Category: Tropical weather

Today and tomorrow, Matt and I will be publishing two posts to summarize the 2020 Atlantic hurricane season, its effects on Houston, and implications for the future. In Part I, today, I will discuss the overall activity this season, and share some thoughts about Hurricane Laura. Part II, tomorrow, will focus on Tropical Storm Beta and what we can learn from this season about future hurricane activity.

2020 season

The numbers for the 2020 season are sobering. Across the Atlantic basin—which includes the Atlantic Ocean, Caribbean Sea, and Gulf of Mexico—there were a total of 30 tropical storms and hurricanes. This surpassed the previous record of 28 set in the year 2005, the historic year of Katrina, Rita, and Wilma. For only the second time, this year, forecasters at the National Hurricane Center in Miami ran out of names and had to resort to using the Greek alphabet.

From Arthur to Iota, what a year it was. (NOAA)

Notably, a dozen of these tropical storms and hurricanes made landfall in the United States, crushing the previous record of nine landfalling tropical storms or hurricanes set in 1916. The state of Louisiana alone experienced five landfalls. (Thanks to the tremendous results of our 2020 fundraiser, Space City Weather will donate $5,000 to SBP, to assist with that state’s recovery efforts). At least one part of Louisiana fell under coastal watches or warnings for tropical activity for a total of 474 hours this summer and fall. And Hurricane Laura, discussed below, became the strongest hurricane to make landfall in Louisiana since 1856.

Harris County’s Jeff Lindner has catalogued some of this year’s other superlatives:

  • On September 14, five tropical cyclones were ongoing at the same time in the Atlantic basin (Sally, Paulette, Rene, Teddy, and Vicky). This ties September 1971 for the most number of tropical cyclones at the same time in the basin.
  • On September 18, three tropical cyclones formed within in six-hour window (Wilfred, Alpha, and Beta). This is only the second time in recorded history that three tropical cyclones have formed in such a short time period (1893).
  • Ten tropical storms formed in the month of September, the most for any month on record
  • A total of 10 systems experienced rapid intensification (35 mph increase in wind speed in 24 hours), Hanna, Laura, Sally, Teddy, Gamma, Delta, Epsilon, Zeta, Eta, and Iot).
  • Hurricanes Delta, Iota, and Eta experienced winds speed increases over 100 mph in 36 hours or less.
  • Of the 6 major hurricanes in 2020, four were in October and November, and bore Greek alphabet names (Delta, Epsilon, Eta, and Iota).
  • Hurricanes Eta and Iota both made landfall only 15 miles apart along the Nicaragua coast both as category 4 hurricanes.
  • Hurricane Iota (160 mph) became the latest category 5 hurricane on record in the Atlantic basin, and the second strongest November hurricane on record only behind the 1932 Cuba hurricane (175mph)
  • NOAA hurricane hunters flew a total of 86 missions for 678 flight hours and 102 eyewall passages. A total of 1,772 dropsondes were deployed.

Despite all of this, however, the 2020 Atlantic season was not all that extraordinary by some important measurements. Perhaps our best tool for determining a season’s overall activity is “accumulated cyclone energy,” or ACE, which sums up the intensity and duration of storms. For example, a weak, short-lived tropical storm counts for almost nothing, whereas a major, long-lived hurricane will quickly rack up dozens of points. The ACE value for the 2020 Atlantic season was 179.8. This significantly higher than the climatological norm for ACE values (about 104), but does not quite make the top 10 busiest Atlantic seasons on record, which is paced by the 1933 and 2005 seasons.

The bottom line is that the 2020 hurricane season was in line with our expectations for 2020 to produce a total cluster of a year. Fortunately, we survived. In Matt’s post on Thursday, he’ll discuss what this may mean for the 2021 season.

Hurricane Laura

It’s also worth reflecting for a moment on what I consider to be the most threatening storm of the year for Houston. There was a time in late August when it appeared that Hurricane Laura might strike Houston as a major hurricane. Personally, it was rather unsettling.

