Most of my family live along the Gulf Coast of the USA, especially from southeast Texas through southern Louisiana. Hurricanes and tropical storms are part of life there. The land is low and flat, and not many places have levees to fight storm surges.
In retrospect, the emails I’ve sent to family about Laura and Marco should have been posts here. My grandfather taught me about hurricanes from his pre-satellite perspective as a retired sea captain. When I fully concentrate on a tropical weather system in the Gulf, my predictions tend to be closer to the mark than those of the weather service. Their computer models have greatly improved their accuracy, but sometimes I still outdo them. I have with these two storms.
The storms are aiming squarely at my family. They should come through this okay.
Grandpa taught me about charting a hurricane’s course and thinking about what is likely to influence it as it proceeds. Once in a while a hurricane makes bizarre course changes. Camille did in 1969. But their behavior is usually something you can make sense of. He and I would have loved having satellite-augmented of weather maps that show where high and low pressure cells or ridges are and predict how those will move. When those became available, I began factoring that into my hurricane predictions.
Alicia in 1983
My very best? Alicia in 1983. Back then I lived in Alvin, Texas, 30 miles inland and 30 miles directly south of Houston. That summer my brother was living with me while working summer jobs and a young cousin was living in an apartment a little over a mile away. The weather service kept saying Alicia would swing west and go toward San Antonio. I kept telling my brother and cousin that she was coming directly for us and we were going to get the eye.
That was important. A trailer park had been put in across the road from my house at the edge of town. Trailers can fly around in a powerful windstorm. When I didn’t evacuate, my brother and cousin stayed too, but my brother chose to ride out the storm with her. He didn’t want to find himself in my living room with a house trailer. I said the wind was going to blow down the street, and then after the eye it would blow down the street in the other direction. It would never blow from me to the trailers or the trailers to me. He said I couldn’t possibly know that.
Alicia’s wind speed at landfall was about 15 mph higher than I expected, but otherwise she did exactly what I predicted. Then she followed the highways directly north all the way to Oklahoma City.
As I said, Alicia was my very best. I’ve never quite equalled that performance again. But I’ve gotten pretty damned close.
Why Bother?
For people who live in a hurricane zone, making a good guess at what the storm will do is more than a fun game or an academic exercise. When a storm was big enough to run away from, everyone who lived south of Houston had to evacuate at least 24 hours before any of Houston began to hit the road. If we all drove away at the same time, we’d have gridlock and a lot of people stuck in their cars when the storm arrived. Everyone south of Houston had to pay closer attention to what was happening in the Gulf and make stay-or-go decisions long before official announcements told us what authorities thought we should do.
While I worked at the Johnson Space Center, I had a bonus. When a cyclonic tropical weather system threatened the Gulf, NASA put the National Weather Service on an audio loop accessible throughout JSC. We put it on speakers in the lab whenever we didn’t need to use an audio loop to coordinate testing. I could stay immersed in weather updates all day.
I forget exactly how we pulled ourselves together, but between 20 and 30 women who lived south of Houston coalesced around my hurricane predictions. It was my job to decide whether we should evacuate, and if so, in which direction. Hurricanes that come ashore in southeast Texas usually go one of two general directions, toward Dallas or toward Austin and San Antonio. Evacuating to where the storm is going to go means riding out torrential rain, floods and possibly tornadoes.
Whenever I said we should evacuate, we met and drove away together in one long caravan. We were all either single women or lesbian couples, some with disabilities, so we handled evacuation this way for our collective safety in case any of our cars broke down. At our evacuation destination, we split up and stayed with friends or in hotels until we could return home.
I didn’t always get everything right. Once we evacuated when it turned out we could have stayed. Once I called the direction wrong, so we went to San Antonio and got the thrill of lots of tornadoes all around us. But my accuracy was still better than the official forecasts, so our arrangement continued until I left the area.
What About Laura and Marco?
Sometimes I find commercial maps of the pressure zones most useful, but I’ve been pleased with the map provided by NOAA, the National Oceanic and Atmospheric Administration, which is updated regularly. I always check theirs first and only switch to commercial maps on rare occasions. Click here to see it. You can stop the playback and step through it one step at a time, which I how I’ve used it.
Here is what I told my family last Friday:
The impending situation in the Gulf is one I haven’t seen before with two tropical weather systems heading for the coast at the same time. Weather people say it’s the first time we’ve had this type of situation since the Great Depression. They aren’t sure how the storms will interact. It looks to me like the computer models don’t know how to factor that in.
I’m trying to get a sense of what’s going to happen, looking at the maps. I think they’re right showing Tropical Depression 14 (or whatever it is by then) will split the difference between the two big high pressure systems, and that would put it coming ashore in southeast Texas, give or take some.
