In terrible conditions for race one, Welsh splashed around in a safe sixth place, taking 10 points and outscoring his title rival Colin Martin, who failed to finish the opening encounter.
At the front, Chris Camps won in dominant fashion on thesportsinjuryclinic.org sponsored Kawasaki, his first win since the opening race of the season at Brands Hatch.
23 seconds later a thrilling battle for the other podium positions ended with Alan Watson second and James Caswell-Cox third, just four thousandths of a second between them at the flag. Caswell-Cox was also the winner of the Sub 64bhp class.
In race two Welsh took his first win of the weekend with Camps second and Francesco Cavalli, who impressed at Pembrey earlier in the year, third. Martin, on his David Simon Tuning Kawasaki, came through the field to finish fourth. Reigning Yamaha Past Masters champion Graham Higlett finished sixth and was the leading Sub 64bhp rider.
On Sunday, Welsh took his second win the first race, edging out Camps at the line by just five hundredths of a second, after a four-way dice for the lead. Cavalli again finished third, just a second behind the leader, with Martin again fourth. Gary Smith was lead Sub 64bhp rider in seventh.
The final race saw Camps take his second win of the weekend, with Martin second and Daniel Ruth third and leading Sub 64bhp runner in a spread out field.
Welsh struggled to a 17th placed finish and outside of the points, but his haul of 60 for the weekend to Martin’s 46 meant he extended his championship lead to 20 points.