Plotting Out a Year of Weather

“Oh no, Adamas Nemesis isn’t going to make those tiresome hypothetical weather tables!”? Well, no…I’m not. But I’ve been doing some more research and worldbuilding for the weather pattern that precedes the historic Great Christmas Blizzard of 2045, which will be featured in a story that I’m conceptualizing now. The setup is that 2045, in my alternate-history-cum-science-fiction universe, is a year of extreme weather, which gradually escalates, culminating with the perfect storm near the end of the year.

A Great Storm for California?

The calendar year starts with a “super El Niño”, an extremely strong event but not unprecedented (in real life they occasionally occur, most recently in 1998 and 2016), which leads the winter of 2045 to feature extreme weather but in relatively typical fashion for a classic strong El Niño, which tends to enhance moisture feeds into the western United States, including California.

Which is where I got the idea that California could get the big one that year in my timeline; no, not the earthquake, the storm. Something similar to the Great Flood of 1861-62, which on average recurs every century or two, a setup driven by a strong “atmospheric river” and series of storms dumping copious quantities of rain and snow into California. Such events can last for weeks, even months; 1861-62 featured 43 days of heavy precipitation. A scenario that was exceptionally severe compared to the 20th century records but much less intense than the 1861-62 storm was modeled in the USGS’s “ARkStorm” scenario. Total economic losses: $1 trillion. 💀 And 1861-62 isn’t even the ceiling; paleoclimatological research suggests a similar weather pattern in 1605 might have been twice as intense as 1861-62!

So 2045 will see an event as bad or worse than the “ARkStorm”, but luckily for farmers, fruit lovers, and my characters alike (quite a few of whom live in Malibu, a vulnerable area), water infrastructure is robust enough to cope, since it was designed with such a storm in mind; in this timeline tunneling is cheap and effective enough that there’s a whole network of storm drains (which are all opened only in emergency situations) covering not just urban areas but populated hills and the cropfields of the Central Valley, shunting the excess water into vast underground reservoirs, where it won’t be able to kill any people or damage any property.

Nevertheless, the copious rains, pouring down with thunderstorms, even accompanies by tornadoes in the stronger bouts, for a couple months at a stretch in January and February 2045 will be remarkable for the denizens of California to experience. In particular, the higher elevations of the Sierra Nevada will receive unprecedented heavy snowfall. Indeed, basically the entirety of the Western United States (westward of the Great Divide) will receive heavy snowfall, much like in 1862, courtesy of this moisture-rich and stormy pattern, which hovers over the Northwest in December before drifting southward in January.

The corresponding pattern in the eastern United States is somewhat more winter-like in December, but turning warm, wet, and stormy in January and February, complete with the Southeast experiencing one tornado outbreak after another as warm fronts sweep through.

For Tornadoes, a Year like no Other

Turns out that will be the theme for the first half of the year, with storm systems stimulating thunderstorm activity not just in winter but into the spring too as temperatures warm further. April will be the peak of the warm and humid weather pattern; as the averages climb up but the tornadic weather pattern refuses to budge, conditions relative to normal change from warm and stormy to cool and stormy, with cold air remaining in place over large sections of the northern United States for much longer than normal.

Copious outbreaks lead to a record-active tornado season already by April, but the storm pattern is just getting started: “Dixie Alley”, the South and Great Lakes, dominated tornado activity earlier in the season, but by May the classic “Tornado Alley” region in the Plains comes to life, just in time for a series of storm systems to move ever-so-slowly across the eastern United States, perfectly set up to produce what’s called a “super outbreak”…only unlike in 1974 and 2011 there’s not just one but multiple storm complexes, tracking over the same areas and feeding on the same air masses, that produce super-outbreak-tier events every week for the entire month of May, not only in the 1974 and 2011 Dixie Alley regions but extending into the classic Tornado Alley as well. 2045 thus becomes a legendary year for storm chasers already by the end of May.

June sees a cold air pattern settle into the eastern United States, prolonging tornado season much longer than normal, with continued exceptionally active activity, though not to the absurd extent seen in May. Strong low pressure systems and fronts continue to develop and sweep unusually far south for so late in the year.

