Via MIMIC, a microwave image of Cyclone Monica.

The minimum central pressure in Tropical Cyclone Monica, a Category 5 monster bearing down on Darwin and surrounding areas in Australia, dropped at least to 879 mb earlier tonight, making it stronger than Hurricane Wilma — the most intense hurricane ever recorded in the Atlantic basin — and nearly as strong as Supertyphoon Tip, whose 870 mb barometric pressure stands as the lowest ever recorded on Earth’s surface. Some commenters on Dr. Jeff Masters’s blog believe Monica may have matched or surpassed Tip, pointing to satellite estimates that show a pressure of 868 or 869 mb. As The Storm Track puts it: “If the satellite estimates are true, Monica has become the most intense storm ever recorded in the entire world. However, in this area the estimates tend to be about 10 mb too strong.” It won’t break the “lowest pressure ever recorded” mark anyway, since they don’t have reconaissance airplanes in Australia, so all of these pressure readings are actually estimates based on satellite views, not direct observations. But regardless, this is clearly one of the most intense storms ever witnessed by modern human eyes anywhere on planet Earth.

That said, satellite views — and observations by the aforementioned commenters — suggest that Monica has weakened slightly in the last few hours, perhaps because of an eyewall replacement cycle and/or the diurnal minimum. But of course, “weakened” is a relative term. This is absolutely a monster storm. The big question is how much more it will weaken before it reaches the Darwin area, and that depends largely on its exact track over the sparsely populated Cobourg Peninsula. The more time it spends over land, the more it will weaken, of course. (Then again, as Alan Sullivan notes, it’s been doing a remarkable job of maintaining its intensity and perfect symmetry even though about one-third of the circulation is already ashore!) Here’s a look at the current official track:

It should be noted, by the way, that Australian hurricane “categories” are different from the Saffir-Simpson Scale that we’re used to; Wikipedia explains. But Monica is a Category 5 by any measure.

Here’s a good page for news about the cyclone. Among other things, the events in Darwin for Anzac Day — “Australia’s biggest day” — have been prudently cancelled as Monica approaches. (Hat tip: Aussie commenter Melanie Dickson, who, incidentally, has been granted guestblogging privileges and may be filing reports as BrendanLoy.com’s official Australia Correspondent soon.)

Previous post here.

The population of Darwin is just over 100,000, by the way. One of those 100,000 is this blogger. More Australia blogs here. Here is a webcam of Darwin Harbor.

Relevant historical note: Darwin was virtually flattened in 1974 by Cyclone Tracy, which destroyed 70% of the city’s buildings, killed 71 people and left 20,000 homeless. “Most of Darwin’s population was evacuated to Adelaide, Whyalla, Alice Springs and Sydney, and many never returned to Darwin,” according to Wikipedia — a scenario that sounds eerily similar to what we’re seeing in this country with Katrina.

As it happens, Tracy was physical the smallest tropical cyclone in recorded history, in terms of the geographic size of the wind field; Tip was the largest. So it’s sort of odd that Monica is, in different ways, competing with both of those two storms for a place in history.

After the jump, an incredible animated GIF image (12.6 MB, so it’ll take a while to load) of microwave imagery of Monica over the last 48 hours. (Source: MIMIC.)

FINAL UPDATE: Good news! The threat to Darwin has lessened considerably. Details in a new post above.