through Houston. The GFS model really wants to send the humidity back south to Cancun, while most other model data shows perhaps a modest drop in humidity, maybe similar to what we saw yesterday and today.

I would lean toward the latter, but there is a world in which the former could indeed come to fruition. History and climatology favors the Euro and other models in this instance. But never say never. Perhaps we’ll come back with good news later this weekend or Monday. One can hope.

Rest of next week

After Monday, the week looks to be somewhere between average and slightly unsettled. We could see a few thunderstorms as a trough settles in over us and we end up placed on the downward side of building ridge to our west and southwest. Temperatures look very benign with generally low-90s and 70s for lows, fairly average for mid-June. We should see temps reach back to the mid-90s by late week or the weekend.

Tropics

Look for a post over at The Eyewall in just a bit that will discuss the potential of a system in the Gulf in about 10 to 14 days. I am not concerned about this from a “big storm” or Houston impacts standpoint. It’s still early in the season and model support is lacking. However, there may be something that tries to get going later next week or after Father’s Day. I’ll have that for you a little later this morning.

In brief: Strong to severe thunderstorms with gusty winds will push across the area through the morning. Street flooding and some scattered power outages are a good possibility. Additional storms are likely this weekend.

This morning

A squall line of strong to locally severe thunderstorms is moving into the area as we post this. Heavy rain, frequent lightning, localized street flooding, and wind gusts of 40 to 60 mph are a good bet as this pushes through.

While these storms are not quite as severe as what we saw back on Tuesday this week, this will likely set the day off on the wrong foot. It wouldn’t be the worst idea to delay your morning commute until these pass. Most wind gusts have been 35 to 45 mph recently as these pass, which is relatively standard for strong storms here. Still, given the area’s sensitivity of late, some scattered power outages may occur in parts of the area.

This afternoon

The morning storms will clear off to the south and east. Since the timing of these storms clearing occurs in the morning hours, the atmosphere may not have enough time to recover this afternoon. While I wouldn’t rule out additional showers or thunderstorms in spots this afternoon, the worst of the action will hopefully be confined to the morning. After a rain-cooled morning, temperatures should recover into the 80s this afternoon. Eric will update later today on any changes.

Tonight & Saturday

Look for additional rounds of showers and thunderstorms tonight or Saturday. The exact timing and location remain frustrating to us in terms of predicting. But we are not done yet, that much we know. Some model guidance has a fair bit of storm activity tonight and Saturday, though mostly not severe and rain-focused. But this will be a period we continue to watch for storminess.

Sunday

Support for thunderstorms should be about ready to exit starting Sunday. I still think there’s enough juice and disturbances left to fire off another round of storms around the area, along with heavy rain and perhaps gusty winds. But the hope is that these will become a little less frequent. Highs in the 80s to near 90 degrees, lows in the upper-70s.

Next week

Storms have tended to move around the periphery of a ridge of high pressure over Mexico that has provided them with absolutely punishing, extreme, record heat this month. As that ridge expands a little next week, we should see storms lift back to the north some each afternoon or evening. So favored areas will be north toward Huntsville or even north of there. We’ll see an uptick in temperatures with low-90s possibly shifting toward mid-90s by mid to late week.

The more noteworthy item for next week will be a disturbance or even some kind of cool front that arrives later in the week. If that happens and pushes off to our south and east as shown, there is the chance that we set the stage for much, much nicer, less humid weather for a couple days next weekend. I would not rule out a morning low in the 60s in the Houston area at this point next Friday or Saturday. It’ll still be plenty hot each afternoon, but the mornings may be refreshing. Maybe. We’ll see!

In brief: Summer’s here, and through Memorial Day you will find little to no relief in the area. From there, the weather pattern may get a little more unsettled next week, but nothing stands out that we can hang our hat on just yet.

I know that no one wants to talk about hurricane season after last week, but NOAA’s extremely active seasonal forecast released yesterday should remind us to plan for the season to come. We wrote about their forecast and the current state of the tropics yesterday at our companion site, The Eyewall. We’ll be updating that site every day or two going forward as the weather requires.

For those struggling with continued poor air quality thanks to the haze and smoke from agricultural fires in Central America and Mexico, I don’t think we will see much relief this weekend. I am hopeful we get a shift in wind next week though.

