Eric Berger

Hurricane Delta likely to make landfall near or east of where Laura did

6:45 am CT Thursday: Good morning. We’re tracking near-term weather issues related to Hurricane Delta, which is still expected to come ashore in southwestern Louisiana on Friday afternoon or evening. Then, we can anticipate a sunny, hot weekend before a cool front arrives early next week to usher back fall-like weather into the region. That’s a lot to cover, so let’s jump right in with an update on Delta.

Hurricane Delta

The storm has slowly organized over night and now has 100 mph winds. Overall, the Delta track forecast remains pretty locked in, with the storm moving to the northwest, and commencing a northward turn Thursday night. Along this track, which is is supported by virtually all of the reliable guidance and therefore of high confidence, the storm will very likely come ashore between Cameron, Louisiana, on the eastern side, and White Lake on the west. As you may remember, Hurricane Laura made landfall near Cameron in August as a devastating Category 4 hurricane. Delta will be weaker, and perhaps a dozen or two miles further east, but it will nonetheless bring repeat misery to a region still reeling from catastrophe only six weeks ago. This is truly horrible.

Map showing the official forecast for Delta (black line) versus where Hurricane Laura (white dashed line) made landfall. (NOAA)

In terms of intensity, forecasters at the National Hurricane Center expect Delta to intensify today, and possibly reach Category 3 before moving over the cooler waters in the northern Gulf of Mexico and encountering higher wind shear. It is forecast to come ashore with 105 mph winds, as a Category 2 hurricane. Let’s briefly address the three main effects from Delta.

Wind

Here’s the latest forecast for maximum wind gusts from Delta. Note, this is not sustained winds, but the maximum winds that may briefly pulse up during Delta’s strongest squalls. These strongest winds will be along, and to the east of the storm’s landfall location.

European model forecast for Delta wind gust swath. (Weather Bell)

The strongest winds will occur on Friday. Much of the Houston area is unlikely to see Tropical Storm-force wind gusts, but coastal areas will definitely become quite windy during the day and evening, with the possibility of some gusts reaching 60 mph, especially along Bolivar Peninsula.

Surge

And here’s the National Hurricane Center’s forecast for “peak storm surge,” which represents the combination of surge and high tide for coastal areas. Again, the worst effects will be to the right of the storm’s landfalling location. For Houston, coastal flooding of 1 to 3 feet will be possible generally north of San Luis Pass, including around Galveston Bay and across the Bolivar Peninsula.

Storm surge graphic for Hurricane Delta. (National Hurricane Center)

Rain

In terms of rainfall, we still have some uncertainties, as there should be a pretty steep rainfall gradient—a line along which, to the west, there will be virtually no rain, and to the east where there will be 1 to 2 inches. We think this line probably will fall somewhere in Houston, but whether it’s along the Interstate 45 corridor, or further east, is difficult to say. Here’s the official forecast for rainfall, but we would rate this as fairly low confidence. In Houston, we should see some outer bands of Delta moving through today, with the heavier rain chances on Friday. We expect no flooding issues in the metro area.

NOAA rainfall forecast for now through Saturday. (Weather Bell)

Thursday

Today should see increasing clouds with the aforementioned chance of rain showers, especially on the southern and eastern sides of the region. Despite the mostly cloudy skies this afternoon, expect highs to reach into the upper 80s, with a warm night, and lows only dropping into the 70s. Hello, humidity!

Friday

This will be the day with the most impacts in terms of surf, winds, and rain. Skies will be cloudy, and highs may struggle to reach 80 degrees for most areas. Winds amp up during the day on Friday, with gusty conditions during the afternoon, evening, and overnight hours as Delta pushes through. With the kinds of winds we’re expecting we do not anticipate power outage issues in Houston, although there could possibly be a few problems right on the coast.

Saturday and Sunday

Showers should be ending by late Friday night or Saturday morning, and skies are expected to clear fairly quickly. The weekend will be sunny and warm, with highs in the upper 80s to lower 90 degrees. My sense is that this weekend and early next week are probably the last times Houston will see highs in the 90s in 2020, but that is a guess, not a promise.

