Greater Houston region faces evolving threat from heavy rainfall

Summary: The Houston area picked up 1 to 4 inches of rainfall on Monday, and we’ll see ongoing bursts of precipitation through Thursday morning. Today the focus shifts north of the metro area, to areas including The Woodlands, Kingwood, and College Station. By Wednesday morning the threat appears to be more centered on coastal areas, including Galveston. We’re maintaining a Stage 1 flood alert for now, but will continue to monitor things closely.

Tuesday

Things are fairly quiet just before sunrise this morning, but showers and thunderstorms are developing to the west of the area in response to disturbance that will move through the region today. This feature will likely bring 1 to 4 inches of rain to areas north of Interstate 10, with the highest totals likely near locations such as College Station and Huntsville. In Houston I expect a somewhat calmer day, with 1 inch of rain or less in the city on down to the coast.

Excessive rainfall forecast for Tuesday. (NOAA)

Temperature-wise, today will be fairly warm for January, with highs of about 70 degrees. Skies will be cloudy, with southeasterly winds occasionally gusting to 15 or 20 mph. Low temperatures tonight will only drop into the mid-60s, with continued humid air. Storms will be possible after midnight in the metro area, which I’ll discuss below.

Wednesday

High-resolution models are indicating the development of strong showers and thunderstorms early on Wednesday morning for locations along and south of Interstate 10. While we cannot have great confidence yet, it does look like coastal areas from Port Lavaca to Galveston to Beaumont could see heavy rainfall during the pre-sunrise hours. Some of these storms could well migrate northward into the Houston metro area, setting up the potential for a messy commute on Wednesday morning.

In any case, unlike Tuesday, Wednesday looks rather wet in the Houston urban area, with the potential for street flooding. If there’s more clarity later today we may post an update. I expect additional accumulations of 2 to 4 inches of rain, with higher totals possible near and along the coast. It will be another warm-ish and humid day for most of Houston, with highs of about 70 degrees, but it may be a bit cooler to the northwest of the city.

HRRR model depiction for radar reflectivity at 5 am CT on Wednesday. For illustration purposes only. (Weather Bell)

Thursday

A weak front that will move into the Houston region and stall northwest of the area should finally push through the city early on Thursday morning. I expect this to drive one more round of showers and thunderstorms during the pre-dawn hours before this mess finally exits to the east. Look for partly clearing skies later in the day with highs in the 60s. Lows on Thursday night should drop into the 50s.

Friday

Expect a partly sunny day with highs of around 70 degrees. We’ll see a chance of showers later on Friday and Friday night as a second, stronger front approaches the area. Right now accumulations don’t look too significant, but we’ll see.

Saturday and Sunday

The weekend should see mostly sunny, winter-like weather. Look for highs in the mid-60s on Saturday, with a northerly wind gusting at times to 20 or 25 mph. Lows drop into the 40s overnight, with highs on Sunday reaching the lower 60s. I’m looking forward to taking advantage of the sunnier and mild weather with a long bike ride.

Next week

Look for calm weather to prevail through Wednesday, with highs generally in the 60s and lows in the 40s. A warming trend begins later on Wednesday or Thursday with some slight rain chances returning by Thursday or so. All in all, it should provide a nice run of pleasant weather after this turbulent week.

Heavy rainfall threat moving into the Houston area this morning

Summary: Rain showers are moving into the Houston area from the west, and we’ll see the threat of heavy rainfall from now through Wednesday. It will be a decidedly soggy period, and we have instituted a Stage 1 flood alert to account for the potential of street flooding.

Monday

As expected, an upper-level storm system is inching toward our area, and this is producing widespread showers to the west of Houston. These showers and thunderstorms will spread across the metro area this morning and remain with us for much of the day. I expect most of the area, from the Brazos Valley on down to Galveston, to pick up 1 to 4 inches of rainfall today and this evening. Rain chances are effectively 100 percent with a saturated atmosphere and ample sources of lift. The one good thing I can say about the showers is that, generally, individual storm cells should push through fairly quickly from west to east. So the overall threat of ‘training’ storms is lower. There may be a brief lull in rain showers this evening or during the overnight hours before a second round of showers pushes in early on Tuesday.

