As if hot and humid weren’t enough (I saw a woman collapse from heat exhaustion during intermission at Circus Flora today), downtown’s been drenched with thunderstorms for the last hour or so — and apparently there’s a tornado warning in effect through the early evening. Solveig Slettahjall’s scheduled to take the stage at the Cistern at 9 p.m., and Spoleto’s press office says they’ll wait to make a decision on moving the show to a rain location — possibly Recital Hall at the Simons Center next door — until the last possible minute. In the meantime, Piccolo’s Reggae Block Party behind the U.S. Custom House is set to go at 7 p.m., and the City Office of Cultural affairs says there’s no rain location for that big beast of a production; they’ll stick a finger into their air at 7 p.m. sharp — and if it comes down dry, the show goes on.