Blizzard Conditions Are Forecast Across Parts of the Northern Plains and Upper Great Lakes

In the north-central U.S., a strong storm will continue to bring heavy snow and gusty to high winds over parts of the northern Plains and Upper Midwest tonight before moving across the Great Lakes with heavy lake effect snow Wednesday into Thanksgiving Day. Read More >

Automatically generated image showing areas of energy helicity index.


Hour - 1	Hour - 2	Hour -3

4 Panel Display | Animated Loop

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.

Back to Convective Parameters Home

FWD RSS Feed

Blizzard Conditions Are Forecast Across Parts of the Northern Plains and Upper Great Lakes

Convective Parameters - EHI