Matt Lanza

Houston’s threat for storms kicks off again today

April 29, 2016 at 6:27 am by Matt Lanza

It looks like it’s going to be another one of “those” weekends here in Southeast Texas. We’ll have rain, storms, and potentially flooding to contend with, and all the while, we have a good deal of uncertainty still in the forecast. Here’s a short breakdown. I’ll follow it with an FAQ type section at bottom.

First, just a reminder: A Flash Flood Watch is posted for Houston and primarily the counties north and west of the city starting later today and going into Sunday morning.

TODAY

I don’t foresee a lot of issues this morning…if any at all. By mid-afternoon, storms should have started in Central Texas, along I-35 and points east. These will organize and spread east toward our area by late afternoon or evening. Storms this afternoon and evening will have the potential to be strong to severe. The main threats will be hail and damaging wind, and given how saturated the ground is, any sort of strong winds can be more problematic than usual. The tornado threat is low, though it isn’t zero (and as we sadly saw in Tomball the other morning, it doesn’t need to be a high risk or a strong tornado to be tragic, so please heed any warnings if issued). Obviously, our main focus will be flooding.

TONIGHT

This is where confidence drops and our risks for flooding begin to go up. I expect we will see repeated rounds of showers and thunderstorms around the region. It’s still a bit difficult to say exactly who will see the most persistent storms, but anywhere in the area around Houston (north, west, or even south of the city) stands the potential to see this happen. It’s simply too tough to say where with any specificity. We will update you on this again later today. But the Friday night timeframe is the one we’re most concerned with, namely because we’ll have a substantial amount of atmospheric moisture to work with.

GFS Precipitable Water (PWAT) forecast this evening shows summer-like levels of available moisture. (Weather Bell)

Usually once you get over 2″, you’re talking considerable moisture, which means that any thunderstorms can produce torrential rain. The concern is that a boundary of storms could sit over one area and tap into this moisture. Hopefully this isn’t what occurs, but it’s something we have to watch.

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Houston area Flash Flood Watch: Friday PM through Sunday AM

April 28, 2016 at 2:56 pm by Matt Lanza

The National Weather Service said this afternoon that a Flash Flood Watch will go into effect for much of Metro Houston (basically along and north/west of US-59/I-69) beginning Friday afternoon and continuing through Sunday morning. This includes the areas hardest hit by last week’s flooding.

Counties under the Flash Flood Watch Friday-Sunday (Iowa State/NWS)

As Eric pointed out this morning, there’s good reason for this. Most bayous in the city (Buffalo Bayou an exception) are back at their baseline levels. But, outside the city, streams, creeks, and bayous are running a few feet higher than normal still. And with a soggy ground any additional rain is unwelcome and can cause flooding concerns depending on how quickly it falls.

Basically, at this point all you need to do is continue to watch the forecast. There’s a bit less certainty with this event than there was last week. Also, it can’t be underscored enough that the rain totals implied by all models with this event aren’t anything like the last one. We want you to be prepared but not to panic here. We still don’t know exactly where the heaviest rain will fall, but we know there will be a few spots that see a pretty substantial amount of rain (not 15-20″ like last week, but 4-8″ in a few spots isn’t impossible).

So just stay tuned in through the weekend, especially if you have to travel around the area or live in an especially flood prone spot. We will have you covered.

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Houston’s Tax Day flooding put into historical perspective

April 26, 2016 at 9:00 am by Matt Lanza

Note: This is the first in a series of reports by Matt Lanza that puts the Tax Day floods into perspective, and discusses what Houston should learn from this natural disaster.

On Monday afternoon the Harris County Flood Control District released its first official summary of the historic flooding that occurred last week in the greater region. I’ve read through it and compiled some highlights for here. (You can also view the report yourself in its entirety here). A serious thank you to Jeff Lindner at the flood control district who has worked tirelessly since last week to provide critical, useful, and interesting information to put this event into context and keep the region informed. He is also a must-follow on Twitter if you’re into weather, haven’t done so yet.

Report highlights

Rainfall rates of 1″ in just 5 minutes were observed in Harris County. The maximum hourly rate was 4.7″. The maximum amount in 12 hours was 16.7″
Harris County averaged 7.75″ of rainfall for the event. That’s equivalent to 240 billion gallons of water falling on the area. This exceeded Memorial Day (162 billion gallons) by almost 80 billion gallons of water. That event was more confined, whereas the Tax Day rains were much larger spatially.

Map of 12 hour rainfall totals and location/flooding description of significant waterways. (HCFCD) — Map of 12 hour rainfall totals. Click to enlarge. (HCFCD)

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A rain-free Friday for Houston? Let’s try it

April 22, 2016 at 6:32 am by Matt Lanza

The rain is over. After days of being tortured by Mother Nature (and, you know, tigers), we can at least turn the faucet off for a bit, as drier weather builds into Southeast Texas for the weekend.

TODAY

As the upper level storm partially responsible for repeated rains finally begins to pick up some speed as it exits the Mid-Continent, that will allow for high pressure to settle in over our region for a couple days. That means we should have a good bit of sunshine today. Temperatures will pop into the low to mid 80s.

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