Pretty much everyone is at risk of heavy rainfall on Monday. (NOAA)

In terms of temperatures, after a cold weekend, we’re seeing a surge of warmer air that will remain with us for most of this week. Highs today should reach the low- to mid-60s, with low temperatures tonight only dropping to around 60 degrees. Winds will also be noticeable today, blowing from the southeast at 15 or 20 mph, with gusts up to 30 mph. So yeah, not a great day for a picnic.

Tuesday

This will be another day that favors widespread rainfall. However, it’s possible that this setup will produce higher rain totals to the north of Interstate 10, and areas further inland, instead of closer to the coast. In any case, much of the area could pick up an additional 1 to 3 inches of rainfall. Highs will again be in the 60s to near 70 degrees. It’s possible that we see another lull in rain chances during the evening or overnight hours.

The story is the same for Tuesday. (NOAA)

Wednesday

This should be the region’s final day of widespread showers, although conditions look marginally less favorable than on Monday and Tuesday. Still, pretty much everyone is going to see rain, with totals in the vicinity of 0.5 to 2 inches, probably. Highs will be in the upper 60s. I expect most people to pick up 4 to 6 inches of rainfall through Wednesday, with some areas seeing greater bullseyes.

Thursday and Friday

These will be a pair of partly sunny days, with highs around 70 degrees, slightly less humidity, and nights in the 50s. Rain chances won’t go away entirely, but they should drop down to about 20 or 30 percent each day.

Saturday and Sunday

Saturday should be partly sunny, with highs perhaps in the 60s. We’ll see a decently strong front push through sometime during the early morning hours or daytime, and there may be a smattering of rain with the front. Afterwards lows drop into the 40s. Sunday should be sunny, with highs perhaps around 60 degrees.

Next week

Most of next week looks quiet, with highs in the 60s and lows in the 40s. Rain chances look fairly low through at least Wednesday or so, giving us some needed time to dry out.

Site note

Matt and I will be monitoring today’s rainfall closely, and if an update is needed to our flooding expectations, we’ll update accordingly.

Widespread rain showers likely on Monday: We’re issuing a Stage 1 flood alert

Summary: Today will be cloudy and cold, but there should be no issues with outdoor activities. That begins to change tonight and especially on Monday morning, as a storm system moves in from the west. Expect on-and-off showers, along with heavy rain and potentially some street flooding through the middle of the week.

Sunday

Most of the region is starting out in the mid- to upper-30s this morning, and we’re going to see overcast skies. This will help to limit highs in the low 50s today, with an easterly breeze, perhaps gusting to 20 mph at times. From there, temperatures aren’t going to fall much tonight, if at all. Any rain showers should hold off until after midnight.

Monday

This is the day we expect the heaviest and most widespread rain to fall in Houston this week. An upper-level system will bring favorable conditions for rainfall, and this should spread into the region during the morning hours. At this point I expect a mass of showers to congeal west of Houston before sunrise, and potentially reach areas such as Katy by around 6 to 8 am. Please understand that these times are approximate, and there is the potential for some messy commuting on Monday morning.

We should see widespread showers and thunderstorms for pretty much all of the daytime hours in Houston, and I expect most of us to pick up 2 to 4 inches of rainfall. That should be mostly manageable, but we have a few concerns. One is that some areas may see bullseyes of 5 inches or more. The second concern is that the ground is hard from our recent freezes, so instead of soaking up a lot of this rainfall, the water will run off. So 4 inches of rain in January will back up much more quickly than 4 inches in August.

Excessive rain outlook for Monday and Monday night. (NOAA)

For this reason we’re issuing a Stage 1 flood alert for Monday due primarily to the potential for street flooding. It will be a good day to be weather aware before heading out. Certainly not everyone will see impacts, but the potential is there.

Tuesday and Wednesday

After a possible lull on Monday evening, we are likely to see additional rounds of showers from the period of Monday night through Wednesday. It’s a little early to have much confidence in the contours of these additional periods of rainfall, but it’s my hope that they won’t be quite as intense on Monday.

In terms of temperatures, we’re going to be much milder after Sunday. Expect highs in the 60s with lows in the upper 50s. Conditions turn a bit cooler by the weekend, probably.

All told, I expect the Houston region to pick up between 4 and 8 inches this week. Matt and I will be monitoring the situation closely today, and the rest of the week to ensure that you remain on top of conditions. We will update the site, and our flood scale predictions, as warranted.

