Imagine a newscaster standing near the shore in a town where experts have issued a tsunami warning.

In his first report, he notes sea levels are normal. No cause for concern.

In his second report, he says the sea is now a foot above normal — though that’s below where it would be at high tide, a daily occurrence.

In his third report, he assures people that while the sea is now five feet above high-tide levels, it’s nowhere near the levels seen in the big flood of 1936.

No fourth report, since the town is now underwater.

In each case, the reports were accurate and the comparisons valid. What was missed was the trend. Individual snapshots could be explained as something not worthy of concern. But with one reading after another showing higher levels, something more concerning seemed to be underway.

This is a hypothetical, of course, making it easy to massage the situation to make the reporter look as if he’s obfuscating. The worry, though, is that this is precisely what President Trump is doing in his updates about the spread of the novel coronavirus in the United States.

On Monday morning, Trump offered his latest assessment of the spread of the virus, among tweets apparently aimed at calming plunging markets — or, at least, directing blame for the plunge elsewhere.

“So last year 37,000 Americans died from the common Flu,” Trump wrote on Twitter. “It averages between 27,000 and 70,000 per year. Nothing is shut down, life & the economy go on. At this moment there are 546 confirmed cases of CoronaVirus, with 22 deaths. Think about that!”

Trump is right about the flu, as we’ve reported. There are tens of thousands of flu deaths every year, which is why authorities encourage people to get flu shots. The country’s medical infrastructure can accommodate flu season, even as it ramps up over the course of the winter.

Data from the Centers for Disease Control and Prevention show how the flu season evolves over the course of a year. The number of positive flu tests surges as the illness spreads and the number of deaths related to flu or pneumonia (which are tracked together) increases in correlation. As flu cases drop, so do deaths.

In a normal year, about 0.1 percent of flu cases are fatal. In years with more dangerous flu variants, that number can increase.

The problem with Trump’s analogy is twofold. The first problem is he’s ignoring the upward trend in coronavirus cases. The second is he’s downplaying the deadliness of the disease.

Since last January, he’s regularly talked about how many cases of coronavirus there are in the country. In each case, he offers a view of the situation akin to our hypothetical newscaster: Things aren’t that bad compared with other countries or other illnesses.

On Jan. 30, speaking during an event in Michigan, Trump said, “We think we have it very well under control. We have very little problem in this country at this moment — five. And those people are all recuperating successfully.”

“We think it’s going to have a very good ending for us,” he added.

A month later, in his first news conference focused on the virus, he focused on 15 cases not related to passengers on a cruise ship that had been docked in Japan.

“When you have 15 people, and the 15 within a couple of days is going to be down to close to zero,” he said, “that’s a pretty good job we’ve done.”

A couple of days later, he tweeted an update on those numbers.

That was shortly after noon on March 5. Later in the afternoon, he participated in a town hall broadcast on Fox News.

“It’s still 11 people, versus tremendous numbers of thousands of people that have died all over the world,” he said. “We have 11. We have 149 cases as of this moment.”

See that increase? From 129 to 149 in a few hours. And, again, this was last Thursday. Remember that on Monday morning, he was waving away 546 cases — a 266 percent increase.

It’s snapshot after snapshot of coronavirus numbers, contextualized in a way that the effects seem more limited. The trend, though, looks like this.

That graph (which includes only reported cases through the morning of March 9) indicates we’re on the upswing. Trump is comparing the current situation to the peak of the flu season — but we don’t know where the peak of the coronavirus spread will be. Maybe it will be 600 cases. It’s far more likely it will be in the thousands or tens of thousands.

Notice, too, how Trump’s own numbers undercut his arguments about the mortality rate of the illness.

Speaking to Fox News’s Sean Hannity last week, Trump said he didn’t accept the World Health Organization’s estimate that 3.4 percent of coronavirus cases would be fatal.

“This is just my hunch,” he said, “but based on a lot of conversations with a lot of people that do this. Because a lot of people will have this and it’s very mild. They’ll get better very rapidly. They don’t even see a doctor. They don’t even call a doctor. You never hear about those people. So you can’t put that down in the category in the overall population in terms of this corona-flu or virus.”

In his tweet on Thursday, though, Trump compared 3,280 deaths from 100,000 cases internationally — 3.3 percent mortality rate — to 129 cases in the United States with 11 fatalities. That’s an 8.5 percent mortality rate, significantly higher than what the WHO estimated. His numbers on Monday were better, yielding a 4 percent mortality rate. Still, his hunch isn’t supported by the data.

One of two things is true. Either the disease is much more deadly in the United States, which isn’t likely, or the number of cases is much larger than what has been recorded. That’s likely, given the slow rollout of tests across the country. But Trump would rather have low numbers to reassure the public — and to convince them he has it “very well under control,” as he said in January. Hence his comment on Friday that he was less worried about treating the passengers on a cruise ship anchored near San Francisco than he was about keeping the number of recorded cases down.

The lesson from our tsunami newscaster is not that the flooding of the town was necessarily historic. Maybe it was just a bad flood; nothing exceptional in nature. It’s that presenting the rising sea levels only as snapshots relative to the worst case doesn’t accurately convey the threat.

The coronavirus epidemic may be historic and may end up being as pervasive as the flu, straining or breaking the country’s ability to handle the existing cases. If you read Trump’s Twitter feed or listen to his public comments, though, you wouldn’t understand that risk.

Which is the point.