1970 Atlantic hurricane season

Seven named storms in 1970, fourteen today

The National Hurricane Center's 1971 review listed only seven named storms, three of them hurricanes, against a two-decade average of about nine storms a year. It called 1970 a lean Atlantic year beside a bumper crop in the eastern Pacific. The forecasters traced the quiet to the middle of the season, when the mid-level ridge sat farther south than normal and no broad belt of deep easterlies formed over the tropics. Disturbances leaving Africa tended to drift south toward the equatorial trough instead of growing.

The current best track looks different. A 2022 reanalysis added or upgraded several systems that the original advisories never named, including an August storm off North Carolina that it now rates a hurricane. The site counts 14 tropical storms, 7 hurricanes and 2 major hurricanes from one-minute winds during the tropical stage, which matches the current best-track tally. Accumulated cyclone energy comes to 66.6 in the site's calculation. Twenty-one tracked systems give the map its first tropical-stage point on 17 May and its last on 1 December.

The season also changed how aircraft flew. For the first time, Air Force and Navy reconnaissance planes flew standard profiles across all four quadrants of each tropical storm and transmitted temperature, pressure and wind along the way. Forecasters also watched time-lapse loops of ATS satellite pictures in real time, first with the depression that became Becky. Average 24-hour track errors fell to 76 nautical miles, against 135 in 1969, though the review credited slow, straight tracks for part of that gain.

Alma in May and Becky in July

Hurricane Alma formed in the southwest Caribbean on 17 May and deepened fast on the night of 19 May. A Navy flight on 20 May found 993 mb, and the site marks its hurricane status at 18:00 UTC that day with a 65 kt peak. The MWR called it only the third May hurricane on record. Westerly shear tore it down within a day. Rain ahead of the center caused flash floods in central and eastern Cuba that killed seven people, and the leftover depression later crossed western Cuba and Florida's upper west coast with only about 30 kt winds, even as Tampa radar showed an apparent eye.

No storm formed in June. Tropical Storm Becky grew in July from a rain mass that surged north from near Panama, and reached 55 kt over the eastern Gulf. Radar hinted at an eye and prompted hurricane warnings for the Florida Panhandle, but the eye never held. Becky came ashore near Port St. Joe on 22 July after weakening, and over 8 inches of rain flooded the Tallahassee area, where the Red Cross counted 104 families with losses. A tornado destroyed a house near Panacea. Becky caused one death and about $500,000 in damage in 1970 dollars.

Hurricane Celia and the Corpus Christi wind bursts

Celia came from a tropical wave that crossed the Atlantic in five days, slowed in the Caribbean and closed off a circulation near the Cayman Islands on 30 July. It crossed the western tip of Cuba as a tropical storm, where flash floods and a downed power line killed five people. In the Gulf, a moisture band feeding in through the Yucatan Channel drove a pressure drop from 990 to 965 mb in under eight hours on 1 August. The storm then weakened for a day before a second band from the Bay of Campeche fed a new burst of deepening on 3 August.

The reanalysis places landfall near Port Aransas at 21:00 UTC on 3 August with 120 kt winds and a 944 mb pressure, taken from a checked barometer in Ingleside across Corpus Christi Bay. That makes landfall the same moment as the site's peak, and it raised Celia from Category 3 to Category 4 at the coast. Aransas Pass measured 113 kt sustained winds before its anemometer blew away.

Celia's damage did not follow the usual pattern. The worst of it came in the left semicircle and behind the eye, where short bursts lasting seconds hit two to three times the sustained wind. The Corpus Christi weather office logged sustained winds of 70 to 80 mph before a gust reached 161 mph, and hangars at the airport and a nearby mobile home park were wrecked in streaks of damage across the city. Storm surge peaked at 9.2 feet at Port Aransas Beach but caused only a small share of the losses.

The NHC review counted 16 deaths from Celia, including the five in Cuba and five around Corpus Christi, and put Texas property losses at $444.9 million plus $8.8 million in crops, in 1970 dollars, a Texas record at the time. Later totals give 28 deaths across the storm's path, including eight drownings in rough surf off Florida. The name Celia was retired.

Martinique floods and a Gulf that stayed busy

A small storm that the original advisories never named crossed the Outer Banks on 17 August. The reanalysis gives it landfalls at Atlantic Beach at 50 kt and at Rodanthe at 55 kt, then a brief spell at hurricane strength on 18 August as it raced toward Newfoundland. About 20 boats capsized along the North Carolina coast, and four people drowned, two in North Carolina and two in Virginia.

Tropical Storm Dorothy followed a straight west-northwest path from Africa and peaked near 60 kt as it reached the French West Indies on 20 August. Its center crossed Martinique, where floods and landslides left 50 people dead or missing by the NHC's count, with one more death on Dominica. The storm destroyed 186 homes on Martinique.

Hurricane Ella formed near Swan Island on 8 September, crossed the northeast tip of the Yucatan Peninsula and strengthened as it curved west across the Gulf. The reanalysis puts its landfall north of La Pesca, Mexico, at 10:00 UTC on 12 September at 110 kt and 962 mb, which the site also records as its peak. A gust of 130 kt was reported at La Pesca, rivers rose above flood stage, and one person died in Abasolo, Tamaulipas.

Two weaker storms followed Ella into the Gulf. Tropical Storm Felice formed north of Nassau, drifted past Key West and came ashore at High Island, Texas, with about 6 inches of rain and no reported casualties. Tropical Storm Greta threatened South Florida as it formed near the Bahamas on 26 September, then fell apart before crossing Key West and ended near Tampico, Mexico, on 4 October.

Puerto Rico's record rain and October's hybrid storms

The costliest system after Celia never received a name. It formed east of the Lesser Antilles on 30 September, weakened in the Caribbean, crossed the Dominican Republic as a depression and later became a hurricane between the Azores and Madeira. Before that, it poured rain on Puerto Rico: Jayuya measured 41.68 inches, at least 18 people died on the island, three died on Barbados and one in the U.S. Virgin Islands.

NHC forecasters in 1970 wrestled with storms that were neither fully tropical nor cold lows, which Simpson called neutercanes. One formed north of Puerto Rico in mid-October and passed just northwest of Bermuda on 16 October, where the naval air station read 984.4 mb and a NASA anemometer recorded 87 kt. They left it out of the 1970 storm list. The best track now counts it as a hurricane that peaked at 85 kt, and it caused damage on Newfoundland's Burin Peninsula.

A tiny storm near the Azores in late October, which the ship Pretoria measured at 65 kt and 994 mb on 27 October near Flores, now also counts as a hurricane. The last storm of the year began as an extratropical low near Bermuda in late November and held tropical status only on 30 November and 1 December, which is why the season's final tropical-stage point falls in December.