Back to a slightly less harsh, rather brief dose of winter in Houston before next week’s rain

Summary: A hard freeze is likely north of Houston tonight, while much of the area sees 20s for lows. A light freeze is possible tomorrow night before we warm up. Next week’s rain chances are coming into better focus, with Monday and perhaps Wednesday seeing the most rain, but chances persisting all week long. Localized flooding is something we’ll be watching for, but we’re hopeful the rain is spread out over a long enough period to avoid anything too serious. We’ll have another update on this by Sunday.

Today & Saturday

We’re back at it today, with gusty winds and chilly temperatures, as a second plunge of cold air descends on Texas. This one is much more moderate than the one we saw earlier this week, but still after yesterday’s mid-60s, today’s blustery 40s will feel cold. But, we have the sun, so that counts for something. Winds will be 15 to 25 mph, with gusts to 30 mph, stronger over the water.

In terms of tonight’s freeze, as winds settle and skies remain clear, temps should drop efficiently into the 20s virtually everywhere away from the coast. For the city of Houston and most areas south or east, this will be a light freeze. Northern and western outlying areas are at risk for a brief hard freeze tonight, with lows expected in the mid-20s for The Woodlands, Conroe*, and Brenham. (*Conroe is always an interesting case given that they consistently record the coldest temps in the region, likely due to the location of the airport. So it’s possible they dip into the upper teens tonight)

Overnight lows will be in the 20s away from the coast, with low to mid-20s north and a hard freeze likely up that way. (Pivotal Weather)

This will still be about 6 to 10 degrees milder than the hard freeze earlier this week but certainly still capable of hazards to exposed plants (and pets).

Saturday will be breezy and chilly but a little less harsh than Friday. We should see highs in the mid to upper-40s with breezes of 10 to 15 mph or a bit gustier at times. Expect sunshine as well.

Sunday

Expect one more risk of a freeze Sunday morning, mainly north and northeast of Houston. A hard freeze is unlikely anywhere in our area. We will see increasing clouds with a chance of a few showers as early as Sunday afternoon, as high temperatures slow-climb into the low-50s (40s again north).

Next week

The rain we expect next week continues to show up in the forecast rather substantially. We’re starting to hone in on when the worst of it may be now. It looks like we have one pretty strong disturbance that moves through the area on Monday, which should mean numerous to widespread showers and thunderstorms.

The entire region between Victoria and Matagorda through Lake Charles is highlighted under a slight (level 2/3) risk of excessive rainfall on Monday. (NOAA)

This could deliver us anywhere from 1 to 4 inches of rain, and locally higher amounts can’t be ruled out. I would probably say the highest totals may fall to the south and east of Houston, but that is a very low confidence forecast call right now.

Tuesday should see isolated to scattered showers and storms. Rainfall should be a bit more erratic here, with some places seeing a quarter-inch or less and others another 1 to 2 inches perhaps. Then Wednesday may see another strong disturbance with the potential for at least another 1 to 2 inches over a broad area, with higher amounts.

Additional shower chances will follow Thursday and Friday, but it’s tough to say what those look like right now. When all is said and done, the rainfall amounts will tally 3 to 8 inches by Thursday, with higher amounts possible.

Does this mean flooding? It may. With the ground rather firm after this week’s freeze and the subsequent one this weekend, a lot of this water will be quick to run off, which means ponding and street flooding are a good bet in the usual trouble spots. The hope is that the total rainfall will be spread out over a long enough period with enough breaks in between that we avoid any more serious flooding, but it’s something we’ll continue to monitor this weekend. We’re going to especially watch to see how watersheds like Cypress Creek, Spring Creek, the San Jacinto River, and other slower responding basins handle this. This will also impact the Beaumont and Lake Charles areas to some extent. Which location wins the rainfall derby is still TBD.

After a cold weekend, a very mild week is in store. (Weather Bell)

What about temperatures, you ask? We should see high temperatures well into the 60s most of next week with lows generally in the 50s to low-60s. This may also lead to periods of sea fog on Galveston Island, Bolivar, and along the bays. Maybe some cooler weather resumes by next weekend.

We will have another update for you by Sunday regarding Monday and next week’s rainfall, and I expect we will be implementing our flood scale then as well.