Vaughan's form puts Kent on the back foot; County review.
On another day of rain delays and wash-outs, Vaughan made 71 at the top of the order to set Yorkshire on the way to a first-innings lead over the hosts, who made just 142 all out.
Yorkshire, with 68 from Lehmann, were 208 for four by the close of a stop-start second day.
Kent pace bowler Martin Saggers (three for 57) at least had something to smile about, having taken the first three wickets.
Northamptonshire had reached 119 for four when rain forced an early close at Chelmsford as they sought to push for a first-innings lead over Essex, who managed 206 all out.
The hosts' innings subsided as they added only 52 for their last four wickets. Former Essex pace bowler Darren Cousins did most of the damage, with figures of four for 62.
Glamorgan made up for a first-day wash-out at Cardiff by reaching 330 for seven against Somerset - with Michael Powell and the in-form Adrian Dale both hitting 64 and Adrian Shaw chipping in with an unbeaten 62.
Somerset new boys Keith Dutch and Richard Johnson - both formerly of Middlesex - were in the wickets, off-spinner Dutch finishing with two and paceman Johnson three.
But there was still no joy for Lancashire and Surrey, who again failed to get on the pitch and have yet to bowl a ball in their match at Old Trafford because of rain.
In Division Two Middlesex seamer Simon Cook gave the Londoners the edge when play finally got under way after another first-day wash-out against Derbyshire at the Racecourse Ground. Cook finished day two with three for 53 to his name while Phil Tufnell and Tim Bloomfield bagged two wickets each as the home side mustered 171 for seven.
Durham's Paul Collingwood was the day's top-scorer with 95 out of his team's 284 all out against Nottinghamshire at Trent Bridge, where the northerners progressed from 148 for five at start of play.
Fomer Northants seamer Richard Logan had the best day among the home pace attack, finishing with four for 69, while all-rounder Paul Franks took three wickets.
Notts' reply was worth 38 for one by stumps after opener Guy Welton had gone caught behind for a duck off Neil Killeen.
Pakistan have named Australian Daryl Foster as bowling coach of the national team for next month's tour to England.
'Foster will join the team in England and his initial contract is for two tests but is extendable up to the one-day series,' Pakistan Cricket Board director Munawwar Rana said.
Pakistan leave for England on May 2 with the first of the two Tests starting at Lord's on May 17. The tri-nation one-day series, which also involves Australia, will begin on June 7. The final tour party is expected to be named today, when the overall coach will be confirmed.
Foster is with the University of Western Australia in Perth which this week cleared Shoaib Akhtar's bowling action.
The PCB said a 'final report' from the University of West Australia showed that the bowler was not guilty of throwing.
Akhtar has twice been cited over his action, by Australian Darrell Hair and Peter Willey in Perth in the third Test against Australia in December 1999.