Eric and I just want to provide a quick update on the situation that is expected to evolve tonight southwest of the Houston metro area. There have been a few things that have come together today to lead us to think a significant thump of rain is possible in the Matagorda Bay area, extending into Wharton and possibly southern Fort Bend and Brazoria Counties at times. For the vast majority of the Houston metro area, periods of rain are expected, some of which could be heavy, especially in the southern half of the metro area. But serious, widespread flooding is not a concern for us at this time.

How much rain is expected?

As of right now, the thinking is that a general 4 to 8 inches of rain will fall between this evening and tomorrow morning for those areas in Matagorda, Wharton, and Jackson Counties.

There are a couple models we utilize for higher resolution in these types of events that are spitting out some pretty hefty totals, in excess of 10 to 15 inches. So in a worst case scenario, we could be talking about some pretty big rain totals down there. Some of the heavier rains could extend into southern Fort Bend, Brazoria, or Colorado Counties. Galveston County could be on the fringe of heavier rain at times also.

Why is this a problem?

Besides the obvious reason that 8 to 10 inches or more is a lot of rain, the area just southwest of the Houston metro is especially vulnerable right now to flash flooding. Gauge data from the Lower Colorado River Authority (LCRA) shows that once you get close to Bay City, 72 hour rainfall totals have been up over 4 to 7 inches.

Basically, an area that has seen this much rain already cannot handle 8 to 10 inches or more of it, so flash flooding is very likely to begin quickly as heavy rain falls.

Could the rain forecast change?

Absolutely. Models are pretty locked in on the region of greatest impact tonight (southwest of Houston), but their performance has struggled at times this week. We are dealing with a slow moving non-tropical system that is behaving like a tropical system. There’s inherent uncertainty on the finer details of the forecast, but for the most part we know that heavy rain is likely in spots, primarily southwest of Houston, and that heavy rain should be enough to cause flash flooding down that way.

Is there a chance this shifts to the Houston area?

As noted above, forecasts can change of course. But right now we feel pretty confident that the risk of serious flooding will not expand into the Houston metro area. Modeling is in good agreement on this, the meteorological variables are best aligned for heavy rain to the southwest, and those areas have had much more rain than the Houston metro has over the last 3 days. That doesn’t mean there won’t be periods of heavy rain in spots tonight. That also doesn’t mean that we won’t have any street flooding issues to contend with. Those are possible, as they always are when heavy downpours are forecast. But we do not expect serious, widespread flooding in Houston.

Why no flood scale alert?

This is a little trickier to answer, but basically since we don’t expect more than some nuisance street flooding in the Houston metro area right now, we are holding back the flood scale. At best it would be a Stage 1 for Houston. But for Matagorda, this would be higher than that, so we don’t want to confuse people southwest of Houston, needlessly panic the bulk of our readers in the Houston metro area, or send any kind of mixed message in general.

The bottom line is: Heavy rain is possible anywhere tonight. Street flooding is always a possibility, though we don’t believe it will be a huge deal in Houston. Significant, potentially widespread flooding is possible in Wharton, Jackson, and Matagorda Counties.

How does Friday look?

Without getting into too much detail: Expect scattered showers and thunderstorms, but the overall coverage of the rain should begin to decrease again tomorrow, as previously expected. We will have the latest for you on that in the morning.

Good morning. While Houston has largely been spared by heavy rains over the last several days, a significant flooding event has unfolded to our south, with more than 10 to 15 inches falling in locations such as Rockport and Palacios along the Coastal Bend of Texas. These areas lie at significant risk again today. While Houston should see a wet day as well, accumulations will be lower in the metro area, especially along and north of Interstate 10. The threat for heavy rainfall should begin to back off somewhat on Friday.

Thursday

Texas’ coastal storms are being driven by a large area of low pressure over the southern part of the state that is drawing Gulf of Mexico moisture into the coast. This low should eventually weaken and move west later on Friday, but until that time very heavy rainfall will be likely for coastal areas, with the Coastal Bend the most favored area. An additional 3 to 6 inches are possible today from Corpus Christi through Matagorda Bay, with higher isolated amounts.

Closer to Houston, within the metro area, locations south of Interstate 10 may see 1 to 3 inches with higher isolated amounts, and areas north of I-10 likely will see 1 inch or less. These rains will again moderate highs, such that locations closer to the coast peak at about 80 degrees, with slightly warmer conditions inland. On and off stormy conditions may well continue overnight into Friday morning.

Friday

As the low eases westward, heavy rain impacts should be more scattered on Friday in the Houston region, but will not go away entirely. I still expect more than half of the area south of I-10 to see rainfall. Highs will again be in the low 80s, with winds increasing to about 15 mph from the east. Skies should remain partly to mostly cloudy.

Saturday

The first half of the weekend should see a mix of sunshine and clouds, allowing high temperatures to recover to about 90 degrees for much of the area. Afternoon showers will definitely be a possibility, but they should lack the organization of our recent, heavy rains.

Sunday

This should be a sunny, warm day with highs in the low 90s. While I can’t entirely rule out some passing showers, most of the region should stay dry.

