May 25, 2021

Let's Talk About Tonight's Made-Up-Clickbait-Name Moon

Did you hear about the moon tonight? The moon is a wonderful sight every night, but sometimes it gives us a real treat. Tonight's moon has been dubbed—and I typed this in the most passive, judgmental way possible—the "Super Flower Blood Moon," which, to my great disappointment, is not the name of Elon Musk's second child, but rather some hyped-up amalgam news editors decided to use to lure people into clicking on posts they would otherwise scroll by.

Bloggers and news outlets have a strange relationship with astronomy. An interesting event can't just be a lunar eclipse or a noteworthy alignment of the planets. We have to come up with flashy names to sell the story to people who might not care.

One great example is last year's "Christmas Star." Remember that? Saturn and Jupiter passed very close to one another in our night sky late last December, appearing to the naked eye like a bright star suddenly appeared near the horizon.

The conjunction of the two planets quickly earned its nickname, and many popular news articles and social media pages illustrated the upcoming event with Christian-themed art that featured a prominent twinkling cross in the night sky. Many (many, many, many...) people came to expect a giant cross to appear in the sky as a result of this coverage, finding only disappointment when they saw a bright star on the southern horizon after sunset. 

It's strange how things take on a life of their own. It's obvious why the polar vortex became a sensation in 2014—it froze a critical mass of America's journalists and it's a great term that hardly anyone had heard before. But the moon falls victim to this strange phenomenon more than anything else outside of our atmosphere through a combination of longstanding lore and a need for traffic. 

That brings us to the "Super Flower Blood Moon," which should earn someone a marketing award. Whew.

Let's break down the name bit by painful bit:


The moon's orbit isn't perfectly centered on Earth. The moon is about 224,000 miles away from Earth at its closest point, called the perigee, and about 251,000 miles away at its farthest point, called the apogee.

Occasionally, the full moon will occur during perigee or apogee. A full moon during perigee is known as a "super moon" because it appears a little bit bigger in the sky compared to other full moons. (A full moon at apogee is a "micro moon.") The embiggening of a super moon is barely perceptible unless you're good at photography.


We've always had names for different full moons depending on the month or season. There's the Harvest Moon, the Wolf Moon, and the occasional Blue Moon when two full moons occur during the same month. A full moon during the month of May is called a Flower Moon, because flowers bloom in May. (Clever, right?)


Lunar eclipses are sometimes called "blood moons" due to the rusty red appearance of the moon's surface at the peak of a total lunar eclipse. Even though the moon is covered by Earth's shadow, light still passes through Earth's atmosphere and reaches the lunar surface. All the gasses and pollutants in our atmosphere scatter out the shorter wavelengths like blue and green, leaving only dark red light to escape our grasp and reach the moon. 

The term's popularity is relatively new, and it's largely due to evangelical pastors (such as John Hagee) using the phrase in relation to their prophecies about the end times.


Because it's the moon.

Source: NASA

If you're lucky enough to spot tonight's lunar eclipse—which is most visible in the Pacific region and the western half of the United States—please get out there early on Wednesday morning and enjoy the sight. It's really wonderful to catch a full lunar eclipse in all its glory. Astronomy is awesome. Our atmosphere is awesome. We don't need to gussy them up with ridiculous terms to get people interested in the skies above. (Speaking of which...I can't wait to share what I've been working on for the past five months!)

Correction: A commenter who's much smarter than I am pointed out I was wrong to say "the moon's orbit around Earth isn't perfectly circular." The Moon's orbit is not perfectly centered on Earth, accounting for the difference in distances between apogee and perigee. I corrected and apologize for making a mistake while mocking people who make mistakes.

[Top Image: Me (Not me me. Taken by me. I am not the moon.)]