Yesterday’s low temperature at Hobby Airport was 80 degrees, the third time already we’ve failed to drop below that mark this year. We’ve already tied for the earliest first 80 degree morning on record at Hobby this year, on May 21st, matching the previous record set in 2022. We are running about a month and a half ahead of normal, for whatever “normal” is worth anymore. Today will be the seventh morning where the low temperature has failed to drop below 78 degrees, which sets a new record at Hobby for the most before June 1st. We should add at least three or four more days to that before we get a wee bit of relief next week just before the calendar changes.

Anyway, I write all this to say that this is not a normal start to summer. It’s hitting strong and fast. And don’t be shocked to see a heat advisory this weekend. Practice heat safety this weekend. Yeah, it’s Houston and it’s always hot in summer. But we are not yet acclimated to these temperatures for the season, so heat illness can come on quick and unexpectedly. Some of us are still cleaning up from last week or even still without power. Check on those folks, keep your pets cool, and look before you lock.

Today through Sunday

The front portion of the holiday weekend looks partly to mostly sunny and hot. Expect highs in the mid-90s and lows near 80, or essentially normal weather for late July, not late May.

I would not be entirely floored to see an isolated thunderstorm roll through areas north of Houston, perhaps as close as The Woodlands or Magnolia. Most people will not see one, but if you do, it could rain hard for a short time, with lightning, gusty winds, or even some hail. Again, this is most likely to be isolated and north of Highway 105, but perhaps as close as Montgomery or northern Harris County.

Memorial Day

This should be the hottest day of the stretch. Expect mid to upper 90s and a mix of sun and clouds with just a slight chance of a late shower or storm north and west.

Sunday and Monday’s heat will border on “extreme” levels, so maximum heat precautions should be taken here.

Rest of next week

Things start to change a bit next week. Temperatures will shift to become a little “less hot,” which means more like low-90s than mid-90s. Nighttime lows may drift back more into the mid-70s. A series of disturbances may try to erode away the northeast portion of the ridge of high pressure over Texas, so that could be just enough to fire back up some thunderstorms after Monday. I don’t even want to begin to speculate on timing or details or any of that. Just know that the stagnant pattern of this weekend may change a bit next week.

In brief: This post explains what a derecho is, where the term came from, and talks a bit about some past thunderstorms of note in Houston.

What is a derecho?

The National Weather Service has concluded that Thursday’s severe storms in Houston constituted a derecho. So what does that mean?

First off, it’s pronounced “deh-REY-cho.” Meteorologists have debated what the definition of one of these things actually is for years. And we still don’t have a concrete, universally accepted definition. However, progress was made after a 2011 storm that hit the Southeast and a 2012 derecho that ravaged the Mid-Atlantic and Midwest to work toward something more widely accepted. Ultimately, NOAA/NWS defines a derecho as a continuous or intermittent path of wind damage from a squall line of thunderstorms, bow echo, or quasi-linear convective system (QLCS) that extends at least 400 miles and is at least 60 miles wide. In other words: It’s a swath of wind damage from mostly non-tornadic thunderstorms that extends for 400+ miles and is at least 60 miles wide.

What makes it different than typical severe thunderstorms?

A derecho, as noted above can be a squall line, bow echo, or QLCS. We get several of those types of events every year in Houston. What sets a derecho apart is the wind damage. It’s not normal. It’s not a couple trees on power lines. It’s a lot of wind damage over a long path.

Are all derechos the same?

No! Derecho events are broken down into three categories: Serial, progressive, and hybrid. A serial derecho is basically where you have one giant squall line that is hundreds of miles long with multiple embedded bow echoes producing widespread wind damage. A progressive derecho is the one we experienced in Houston last week that is typically no more than about 250 miles wide. You also have hybrid outcomes, which basically share characteristics of the two others.

Why is it called a derecho?

According to NOAA, Dr. Gustavus Hinrichs, who was a professor at the University of Iowa coined the term in 1888. The literal Spanish translation of derecho is “straight ahead” or “direct” or even “right.” Here’s where the etymology gets kind of fun. “Tornado” derives from the Spanish “tronada,” which literally means thunderstorm. But there is also a Spanish word “tornado” which essentially means “twisted,” and it derives from the Spanish verb “tornar,” which means “to twist.” So essentially, Hinrichs took the “opposite” of twisted and decided that derecho (or “straight”) would be a good way to distinguish tornado-like wind damage that was not caused by a tornado.

Are derechos common?