Next week

The forecast for next week remains somewhat uncertain, as it does not look like Houston will fall under the sway of a dominant ridge of high pressure. At the same time, right now there don’t appear to be any solid triggers for widespread rainfall. So perhaps we’ll strike a happy medium for July, with highs of around 90 degrees, partly sunny skies, and a chance of daytime showers? I would not turn that down at a time when temperatures can often push into the upper 90s, but for now we’ll have to wait and see.

Houston’s dreary pattern will continue for a few more days, especially over coastal areas, in the absence of high pressure to shut off rainfall. Our biggest concern lies well to the southwest of Houston, where several inches of rain have already fallen near Matagorda Bay. These areas are likely to see the potential for the heaviest rainfall again today and Thursday, raising our flooding concerns.

Wednesday

The overall pattern remains, with a broad upper-level low pressure system over coastal Texas that is helping to rain moisture down upon the Gulf, and parts of the state near the Gulf of Mexico. Showers are largely confined to coastal areas this morning, but models indicate they will push further inland later today, with areas north of Interstate 10 seeing at least a scattered chance of rainfall this afternoon.

For the Houston region, accumulations will likely be 1 to 3 inches right along the coast, with higher isolated amounts, and less than 1 inch for most inland areas north of Interstate 10. The map below, from NOAA’s Weather Prediction Center, shows the area along the upper Texas coast most at risk for heavy rainfall later today. Matagorda Bay could see 2 to 4 inches of rain, with higher isolated totals. Due to clouds and rain, highs today will likely be in the low- to mid-80s for much of our area.

Thursday

This will be another wet day, quite possibly a repeat of Wednesday in terms of rains and temperatures, with heavy rainfall along the coast, and especially southwest of Houston near Matagorda Bay. After all of this accumulating rain, areas such as Port Lavaca and Victoria could definitely see the potential for flooding, which is something to consider if your travels take you southwest of Houston, along the Highway 59 corridor.

Friday and Saturday

As the low-pressure system begins to depart the potential for heavy rainfall should start to diminish some, but both of these days should see the potential for widespread, intermittent showers. Skies will otherwise be mostly cloudy, with highs in the upper 80s to 90 degrees for most. Have a backup plan for any outdoor activities on Saturday.

Sunday and beyond

Sunday should bring the return of at least some sunshine to the region, although we’re probably not talking full-on blue skies. Beginning Sunday, and into early next week, we should see a more summer-like pattern, with highs in the low 90s, and a 20 or 30 percent chance of a passing shower during the afternoon due to heating and the sea breeze.

Tropics

Tropical Storm Elsa is approaching the coastal bend of Florida this morning with 65 mph sustained winds. After landfall today it will cross the southeastern United States, likely maintaining tropical storm-strength winds before reemerging into the Atlantic just off the eastern shore of the United States. It could bring messy conditions up the eastern seaboard on Thursday and Friday as it accelerates to the northeast. After Elsa, the Atlantic tropics should remain mercifully quiet for at least the next week or so.

Good morning. Houston’s wet pattern continues with the potential for moderate to briefly heavy rainfall across the region this week. However, while it will be wet, these storms are mostly not producing flooded roadways. The upside is that cloud cover will generally keep our highs in the upper 80s this week at a time when the mercury often rises into the mid-90s.

Tuesday

The heaviest rains this morning are concentrated in the Matagorda Bay region, to the southwest of Houston. Short-term models suggest showers will most likely remain along and south of Interstate 10 today, with inland areas likely to have a drier day with perhaps no rain. As a result, inland highs may reach the upper 80s, with mostly cloudy skies, whereas the coast remains in the lower 80s. Winds will be light, out of the southeast, and rain chances will back off a bit this evening.

Wednesday

Wednesday looks similar to Tuesday, with storms starting near the coast or offshore, and again migrating inland. I would again expect better rain chances south of Interstate 10, with warmer temperatures near 90 degrees inland, and 80s closer to the coast. For Tuesday and Wednesday, overall accumulations north of Interstate 10 will probably be 1 inch or less, with 2 to 4 inches along the coast.

Thursday and Friday

The potential for organized storms starts to decrease Thursday as the atmosphere becomes slightly more stable. But we’re still going to see showers fire up with daytime heating, and I’d say about half of the area will at least see some brief showers on each of these days. High temperatures for most will likely get into the upper 80s.

Saturday and Sunday

At this point rain I think rain chances will probably diminish further for this weekend, likely into the 30 to 40 percent chance each day. Sunday probably has a better chance of seeing sunnier skies with only very scattered showers. However, the global models are not in great agreement about the pattern, so stay tuned.

Tropics

Tropical Storm Elsa is passing near the Florida Keys this morning, and will now move northward, just offshore the west coast of the Florida peninsula. Its primary threat remains rainfall, but it will also bring breezy conditions and swells to areas such as Tampa Bay today and tonight. After Elsa moves across Florida and up the Atlantic coast, the tropics should remain quiet for a few days—which is frankly how we expect things to be during early July.