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May 22, 2021

Ana Forms Near Bermuda; Hurricane Season Starts Before June For Seventh Year In A Row

Subtropical Storm Ana formed north of Bermuda on Saturday morning, kicking off the 2021 Atlantic hurricane season more than a week before the season's "official" start date of June 1—again. This is the seventh Atlantic hurricane season in a row that began early. Ana will remain far out to sea, posing little more than a nuisance to shipping interests and a source for rough seas around Bermuda and parts of the U.S. East Coast.

A low-pressure system meandering in the western Atlantic Ocean took advantage of a brief window where conditions allowed the system to develop into a subtropical storm.

It's a cute li'l storm on satellite imagery today. The storm has a delightfully swirly appearance and even a clear eye-like feature right at the center of circulation. Ana is conspicuously devoid of much thunderstorm activity, which is common for subtropical storms.

Forecasters expect Subtropical Storm Ana to remain far from land and dissipate in a couple of days. The Bermuda Weather Service dropped their tropical storm watch this morning because the storm's winds should stay away from the island.

Rip currents are the only effect this storm will have on land. Some beaches in places like North Carolina are on high alert for these fast-moving currents that can pull swimmers out to sea. A rip current forms between waves that hit the beach head-on, forcing this water to drain away from the beach straight out rather than on an angle. Remember, if you're ever caught in a rip current, don't panic—rip currents pull you out, not under. Swim parallel to the shore until the current releases you, or tread water and calmly signal for help if possible.

Like most early-season systems, Ana didn't originate in the tropics and it's not a fully tropical cyclone. "Cyclone" is the catch-all term for any low-pressure system, regardless of strength or location. A subtropical cyclone is a low-pressure system that has some characteristics of both a tropical cyclone and an extratropical cyclone, or the common type of low-pressure system that brings us most of our active weather.

Subtropical storms aren't purely tropical because air temperatures aren't warm all throughout the system and they don't derive all of their energy from the ocean. Tropical cyclones are powered by thunderstorms around the center of the storm, while subtropical cyclones get at least some of their energy from upper-level winds. Despite their differences, subtropical cyclones are close enough to tropical cyclones in composition and impacts that they warrant full tracking and forecasts from the National Hurricane Center.

This is the seventh hurricane season in a row where we saw the first named storm of the season form before June 1. This trend far surpasses the previous streak of three consecutive early-starting hurricane seasons in 2007, 2008, and 2009. It's a clear and undeniable trend—probably the mixed result of both a changing climate and better detection methods—and it's prompted the experts to ponder moving that climatological start date from June 1 to May 15.

The World Meteorological Organization wrote a recommendation a few months ago asking the National Hurricane Center to consider moving the official start of the season in light of all May storms we've seen in recent years. The NHC met them halfway for now, beginning their regular tropical forecasts on May 15 while continuing to call June 1 the beginning of the season. It's likely that they'll consider officially moving the start date in the years to come.

[Satellite Image: NOAA]

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May 18, 2021

More Significant Flash Flooding Is Possible Across The South Through Thursday

Thunderstorms will pose a significant threat for flash flooding across parts of Texas and Louisiana over the next couple of days, with the threat for more than half a foot of rain possible in some communities this evening through Thursday. Stubborn thunderstorms already produced destructive flooding across Louisiana on Monday evening, and some of those same areas could see even more heavy rain to come.

Flash flood watches cover a significant portion of the southern United States this evening, including a huge chunk of Texas, most of Louisiana, and parts of Oklahoma, Arkansas, and Mississippi.

The greatest threat for widespread flash flooding appears to exist in Texas and Louisiana, where the Weather Prediction Center issued a moderate risk for excessive rainfall for Tuesday, Wednesday, and Thursday. The WPC mentioned on Tuesday that they might upgrade parts of Texas to a high risk for flash flooding on Wednesday—these high risks are reserved for days when forecasters are confident that excessive rainfall could lead to significant flash flooding (and it usually does).

The agency's latest rainfall forecast calls for five or more inches of rain across a huge portion of eastern Texas, with isolated pockets of extreme rainfall totals that could lead to major flooding problems in vulnerable areas. This includes the cities (and suburbs) of Houston, San Antonio, Austin, Dallas, and Corpus Christi. 

