Forecasters are watching a low southeast of Hawaii with a 40% chance of forming

A broad area of low pressure is forecast to develop well southeast of the Hawaiian Islands by early next week, and the National Hurricane Center gives it a 40% chance of becoming a tropical cyclone within seven days. The odds for the next 48 hours are near zero. Forecasters say a tropical depression could form by the end of next week, as the system drifts west or west-northwest across the Central Pacific.

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Nothing is spinning yet. The East Pacific basin has no active tropical cyclones, so the outlook describes a possibility that is still a few days from taking shape, not a storm with a name and a track. The 48-hour column reads near 0 percent because the low has not yet formed; the 40 percent sits in the seven-day column, where forecasters expect the environment to turn favorable.

What forecaster Gibbs wrote on Friday

The outlook was issued at 200 PM Hawaii time on Friday, October 30, and carried on the Eastern North Pacific seven-day outlook page under the signature of forecaster Gibbs. It says conditions appear generally favorable for gradual development once the low forms. The word gradual matters, and the outlook text repeats it: forecasters are not describing a system that explodes into a hurricane over a weekend, but one that organizes slowly if the environment holds.

The same product notes that the low is expected well to the southeast of the islands, not near them. An earlier version of the outlook, posted in the center’s East Pacific feed and signed by forecaster Hagen, used the same wording about a broad area of low pressure developing by early next week, and that feed also lists no tropical cyclones in the basin.

What a medium chance means

The hurricane center does not issue free-form percentages. Its product descriptions say each disturbance gets a categorical formation chance for the first 48 hours and for the full seven days, rounded to the nearest 10 percent, and that the categories are low for 0 to 30 percent, medium for 40 to 60 percent, and high for 70 to 100 percent. A 40 percent chance sits at the bottom of the medium band, one step above the top of the low band.

The figure is a formation chance, not a forecast of impacts. It says nothing about whether the system would reach hurricane strength, where it would be on any given day, or whether it would approach Hawaii at all. Those questions only get answered if a depression forms and the center begins issuing advisories with a forecast track. Put another way, a 40 percent chance also means a 60 percent chance the low never develops into a depression within the window.

Honolulu’s Central Pacific Hurricane Center takes over west of 140 degrees

Storms that form southeast of Hawaii and move west cross into the area watched by the Central Pacific Hurricane Center in Honolulu, whose outlook, according to the NHC page, covers the central North Pacific between 140 degrees and 180 degrees west. The Honolulu office of the National Weather Service keeps a separate tropical information page for the state and surrounding coastal waters. The timing sits inside the formal season: the center issues Central North Pacific outlooks from June 1 through November 30, four times a day at 2 am, 8 am, 2 pm and 8 pm Hawaii time, and the season has about a month left. The Atlantic is quiet by comparison. Forecaster Beven’s outlook on the center’s main outlook page says tropical cyclone formation is not expected there during the next seven days, which leaves the Pacific low as the only area of interest on the map in the Friday evening update.

The timing language is specific enough to track. The low is expected to form early next week, in the first days of November, and the outlook puts a depression at the end of that week, which means the 7-day window ends about when the first signs of organization would appear. If nothing has formed by the time the next few outlooks roll over, the chance will shrink as the window slides forward past the end of next week.

What to watch next

The next few outlooks matter more than the current number. If the low consolidates early next week, the odds will likely move from medium to high, and the 48-hour column, now near zero, will start to climb. If the disturbance stays diffuse, the percentage can just as easily drop back into the low category.

Two things will decide the outcome. One is whether the low actually forms where forecasters expect it; the other is whether the westward drift keeps it over water warm enough to support gradual development. The hurricane center has not yet said how far south or east of the islands the low will sit, which is the figure that would show whether Hawaii is in its path or well clear of it.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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