The short answer is: Kind of. The most recent derecho prior to Thursday’s in Houston occurred back on April 1-2 from just west of Missouri through West Virginia. A storm that almost met derecho criteria occurred just this past weekend in Kansas and Missouri. There were derechos in 2023, 2022 in Canada, 2021, and so on. In fact, the quad-state area around Kansas, Missouri, Arkansas, and Oklahoma northeast of Tulsa averages more than one derecho per year.

Derechos are most common in May, June, and July. Keep in mind that a lot of the areas that see derechos every 1 to 2 years are more rural, so it’s likely you hear less about them than when they hit places like Chicago or DC or Houston directly, causing billions in damage.

You can read about a bunch of pre-2012 events across the country here. Some even occur out West. I was introduced to derechos when I worked in Upstate New York early in my career. The memories of the 1998 Syracuse derecho were still incredibly sharp, much like Houstonians will remember last week’s. That was followed up by a second derecho event that moved from Michigan to New York City. The 1995 Adirondack derecho (or Adirondack blowdown) was responsible for knocking over more than half the trees in 100,000 acres of Adirondack Park.

The Houston area’s history with derechos and thunderstorm wind events

There are a few thunderstorm wind events and derechos that have stood the test of time in this area. First and foremost was just last summer when a squall line delivered a 97 mph wind gust to Bush Airport.

That storm on June 21st was one in a series last June that caused damage across the area. It was not a derecho, but it certainly caused severe damage north of downtown Houston.

A storm system in 2002 did a good bit of damage, including to the I-10/Gessner area, according to the Houston Chronicle’s archives. Just shy of $1 million in damage was reported with fortunately no injuries.

In early May 1993, a powerful squall line knocked out power to 200,000 homes in Harris County and went on to rampage Galveston County, causing at least $50 million in damage and delivering a 98 mph wind gust to Scholes Field in Galveston.

There was also an event the year after this in March that brought 100 mph winds to the less populous western end of Galveston Island.

Texas Boaters’ Derecho (May 1986)

While not Houston, the “Texas Boaters’ Derecho” of May 1986 makes the list of memorable derecho events in the United States. You can read a full summary of the event on page 20 of the May 1986 NOAA StormData publication.

It’s tough to find a lot of good information on how this particular event impacted Houston specifically, but it is infamous due to the fact that it drowned six. There was a fishing tournament and boat race on Lake Livingston that day when the storm hit, bringing winds estimated to be 90 mph and waves of 10 feet on the lake. Much like we see with the damage from this year’s derecho, there were pockets of more significant damage within a broad damage field during the 1986 storm.

May 1983 storms

Thanks to Bill Read for pointing this one out to us last week. Three years prior to the ’86 derecho, a particularly bad thunderstorm event impacted much of the Houston area.

According to NOAA’s May 1983 StormData, approximately four downburst events, including one over the city of Houston, combined with eight tornadoes for a deadly severe outbreak in our area. Winds were estimated at 75 mph or stronger in spots, with several transmission towers crumpled over, much like in this month’s event.

Over 300,000 customers were left without power in that storm, which would have been a bit less proportionally to this year’s storm. Winds were measured as strong as 110 mph during a tornado in Nederland, near Beaumont with this one. According to a Houston Chronicle recap of this event at the time, the spokesman for the Houston-Harris County Civil Defense stated that the damage was worse than in Hurricane Carla in 1961.

Approximately 10 people died with over 100 injured from this storm. Arguably, this was the previous worst non-hurricane wind storm in Houston until last week’s. It’s tough to find an official estimate on the damage caused by the May 1983 event, but it was likely in the tens of millions of dollars at the time.

Other events that seemed to garner some attention were a combination of severe storms and tornadoes on May 2, 1979, which primarily impacted western and northwestern parts of the area. On May 7 of 1976, significant wind damage occurred east and southeast of Houston, along with a few tornadoes nearby. The Exxon facility in Baytown apparently observed winds of 90 to 95 mph with considerable damage in that community. Back on June 4, 1962, a torrential squall line of storms seems to have had something of a similar impact on parts of the city as the recent derecho. Many people lost power, wind gusts hit at least 75 mph, and some windows were blown out downtown.

While last week’s derecho was extreme by any real definition of Houston thunderstorms, I think we can assume that perhaps the return period on such a storm may be less than we might have thought. And Houston can now add destructive thunderstorm winds to a litany of periodic weather disasters including freezes, floods, hurricanes, extreme heat, and drought.