I first began writing extensively about hurricanes back in 2005. This was before I had become a meteorologist, and just after I started a blog for the Houston Chronicle. First, I tracked Hurricane Katrina and then, much closer to home, there was Rita. You may not remember the storm, or it may not have formed much of an impression on you. But it certainly did on me. I distinctly recall the evening of September 21, 2005—a Wednesday. Rita had intensified to 175 mph over the central Gulf of Mexico, and it was forecast to make landfall a little more than two days later just below Houston on the Texas coast. This was the worst-case scenario for our region. I’d bought a home in the Clear Lake area a couple of years earlier. Not going to lie, this one scared me. Eventually, Rita weakened some, and turned, making landfall near the Texas-Louisiana border.

Hurricane Rita forecast for Sept 21, 2005, about 30 hours before landfall. (National Hurricane Center)

Since then, Rita has been the measuring stick for me in terms of dreading a hurricane landfall. And in those 15 years, no storm has ranked so highly as Laura did in late August. Why? Because although Houston has been battered by a strong storm surge (Hurricane Ike) and massive floodstorm (Harvey) in the last dozen years, it has not seen a major wind storm in nearly six decades. That was the potential Laura had with a track that could have come to Texas, across a very warm Gulf of Mexico. Ultimately, that didn’t happen, Laura turned away from Houston and made a devastating landfall in Louisiana.

Thanks to fine forecasting and smart calls by local officials, the greater Houston area was spared a major evacuation. But Laura was a close call in many ways for the nation’s fourth largest city. And I won’t soon forget it.

Sponsor Note from Reliant

A big thank you goes to the Space City Weather team for keeping Houstonians informed during the 2020 hurricane season. Just as Eric and Matt provide hype-free forecasts to ensure readers are prepared for a storm, Reliant keeps Houston powered with personalized electricity plans and back-up power solutions. Reliant is also here to help before, during and after the storm with helpful guides, tips and information on reliantstormcenter.com. We all hope for a quiet hurricane season in 2021, but know we’ll be informed and in good hands with Eric and Matt should any storms develop. Thanks for all you do, SCW!

Good morning, and it’s a cool one again across the area. We have mostly 40s and some low-50s peppered in everywhere.

Temperatures are generally in the 40s and low 50s across most of the area this morning, a cool start! (NOAA)

Yesterday began one of the coolest but nicest stretches of weather for us in a long while that will continue through the weekend.

Today & weekend

Look for simply spectacular autumn weather all weekend long. We’ll top off in the upper-60s today with wall to wall sunshine. Look for low-70s tomorrow and mid-70s on Sunday. Morning lows will generally be in the mid-40s to mid-50s through Sunday. Winds should be lighter than they’ve been the last couple days.

For trick or treating, look for comfortable weather this year. Expect upper-50s to low-60s north and mid to upper-60s or a tick or two warmer in the city of Houston and points south.

Early next week

A reinforcing shot of drier, cooler air will arrive Sunday evening, so you’ll notice offshore winds kick up again later Sunday and on Monday. Look for cooler temperatures again Monday with highs in the 60s for most of us. Tuesday should see low-70s with lighter winds, and Wednesday likely sees mid-70s. Morning lows look cool on Monday and especially Tuesday. Look for upper-40s or low-50s Monday morning and mostly 40s on Tuesday morning.

Morning lows on Tuesday will bottom out in the low to mid-40s most places. (NOAA forecast via Weather Bell)

Look for some high clouds and warmer temps to return on Wednesday, and that heralds a pretty substantial and possibly lengthy warm-up that may linger through next weekend and into the following week.

Tropics

We knew 2020 was going to be an active hurricane season, but the absurdity of it all has still been surprising. It’s really been non-stop in the Gulf, either dealing with a threat or looking ahead to the next one since Hanna struck South Texas back in late July. Hurricane Zeta may have been the most impressive of them all for how anomalous it was.

