Writing this article is challenging. The thought of families losing loved ones and those who remain unaccounted for is devastating. Covering a tragedy like this can leave one feeling powerless because there are sometimes no adequate words to express such a deep sadness.
We are frequently left wondering, “Why did this happen?” when catastrophic weather disasters like this occur. How could things suddenly turn so bad? In order to help you understand how the atmosphere came together to produce such a hazardous condition, I would want to take you through the meteorological setup that led to this incident, not to minimize the number of fatalities.
-
Death toll rises in Houston-area families following Texas Hill Country flooding
I spoke on-air about the increasing risk of flooding in the Hill Country on the evening of Thursday, July 3. Rounds of intense rain were fueled by tropical moisture that had migrated into Texas from the leftovers of two systems, Barry and Flossie.
Rainfall totals can double or even treble when dealing with tropical remnants, despite the initial forecast calling for one to three inches. These systems can swiftly escalate, which is what makes them so hazardous.
What was in effect for the Hill Country from Thursday evening until Friday morning is depicted in the graphic below. Regretfully, what transpired was better than anticipated.
There’s a reason this region of Texas is called “Flash Flood Alley.” Here, flooding is nothing new; it has happened before with tragic results. Ten teens sadly perished in 1987 when floodwaters surged quickly close to this exact location.
A number of circumstances combine to make this location particularly vulnerable: the Guadalupe River flows directly through it, it experiences heavy rainfall, and on a busy holiday weekend, the area was crowded with people enjoying the outdoors.
“This is the most dangerous river valley in the United States, and we deal with floods on a regular basis,” said Rob Kelly, the Kerr County Judge.
-
Who is still missing after Texas Hill Country floods
We may have mentioned training thunderstorms to you.This occurs when storms, like train cars traveling over the same stretch of track, repeatedly pass over the same location. It is among the essential components of flash floods.
This is precisely what took place.
Just west of Kerrville, an estimated fell between 1:00 and 4:30 in the morning. With amazing intensity, all of the water poured into the Guadalupe River and funneled downstream.
The river was 7 feet deep and flowing at 8 cubic feet per second at midnight. At a rate of 120,000 cubic feet per second, the river’s enormous outflow caused it to level out at 29.45 feet three hours later!
Training storms are depicted in this video. From one until four in the morning, it is pouring!
When asked if there was any warning before this incident, the response is definitely yes.
-
At
3:35 p.m.
, a
Flood Watch
was issued, forecasting
1 to 3
of rain, with isolated areas possibly receiving
5 to 7
. That was the first alert that conditions could become dangerous.
-
Then, in the early morning hours
1:14 a.m.
and again at
3:19 a.m.
Flood Warnings
were issued. These alerts specifically warned of
life-threatening flash flooding
.
-
By
4:03 a.m.
, the situation had escalated. A
Flash Flood Emergency
was issued one of the most serious weather alerts we have. These are rare and only used when catastrophic, life-threatening flooding is underway or imminent.
Unfortunately, though, the timing couldn’t have been more dire. The majority of people were asleep when these notifications were sent. Many people might not have heard the warnings in time if phones were turned off or notifications were silenced.
This raises still another important query: even if everyone received the alert?
In the next days, investigators and emergency personnel will be investigating these kinds of inquiries.
The problem wasn’t staffing. The San Antonio office of the National Weather Service actually employs more meteorologists than the Houston branch.
However, we must face the harsh reality that there is a limit to predictability when it comes to predicting extreme weather.
The high-resolution HRRR model started to predict 10 to 20 inches of rain as we approached the inundation. Even yet, the model failed to account for the severe rainfall that eventually occurred west of Kerrville.
What would have happened even if it had?
In the middle of the night, would emergency management have issued a preventive evacuation? For reasonable reasons, such behavior is practically unheard of. It is quite unlikely, statistically speaking, that a single area will receive more than 10 inches of rain in three hours. However, even low-probability scenarios might turn into disastrous reality when the risk is great.
The question that remains is how the National Weather Service, emergency managers, and meteorologists convey severe but improbable dangers. Since worst-case scenarios rarely occur, how do we communicate them?
This conundrum was aptly described by meteorologist Alan Gerard in his Balanced Weather newsletter:
In actuality, the current state of science does not enable us to predict that a small area, such as the south fork of the Guadalupe River, will receive eight hours of rain in three hours, even a few hours in advance, let alone with the kind of lead time that would, for instance, prevent people from camping there on a particular night.
Our greatest option is to create better models with more accurate probabilistic data that can be presented in a way that encourages individuals to take more proactive, smarter decisions.
Over the past ten years, forecasting has advanced significantly, and there is a genuine chance that we will be able to issue earlier, more focused warnings. We can achieve that future.
However, almost all funding for the type of research that would enable these next-level forecasts is eliminated in the newly enacted NOAA budget.
We must have that discussion, but it is for another time.
Click below to view my entire video on this subject.
See Our Email Newsletter for More Stories Like This One
