From Dallas to Del Rio, the entire state of Texas has been feeling the heat this summer.
Texas A&M University Regents Professor of Atmospheric Science and Texas State Climatologist, Dr. John Nielsen-Gammon, gave his input on the weather conditions we’ve seen so far and what to expect for the remainder of the summer.
I want to start with a general overview. Is this summer significantly different than what we’ve seen in the past?
We started out fairly mild beginning of June, but then things turned hot for basically the southern and western half of the state, including San Antonio. Since mid-June, it’s been one of the hottest summers on record. North Texas, as has so far, been a bit milder, but still sort of on the warm side. So, exceptional in parts of the state and just annoying in other parts.
Last May, we had temperatures that were hitting 100 degrees by mid-May. We didn’t have those 100-degree temperatures until mid-June this year. Why is that? Was there a different pattern at play this year?
- The rain we had in the middle of the spring ended drought conditions in much of the state; however, the western part of San Antonio and eastern part of the Hill Country is still in serious drought.
- Areas to the south had plenty of rain that helped put a damper on high temperatures because most of the sun’s energy went into evaporating water. As the moisture was evaporated we had very high humidity, making the heat index values very high at the same time.
- Another contributor was hot air from Mexico, Arizona, New Mexico that came in at higher altitudes, which kept all the moisture at lower levels.
Can you explain why elevated temperatures are often associated with the high-pressure systems?
- High-pressure systems are typically where air is sinking. As air is sinking, it’s warming, and upward motion for thunderstorms is suppressed. Thus, we are warm and dry, which allows for really high temperatures when a high pressure is on top of us.
- The worst possible temperature conditions is when the circulation brings hot air from the high desert southwest across the top of Texas. So, in addition to having warm air in the high atmosphere, we are getting much warmer air at the surface as the high air is sinking.
We’ve seen quite a few high pressure systems this summer. Do we normally see this many during this time?
- High-pressure systems like to camp out over the southwestern United States, but usually not this frequently or persistently.
- It’s not normal for this to happen, but it’s not all that unusual either; it’s just a sign we’re going to have a dry summer.
- The favorable circumstance is when a band of high pressure stretches across the country, which brings us tropical air allowing for more of the pleasant Caribbean type summer, rather than the dusty heat we have now.
With that, would you say that this transition into the El Nino is having any impact on why we’re seeing what we’re seeing?
- The El Nino that’s been developing for the past month or two is probably not really affecting our weather that much right now.
- Around October and November, El Nino begins to influence the jet stream by driving it farther south than usual. Cooler conditions can be expected to begin in the fall and persist until sometime in the spring.
With the warm waters that are in the Gulf of Mexico right now, do you have any expectations for the tropics?
- The outlook is for something similar to a normal season.
- El Nino is producing wind shear that tries to rip hurricanes apart before they form, and the very warm water temperatures favor development of tropical disturbances. I expect going forward, this can only be sort of a tug of war in that regard.
- One thing to watch for is because we’ve had warm temperatures in the Gulf of Mexico for so long, we’re vulnerable for late season disturbances, potentially because of an Atlantic wave.
Can you explain what variables are considered when publishing the next updated drought monitor?
The Drought Monitor author looks at literally hundreds of different maps and charts showing:
- How rainfall totals compare to historical values
- How temperatures might have been affecting evaporation
- Soil conditions
- Reservoir levels
- Streamflow levels
- Impacts on the groundwater
Agriculture, water supplies, wildfires- that sort of thing.
Do you foresee the drought getting worse and spreading across Texas?
- Right now, the worst places are the ones that have a combination of being dry recently and still in a rainfall deficit that hasn’t been made up.
- Expect by early to mid-August drought will be kind of even more widespread than it is now.
- After that it will depend on what happens with tropical disturbances. We don’t really want to see a hurricane come through partly because it’s damaging, but also because it only brings rain to a narrow swath of Texas. We’d like to get a nice tropical pattern where we get rain frequently throughout the week. That’s the best way to end the drought.
What are your expectations for the rest of the summer? What do you think it’ll be like next summer?
- We’re expecting a relatively warm summer for the rest of this summer, probably going to come into top ten for Texas in terms of heat.
- Things have dried out so much that we’re basically put in a place where normal weather conditions will give us above normal temperatures.
- Next year is going to depend upon how much rain we have leading into the summer. And since it’s an El Nino year, we should get plenty of rainfall, which would translate into a relatively mild summer next year. So I’m certainly hoping for that.
Do you have any recommendations for large landowners or just your average homeowner going forward with the drought and the heat this summer?
- Well, a lot of preparations for drought and heat need to happen before the drought hit. Unfortunately, it’s too late now in that sense.
- If you have a ranch you want to make sure your carrying capacity will be able to withstand the drought, in terms of hay and stock tanks.
- For homeowners, you want to have landscaping that will still do okay in the middle of a drought when you might be under water restrictions.
The important thing, at least for the sake of everybody else, is if water restrictions get imposed or get increased, don’t water more to to make up for it. That sort of defeats the purpose and makes makes things even worse later on for everybody.
Is there anything else you’d like to add?
- One issue that we’re starting to see and we may see more of as the summer goes on is wildfire, because we had so much lush growth during the spring and early summer that’s now dried out.
- If we happen to have a period with windy conditions, the fires can spread rapidly.
Unfortunately, this combination of wet and dry is is ideal for wildfires and presents an additional danger.
This interview has been edited for length and clarity.