Zeta is the strongest known storm back to at least 1850 in the western Gulf this late in the hurricane season.

Zeta peaked at 95 kts. (and I wouldn’t be shocked to see it reanalyzed at 100 kts. (115 mph) in the offseason), which shatters the record of 75 kts. that far northwest in the Gulf for this late in the year. More impressively, Zeta’s intensity ramped up 40 kts. (45 mph) in 26 hours.

The previous record from late October onward was somewhere between 10-21 kts. In that respect, Zeta is in a league of its own. Hurricane season technically runs through November 30th, but in the western Gulf, we usually shut down in mid-October. Zeta obliterated that paradigm. Why? Well, it’s not that the Gulf is super-warm. In fact, Zeta continued steadily strengthening over cooler water in the northern Gulf. The amplified, weird pattern over the West and Plains, responsible for our cold front, the ice storm in Oklahoma and parts of Texas, and the snow in the Rockies helped supercharge Zeta as it approached Louisiana.

This was a case where shear was actually in a sweet spot for a storm and helped it along. The deep trough and very strong jet stream winds over Texas (known as a jet streak) actually helped Zeta find an environment that would be hospitable for a low pressure system to intensify within. This further underscores that water temperatures are far from everything when it comes to hurricane intensity. In this case we had a Gulf of Mexico that was only slightly supportive for a storm, but the storm got juiced by the atmospheric pattern over the Plains and Southeast. And the end result was a memorable, odd late season storm. Zeta also will end up being the strongest storm to make landfall so late in the season on the entire Gulf Coast. Zeta’s forward speed of over 45 mph over the Southeast made it one of the fastest moving storms on record (for any date) over the continental United States.

And we aren’t finished. The National Hurricane Center has 80 percent odds that a tropical wave in the Caribbean (dubbed Invest 96L) will develop into a depression or storm in the next 5 days.

A tropical wave tagged as Invest 96L has an 80% chance of development over the next 5 days. (NOAA)

If it gets a name, it will be called Eta, and 2020 would officially tie 2005 for the most storms on record in the Atlantic basin. As much as it pains me to write this, Eta is a storm that should probably be watched from Louisiana to Florida. It’s likely to percolate off the coast of Central America much of next week before perhaps being ushered north next weekend by our next weather maker over the Plains & Texas. How exactly that plays out is TBD. This is highly unlikely to come to Texas, but there a number of model solutions that bring it into the eastern Gulf or off the Florida coast. So, yet again, another one for our neighbors to the east to watch. We’ll update you on Monday.

The cold front has finally pushed all the way into Houston and Galveston this morning, and it is going to be a cold day for the region. Yes, I said cold—as in temperatures this afternoon will likely remain in the 50s for much of the area. And the big change with this front is that it will have sticking power, as we anticipate cool, dry air hanging around into early next week. In today’s post we also discuss Hurricane Zeta, which is intensifying as it moves toward southeastern Louisiana and Mississippi.

Wednesday

The front has moved to the coast, but it still will require another shove to completely pass through. Essentially, as Hurricane Zeta moves into the Norther Gulf Coast today, and toward the northeast, this front will follow. In the meantime, we’re likely to see on-and-off light showers today, with northwest winds of 10 to 15 mph. Rains should end this afternoon, from west-to-east. As the front gets pulled away, we will see some clearing skies tonight, and lows should drop into the 40s for much of the area.

Here are the temperatures you’re going to wake up to on Thursday morning. (Pivotal Weather)

Thursday

Skies should be clear Thursday, but we’ll see fairly pronounced northwesterly winds as the front moves well clear of the area, perhaps gusting to 25 mph. Despite sunny skies high temperatures will probably crest in the mid-60s for most. It will be another cool, clear night with blowing winds.

Friday

Sunny, highs near 70. Damn near perfect.

Saturday and Sunday

This weekend will see fine weather too, with highs in the 70s, and lows in the 50s. A reinforcing front should reach the region by Sunday night or so, but with a dry atmosphere we don’t expect any rainfall.

