In brief: While rain totals across the Houston area have been rather variable (ranging from less than an inch in some spots to over 8 inches in far southern Brazoria County), we expect everyone to participate in rain and storm chances this weekend, especially from Saturday night into Monday. Flash flooding remains a distinct possibility, and our Stage 2 flood alert will remain up through at least Monday.

Rainy pattern check-up

We’re a few days into this relatively significant change to a rainy pattern, and so far, so good for the most part. We’re going to maintain the Stage 2 flood alert through the holiday weekend. I think the rains we saw Wednesday down in Brazoria County (7 inches) exemplify what this setup is capable of.

So far, the northern half of the area has seen a relatively pedestrian 1 to 2 inches (even less in spots), while the southern half has seen 1 to 4 inches on average, with pockets of 5 to 8 inches. We expect another 1 to 4 inches on average over the next week across the entire area. Isolated higher and a couple lower amounts are indeed possible.

For those concerned about the situation in Corpus Christi, Lake Texana has seen about 3 inches of rain, while Lake Corpus Christi has seen about 4 inches of rain so far. Areas upstream of those lakes have received anywhere from 2 to 4 inches as well. By no means does this “save” Corpus Christi from a very bad situation, but it obviously helps buy some time. And any help is great news down there right now.

Today through tomorrow afternoon

Right now, weather modeling is suspiciously calm today and much of Saturday across the area. Obviously, showers and thunderstorms are still possible. But I would suspect most places stay dry as the best “oomph” for storms remains south or offshore in the Gulf. We’ll probably see clouds and sun. Highs may nudge back up into the middle or even some upper-80s after a couple days of lower 80s. There will be plentiful humidity to go along with that.

Saturday night through Monday

If we’re going to get smacked by rainfall, Saturday evening through Memorial Day would be the timeframe I’d be watching closest. A rather vigorous disturbance in the middle and upper atmosphere is going to swing into the Houston area on Saturday evening. This should provide the trigger necessary to get storms off and running. It’s impossible to really say exactly how things are going to setup right now, but expect increasing thunderstorm chances after about 4 PM on Saturday into Saturday night across the Houston area.

We’ll then need to watch for repeated development of storms and the risk for flash flooding, including in areas that have not seen much rain so far. With moisture in the atmosphere much higher than normal, any storms will be capable of dropping 2 to 4 inches of rain in an hour or so. Any “training” or repeating thunderstorms over the same area means those totals could add up quickly, hence the concern for some localized flooding and our Stage 2 flood alert. More to come on this throughout the weekend as we get more clarity on timing and locations impacted.

Next week

The area will remain under the influence of an unsettled weather pattern and above normal atmospheric moisture. I would expect this on again/off again type rain and storm stuff to continue through much of next week, though perhaps at a slightly slower pace. Either way, what we can say with fairly high confidence right now is that any sustained, strong early summer heat is not in the cards through at least early June.

In brief: A round of storms moving into the region today should impact areas south of Houston, including southern Brazoria County which has already been hard-hit by rainfall. Storms should be more scattered in nature on Friday before the likelihood of widespread heavy rainfall ramps up over Memorial Day Weekend.

Rains recap

Since the beginning of these late May storms on Tuesday, most of the Houston area has picked up 1 to 3 inches of rainfall, which has been manageable. However areas south of Houston, particularly in southern Brazoria County near Angleton and Lake Jackson, have had a far wetter time of it. Some of these locations have already received 6 to 8 inches of rainfall. Unfortunately for these locations, it appears that rainfall on Thursday will be mostly concentrated over areas south of Interstate 10.

Thursday

A check of the radar this morning shows a large mass of showers off to the southwest of Houston near Victoria Port Lavaca. These showers and thunderstorms should slowly move to the northeast, toward the metro area this morning. Our latest high-resolution guidance suggests these storms will largely remain confined to areas south of Interstate 10 as they move through during the morning hours, and likely exit to the east by early afternoon. Rain accumulations of 1 to 3 inches will be possible for coastal areas, but I’m hopeful that much of the heavier rain will fall just offshore.

For the rest of the Houston area rain showers and thunderstorms should be more scattered later this afternoon. Skies will be mostly cloudy with high temperatures in the upper 70s to lower 80s. (I have to say that afternoon temperatures on Wednesday afternoon were very comfortable for late May in Houston). Rain chances should be low overnight, with lows around 70 degrees.

Friday

This is looking like a day during which showers and thunderstorms are more scattered in nature rather than organized into a broader system; which is to say rain chances will be a bit lower than the weekend at about 50 percent. With mostly cloudy skies we can probably expect highs in the vicinity of 80 degrees.

Memorial Day Weekend

The upper-air pattern will become more amenable to supporting widespread showers and heavy rainfall this weekend as a low pressure system allows the passage of multiple disturbances over the region. Rain chances will be near 100 percent on Saturday and Sunday, and perhaps only a little bit lower on Monday. Most of the area is likely to pick up an additional 3 to 6 inches of rain this weekend, with higher isolated totals leading to at least street flooding, and possibly some flash flooding. For this reason we are maintaining our Stage 2 flood alert through the holiday weekend.

It’s still a little too early to have precise details about timing, but basically you should be prepared for some disruptions at any point this weekend. Certainly roads should be passable most of the time, but these are the conditions that support some impacts to mobility where rainfall is heaviest and/or prolonged. Basically we want you to be alert to the possibility of flooding, but not fear widespread mayhem.

High temperatures should remain in the low- to mid-80s this weekend with plenty of humidity, and nights not cooling down much. Saturday looks to be mostly cloudy, but we could see some breaks in the sky on Sunday and Monday when it’s not raining.

