Category: Tropical weather

Good morning. There’s a lot to discuss this morning, including some uncertainty in the near-term forecast, a bonafide fall-like weekend ahead, and a strengthening Tropical Storm Zeta. So let’s jump right in.

Monday

Skies are generally partly cloudy across the region and will likely remain so during the daytime. High temperatures for most areas should reach around 80 degrees. The big question remains the timing and impact of a front moving in from the northwest. It should reach areas west and north of Houston by roughly around sunset, plus or minus an hour or two. Some scattered showers and gusty winds are possible, but we’re not anticipating any strong storms with this front. The front should keep on moving, but it’s difficult to say how far it will get—the Interstate 69 corridor? All the way to the coast? The bottom line is that if you live in the western half of Houston, you’re waking up to cooler, drier air on Tuesday morning. If you’re southeast of I-69? We’re making no promises.

HRRR model forecast for front’s position (by wind direction) at 10pm CT Monday. (Weather Bell)

Tuesday

High temperatures on Tuesday will likely fall somewhere in the 70s for most people, with partly to mostly cloudy skies. Dewpoints will depend on how far east the front makes it. This frontal boundary should linger nearby, so we may see some additional, mostly light rain.

Wednesday

Conditions may be a bit warmer and muggier on Wednesday morning, but during the afternoon and evening hours we expect a stronger front to push through. Unlike several recent cool fronts, we expect this one will have sticking power, bringing cooler weather and lower dewpoints into the region through much of the weekend. I have some hope that most areas will also see some precipitation with this front, and as a guess I’ll go with 0.25 to 1.0 inch of rain through Wednesday night. The front should drop Wednesday night’s temperatures into the 50s.

Thursday through Sunday

We still have some questions about the strength of the front, but generally I think we’ll see highs in the low- to mid-70s through the weekend. As for low temperatures, they’re likely to vary from 40s for areas well inland (i.e. Conroe) to 50s for the city of Houston generally. This will be some of the coolest air of the season, and it will be sustained for several days. We also should see mostly sunny skies through the weekend. Cannot wait!

Forecast low temperatures for Thursday morning. (Pivotal Weather)

Next week

A gradual warm-up should begin by Monday or so, but temperatures should remain mild.

Tropical Storm Zeta

As anticipated, Tropical Storm Zeta formed this weekend, and after meandering around the Caribbean Sea it has begun a motion to the northwest. For much of the weekend, the track models were widely divergent in terms of where Zeta will go along the northern Gulf of Mexico coast. However, with better data, the models are now tightening in their solutions, showing a landfall somewhere along the central or southeastern Louisiana coast on Wednesday evening or Thursday morning. The track forecast from the National Hurricane Center captures this well:

Confidence is increasing in Zeta’s track. (National Hurricane Center)

Unfortunately, Zeta has found low shear in the northwestern Caribbean Sea during the last 24 hours, and has now strengthened to near hurricane status, with 70 mph winds. Tonight the storm will make landfall—likely as a Category 1 hurricane—in almost the same location struck by Hurricane Delta only three weeks ago. Then the storm will move into the Gulf of Mexico. Zeta is likely to remain a Category 1 hurricane over the southern Gulf of Mexico before reaching cooler seas and increasing shear in the northern Gulf. It likely will make landfall in Louisiana as a strong tropical storm, although some uncertainty remains—more misery the state does not need.

Good morning. We are interrupting what is going to be a gorgeous Saturday in Houston with a brief tropical update due to popular demand. Several of you—dozens, even—have written to ask about the low pressure system expected to enter the Gulf of Mexico over the next couple of days. The National Hurricane Center gives this system a 90 percent chance of becoming a tropical depression or storm, so we’re probably looking at Tropical Storm Zeta within a day or two.

Five-day tropical outlook from the National Hurricane Center.

This system, dubbed Invest 95L for now, is likely to meander around the northwestern Caribbean Sea for a day or two before moving west-northwest into the Gulf of Mexico. By early next week the system is going to be moving almost directly toward Texas, which may seem fairly ominous.

Forecast position, per European model ensemble, for Invest 95L next Wednesday. (Weathernerds.org)

However, after this time a couple of things are expected to happen. One, a cold front is going to be moving down across Texas, and this stronger push should reach the Upper Texas coast by around late Wednesday or early Thursday. This will ultimately steer the storm north, and then northeast. Additionally, wind shear is forecast to increase over the northern Gulf of Mexico next week, which should weaken whatever develops.

In any case, it seems possible that a tropical storm could come ashore along the central or southeastern Louisiana coast, or further east, sometime next Wednesday or Thursday. It’s difficult to say too much more, too precisely, given that 95L remains fairly broad in appearance and lacks a distinct center. However, we can be confident this is not something Texas should lose much sleep over.

2 pm CT Friday Update: Hurricane Delta is now moving north-northeast toward Louisiana, and will make landfall later this afternoon or early evening, likely around sunset. Delta has weakened slightly, to 110 mph, but because it has grown into a large storm it will push a powerful storm surge into Vermillion Bay and nearby areas. Its winds will batter areas already devastated by Hurricane Laura just six weeks ago.

The winds we’re feeling in Houston today are due to that expanding wind field. Galveston Island recently recorded a gust of 58 mph, to go along with sustained winds of 45 mph—above Tropical Storm levels. Further inland, many locations in Houston have recorded gusts of 30 mph or above today. These winds are probably about at their maximum levels, and will begin to wind down later this afternoon or early evening as Delta moves further to the northeast.

