Extreme Heat Lingers; Severe Thunderstorms for Portions of the Plains and Southeast; Heavy Rainfall Threats

Gusty winds and heavy rainfall may impact the Big Island of Hawaii as a nearby tropical system passes west of the islands. From the Southwest U.S., Rockies and across the Gulf Coast, heavy rainfall could lead to isolated flash flooding. Severe thunderstorms are expected for areas of the Plains, Gulf Coast and Southeast through Tuesday. Extreme heat lingers for the southern Plains and Southwest. 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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Extreme Heat Lingers; Severe Thunderstorms for Portions of the Plains and Southeast; Heavy Rainfall Threats

Convective Parameters - EHI