La Niña del Diablo

This is when, in the whole foreshadowing process, people start to raise their eyebrows and wonder if something more freakish than garden-variety extreme weather might be going on. Eyes turn toward the equatorial Pacific, as the super El Niño dissipates at a record-fast rate, with the ENSO reaching neutral conditions already by summer, heading fast toward the polar opposite: La Niña.

And not just a garden-variety La Niña: this event reaches super La Niña proportions by the end of 2045, a record-fast transition between the two most extreme ENSO states. More freakishly, it’s not a traditional super La Niña, with the locus of the cold water anomalies in the eastern Pacific near South America.

I was originally thinking I would make the super La Niña a “Modoki” event, with the locus of the cold water in the central Pacific, near the International Date Line (hence the term “Modoki”, a Japanese word meaning “similar, but different”). These do occasionally occur in real life, and they tend to be much less predictable in their global effects than a traditional La Niña. But then it hit me yesterday: why not a more exotic type yet, a La Niña centered not in the central Pacific but outright in the western Pacific, near New Guinea. An ENSO event of this type has never been recorded, but is theoretically possible, and it may well have more intense and unpredictable effects than even a Modoki super La Niña, let alone a traditional one. Aha! Just what I wanted. Call it La Niña del Diablo, “The Devil’s Girl”.

This super La Niña will have record-cold waters across a broad area of the western Pacific, with waters as cold as during the strongest La Niñas extending clear to the coast of South America. As the event deepens the band of cold equatorial waters extends well westward of what are normally considered ENSO zones, through Indonesia and even eventually extending into the equatorial Indian Ocean as well.

Freakish. But that’s just the beginning. Already by June Atlantic sea surface temperatures are starting to rise into record-warm territory in many regions, an ominous harbinger for the hurricane season…but the saving grace is an exceptionally strong Saharan Air Layer that spreads haze, and spectacular sunsets, across the Atlantic, into the Caribbean and even the southeastern United States.

When the Frost is on the Fireworks…

The tornado outbreaks and flooding rains finally come to an end in spectacular fashion in early July, as the polar vortex destabilizes in a fashion much resembling what normally happens in midwinter, letting loose copious quantities of arctic air into an already chillier-than-normal eastern United States.

A sharp cold front sweeps down through the warm and humid air mass, igniting one last outbreak of severe weather: a massive derecho racing southward with the front. In Nashville, home to several characters in my story, July 3 sees highs only in the seventies, the derecho sweeping through in the evening with winds in excess of a hundred miles per hour, stiff synoptic winds blowing out of the north afterwards, temperatures reaching the mid forties overnight, record low territory.

July 4 is by far the coldest Independence Day on record, windy and sunny (through the already-thick Saharan dust haze) with afternoon highs not even reaching 60 degrees Fahrenheit. As winds die down, the clear night sees temperatures plummet to the mid thirties, smashing the record low for the month of July. The Independence Day fireworks show takes place in crisp air that barely exceeds 40 degrees, perhaps dropping into the thirties by the finale.

The Cumberland Plateau might actually see a midsummer freeze, as will almost the entirety of the Midwest. Luckily, the arctic air swept through fast enough the temperature gradient is limited; even in the upper Midwest temperatures might not drop further than the mid twenties. And seasonality reasserts itself; after perhaps another night or even two, weather warms up substantially, but will remain well below average for the remainder of the summer, as a very cool and very dry pattern settles in over the eastern United States.

The odd pulse or two of record cold, though even then not nearly as strong as the Independence Day cool wave, pours into the United States, but overall prevailing conditions are toward the stronger end of “seasonably cool”, and remarkably consistent: sunny and hazy, with nary a heat wave (or a drop of rain…) in sight. Nashville even at the end of August has yet to record a 90-degree temperature for the entire calendar year of 2045, a nigh-unprecedented occurrence. One last pulse of record summer cold might plunge parts of the Plateau into a light frost or two in late August and early September. Trees might start showing their autumn colors exceptionally early across the eastern United States.

Indian Summers and Blue Northers

But September will see a major pattern change; after that one last pulse of cooler air, a strong ridge of high pressure will make itself felt, building week after week, and raising temperatures. Sunny, hazy, and dry remains the order of the day, with hardly a drop of rain in sight. This does not mean a return to the customary humidity, however; the atmospheric pattern effectively shuts down the transport of humid air from the Gulf of Mexico, and instead favors an outpouring of hot dry air (and dust…) from the Sonoran Desert into the eastern United States.