Next week

The front should keep Monday and Tuesday of next week on the cool side, before we warm back up toward the 80s by Wednesday or Thursday. Rain chances likely won’t return until the end of next week, at the earliest.

Tropics

Zeta has strengthened into a hurricane overnight with 90-mph winds, and is moving rapidly toward the Mississippi River delta where it will likely make landfall this afternoon as a Category 2 hurricane. This will produce a greater than anticipated storm surge, particularly from the mouth of the Pearl River to Dauphin Island, Alabama.

Updated track forecast for Hurricane Zeta. (National Hurricane Center)

The storm is moving quickly enough that, although it will generate heavy rainfall, accumulations should generally be less than 5 inches for most areas as storms move through. The other big concern is wind, with hurricane-force wind gusts likely in New Orleans this afternoon.

Forecast for maximum wind GUSTS from Hurricane Zeta. (Weather Bell)

Conditions should rapidly improve in Louisiana and Mississippi after the storm passes, and this cold front follows through, with a sunny, placid weekend ahead for the northern Gulf of Mexico coast.

Houston’s weather this morning is something akin to the opening of Charles Dickens’ A Tale of Two Cities: It was the best of times, it was the worst of times. It was the coolest of times, it was the warmest of times. By this I mean that a cool front has sagged into the Houston region, and pretty much stalled right on top of our heads. To the west, it is cool and dry, to the east, much warmer and humid. Conditions will remain this way until the front bulls all the way through on Wednesday.

Tuesday

Temperatures are generally in the 50s this morning on the west side of town, in places such as Sugar Land and Katy. They are in the mid-60s in the central part of the city, and mid-70s along the coast and to the east. The line demarcating cooler and warmer air should waffle back and forth some today, and it’s impossible to predict precisely where with the front stalling overhead. So highs will vary from the 60s to 80s across Houston. Pretty remarkable. Skies should be mostly cloudy, with a few light showers possible.

That’s quite a temperature gradient as of 6:45am CT across Houston. (Weather Bell)

Wednesday

A reinforcing push of colder air arrives on Wednesday, probably during the middle of the day, and this will bring fall-like weather to the entire area. We should see some better rain chances during the day on Thursday as the front slogs through, primarily from shortly before sunrise into the late afternoon hours. I think most areas will see 0.25 to 1.5 inches of rain, and I don’t have high confidence in pinning down where. Temperatures will drop to around 50 degrees Wednesday night in the wake of the front—cooler inland, and warmer along the coast.

Thursday

This should be a breezy day due to a strong pressure gradient in the wake of the front, with gusts possibly as high as 30 mph. Please take note of this if you have outdoor activities planned. Skies will otherwise be clearing out, and highs likely will only get into the upper 60s in most locations as colder air moves in. Winds should back off some toward evening.

Friday, Saturday, and Sunday

This weekend’s weather looks splendid, with sunny skies, highs in the upper 60s to low 70s, and overnight lows in the 50s. For those wondering about Halloween rainfall, there will be none this year. Enjoy!

This is what Thursday, Friday, and Saturday mornings will feel like. (Pivotal Weather)

Next week

The models are suggesting another front may arrive by around Monday to keep the cooler, drier pattern going. However, overall confidence in this is not yet high.

Tropics

Tropical Storm Zeta crossed the Yucatan Peninsula during the overnight hours and is now emerging into the Gulf of Mexico as a strong tropical storm, with 70 mph winds. Confidence in a track toward the northern Gulf Coast is high, with the storm likely making landfall in southeastern Louisiana on Wednesday afternoon or evening. It should be a Category 1 hurricane at this time and its center may pass near, or directly over New Orleans.

European model forecast for wind GUSTS due to Zeta. (Weather Bell)

The storm will be moving quite rapidly to the northeast at this time, so while it won’t linger on Wednesday night, it could produce briefly very heavy rainfall and wind gusts above 90 mph over southeastern Louisiana. This is a nasty, late-season storm no one wants.