Rainfall spikes, or over reporting.
Rainfall spikes, or over reporting is generally caused by pole vibration.
Pole vibration can occur when it is very windy, or a bird lands on the weather station.
Hail can also cause the rain gauge mechanism to vibrate.
Make certain the pole is not vibrating during windy conditions, causing false readings.
If you were working on the weather station, the vibration may also result in rainfall spikes.
Debris and snow melt can also cause a delayed reporting of rain.