Temperatures climb steadily, with Nashville at last recording its first 90-degree temperature of the year. Humidity trends lower and lower, as nights remain stubbornly cool, morning lows not even climbing out of the fifties, forties on some days. 100 degrees is reached by the end of the month, record high territory, with Nashville cresting 105 degrees in the first few days of October, the hottest weather experienced during the whole year of 2045. Nighttime lows never leave the fifties.

The Saharan Air Layer starts to dissipate, permitting the tropics to come to life, the first hurricanes spawning from that record-warm water early in October, a record-late start to an Atlantic hurricane season, prompting some on that 105-degree day looking at satellite pictures of the season’s first hurricane to jokingly wonder if it’s October or August.

That last 105-degree day will be courtesy of an approaching storm system, one last blast of Desert Southwest air, the culmination of the strongest Indian Summer on record in the region, being funneled ahead of a cold front of unprecedented ferocity: a true “blue norther”, and one of comparable magnitude as the November 11, 1911 event. That arctic outbreak that went away after the summer? As of early October, it’s back. Boy, is it back…

Across a wide swath of the eastern United States, record highs set that October day will be followed by record lows. The weather pattern is so dry the front will be experienced as a windstorm under clear skies, free of precipitation. Drought conditions are severe enough that the front’s passage might be accompanied not by a derecho but rather a dust storm, fueled by exceptional drought conditions in the High Plains. Hurricane-force wind gusts shifting to the north herald an unprecedented plunge in temperatures: from 105 degrees that afternoon, temperatures could plummet below 30 in Nashville the following morning, autumn beginning in earnest with a flash freeze for the ages.

The cold weather pattern remains locked in place as the eastern United States experiences its coldest October on record, with temperatures often resembling midwinter rather than midautumn, culminating in a blizzard dumping a foot of snow from Arkansas to New England over Halloween, its track similar to the January 2016 blizzard. And yes, a Halloween snowstorm can be a dead ringer for a midwinter counterpart: just look at the October 2011 nor’easter in real life.

Admit it: if it didn’t have “October” plastered onto it you couldn’t tell the difference…

There is a known correlation between the weather pattern in October and the weather pattern in the subsequent winter, and (in stark contrast to 2011-12, where it didn’t hold) 2045-46 will vividly demonstrate what one might call the “October effect”. As often as not in winters that fulfill the October effect, November will see a respite from the cold, and 2045 will see this in spades.

“We’ve had One, yes, but what about Second Tornado Season?”

The first real intrusion of warm humid air from the Gulf of Mexico since April pours into the eastern United States, in a reprise of the weather pattern seen the previous winter, as if El Niño gives its last gasp: a profusion of moisture into California, chilly weather in the west, and warm stormy weather in the east, complete with a spate of tornado outbreaks. November is known as the “second severe thunderstorm season” in the southeast, and 2045 will be an unusually strong one, though not nearly as record-breaking as the spring was. The warm weather, and the northward steering currents prevailing in tropical waters, invites any hurricanes that may form in the western Caribbean to make a beeline for the United States, and 2045 proves to be an exceptionally active November in the tropical Atlantic (remember: sea surface temperatures are at record-warm, and there is a super La Niña afoot…)…

80-degree weather in Nashville, first seen in 2045 as early as February, has its last gasp around Thanksgiving as the warm weather pattern starts to weaken, a series of storms rapidly moving through the eastern United States, Alberta Clipper after Alberta Clipper delivering snowfall and tracking further and further south, quickly building up December snow cover in the eastern United States and sending temperatures plunging to record lows within two weeks’ time. In the middle of December a particularly strong arctic front sweeps through and delivers a very broad swath of snowfall, stretching deep into the South, the extension of the polar vortex even expanding to take in the West as well, locking in temperatures approaching or even setting monthly record lows from coast to coast, as an off-season major hurricane starts to approach from the western Caribbean…


I’m liking this setup already. It would be a rather sprawling meteorological chronicle to include all this in addition to the main story I have planned out, but so what? It has atmosphere, creepy and ominous enough to pay off with what I have planned for the climax of extreme weather on Christmas, and to be an enjoyable ride along the way. I’ll continue my brainstorming efforts…

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