Next week

I don’t have great confidence in the forecast for next week. Daily rain chances continue to look healthy, perhaps in the vicinity of 50 percent or so, but at this point I think (and hope) amounts will be trending downward after Monday. Highs remain in the 80s, probably.

In brief: Tuesday night’s rains were mostly manageable, but they are just the first round of storms that our region will experience over the next week. We now believe the heaviest rain is likely to come this weekend, when flooding concerns will be greatest.

This is just the beginning, not the end

In recent years Houston has often experienced a pattern in which we will see one or two days of rain before a front moves through, or high pressure sets in, or something else happens to turn off the spigot. Then we’ll have a few weeks of sunny skies and no rain. Only rarely have we seen periods of several days of moderate to heavy rainfall as we are now experiencing.

The ongoing rounds of storms that will rotate into Houston through Memorial Day weekend, and possibly beyond, is probably due to the early phases of an El Niño that appears to be developing in the equatorial Pacific Ocean. This generally promotes a wetter pattern across Texas. This El Niño is likely to peak later this fall or over the winter months, and based on recent model forecasts it could be a rather strong El Niño. So maybe we will see more prolonged periods of rain, and fewer prolonged periods of dry weather.

In any case, the rounds of showers and thunderstorms that passed through the Houston region overnight are likely to continue into early next week. It won’t rain all the time, but for most locations it probably will rain at some point each day. Saturday and Sunday look to have the best chance of precipitation, which will probably spoil a lot of Memorial Day weekend plans. So it goes here at Space City Weather where we don’t control the weather, we just get blamed for it. We’ll be here all weekend, alongside you.

Wednesday

The storms that rolled through over night brought between 0.5 and 3 inches of rain to most locations. As expected, all streams, creeks, and bayous are well within their banks this morning. Flooding will become more likely this weekend, as rain accumulations stack up, and for this reason we issued a Stage 2 flood alert on Tuesday, and plan to hold it in place through the holiday weekend.

Light to moderate rains are ongoing this morning, and the overall trend is one toward weakening rather than strengthening storms. Activity will shift southward over the next couple of hours, and I expect the rains to end entirely across the Houston metro area by or before noon. This afternoon we may briefly see some partly sunny skies, with high temperatures pushing into the mid-80s or so. Lows tonight will fall into the mid-70s. As for rains, I expect low-end chances through the evening hours, so if you have outdoor plans for later today I would be cautiously optimistic.

Thursday and Friday

By early Thursday, with our atmosphere recharged, we are likely to see another rain-making disturbance moving into the region from the west. I don’t know whether these storms will be as widespread or active as what we experienced Tuesday night, but they definitely will have the potential to produce another 1 to 3 inches of rainfall. Another, similar, round of storms will be possible at some point on Friday. Highs on both days will be in the low- to mid-80s, with partly to mostly cloudy skies. Again, there are likely to be extended periods when it is not raining, so there will be some time to get outside and enjoy the moderate temperatures (for May).

Memorial Day Weekend

This weekend often kicks off summer in Houston, with sunny skies and our first temperatures in the low- to mid-90s. Well, not this year. A surge of moisture should lead to widespread showers and thunderstorms on both days, with some of these showers producing very heavy rainfall.

By this point we may see rain accumulations from storms this week pushing up to 4 to 8 inches for some locations, so we’ll be tracking creeks and bayous closely. Harris County has an excellent tool for you do to this for locations near you. The National Weather Service also has a good resource for tracking river flooding in our region. Rain chances by Monday may drop to 70 percent.

Highs will be in the low 80s, probably, and if we continue to get morning storms there may be some breaks in the clouds during the afternoon hours. Basically, you’ll need to continue to remain weather aware.

Next week

After Memorial Day rain chances will probably fall back some next week, but we probably are still looking at something like at least 50 percent daily. This, as well as ongoing partly cloudy skies, should help keep temperatures in check for the remainder of the month—which is to say we might not see 90 degrees again until at least early June.

In brief: After a mostly quiet Tuesday, the potential for widespread showers and thunderstorms will increase tonight and into Wednesday morning. Here’s our latest thinking.

This post will only cover the forecast for Tuesday evening through Wednesday morning. However, in the big picture, not much has changed with our forecast through Memorial Day weekend. We still expect periods of widespread and, at-times heavy rainfall. Our Stage 2 flood scale alert remains in effect through that time.

As for tonight, we still do not have great confidence in the finer details of the forecast. But there are a lot of red flags out there, including an atmosphere that is extremely rich with moisture, an approaching (but dying) front, and a fair amount of instability. This, typically, leads to moderate to heavy rainfall. There’s still a chance this could bust, but I do feel as though the region will see some activity tonight.

As a best guess, I think we’ll see a line of storms, possibly broken, form north of Houston roughly along Highway 105 tonight around midnight, or maybe a bit before. This line of storms should then move southward shortly after midnight. Possibly we could see some damaging winds within the stronger storms, but the bigger threat is heavy rainfall. Whether those storms hold together all the way through the Houston metro area and down to the coast is not entirely clear, but that mess should be moving offshore before sunrise.

Even as it does so, another mass of showers and thunderstorms may advance into Houston from the west. Most of our guidance indicates that the threat of rainfall from these storms will be highest along and south of Interstate 10, so basically areas closer to the coast. These storms could reach Houston around sunrise on Wednesday, give or take a couple of hours, before weakening. Or maybe the atmosphere will already be too worked over for them to have too much impact.

Again, there’s a fair amount of guesswork here, but we wanted you to be aware of the potential for heavy rainfall overnight—amounts will vary broadly, from 0.5 inch to 4 inches (maybe) in isolated areas—and into Wednesday morning.

We’ll be back by 7 am with a full forecast for you.