While the Atlantic is quiet for the moment (and should stay that way for the next week or so and maybe longer), the Pacific is active. Lets look at the storms off of Hawai’i and Japan, then explore why the Atlantic is quiet.
First, there are two storms headed in the direction of Hawai’i, but neither should make landfall. The first is still in the East Pacific basin, Hurricane Gilma. It is expected to dissipate before reaching the Islands. The second, currently a tropical storm, is expected to brush the Big Island in about two days, passing just to the south. CPHC has raised tropical storm watches for Hawaii County. At present the biggest threat will be excess rain and swells, the rest of the Islands should watch carefully until it is sure the storm will pass to the south.
The storm on track to hit Japan is potentially a bigger problem. According to the US Joint Typhoon Warning Center, Tropical Storm Shanshan is forecast to make a direct hit on the Tokyo area in just over four days. Here is the impact swath using their forecast …
The official forecast from the Japan Meteorological Agency is similar in track, albeit about 15% lower wind speeds. As is often pointed out here, even small wind speed differences make big differences in damage. A 90 knot storm will cause roughly 27% damage in an area, whereas an 80 knot storm will only cause 19% or so damage. So trying to blend all that, if the forecasts hold up this looks like an $8 Billion event.
We’re entering the peak of hurricane season in the Atlantic, and there’s nothing out there at the moment. As noted at the beginning of the season when all of the dire forecasts were causing the unwashed masses to consider evacuating the Gulf and Atlantic coasts, I wrote an article about the fact that while broad scale conditions may be favorable, day to day factors like where there is dry air or the interplay of upper air currents control the formation of individual storms. Thus, even “favorable” years don’t always equate to “busy” – and, in contrast, even a “quiet” year can have a catastrophic storm.
The above image shows there is a lot of dry air over both the Atlantic and Gulf of Mexico. The Atlantic remains warmer than average, although there is a wake visible from Hurricane Ernesto in the latest Sea Surface Temperature analysis …
One of the many benefits of hurricanes, as a natural part of Earth’s system to transport heat from the tropics to the polar regions, is that a passing storm dredges up deep, nutrient rich water and otherwise stirs things up. They can also leave a significant wake in their path that can persist for some time (link to NASA article), and even interfere with subsequent storms.
Another change is that in the East Pacific, off the coast of South America, we are seeing the sea surface temperatures cool off as we move from ENSO neutral conditions towards the expected La Nina conditions in between September and November. That may be too late in the season to boost hurricane chances as much as was feared earlier in the year, as it takes time for cycles to propagate through the atmosphere.
So in short, the “big picture” remains somewhat favorable for storm formation and energy, but the “little picture” is that the specifics are unfavorable a the moment. Hopefully that will persist through the rest of the season, but don’t count on it. If you don’t have a plan yet, take advantage of the lull to ensure your insurance is adequate, and you know what you will do if a big storm threatens.
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Thank you for a calm voice in the otherwise chaos of hurricane season.