Double conditioning of reactive scalar transport equations on mixture fraction and sensible enthalpy is presented as a promising extension to conventional conditional moment closure (CMC) methods. Simple first order, singly conditioned CMC cannot accurately predict combustion phenomena such as partially premixed flames and flames with local extinction and reignition. CMC is applied to turbulent flames with significant temperature fluctuations that bring to light the deficiencies of the conventional CMC approach. Fluctuations of temperature and species around their conditional means cannot be neglected when these quantities are conditioned on mixture fraction only. Comparison with direct numerical simulation (DNS) results demonstrates, however, the great potential for doubly conditioned CMC. Doubly conditioned CMC gives excellent agreement with DNS at all times and it captures phenomena like local extinction and the onset of reignition accurately.

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