We've already seen significant flash flooding over the past 24 hours in Louisiana, where persistent thunderstorms led to flash flood emergencies around Lake Charles and Baton Rouge. Local officials had to conduct water rescues to save residents trapped by waters that rose too fast to escape. The flooding in Lake Charles is especially gut-wrenching given that the community was hit so hard by category four Hurricane Laura in August 2020 and again by Hurricane Delta two months later.

The region is at risk of excessive rainfall because of a slow-moving upper-level trough that's meandering over the southern Rockies. This is the same trough that brought a tease of rain to California over the weekend and led to so many photogenic supercells on the Plains.

Southerly winds flowing between the trough to the west and a building ridge of high pressure to the east will pump humid air northward from the Gulf of Mexico. Any thunderstorms that form in this soupy airmass will have a deep reserve of moisture to tap into, and these heavy storms can linger over the same areas for hours without much in the way of prevailing winds to steer them along. 

The northern and western Gulf Coast is exceptionally vulnerable to flash flooding during high-intensity rainfall events like this. Low, flat, and soggy terrain makes drainage a challenge even during a routine summertime thunderstorm. The combination of persistent high rainfall rates, poor drainage, and communities spreading ever farther into flood-prone areas all leads to fairly routine flash flood emergencies these days. The increasing frequency of heavy rain events (likely influenced by a changing climate) makes matters worse.

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May 14, 2021

A Wet And Stormy Pattern Will Drench The Plains Through Next Week

Bouts of heavy rain and a low-grade threat for severe thunderstorms will cover the southern and central Plains through next week. Some areas in Texas and Oklahoma could see more than five inches of rain from the upcoming stormy pattern, which could cause flooding issues if storms persist over the same areas.

Much of the United States has enjoyed a pretty subdued weather pattern compared to how things usually go in May, which is great for storm-weary areas and a little much for those whose gardens could use a break from the cold weather. This past Thursday, Charlotte, North Carolina, saw one of its latest sub-40°F low temperatures on record this late into the season. That's an impressive chill!

As the upper-level trough that brought the eastern states their late-season coolness moves out into the Atlantic, temperatures will climb closer to average and spring-like humidity will begin to slowly fill out across the country.

This weekend will see a "split" jet stream, with one branch arching into northern Canada while the other swoops south into Mexico, leaving most of the United States with relatively calm conditions aloft. This calmness will allow smaller, more subtle features dictate the weather.

Decent instability over the Plains should allow showers and thunderstorms to develop across the region over the next couple of days. The Storm Prediction Center paints a marginal to slight (1-2 out of 5) risk for severe weather over pretty much the same areas each day through Sunday, with Cheyenne, Denver, Amarillo, and much of Kansas at risk for thunderstorms that could produce damaging winds, large hail, and a couple of tornadoes.

An upper-level trough will move over the West Coast this weekend, prompting the risk for thunderstorms in California on Saturday and Sunday. Thunder and heavy rain are even possible in some spots high in the Sierras. 

That trough will kick off a low-pressure system on the eastern side of the Rockies on Monday and Tuesday, laying the groundwork for heavy rain to fall in earnest over the southern Plains. Tuesday through Thursday looks to be the best bet for folks in northern Texas and southern Oklahoma to see several inches of rain. Some communities could see flash flooding if the rain falls too quickly.

It's worth pointing this out any time there's a risk for flash flooding—please remember that you can't tell how deep the water is until it's too late. Water is deceiving and drivers are notoriously bad at underestimating the depth of floodwaters covering the road ahead of them. Plan out alternate routes ahead of time so you know multiple ways to get around if one road is cut off by high waters.

(This post was originally published at 8:30 PM EDT on May 14, 2021. A technical glitch on Google's part removed the post from the site for a day before it was restored.)

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