Tracking Storms with Impacts in the Eastern and Northwest U.S. into Friday

A storm will track north of the Great Lakes Friday with widespread rain showers across the Eastern U.S. along and ahead of its cold front. Further south along the front isolated severe thunderstorms are possible. A Pacific storm will continue moving across the Northwest U.S. into Friday with additional low elevation rain, gusty winds, and mountain snow. 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 Storms with Impacts in the Eastern and Northwest U.S. into Friday

Convective Parameters - EHI