How much rain we received:
Going back to Sunday April 28th parts of SE Texas like Walker and San Jacinto counties received 25″ of rain. Specifically Huntsville, got near Harvey level flooding.
Tracking three types of weather patterns:
There are basically three main types of weather patterns we track. There are large scale patterns like a dome of high pressure, or cold front. There are meso-scale weather patterns like a trough of low pressure or dry line. And then there are micro-scale patterns.
We were tracking two of these elements Sunday and last week. The meso-scale pattern was a trough of low pressure sitting on top of central Texas.
This trough would send out impulses east, and those impulses would create rain and thunderstorms. If this was the only element we had last week, rain totals would have ranged from 1″-4″.
A micro-scale low pressure:
When you look at where the heaviest rain fell, you see it was isolated. While all of us had a southeasterly winds pumping in a high content of moisture and warmth, only a few northern cities received more than 10″ of rain. There is a reason.
The low you are seeing near Lake Conroe was small. But its effects were huge! First of all, micro-scale lows are hard to predict because they are difficult to see and usually weak. I remember having a conversation with Justin Stapleton last week and we were trying to find why cities like Huntsville were getting so much rain. We found the low and found the problem.
How small was this low?
This low was so small that all of our weather models could not see it. They all saw the trough to the west, but none of them could see the micro-low. After Monday I realized all of our models would be wrong with the timing of these storms and the amount of rain for the rest of the week. I stopped showing the futurecast because it was wrong with timing of the storms. I even received this question from one of our morning viewers, “I have a quick question for y’all. Why do y’all keep skipping the future cast for the morning weather?” Stellasamoska
I wrote back and said, “The reason is because the futurecast is wrong. If I were to show it this morning there would be no rain in the forecast today.” (And we did get more rain that day.)
When we get storms like this, rivers will flood. Our Flood Tracker shows areas of river flooding in and around Harris County. If in live near these areas, avoid parking along streams, rivers and creeks and never drive around a barrier.
The role a warmer world played in this event:
If an attribution study is done on this flood event I’ll let you know. What these studies show is how much more likely this event was because of a warmer world. It would also look at how much more rain we received from this event because of warmer temperatures. We’ve always flooded in SE Texas, but did climate change make this event worse? And by how much? This is what Climate Central found:
From Climate Central:
- Climate change is supercharging the water cycle, bringing heavier precipitation extremes — and related flood risks — across the U.S.
- As the climate has warmed from 1958 to 2021, the most extreme precipitation days have intensified in every major U.S. region, led by the Northeast (+60%) and Midwest (+45%).
- This hazardous intensification is expected to continue with future warming.
- With 2°C (3.6°F) of warming, 85% of 3,111 total U.S. counties are likely to experience a 10% or higher increase in precipitation falling on the heaviest 1% of days.
- High future levels of extreme precipitation intensification are concentrated in: Alaska, Hawaii, Tennessee, Alabama, Georgia, Mississippi, Maine, North Carolina, and Kentucky.
- People, ecosystems, and infrastructure in both wet and dry locations are facing the risks that come with short bursts of extreme rainfall.