Tropical Storm Vance is forecast to drop 2 to 4 inches, with isolated totals above 5 inches, on Sinaloa before it falls apart

The National Hurricane Center’s Public Advisory 33 on Tropical Storm Vance, issued at 8 a.m. MST on Thursday, October 29, 2026 (1500 UTC), forecasts 2 to 4 inches of rain across central and southern Sinaloa, far southwestern Durango and far northwestern Nayarit through that night. Isolated totals above 5 inches are possible in central and southern Sinaloa. Forecasters expect the storm to weaken to a post-tropical remnant low later the same day and to dissipate soon after.

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At the time of the advisory, Vance had maximum sustained winds of 40 mph and a minimum central pressure of 1004 millibars. Its center was near 21.6 north, 108.8 west, about 215 miles west-northwest of Cabo Corrientes and 115 miles southeast of the southern tip of Baja California, moving north at 8 mph. The center had no coastal watches or warnings in effect.

Advisory 33: the rain forecast for Sinaloa

The text of Public Advisory 33 says the rain could cause flooding and mudslides, especially on steep terrain. It adds that moisture from Vance will bring heavy rain to parts of the U.S. Southern Plains and New Mexico through Friday. Those rainfall numbers are forecast totals, not measurements, and they cover the period through Thursday night.

The figures were trimmed from the previous overnight package. Advisory 31, issued at 8 p.m. MST on October 28, still listed Vance as a tropical depression with 35 mph winds and carried isolated totals of up to 7 inches in central and southern Sinaloa. By advisory 33 the storm had been named, its winds had risen to 40 mph, and the isolated ceiling had dropped to above 5 inches. The 2 to 4 inch range itself did not change between the two advisories.

The path from tropical storm to remnant low

The center’s feed for the East Pacific advisories shows the forecast timing tightening. Advisory 33 calls for weakening and a post-tropical remnant low later on October 29, and the accompanying discussion moves that transition up to about 12 hours out, with dissipation expected in roughly 18 to 24 hours over the southern Gulf of California. The forecast table shows a remnant low with 25-knot winds by 0000 UTC on October 30 and dissipation by 1200 UTC the same day.

The reasoning appears in the forecaster’s discussion 31 from the previous evening: Vance is steered by a broad trough over the eastern Pacific, is expected to turn back northward once its thunderstorms fade, and should dissipate shortly after becoming a remnant low as it interacts with the mountainous terrain of western Mexico. That discussion also notes that periods of heavy rain over western Mexico were expected for much of the week.

Comparing the two advisories shows how the forecast moved. In advisory 31, the depression was heading north-northeast at 13 mph with 35 mph winds and a central pressure of 1002 millibars, and its forecast table had it dissipating by 0000 UTC on October 31. Advisory 33 has the storm heading north at only 8 mph, with 40 mph winds and a pressure of 1004 millibars, and the table now ends 12 hours sooner, with dissipation by 1200 UTC on October 30. The discussion from the previous evening had already described the track as slightly east of the earlier forecast, partly because of a revised initial position.

A post-tropical remnant low is the National Hurricane Center’s term for a system that has lost its tropical characteristics, which is why the advisory language shifts from storm intensity to rainfall and flooding. For Sinaloa, the change in label does not remove the rain already forecast through Thursday night. For the Southern Plains and New Mexico, the advisory expects the remaining moisture to turn up as heavy rain through Friday.

Flooding risk with no warnings posted

No coastal watches or warnings were in effect, and the advisory asks interests along west-central and northwestern Mexico and the southern Baja California Peninsula to monitor the storm. A tropical storm that is expected to die within a day does not trigger the watch-and-warning machinery, yet the rain forecast is aimed at the same steep terrain where the advisory flags mudslide risk. Advisory 31 also mentioned swells reaching the coasts of southwestern and west-central Mexico and the southern Baja California Peninsula, with life-threatening surf and rip currents.

One more system shares the page. The center’s East Pacific tropical weather outlook, issued at 5 a.m. PDT on October 29, gives a separate disturbance well southeast of Hawaii a near-zero chance of forming within 48 hours and a 30 percent chance within seven days. It is unrelated to Vance, whose own fate was due to be updated at 2 p.m. MST, when the next complete advisory was scheduled.

The question left open by advisory 33 is how much rain actually falls. The forecast of 2 to 4 inches, with isolated totals above 5, is a prediction from the National Hurricane Center, and the observed totals for Sinaloa will come from Mexican gauges after the remnant low has gone.

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

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