But the projected track for Laura looks wrong. That nice little curl to the right as she comes ashore on the NOAA map? It’s hard to believe. Why would she try to butt heads with a high pressure system in order to swing around the back of it when Laura and TD14 will be pulling at each other practically like magnets?
There are a couple of things I’ll be watching for. As the two storms pull on each other, they will draw toward each other. The question is how hard that pull will be. You may have seen some speculation about whether they will combine into one bigger storm. They will be far enough apart to make that a considerable feat. But if they do, [certain Cajun cousins] and all of that side of the family could get the combined storm.
A lot can happen short of that, though. TD14 could pull Laura to come ashore sooner and farther west than the projection. Sooner is better—it means more of Laura’s energy would go into forward motion and less energy would go into strengthening. But Laura could also entice TD14 to slow down and swing to the east. That’s bad, partly because of where it puts landfall and mostly because slowing down means strengthening before landfall. The Gulf is hotter than normal. Lingering in it means strengthening more than usual.
It’s too early for me to tell where these two will make landfall and how strong they will be. They should both be hurricanes and affect most of the Gulf Coast. They are unlikely to do quite what NOAA’s projections tell us right now. Let’s see how they develop.
We had a family Zoom session on Saturday, so I didn’t publish a written update to them. When we had that session, the forecast had changed and I didn’t believe it. TD14 had become Marco and the computer models thought a low pressure system over Mexico would pull it considerably to the west.
At the start of this post, I mentioned that not many places along the Gulf are protected by levees. New Orleans has levees, and there are whopping levees along the Mississippi river. Port Arthur, Texas, is ringed by a levee system. It’s much lower but it has been enough to save the city more than once. Texas City has a levee too, midway between in height. (You can read about the origins of the Mississippi River levees in the fascinating book Rising Tide: The Great Mississippi Flood of 1927 and How it Changed America
Here is my Sunday update to family:
The two storms are indeed pulling on each other but it doesn’t look like they will try to merge.
Laura has always been “in the pipe” to cross the Gulf and hit Texas or Louisiana. (If she went along the north coast of Cuba, she would probably make landfall from Mississippi to the Florida panhandle. These “pipes” become obvious on historical charts of hurricanes. Grandpa never said anything about them. They simply jumped out as we charted storms.) Laura’s forecast now looks typical for tropical storms and hurricanes that start where she did and move the way she has. The original forecasts for her looked peculiar, abnormal.
The Mexican low pressure cell was too weak to cause Marco to turn westward as shown in earlier forecasts, and I think I mentioned not believing it. What the forecast shows now is believable. Marco has been pulled so far to the east that the eastern high pressure cells will affect it. I thought it would try to go between the eastern and western high pressure areas, so I missed on that. Laura is affecting Marco more than I expected.
That is a bit of a problem. Marco is now projected to curve westward after landfall, seeking to get around the eastern high pressure area. It looks reasonable. But Marco’s forward motion is likely to slow down, pulled toward Laura to the southeast and blocked from going northward by eastern high pressure. Even though neither storm is expected to dump huge amounts of rain, a stalled storm means more flooding. That water will be coming down rivers to the Gulf when the storm surge from Laura arrives. And Marco is pulling on Laura, too, so Laura’s landfall may be Port Arthur, not aimed at Lake Charles.
The levee at Port Arthur should be able to easily handle Marco’s storm surge. [Editorial note: Texas City is far enough to the west, its levee should not see much of the storm surge, and remember it is taller.] Marco isn’t shaping up as a big wind but Laura’s wind speed at landfall may be a little higher than the 100 mph currently forecast. Watch Laura for barometric pressure and how well organized she is at landfall. That’s going to determine her storm surge. So far her barometric pressure isn’t in the range of storms that cause huge surges.
How does it look today?
NOAA’s map shows an alarming development. The eastern high pressure area slid across toward the western high pressure area, leaving only a narrow gap between them that is too far west for the storms to reach. The two hurricanes no longer have an easy path northward. This was beginning to take shape yesterday and is the reason Marco’s projection began curling westward at landfall.
Hurricanes and tropical storms that roll along the coast that way can have weak winds and still wreak havoc. Remember Harvey? As the storm rolls along the coast, it recharges itself with water where its winds continue to reach out over the Gulf. Then the winds come over land to the east of the wandering eye. That cools the air and causes the clouds to dump rain. The high pressure ridge will make it hard for Marco to go inland. He’ll roll along the coast slowly, flooding as he goes.
Then Laura will reach land. She will find enough of an escape hatch north of her, so she shouldn’t linger, although it looks like Marco won’t speed her forward motion as much as I hoped. But she will drop her rain on ground that is already saturated and rivers that are already full.
It could be worse. For a while it looked like both storms could come ashore at the border between Texas and Louisiana. Two hurricanes at the same place in the same week would be cruel. The upper Texas coast is not going to have a great week. But Louisiana’s week looks very soggy.
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