what if Magneto just rips the earth up from under her pressure cooker err dome, and just bfrs her and the dome, out of the earth's atmosphere?
as 2damnloud's long tract on solar wind (how appropriate π) states, the Earth's got a form of magnetic shielding that prevents much of the solar radiation getting through, why couldn't Magneto place a similar shield/bubble around Storm and thus prevent her from accessing any of the solar radiation business... she'd basically be neutralised.
the most simple way for this match to go would be that Storm suffers an aneurysm whilst struggling to get past Magneto's shield with ever more elaborate gusts of wind π
that's with minimal effort on Magneto's part.
with some intent and "bloodlust", Magneto could simple bend the Earth's magnetic fields just enough to let the solar radiations irradiate Storm, frying her on the spot.
or maybe wrap her in copper and other conductive metals whilst she summons lightning ... causing the lightning to strike her and fry her.