Detection of Weyl fermions and the metal to Weyl-semimetal phase transition in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow><mml:mi>WTe</mml:mi></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:math> via broadband high resolution NMR

Weyl fermions (WFs) in the type-II semimetal (WSM) ${\mathrm{WTe}}_{2}$ are difficult to resolve experimentally because bands disperse an extremely narrow region of ($E\text{\ensuremath{-}}k$) space. Here, by using DFT-assisted high-resolution $^{125}\mathrm{Te}$ solid-state nuclear magnetic resonance (ssNMR) temperature range 50--700 K, we succeeded detecting low energy WF excitations and monitoring their evolution with temperature. Remarkably, WFs observed emerge at $T\ensuremath{\sim}120$ while lower temperatures behaves as a trivial metal. This intriguing phenomenon is induced rapid raise Fermi level upon heating, which crosses only for $T&gt;120$ K. The abrupt change NMR parameters this signature topological Lifshitz transition instead cursive energy-bands crossing.