Map of wind gusts and radar at 1:30 pm CT Friday. (National Weather Service)

As expected, rains have been falling primarily over the eastern half of the metro area, with as much as 1 inch near Galveston Bay, while no rain has come down over West Houston. Expect rain chances to ebb later this afternoon and evening as well.

It’s a similar story with tides and waves along the coast, but the storm’s approach at low tide (this afternoon) is helping to mitigate some of the surge we’re seeing along the upper Texas coast. We still expect to see a fair amount of beach erosion.

Delta will move quickly away tonight. The bottom line is that beginning tomorrow, summer returns to Houston, with sunny skies and, by Sunday, highs in the 90s. With fair weather over head, we should probably be thinking about what we can do to help our hard-hit neighbors to the east in Louisiana. They have endured a terrible one-two punch from the tropics this year.

We’ll see you on Monday morning.

6:20 am CT Friday: Hurricane Delta has completed its north turn and is now steaming toward the Louisiana coast. Delta is a large storm in size, and as a result, we are seeing some rain here in the Houston area, especially on the east side. But Delta will exit quickly tonight, setting the stage for a sunny weekend but also the return of heat.

Hurricane Delta Update

As of the 4 am CT advisory, Hurricane Delta still had 120 mph maximum sustained winds, supported by observations from aircraft investigating the storm. Since that advisory, little has changed for the most part, but Delta is now moving into an area of high shear and cooler water temperatures.

Hurricane Delta is moving into a much more hostile environment for a hurricane, with substantial wind shear (indicated by the red contours on this map), cooler water temperatures, and likely some dry air as well. (University of Wisconsin CIMSS/SSEC)

In addition, the southern side of the storm is beginning to feel the effects of drier air being swept off Texas and Mexico in the wake of its passage. The GFS model image below is valid for Noon today and shows drier air (brown) getting dragged into the southern half of the storm. Delta is likely to come ashore fairly lopsided, with a potent northern half and a much more frazzled and weaker southern half.

Dry air will also help to begin to weaken Delta as it wraps into the southern half of the storm through the day today. (Tropical Tidbits)

So this storm has likely peaked in intensity over the Gulf and will slowly weaken up to landfall. That said, it remains a dangerous storm, as the large size of it will allow for a storm surge in Louisiana that is more significant than the storm’s landfall intensity will probably suggest. In addition, the expansive tropical storm force wind field (which now has a radius of 160 miles north and east of the center) will allow for damaging winds in weakened, vulnerable parts of Louisiana. So for southwest Louisiana, this remains a serious storm.

Local impacts from Delta

We have already begun to see tides increase on the Upper Texas coast. San Luis Pass is just on the cusp of minor flooding this morning.

San Luis Pass is just on the edge of minor flooding as of this morning’s high tide. (NOAA)

We are now past high tide, so this will likely level off now or perhaps rise just a little more. A similar story is playing out in Galveston. Tidal levels on our slice of the Texas coast will probably be similar to what we saw with Hanna and Laura and lower than what was experienced with Beta. Watch for the risk of some minor flooding from the Galveston Bay side in Bolivar and Galveston itself later today with winds shifting behind Delta.

Rain continues to circulate in from the east, and most of the eastern half of the Houston metro has seen about a quarter-inch so far.

Rain will continue to pivot through the area during the course of the day. No flooding is expected in the Houston area. (College of DuPage)

Total rainfall in the Houston area should be under an inch for most folks, and no flooding is expected in our area. Look for upwards of 2 to 4 inches in the Golden Triangle, with minimal flooding issues expected and 6 to 8 inches in Lake Charles, where street flooding could be a bit more serious of a problem.

Winds at Galveston are gusting just a bit under tropical storm force this morning (35 mph as of 6 AM). We could see sustained winds or gusts to tropical storm force (45 mph or so) along the immediate Gulf coast. In Houston, wind gusts will be unlikely to get much past 25 or 30 mph, and no serious issues are expected due to wind for the vast majority of the region. Winds in the Beaumont area could gust to 40 to 50 mph, with slightly higher winds closer to the coast. In Lake Charles,  winds could gust as high as 50 to 70 mph for a time later today, with hurricane conditions on the immediate coast of southwest Louisiana, in addition to a significant storm surge on the immediate Gulf coast there.

Eric and I continue to send our thoughts and best wishes to our neighbors in the east. Even a best case scenario outcome with Delta is still a pretty bad day for southwest Louisiana, and they will continue to need our help in recovery.

After Delta: Weekend

With Delta moving off to the north tonight and tomorrow, the Houston area is going to clear out quickly in its wake. Saturday should be a lovely day, albeit a bit warm. Expect sunshine with highs in the upper-80s. Humidity should be tolerable. More sunshine will follow Sunday, but temperatures are going to crank up and so will the humidity. Sunday is going to feel like a summer day, with highs in the low to mid-90s.

Sunday will feel like early September, with highs in the low to mid-90s and fairly uncomfortable humidity. (NWS forecast via Weather Bell)

For the holiday on Monday, expect more of the same, with at least low-90s and sunshine.

Tuesday & beyond

A cold front is likely to press into the area later on Monday, but how far south it gets is an open question. While a few showers will be possible, we expect this wash out over us, which should lead to a slight cooldown in temperatures and slightly lower humidity. By the end of the week, we may see a more robust cold front enter the picture, driving in more pleasant weather for next weekend, but even that is not a guarantee at this point. More on this for you on Monday.

Our next update on Delta will be posted by 2:30 pm CT today.