Do I Dare Smash Pressure Records?

I know for my Great Christmas Blizzard of 2045 that I’m working up for a future story, it will already be a record-breaking storm in terms of pressure, passing the 900 millibar mark on the way down (lower pressures mean greater intensity), freakishly severe for a nor’easter. But I’ve been thinking: considering the exceptionally favorable setup for what’s essentially Superstorm Sandy Deluxe (i.e. it originates from a Caribbean hurricane, goes extratropical, and makes the “left hook” track into the East Coast), might the pressure go even lower? Much lower?

After all, Hurricane Patricia got all the way down to 872 millibars, just 2 millibars short of cresting Typhoon Tip’s world record of 870 millibars (indeed, there’s some speculation it might have actually surpassed Tip), and the second-most intense hurricane in Patricia’s basin, the eastern Pacific, only got down to 902 millibars, a pipsqueak by comparison. Events that don’t just break but smash records do happen every so often.

The Great Christmas Blizzard: a favorable Setup for Record Intensity

The very setup in advance of the Great Christmas Blizzard is unusual: yes, it takes the (for the late season) typical track of drifting northward from the western Caribbean, but I already envisioned it becoming a Category 3 major hurricane, which would be unprecedented for December, or indeed for the off-season in general (the whole period from December through May). More unprecedented still would be my latest idea: making it a Category 5 major hurricane, with pressure dropping to below 900 millibars even before it gets captured by the arctic trough and undergoes its transmogrification.

Needless to say it would be exceptionally intense for that late in the year, but part of the setup is water temperatures in the area are record-warm, so if there was a window of favorable atmospheric conditions, it could happen. Interestingly, the latest Category 5 hurricane to have ever occurred, the November 1932 Cuba hurricane, actually holds the record for the longest duration a hurricane has ever spent at Category 5 intensity. Huh.

It would be a fitting cap-off for the 2045 Atlantic hurricane season; I’ve already decided the Christmas storm is the last hurricane of the season, and 2045 is already set to have a record-late start, hurricanes only starting to form in October, due to record high levels of Saharan dust over the Atlantic during the summer.

Once it completes extratropical transition, which might involve some weakening, this great storm will intensify as it moves westward toward eventual landfall at Ocean City, Maryland. Taking Hurricane Sandy as a prototype, it actually reached the greatest intensity of its whole life cycle as an extratropical storm right before it made landfall, and it was already plenty strong during its tropical phase: Category 3. Carrying this to a semi-fantastic extreme in my story, it suggests the potential for a storm well below even the record pressure set in our timeline by the 1935 Labor Day hurricane: 895 millibars.

Might the Christmas Blizzard achieve the record intensity set by our Hurricane Wilma in 2005: 882 millibars? Given this setup, very possible. It’s even conceivable that such a storm could not only best the record low pressure for an extratropical storm in the Atlantic, but tropical storms as well; i.e. setting a record for any storm. Might it go even lower than the 882-millibar mark? The 870 millibar level reached by Typhoon Tip beckons, and would seem achievable in this scenario.

Typhoon Tip was a very large storm; if it was over the United States its expanse of gale-force winds would cover most of the country! This is true for the Great Christmas Blizzard as well. But on the other hand such intense storms don’t have to have exceptionally large wind fields; Hurricane Patricia, comparable in intensity, was a relatively small storm. The flip side, of course, is that a storm of the same intensity that’s smaller in area has higher wind speeds, and indeed Hurricane Patricia sported sustained winds of 215 miles per hour, considerably greater than Tip’s 190-mile-per hour winds.

An Exceptional Intensity makes so much sense!

I’m toying with the idea of making the Great Christmas Blizzard bottom out at 865 millibars; it’s past the record intensity observed in our world for even a typhoon, let alone a nor’easter, and 865 echoes “1865”, the year of emancipation, which seems appropriately creepy, since post-emancipation history is a theme of the political discussions that are to take place, and there’s a scene at the Lincoln Memorial, right in the middle of the hardest-hit region.

