Nate (2017)

A small tropical depression formed about 35 nautical miles south of San Andrés Island on 4 October 2017 and became Tropical Storm Nate on 5 October. Nate moved northwest, crossed northeastern Nicaragua and eastern Honduras as a tropical storm (5–6 October), emerged over the northwestern Caribbean and strengthened while moving through the Yucatan Channel. The system accelerated across the Gulf of Mexico, became a hurricane early on 7 October, moved north-northwest at high forward speed, made landfall on the northern Gulf Coast, then tracked rapidly inland through the southeastern United States and weakened to an extratropical low by 9–10 October before dissipating near Newfoundland on 11 October.

Nate made its first U.S. landfall at the mouth of the Mississippi River near 0000 UTC on 8 October with maximum winds near 75 kt (about 85 mph). It made a second U.S. landfall near Biloxi, Mississippi at 0520 UTC on 8 October with maximum winds of 65 kt (about 75 mph). Earlier, Nate produced a landfall on the coast of northeastern Nicaragua near 1200 UTC on 5 October while at tropical storm strength.

The storm’s peak intensity was estimated at 80 kt (about 92 mph) with a minimum central pressure near 981 mb, making it a Category 1 hurricane at its strongest on 7 October. Aircraft measurements supporting the peak included flight-level winds of 89 kt and surface estimates near 79 kt from the SFMR instrument.

Storm surge produced substantial coastal flooding along the northern Gulf Coast. Near Biloxi and Ocean Springs, Mississippi, surveyed high-water marks and water levels indicate inundation around 9 ft above ground in spots; tide gauges measured 6.20 ft above Mean Higher High Water at Pascagoula and about 6 ft MHHW at several nearby sites. Mobile Bay, Alabama, saw 4–7 ft above ground in places, with the highest tide gauge reading 5.9 ft MHHW at Bayou La Batre. Along the Florida Panhandle, inundation of 2–4 ft occurred (Pensacola tide gauge 3.1 ft MHHW). Rainfall totals were heavy in Central America—Costa Rica reported up to 19.19 in at Marítima—with widespread 4–7 in amounts there; in the United States, typical totals along the central Gulf Coast to the southern Appalachians were 3–7 in, with a U.S. maximum near 9.93 in at Gulf Breeze, Florida.

The storm caused severe impacts in Central America from heavy rains, flooding, and mudslides. Media reports attribute 44 deaths across the region (16 in Nicaragua, 13 in Costa Rica, 6 in Panama, 5 in Guatemala, 3 in Honduras, and 1 in El Salvador) plus one additional death from a shipwreck in Panama, for a total of 45 direct deaths; 9 people were reported missing. In the United States there were no direct deaths attributed to Nate, but two fatalities were reported as indirectly related (traffic accidents). Damage estimates in Central America were substantial (Costa Rica reported about $562 million), and the U.S. National Centers for Environmental Information reported about $225 million in U.S. damage from wind, surge, flooding, and tornadoes.

Noteworthy aspects include Nate’s very fast forward speed (up to about 25 kt) while crossing the Gulf—making it the fastest-moving tropical cyclone of record in the Gulf—which produced a highly asymmetric wind and surge pattern and likely limited the area of hurricane-force winds. Forecasts struggled with the storm’s formation timing and with its rapid forward motion and intensity changes; NHC track errors were smaller than five‑year means through 36 hours but larger at longer lead times, and intensity forecasts tended to underestimate both the strengthening over the Gulf and the subsequent rapid weakening after landfall.