While many people are concerned with rain, wind, and tornado risks when discussing the impact of hurricanes, the storm surge is by far the most dangerous factor. A 2014 study by the National Hurricane Center showed that 49 percent of all deaths attributable to a hurricane or tropical storm come from storm surges (by comparison, hurricane-spawned tornadoes only account for 3 percent of tropical storm and hurricane deaths). So what causes the storm surge? And when a tropical system makes landfall, what can you do to avoid it?
After a relatively cool and wet first week of our region’s hottest month, we now return you to your regular August programming, Houston. That’s right, high pressure is building, and temperatures are rising.
Thursday and Friday
Skies will become partly sunny to end the work week, and this will allow for warmer days, with highs in the lower 90s near the coast, mid-90s in Houston, and upper 90s for areas further inland. The sea breeze should be strong enough to produce some scattered showers during the afternoon and evening hours, but except for some isolated downpours, I don’t expect accumulations to be too significant. With the humidity, heat index values will be very high, likely above 105 degrees, so please take care outdoors during the warmest part of the day.
Saturday and Sunday
Rain chances should fall back to near zero over the weekend, with highs remaining about the same under partly to mostly sunny skies. This will be a classic August weekend in Houston so if you can manage it, the best outdoor activities will involve some sort of water or other means to cool down. Fortunately the moist ground from our recent rainfall should keep highs in the mid-90s in Houston, rather than the upper 90s, but this is a small consolation.
The National Weather Service has allowed the flash flood watch to expire for the entire Houston region, with the exception of Galveston and Chambers counties. Even for these areas, showers are dying out, and we should no longer face any kind of widespread, heavy rainfall threat. It has certainly been an atypical August so far, with the absence of high pressure allowing for lots of rainfall. Another benefit has been cooler weather. The first two weeks of August are typically the hottest time of year for our region, and we’ve been blessed with highs about five degrees below normal. Here’s what it’s been like at Bush Intercontinental Airport so far.
High and low temperatures at Bush Intercontinental Airport in August. (National Weather Service)
However, as you might suspect, this isn’t going to last. As pressures rise heading into this weekend, temperatures will follow.
Wednesday
The lower pressure system in the mid-levels of the atmosphere has slid off to the east. This means there is no real impetus for widespread, heavy rainfall across the Houston area today. However, atmospheric moisture levels remain high, so we’ll definitely see at least some scattered showers today—with better chances to the east of Interstate 45—and likely some isolated downpours. Fortunately, they should be relatively short lived. Highs will be around 90 degrees.
We aren’t quite done with rains yet in the Houston area, but there is some good news at least.
Taking a look at the satellite imagery from the still-not-quite-operational GOES-16 satellite this afternoon, you can see a “swirl” in the clouds over Southeast Texas. Specifically, this swirl is centered over southeast Montgomery County.
Preliminary and non-operational GOES-16 imagery shows a “swirl” in the clouds north of Houston. The system responsible for last night’s flooding has moved a bit farther east today. (University of Wisconsin SSEC)
This is the mesoscale convective vortex (or MCV) that’s been partially responsible for the mayhem across Texas the last couple days. This was over the Brazos Valley yesterday evening, and the heavy storms tend to develop on the eastern flank of these things. With that roughly over Spring now, that would seem to imply that widespread storms and rain tonight will probably develop east of I-45 and east of the hardest hit areas from this morning. That’s the good news.
In fact, we have some validation for this from the HRRR model, which did an acceptable job with the setup last night.
The HRRR model shows more widespread showers & storms mainly east of Houston tonight. Still, it’s close enough that you should stay aware of the weather tonight. (Weather Bell)
This suggests, yes, perhaps some scattered downpours around Houston this evening and tonight, but the sustained, heavier rains that could cause problems will probably be east of Houston, lined up roughly on an axis from Galveston through Winnie into Beaumont. Those areas can handle a little more rainfall than, say, Katy or Jersey Village can. Still, if you live in Galveston or Baytown or east of Houston, obviously you’ll want to stay alert tonight. And even if you live in Houston, it’s smart to remain cognizant of the situation. Though it’s unlikely we see a repeat of what we just went through, it’s always a good idea to stay weather aware during these heavy rainfall patterns.
A Flash Flood Watch is in effect for Harris, Chambers, Montgomery, Liberty, Polk, and San Jacinto Counties through Wednesday morning.
The bottom line? A repeat of this morning is not expected in Houston tonight. Areas east of Houston stand the best chance of heavy rain tonight. Regardless, in Houston and east of Houston, it’s a smart idea to stay aware of the weather tonight and Wednesday morning.