Considering there are strong surface highs in Newfoundland and (especially) in the Northwest, the pressure gradient only becomes stronger in the revised version, expanding the gale-force windfield to encompass Texas, and upgrading perhaps even Florida to major-hurricane-force gusts. The hardest-hit areas may well experience sustained winds and gusts comparable to a Category 5 hurricane…only unlike a hurricane it’s spread out over a much wider area. 200 mph wind gusts at Georgia’s vacation house in the Shenandoah couldn’t be ruled out at that point.

The exceptional intensity also makes a well-defined eye with a starkly-defined vertical structure resembling that of a major hurricane much more plausible than in the original version. Garden-variety strong nor’easters often develop “eye-like features”, but even when the very center of the storm has clear skies the surrounding clouds are often low, scattered, and disorganized. There is an observed trend of tighter eye-like features that are better defined and have clouds rising more vertically the more intense an extratropical cyclone gets, even if the resemblance to a hurricane’s eye is only superficial (the underlying physics are quite different).

I want that visual of Aoifan at his piano in Ocean City surrounded by those hurricane-like vertical walls of cloud, even if it does give off “The Day After Tomorrow lite” vibes. It’ll also really drive home just how freakish the storm is: although very much a cold-core storm, and hence not classified as a hurricane by the weather bureau, it will superficially resemble a giant hurricane, only with snow rather than rain.

The Turks and Bermuda Hurricane

Another reason I’ve been thinking along these lines is that the exceptionally warm water drives explosive intensification of storms earlier in the season; very intense Category 5 hurricanes might form in unusual abundance during the relatively short window for tropical storm formation in the Atlantic that year.

In particular, my story calls for a treasure chest to be unearthed on a northern Caribbean island due to a direct hit from a Category 5 hurricane, for the main character to uncover there during a snowstorm after New Year’s brought by a polar low that formed out of an exceptional arctic front that sweeps through the region. I’ve decided the island will be Salt Cay, which is in the Turks Islands, and said Category 5 hurricane impacts the island early in December; so what becomes the Christmas Blizzard isn’t even the first intense hurricane that forms in the off-season!

The Turks Islands are very far north for a Category 5 hurricane any time of the year, much less December, but it’s not unprecedented; Hurricane Dorian became among the most intense Atlantic hurricanes on record considerably further north in the Abaco Islands, and in my 2045 water temperatures are record-warm. Perhaps there’s a short window of favorable atmospheric conditions for explosive intensification?

It does track with my plans for early December; steering currents, courtesy of the building arctic outbreak in the United States, blow the storm sharply northeastward after a few days of drifting southwestward after it formed in the open Atlantic, on its way out from the Turks Islands making a direct hit on Bermuda as a major hurricane. In the meantime, might the storm achieve top-tier intensity? Hurricane Dorian reached sustained winds of 185 mph at a pressure of 910 mb. Inspired by Patricia’s compact yet intense nature, might the Turks and Bermuda Hurricane, as it might become known as, drop substantially below 900 millibars and sport sustained winds exceeding the 200 mile-per-hour mark at its peak? It won’t compare with Patricia, but could it compare with the Labor Day Hurricane’s 892 millibars? Maybe.

Further Thoughts

Several other Category 5 hurricanes will develop over the course of the season. 2005 holds the record in our timeline, with four, and 2045 in this timeline will likely exceed that mark, even if the total number of tropical storms isn’t particularly high overall, owing to the season only starting in October and lasting through the middle of December, when the potential for Cape-Verde-type storm formation has largely shut down, and severe wind shear is prevailing much of the time, especially northward of the tropics. Conditions for intensification, however, will often be exceptionally favorable.

I’ve not worldbuilt the whole hurricane season, and I might not even want to, but there is a lot of potential there for some interesting storms. The only real constraints are that the track of the Christmas hurricane and the Turks and Bermuda hurricane need to be undisturbed by any previous tropical storm activity (which tends to stir up cooler water and deplete warmth).

October is the coldest on record in the United States, so with such a pattern any hurricanes would be blown far away from the mainland. November, however, sees a pattern flip, so steering currents could cause hurricanes forming in the Gulf of Mexico or the western Caribbean to track northward into the mainland.

Anyway, these aren’t exactly complete thoughts, but I hope I have elucidated my latest thinking on this whole topic. This story is gonna be lit… 😀 

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