The ghosts of record Pacific Ocean heat content may well be coming back to haunt us…
Very powerful near Category 5 Ita is now bearing down on the Australian Coastline. Regions near where the center makes landfall, projected to be near Cape Flattery, could experience 155 mph sustained winds with gusts in excess of 185 mph and storm surges in excess of 25 feet. Interests throughout North Queensland should remain abreast of what is a very powerful and dangerous storm capable of producing record or near record effects.
(For reference, a category 5 storm has a wind speed intensity of 156 mph or greater.)
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An outrider of an El Nino pattern that appears to be gradually emerging and strengthening in the Tropical Pacific, Ita had her stormy beginnings near the archipelago of the Solomon Islands. There, what at first started as a tropical disturbance dumped three days of torrential rainfall over the island chain, setting off worst-ever floods on record, washing away hundreds of buildings, and leaving more than 50,000 people homeless.
Major rainfall events are not uncommon in the Solomons. But what occurred as a result of current and abnormally intense heat-spurred Pacific Ocean convection is. For the massive shield of thunderstorms that spawned Ita also dumped one meter (1000 mm or 39.4 inches) of rainfall during a three day period over some sections of this tropical island chain. The far-reaching floods ruined roads, bridges, buildings and forced the cessation of strip mining operations in interior sections.
(Thunderstorms associated with the newly forming Ita boil over the Solomon Islands on April 3rd and 4th. Some locales received single-day rainfall totals in excess of 18 inches with three day measures topping 1 meter. Image source: LANCE-MODIS.)
The Solomon Islands lie just east of New Guinea and are on the southern edge of what is currently a very deep, hot pool of water — one that appears to be in the process of rushing eastward. There, over waters ranging from 85 to 87 degrees Fahrenheit (29-30 degrees Celsius, or about 1-2 C above average), Ita had her genesis in a shield of convection forming along the hot pool’s southern flank.
Slow Westward Trek
After lingering for days over the Solomons, Ita gradually shifted southwestward, churning on into the Coral Sea and reaching category 1 intensity by April 8th. Water temperatures throughout the region remained well in excess of 80 degrees, more than enough to fuel rapid intensification. By late April 9th, many models showed Ita potentially reaching category 4 or 5 intensity before roaring into northern Queensland.
Concerns were raised about both projected storm intensity and projected track. Clockwise circulation of a slow-moving but very powerful storm could pile a very significant storm surge along the Queensland cities of Port Douglas and Cairns. Northern locations could experience very intense and prolonged storm conditions including heavy rainfall, extreme coastal flooding, and winds in the range of 90 to 155+ mph over a tightly compact zone.
Cape Flattery, Cooktown and Port Douglas, sparsely populated towns of between 2,000 and 3,000 residents, respectively, are likely to bear the brunt of the storm. But Cairns lies only a little further south along the storm track and boasts fully 150,000 residents — a more densely populated region that could also see extreme impacts.
By early April 10th, favorable environs and extremely warm water temperatures in the Coral Sea had resulted in the rapid intensification predicted. By 1600 Eastern Time in the US, Ita had bombed out to a 155 mph monster storm with a lowest central pressure around 921 mb, exploding from a Category 1 to a near Category 5 storm in less than 48 hours, as it headed toward the Australian coastline at an excruciatingly slow pace of 6 mph SSW forward motion.
It’s worth noting that a 921 mb reading is very low and may justify a new winds speed of closer to 165 mph or more considering how compact this storm. Early model runs had projected peak intensity at 920 mb and around 165 mph wind speeds. That said, ITA remains over open water and retains a very compact wind field, so further intensification is possible before land interference begins to disrupt circulation.
Even now, conditions may seem disturbingly tranquil along the coastline. Winds there are currently running in the range of about 20-30 mph. But gale force winds lurk about 100 miles offshore and the intense, hurricane force, winds are not fare behind. The most intense winds, of up to 155 mph sustained with 185 mph gusts, are in a tight band just about 10-20 miles from the center. It is regions within this band of clockwise onshore flow where most damaging effects are likely to be witnessed.
(Most recent projected path of Ita. It’s worth noting that the Australian Bureau of Meteorology puts Ita at 907 mb and Category 5 status. This conflicts with NOAA’s 921 mb estimate. Image source: Australian Bureau of Meteorology.)
Ita is expected to maintain Category 4-5 intensity all the way through to land-fall sometime tomorrow. As such, storm surge flooding in excess of 25 feet is likely near where the center makes landfall. A storm of similar strength, Typhoon Mahina, brought a 45 foot storm surge ashore near Bathurst Bay in 1899. It is the same region where Ita is expected to make landfall sometime tomorrow.
This storm surge of 45 feet ties Bangladesh for the highest storm surge on record anywhere in the world.
Mahina made landfall with a minimum central pressure of 914 mb. Ita would only need to drop another 10 mb to exceed that mark. But, if it does, a world storm surge record could be set to fall.
UPDATE: Ita shows some slight weakening in both satellite and pressure estimates. Pressures (NOAA) as of about 7 PM were around 926 mb with maximum sustained winds still estimated in the range of 150 to 155 mph. Australia’s Bureau of Meteorology maintains ITA at 907 mb and CAT 5. Still a very powerful storm.
UPDATE: As of 9 PM EST, US, Ita continued to show some signs of slight weakening. NOAA now shows Ita as a 931 mb storm, while Australia’s Bureau of Meteorology puts it at 914 mb. No cause for comfort, as yet, since these pressure estimates are well within the range of a strong CAT 4 or CAT 5 storm.
Perhaps more ominous, however, is a slight job to the south. Too early to call but if a more southerly track continues, locations such as Cairns may be in for more of an impact. Still too early to call.
As per the recent VMAX wind profile Ita’s gale force winds are now on shore. Measurements are in knots. In this measure maximum sustained winds are just into CAT 5 status (138 kts). Image source is NOAA.
UPDATE: Slow strength degradation continues pushing Ita into strong CAT 4 status. NOAA shows 937 mb and ABM shows 922 mb at 11 PM. Wind strength remains between 145 and 150 mph max sustained. Southward jog continues as it appears possible Ita may skirt the coast.
UPDATE: Ita came ashore as a Category 4 storm with effective one minute sustained winds in excess of 135 mph and a ten minute sustained wind of 120 mph near Cape Flattery in Queensland. Pressures at landfall were in the range of 935 to 948 mb. Ita has continued to track just inland and is now just west of Cooktown. Interaction with land has continued to degrade Ita, which as of 12 PM EST was estimated at Category 3 intensity.