Tracking a Couple of Storm Systems Across the Country

Showers, along with a few strong to severe thunderstorms, are expected from the Great Lakes, New England and southward into the Ohio and Tennessee Valleys. In the wake of this system, a stronger storm is expected to track from the Pacific Northwest, Plains and through the Eastern U.S. this weekend. Strong winds, showers and a larger drop in temperatures are expected this weekend into Monday. Read More >

Automatically generated image showing areas of energy helicity index.


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EHI

The Energy Helicity Index (EHI) is a number which represents the combination of instability and storm relative helicity. Our calculation uses mixed layer CAPE (surface to 3000ft average parcel) and 0-3 km storm relative helicity. Values greater than 2 or 3 have been correlated to cyclonic supercells with increased tornadic potential. Negative values are indicative of an environment favorable for anti-cyclonic (left moving) supercells, but tornadoes associated with anti-cyclonic supercells are extremely rare.

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Tracking a Couple of Storm Systems Across the Country

Convective Parameters - EHI