A rain-wrapped tornado is a tornado partly or completely obscured from view by heavy precipitation, most commonly on the back side of a high-precipitation supercell where rain and hail cycle around the mesocyclone. The tornado is real; the precipitation simply blocks it from the human eye.
Why it happens
In HP supercells, moisture-laden inflow feeds a strong updraft, and precipitation from that updraft is transported around the back and southern sides of the mesocyclone by the storm's rotation. As the tornado develops within or near the mesocyclone, precipitation wraps around and encases the circulation.
This is very different from a classic supercell where the tornado sits in the storm's rain-free base south or east of the precipitation core and is visible from miles away. In an HP storm, the rain-free base can be small or absent, and the tornado forms in a region that is already precipitating.
How forecasters and spotters interpret it
Radar takes on primary responsibility when visibility fails. A tight velocity couplet, a tornado vortex signature, or a dual-pol tornadic debris signature within the wrapped area provides confirmation that the eye cannot. NWS documentation from HP supercell case studies stresses that visual confirmation may lag radar in these storms by many minutes.
For chasers and spotters, the safe position for HP storms is south to southeast of the meso, well outside the precipitation cascade, with a clear escape road east and south. The classic notch-viewing distance used on LP and classic supercells is often unusable because the notch is filled with rain.
Where positioning misleads
Attempts to punch the precipitation core to reach the meso are how chasers get hit by tornadoes they never saw. The visual reference used to gauge distance is gone inside the rain, and the tornado's cyclic behavior can bring the vortex through the same corridor multiple times.
Public messaging around a rain-wrapped tornado must be blunt. If you are in the threatened region of an HP supercell, have a plan to take shelter if a warned storm approaches you, even if you look outside and only see rain. The tornado can be inside that rain.