National Weather Service United States Department of Commerce

Flood Threat For Several Locations Today

The active monsoon season will continue the rest of the week and the flood threat today stretches from the Arizona to portions of the Intermountain West. Meanwhile, a humid and moist air mass ahead of a cold front may result in heavy rain and flooding from the Mid-Atlantic to the eastern Ohio and Tennessee Valleys. Finally, slow moving storms may produce flooding for the central Gulf Coast states. Read More >

Automatically generated image showing areas of energy helicity index.

 

Thumbnail of an automatically generated image showing areas of energy helicity index. Thumbnail of an automatically generated image showing areas of energy helicity index. Thumbnail of an 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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