National Weather Service Weather Forecast Office

Overview
Developing broad low pressure primarily in the south central Gulf of Mexico beginning around November 8th will move slowly through the central Gulf through November 11th or so (image at bottom of page). The system, which could include the remains or redevelopment of Ida, will combine with high pressure across the eastern half of the U.S. to produce increasing long period swell over at least the central and western Gulf, which will eventually build higher tides along the Texas Gulf coast and result in some overwash of the dune line, minor to moderate beach erosion, and a prolonged threat for dangerous rip currents. Seas will build to dangerous levels for small craft, and the potential for gale-force sustained winds or gusts across the Gulf between the 9th and 11th could build seas well in excess of 12 feet. Boaters and beachgoers are in for several days of tough conditions, which could become life threatening for ill equipped small craft.

Through November 9th
An area of low pressure, not related to the remains of Ida, will drift northward about 100 miles or so east of the Texas Coast on the 8th and 9th. Building northeasterly swell will bring sea heights above 10 feet offshore, perhaps to 12 feet or more by early Sunday. At times of high tides Saturday night and Sunday, departures from predicted values could reach 1 foot above mean lower low water (MLLW) which, given the high astronomical tides this time of year, bring values to or just above 3 feet above MLLW. Such levels typically result in overwash up to the dune line on South Padre Island, putting vehicles at risk. While the higher tides will reduce the width of the beach around high tide, structures should remain flood free. While surfing waves will grow, rip current danger will increase to a high risk. Inexperienced swimmers should stay out of the water beginning on the 8th.

In addition to the tides and swell, weather conditions will go downhill. In the open Gulf, periods of rain will develop Saturday night, and could become heavy at times on Sunday. Along the beach, periods of light rain and occasionally gusty winds will render Sunday a better indoor day than not. Some of the rain will reach toward the Highway 77 corridor, but not enough to be welcome relief from the recent dry spell.

November 10th-11th (and Beyond?)
A broader cyclone, including the future offspring of Ida, will set up camp in the central Gulf and move or meander slowly northward and/or eastward through at least the 11th. A reinforcing surge of high pressure will slide into the Ohio Valley during the period, and the difference between the developing cyclone and the high pressure ridge will increase winds to or above gale force in portions of the central and northern Gulf, possibly extending to the Texas coast. These increased winds over a larger area and for a longer time are certain to churn the Gulf into dangerous seas and waves for small and larger craft alike. Seas above 15 feet, and perhaps 20 feet or higher, along with swell periods that could rise above 12 seconds, will radiate above normal tides for many shorelines.

Along the Lower Texas coast, the swell direction and exact wind direction will play a critical role in how much above predicted levels the actual tides will get. No matter what the direction, it is likely that overwash to the dune line and perhaps a bit farther will continue at times of high tide, as tide departures should remain, at a minimum, of 1 to 1.5 feet. Trouble could begin, however, if the wind direction remains just east of north with a swell persisting from the northeast (vs. from the north). Such a swell would radiate water toward our beaches rather than parallel to them, and build tide departures to 2 feet above predicted or more. Such departures would push MLLW values well above 3 feet, increasing the threat for more notable coastal flooding, along with the potential for severe beach erosion, somewhere between the impacts of Hurricanes Gustav and Ike in 2008. A parallel flow, more likely with a swell from the north, would reduce the amount of beach erosion. In all cases, dangerous rip currents will continue.