Next week

A cool front appears to be on track to arrive on Tuesday to sap some of the region’s heat, with another stronger front probably arriving by or before the weekend.

Our next update will come no later than 2:30pm CT today.

Delta makes landfall on the Yucatan, next stop Gulf of Mexico

7 am CT Wednesday Update: Good morning. We’ll take a quick look ahead at our forecast for this week and then turn our attention to Hurricane Delta, which made landfall near Puerto Morelos, in the Yucatan Peninsula, around 5:30 am CT today. It had maximum sustained winds of 110 mph. The hurricane will move into the Gulf of Mexico later today.

Wednesday

Today will be warm and sunny, with highs likely climbing into the mid- to upper-80s with light northeasterly winds. We should really start to feel the return of moisture at the surface today, so it will feel a bit more humid, and nighttime temperatures will be a few degrees warmer than Tuesday night, likely not falling below 70 degrees in Houston.

Thursday and Friday

Our weather on both of these days will depend heavily upon how close Hurricane Delta gets to Texas as it moves into the western Gulf of Mexico. In terms of precipitation, for now, we’ll guess (emphasis on guess) the eastern half the region sees perhaps 0.25 to 0.5 inch of rain, with lesser amounts west of Interstate 45. The best rain chances should come on Friday, and partly cloudy skies should help to limit temperatures into the low 80s. Winds may gust up to about 30 mph, or higher, especially on the city’s east side, and along the coast.

NOAA rain accumulation forecast for now through Friday night. (Pivotal Weather)

Saturday, Sunday, and beyond

Some showers may linger into early Saturday, but for the most part, the weekend looks warm and sunny, with highs near 90 degrees. There is the potential for a cold front to arrive on Tuesday or so of next week, but it may get hung up for a few days and not move in until later. Still, we do anticipate more fall-like weather to return in about a week, give or take.

Delta, Delta, Delta

Delta has weakened overnight due to the influence of wind shear at mid-levels of the atmosphere, and it may weaken a little bit further this morning as its center briefly crosses the northeastern corner of the Yucatan Peninsula. As it reaches the southern Gulf of Mexico, the storm should begin to re-intensify tonight, and the National Hurricane Center anticipates Delta briefly pulsing back up to a Category 4 hurricane over the Gulf. (We’ll see).

As the storm moves north it will encounter less favorable conditions and should be on a weakening trend near landfall Friday. Frankly, I have significant questions about how strong Delta will be at landfall, and anything from a Category 1 to Category 3 hurricane seems possible. Most likely, the further east the storm tracks, the stronger it will be.

4am CT Wednesday track forecast for Hurricane Delta. (National Hurricane Center)

In terms of track, our overall thinking has not changed in terms of approaching Texas and then turning north. As you can see in the forecast graphic above, as we get closer to Delta’s Gulf coast landfall, the “cone of uncertainty” in the National Hurricane Center’s official track has narrowed. It now essentially runs from the border between Texas and Louisiana, on the west side, to southeastern Louisiana. This reflects what we’ve been telling you over the last several posts, that the forecast models are generally in quite good agreement on a landfall between the Texas-Louisiana border and Morgan City. Landfall now looks likely to occur some time during the middle of the day on Friday, or during the evening.

Along this track, as noted above, the greater Houston region would only see moderate effects, including increased winds on Thursday and Friday, some decent rain chances, and moderate coastal flooding at high tides. We will need to continue to monitor the storm’s track closely, but the greatest likelihood remains that Delta will be a near-miss for our area.

In terms of Louisiana, Delta’s effects will depend heavily upon its intensity. It does seem really, really cruel that this storm will probably make landfall not too far from where Hurricane Laura did so in August. However, we do think Delta’s winds will probably be less at landfall than Laura, and surge as well. Because the storm is expected to be moving fairly quickly to the north-northeast, rainfall amounts should generally be less than 8 inches for most areas.

Our next post will come no later than 2:45 pm CT.

Delta nearing Yucatan, will move into Gulf on Wednesday

7:40 pm CT Update: Just a quick post this evening on Hurricane Delta. The storm has intensified further since this afternoon, reaching maximum sustained winds of 145 mph at 7pm. However some wind shear in the mid-levels of the atmosphere has lately begun to affect Delta and may prevent further strengthening tonight, or even weaken the storm.

