GEFS Ensemble Trend Analysis
Regionwide ensemble spread for the selected parameter
These products rely on projects, data, and operations supported by NSF and NOAA and would not exist without those resources.
Official severe weather and fire weather forecasts are provided by NOAA/NWS Storm Prediction Center and local National Weather Service offices.

How to interpret the week 1 plots

Time series of the maximum regionwide values for each 6-hour period.

Typically, a value of 1 or greater suggests a conditionally favorable environment for hail (SHIP), tornadoes (STP), and supercells (SCP).

Values above 5 represent extreme environments with a relatively high level of conditional concern.

The grey lines extending into the yellow (favorable) or red (very high) parts of the graph represent a non-zero chance of that environment being realized.

Of particular concern is when the mean or interquartile range (grey fill) is entirely within the yellow (favorable) or red (very high) categories.
This suggests that many (or all) of the ensemble members are realizing environments supportive of significant severe weather for that time period.

How to interpret the week 2, 3 and 4 plots