Storm Surge/Tide — Coastal Kenedy County, Texas

2020-10-10 · Coastal Kenedy County, Texas

Event narrative

Continued high seas and swells propagating to the west from the long-departed Hurricane Delta (which made landfall at around 6 PM CDT on October 9th) produced another, though lesser, round of tidal run/up and overwash that may have produced a bit more beach erosion following the larger impacts a day earlier. Seas at NOAA Buoy 42002, 200 miles east of South Padre Island, were still between 8 and 10 feet with swell continuing at 10 to 11 seconds.

A tide gage at Rincon Del San Jose reached 1.92 feet above Mean Sea Level (MSL) around 7:18 PM CST on October 10th. Water levels peaked at 2.01 ft above MSL around 7:00 PM CST on October 11th. Levels then fell slightly to around 1.9 ft above MSL through 11:12 PM CST, after which water levels gradually fell through the end of the event.

Though the gage rose and peaked during the *evening* of October 10th, it's tides were inside Laguna Madre and were likely not representative of actual impacts on the beach, as wave heights fell below 4 feet and swell dropped below 7 seconds by the afternoon of October 10th at Buoy 42002.

Wider weather episode

As Hurricane Delta moved northward across the Gulf of Mexico in early October, outgoing swell propagated into the lower Texas coastal waters on October 8th through the 10th. This swell was powerful enough to push water into the dunes across South Padre Island around high tide, which occurred at 12:11 AM CDT on the 8th, 1:15 AM CDT on the 9th, and 2:08 AM CDT on the 10th. The most significant erosion and overwash occurred during the pre-dawn hours of October 9th, as Delta passed directly over a NOAA buoy around 200 miles east of South Padre Island at around 1150 PM on October 8th. However, the highest *tide* level that was reported was 2.38 feet above Mean Higher-High Water (MHHW; or the level above normally dry ground at the shoreline) a day later at 3:42 AM CDT on the 10th. Levels remained above 1.25 feet MHHW for several hours surrounding the occurrence of high tide on the evenings of October 7th through the 10th. This activity was enough to cause some coastal erosion, with the more significant flooding and erosion occurring on the 9th, with additional run-up and lighter erosion on the 10th.

Farther up the coast, similar wave action and minor coastal flooding was likely - but there were no comparative measurements based on MHHW.

Source: NOAA Storm Events Database, event_id 925001. Narrative written by the NWS forecast office that issued the report.