  The HAWC Gamma Ray observatory consists of 300 water Cherenkov detectors
(WCD) instrumented with four photo multipliers tubes (PMT) per WCD. HAWC is
located between two of the highest mountains in Mexico. The high altitude (4100
m asl), the relatively short distance to the Gulf of Mexico (~100 km), the
large detecting area (22 000 m$^2$) and its high sensitivity, make HAWC a good
instrument to explore the acceleration of particles due to the electric fields
existing inside storm clouds. In particular, the scaler system of HAWC records
the output of each one of the 1200 PMTs as well as the 2, 3, and 4-fold
multiplicities (logic AND in a time window of 30 ns) of each WCD with a
sampling rate of 40 Hz. Using the scaler data, we have identified 20
enhancements of the observed rate during periods when storm clouds were over
HAWC but without cloud-earth discharges. These enhancements can be produced by
electrons with energy of tens of MeV, accelerated by the electric fields of
tens of kV/m measured at the site during the storm periods. In this work, we
present the recorded data, the method of analysis and our preliminary
conclusions on the electron acceleration by the electric fields inside the
clouds.
