Author: Matt Lanza

Moving on from Imelda

Posted by Matt Lanza at 6:27 AM

Imelda is thankfully in our rear-view mirror now, and we can begin the process of cleaning up from the latest in a slew of problematic flooding events in Southeast Texas in recent years. Eric and I will take some time to process this and recap it for you in some capacity next week. The weather doesn’t stop, so let’s discuss our weekend.

First, let’s talk about residual Imelda-related issues. Most bayous across central, southern, and western Harris County are back in their banks this morning. We do still have flooding issues in eastern Harris County.

  • Greens Bayou is still out of banks downstream of Highway 59 to the Ship Channel. It has crested and should be back in its banks soon at Mount Houston. Greens will continue slowly falling downstream today.
  • Garners Bayou is out of its banks at the Beltway, but is falling.
  • Cedar Bayou has crested at Highway 90 and is falling. It should crest soon at FM 1942.
  • Both the East and West Forks of the San Jacinto River have crested in major flood. They should both be back in moderate flood later today.

The San Jacinto River below Lake Houston will rise and crest in major flood today before slowly dropping back this weekend. (NOAA/NWS)

The San Jacinto River near Sheldon (above) continues to rise and should crest this afternoon before slowly falling this weekend.

Folks living along the Brazos River, you have nothing to worry about, as rains both over you and upriver were not too significant this week.

Those trying to travel to or from Beaumont, note that I-10 is shutdown at the San Jacinto River due to multiple barge strikes. And it sounds like it might be awhile.

I-10 also remains closed in both directions between Winnie and Beaumont due to high water.

Today

Not everyone will see showers or storms today, but they will be around. Any storms today will probably move south to north at a slow, steady clip, so they could put down a quick inch or so of rain. While this won’t lead to widespread problems, there could be a handful of locations today that see some short-fused street flooding or some rises on bayous. Again, we don’t expect anything significant. With a good deal of clouds still, we should see highs in the mid- to upper-80s.

Weekend

Both Saturday and Sunday should see a mix of sun and clouds with just a chance of a shower or storm in a few spots. We’re sort of back to typical late summer this weekend. Look for highs near 90 degrees or in the low-90s and lows in the mid- to upper-70s.

Read More…

After a mostly benign afternoon, with the exception of some street flooding in Galveston, we are back in the thick of things now, as Imelda’s Wednesday night show is underway.

We just had a reported tornado west of Mont Belvieu, and a funnel cloud sighted in Deer Park. Other storms across the area are exhibiting at least some weak rotation, and it would not be surprising to see at least one or two more tornado warnings get hoisted before all is said and done.

In terms of rainfall, a transient heavy rain band is setup along and south of I-10 from near Fulshear through Baytown as of 5:35 PM. That does not appear to be a “training” band at this time, but we’re watching to see if additional development will occur on the western flank. A secondary band is setup over Wharton County moving toward hard hit Matagorda County and parts of Brazoria County as well.

The radar situation at 5:35 PM Wednesday shows heavy rain in spots along and south of I-10 and also toward Wharton County, heading toward Matagorda and Brazoria Counties. (RadarScope)

So what are the expectations for the rest of tonight? I’ve tried to digest as much observational and model data as I can, and here are the key bullet points I think we can emphasize.

  • For Downtown Houston and points north and west (including The Woodlands, Conroe, Katy, Sugar Land, Kingwood, and Humble): Periods of heavy rain through the night. It may be more dry than wet in many locations, and at this point, I don’t see much reason to be too worried about things in those areas. We will watch late tonight for some heavier rain perhaps in the city of Houston or up toward Spring, Kingwood, and Humble.
  • South of Houston (including Pearland & northern Brazoria County) and southeast to Galveston County (Texas City, League City, Webster, and Friendswood): Periods of heavy rain early, perhaps becoming a bit more intermittent as the evening goes on. Given heavier rains here earlier today, some flash flooding is very possible.
  • Far south of Houston (Matagorda County, Lake Jackson, Freeport): Heavy rain this evening, with potential for another period or two of heavy rain overnight. Rain totals should be significantly lower than earlier today though.
  • Eastern parts of Harris County (Baytown, Mont Belvieu, Crosby): Heavy rain at times this evening, and then occasional periods of rain overnight. More concentrated, heavier rain possible toward daybreak. Flash flooding is a possibility.
  • Far eastern parts of the region toward Beaumont (Liberty, Hardin, Chambers Counties east to Beaumont): Frequent periods of heavy rain this evening and overnight. Flash flooding likely in spots. Significant flash flooding possible closer to Beaumont and perhaps points north.

