National Weather Service United States Department of Commerce

Dangerous, Heat Wave Persists in the Eastern U.S.; Severe Weather Expected in the Central Plains and Mid-Atlantic

A prolonged, dangerous heat wave will persist through the Independence Day weekend across the Ohio Valley, Mid-South, and East Coast. Severe thunderstorms are expected to produce damaging wind gusts from the Upper Ohio Valley into the Mid Atlantic, and across the central Great Plains this afternoon and evening. Large hail and heavy rain is also possible across the Great Plains. Read More >

Other Domains: Baxter S.P. | Marine/Coast | Northern/Eastern Maine

Wet Bulb Globe Temperature (WBGT) is a measure of the heat stress in direct sunlight, which takes into account: temperature, humidity, wind speed, sun angle and cloud cover (solar radiation). This differs from the heat index, which takes into consideration temperature and humidity and is calculated for shady areas. For more background info on WBGT, click here.

 

 

 
 

 

 
  • 101% means summit in and out of clouds
  • 102% means summit obscured
 

 

 

 

 
Lightning Threat represents thunderstorm coverage at any one time in the forecast period.
 

 

 
 
Lightning Legend         Lightning Safety Tips
 
Risk Level
Definition
None
No lightning risk
Limited
Thunderstorms expected to be isolated in coverage. 
Atmospheric conditions support cloud to ground lightning strikes in and near thunderstorms.
Be aware for thunderstorms in your area.
Elevated
Thunderstorms expected to be scattered in coverage.
  Atmospheric conditions support cloud to ground lightning strikes in and near thunderstorms.
Be prepared to take immediate shelter from thunderstorms and lightning.
Significant
Numerous thunderstorms are expected.
  Atmospheric conditions support cloud to ground lightning strikes in and near thunderstorms.
Plan to take immediate shelter from thunderstorms and lightning.
Extreme
Widespread thunderstorms are expected.
  Atmospheric conditions support cloud to ground lightning strikes in and near thunderstorms.
Plan to take immediate shelter from thunderstorms and lightning.