Regardless, Delta will bring devastating winds and storm surge to the Yucatan Peninsula later tonight and on Wednesday. After this time it will enter the Gulf and track west-northwest across the Gulf of Mexico. In terms of what happens after that, not much has changed with respect to the track forecast, which turns Delta north and brings a hurricane to the Gulf coast Friday evening or early Saturday—about three days from now. It seems the most likely location for this landfall will lie somewhere between the Texas-Louisiana border, on the western side, and Morgan City, on the eastern side. Even though we are within three days of landfall, some uncertainty remains, and this is reflected within the National Hurricane Center’s forecast cone.

4pm CT track forecast for Hurricane Delta. (National Hurricane Center)

By tomorrow morning we should have a pretty good sense of the ultimate track forecast for Delta, as the overnight model runs ingest data from today’s aircraft reconnaissance missions as well as supplemental weather balloons to sample the atmosphere helping to control the steering flow for this system. The odds still strongly favor a landfall in southwest or south-central Louisiana, but there is enough uncertainty that we’re going to need to continue to watch Delta closely along the upper Texas coast.

That’s just what we’ll do, of course. In tomorrow morning’s post, which will go up no later than 7:30am, we’ll have the latest on track and potential impacts along the upper Texas coast later this week, as well as Louisiana.

 

Delta rapidly intensifying as it nears Cancun, Gulf of Mexico

2:10pm CT Tuesday: We’re talking about Hurricane Delta this afternoon, which has undergone rapid intensification and is now a powerful Category 4 hurricane with 140 mph winds. (It was only named Delta 30 hours ago.) The storm will approach the Yucatan Peninsula tonight, and likely make landfall somewhere near Cancún early on Wednesday. This will be a dangerous hurricane for that area. By Wednesday evening the storm will be back out over the Gulf of Mexico, moving to the northwest.

Track

Overall, the track forecast remains largely unchanged. The 12z models are beginning to show a tighter cluster of solutions in which Delta moves to the west-northwest, or northwest for most of Wednesday and Thursday. Then, when Delta is a few hundred miles offshore from South Padre Island, it should begin a pretty sharp turn to the north. All of the best available guidance now shows a final landfall between the Texas-Louisiana border—very near where the devastating Hurricane Laura came ashore in August—and further east, around Morgan City and Houma. This tighter clustering of models is consistent with the National Hurricane Center forecast track, and increases our confidence in where Delta is going to go.

National Hurricane Center forecast track for Hurricane Delta at 10am CT.

With that said, we are still roughly three-and-a-half days away from landfall, so the average track error is about 120 miles, and we also have to account for the possibility of wobbles. The bottom line with Delta’s track is that right now every available bit of evidence we have suggests this storm is going to turn toward Louisiana—but its future path is not 100 percent locked down.

Intensity

Delta has had near ideal conditions for strengthening over the last 24 hours, including very warm waters not just at the surface, but also below. This is important because, as the storm moves across the ocean it churns up seas from below, a process known as upwelling, which can bring cooler water to the surface. One measurement of an ocean’s depth of warm waters is its “Tropical Cyclone Heat Potential,” and basically any value of 80 or higher is conducive for intensification. As you can see from a recent map of this potential, the waters in the northwestern Caribbean Sea are explosively warm.

Plot of Tropical Cyclone Heat Potential. (NOAA/AOML)

This will begin to change as Delta moves away from the Southern Gulf of Mexico, at which time the storm also should begin to encounter more wind shear. These factors should help to limit the intensity of Delta as it moves toward the northern Gulf of Mexico, but it remains possible that this system could be a major hurricane at landfall.

Houston effects

Along this track Houston is likely to experience only very mild effects from Delta—perhaps some rain showers on Thursday, Friday or Saturday. Seas will reach their maximum on Friday, but should be below the levels the region experienced during Hurricane Laura.

Needless to say all of this depends upon the storm’s track, and if that changes significantly, so will our local forecast.

Our next update will come no later than 8:30 pm CT.