I tried to cover as much as possible there. Folks farther northeast, in San Jacinto, Polk, and Tyler Counties will also see periods of heavy rain tonight and potentially some flash flooding.

Weather modeling has been all over the map in terms of how things finish late tonight and Thursday morning to the point of agitation, to be honest. However, some newer data is indicating that a more concentrated band of heavy rain could develop across Grimes and Montgomery Counties into northeast Harris and Liberty Counties, extending east, again, toward Beaumont. Should that occur, significant rain and potential flash flooding would occur, which could include The Woodlands, Spring, Humble, Bush Airport, and Kingwood. I want to just urge caution on that, as we still have some uncertainty surrounding how that will unfold. We will either update you later this evening or very early tomorrow morning.

Good morning. For most of the city of Houston and points north and west, overnight rainfall caused few problems and has really only served to saturate soils a bit. Imelda’s dissipation has allowed for one main band to focus this morning well to our south into Matagorda County, which then arcs offshore back inland east of Galveston and Bolivar, aimed primarily at the Beaumont area.

Radar this morning shows extremely heavy rain well south of Houston and east of Houston, along with a smaller band northeast of downtown Houston. (RadarScope)

The radar snapshot above from just after 5 AM shows limited heavy rain around Houston, with one narrow band extending from northeast of downtown into Liberty County.

Focusing a little closer on Matagorda County for a moment: This band means business.

Rainfall rates of 3″ to 5″ in an hour were being observed in parts of Matagorda County this morning. Flash flooding is likely there. (RadarScope)

Rainfall in the hour prior to my writing this post was over 5 inches (!) in parts of the county. A gauge near Sargent has received over 18 inches of rain in the last 24 hours. Those are extreme rainfall rates that will quickly cause flash flooding in that area. Travel across much of Matagorda County is not advised this morning, and it will likely get a bit worse before it gets better. These beefier rainfall rates will likely push into southern Brazoria County as well, so folks from Lake Jackson and Freeport through Surfside will probably want to use caution this morning as well.

Rest of today

So the million dollar question is: Where is this going? Saving the meteorology lesson for another day, we often see blow ups like this in tropical systems late at night and in the morning. Over the next few hours, this will probably yield areas of heavy rainfall across Matagorda, Brazoria, and Galveston Counties. Given that many of these locations have seen 4 to 9 inches since yesterday, it won’t take much for flash flooding to begin if rainfall rates are intense enough. Rainfall may begin to taper off this afternoon or shift more to the east toward Beaumont or Port Arthur. We do expect some new showers and thunderstorms to develop in and around Houston by later this afternoon. More on that in a moment.

Bottom line: What should you do today? Be cautious, but most of us can go about most of our day as usual (unless you’re down in southern Brazoria and Matagorda Counties as noted above). If you live southeast of Houston, be extra vigilant in case rain rates escalate a bit this morning. Eric will update you on the progress of that a bit later. In Houston and points north and west, I think most daily activities will be fine through 3 to 4 PM, though it will be raining at times. After 3 to 4 PM, things could begin to go downhill a bit. Given all this, if you work daytime shifts and can work your way home a little earlier than usual today, that would not be the worst thing in the world.

Tonight

All along, it appeared tonight would be the “main event” so to speak for the Houston area. Look for storms to begin to show up around 3 to 4 PM or so in and around Houston. Some of the storms will be heavy with impressive rainfall rates. As we work through the evening, I think the general trend will allow for those storms to slowly lift north and east, while becoming more numerous. For Houston, the hope is that the storms will lift out quickly enough to limit significant problems. We would then see the heaviest rain tonight up into Liberty County or point northeast from there. There is still a good deal of uncertainty regarding tonight’s forecast, so be sure to check back with us later today for an update when we should hopefully know more. It could get a bit rough this evening, but we’re hoping for the best possible outcome right now.

We still see rain becoming more scattered tomorrow and Friday, with a mostly dry weekend expected. Eric has you covered a little later this morning.

Tropical Storm Imelda has begun its transformation into a significant “blob” of rain over Southeast Texas this evening. Let us walk you through what we are expecting through Wednesday morning.

Now

Imelda is now classified as a tropical depression, and if I’m reading the radar correctly, the center as of 7:45 PM was located just west of Pearland and becoming more diffuse.

Tropical Depression Imelda is spinning away and crawling north this evening across Brazoria County. (RadarScope)

You can see from the radar loop above that Imelda has 2 or 3 areas of main concern, as it relates to rainfall. There is the main “core” of the storm over Brazoria County. This will be the primary rain producer this evening. As the center crawls north, that will come with it. This is what we are concerned about for the bulk of the Houston Metro.

The second area is a feeder band to the east of Baytown. That is aimed at parts of Galveston Island and north toward Chambers and Liberty Counties. That is not expected to move much, and within this region, expect heavy rain and potentially localized flooding overnight.

The third area is a band well to our east, aimed at the Beaumont/Port Arthur area or just west. That will be capable of some heavy rainfall tonight as well. But it may weaken a bit as this band near Baytown takes over.

So a lot happening here.

Overnight

I mentioned above that Imelda’s center is becoming more diffuse. That means that more erratic behavior of the storm track could occur. So expect that heavy rain currently located over Brazoria, Galveston, and southeast Harris Counties to lift north into the bulk of the Houston metro area. At nighttime, tropical systems can sometimes see rains intensify a bit. So I fully expect heavy rain at times in Houston and points south and east. At a minimum we would expect 2 to 5 inches of additional rain in these areas by sunrise on Wednesday. We could see some spots pick up as much as 5 to 8 inches or even more, however, and those would be the areas we’re most concerned with in terms of flooding. Again, that would be most likely from Downtown Houston south and east.

For those north and west of Downtown Houston, we expect periods of rain overnight, locally heavy. While we will monitor those areas for flooding risks, we do not think it is quite as serious as south and east. But given that there is still a degree of uncertainty with this system, the entire region should monitor the progress of the rain, both before bed and when you wake up. Do not assume tomorrow that you’ll be able to get to the airport or to work without issues, so make sure to check in on what has transpired overnight in the morning.

Wednesday daytime

We should see rains continue off and on through the day Wednesday. We could see a bit of a lull in the activity for a time during the afternoon hours before heavy rain sets back up late. Again, we have some uncertainty around exactly how tomorrow will unfold. Eric will have an update later this evening, and I will update you more on Wednesday’s outlook in the morning.

Wednesday evening and beyond

We expect another round of heavy rain tomorrow night, again in multiple areas. We’ll likely see the “core” of the storm reignite tomorrow night with heavy rain gradually lifting north of Houston. We aren’t entirely sure if that will be aligned over the center of the city or more to the east. We also will likely see another significant “feeder” type band east of Houston, though we’re not quite certain where that will be aimed. Check with us tomorrow for the latest on these aspects of the storm. We could see some very heavy rain from this, and with the grounds certainly saturated by then, we would expect a good amount of flooding risks, potentially significant to develop. We continue to expect event totals to be on the order of 5 to 10 inches on average, with isolated smaller areas seeing as much 20 inches or more.

(Space City Weather)

Eric and I will continue with a Stage 3 flooding event expectation for Imelda’s rains tonight, tomorrow, and Thursday. This remains an evolving situation though, and it would be best to check back for the latest several times through the event. Eric will have an update around midnight.