National Weather Service United States Department of Commerce

Watching Hurricane Erin; Heavy Rainfall Threat for Upper Midwest; Heatrisk for Mississippi Valley

Hurricane Erin continues to track westward with its outer bands bringing heavy rainfall and gusty winds for Puerto Rico and US Virgin Islands. Life-threatening surf and rip currents are occurring and will spread across the Atlantic coasts this week. Meanwhile, heavy rainfall and possible flooding are in the forecast for upper Midwest through Monday. Heatrisk continues for the Mississippi Valley. Read More >

 
 
 
 

The National Weather Service uses the following definitions when describing winter weather:

An advance statement that severe winter weather conditions are possible within the next day or two.

An urgent statement that severe winter weather conditions have begun or will begin within about 12 hours.

 Advisory

A statement that winter weather conditions are imminent or occurring. These conditions will cause significant inconvenience, and may become hazardous or life-threatening if safety tips are not followed.

 Heavy Snow

Snowfall which accumulates to a depth of at least 4 inches in 12 hours or 6 inches in 24 hours.

 Sleet

Pellets of ice composed of frozen or mostly frozen raindrops, or snowflakes which have melted and refrozen.

 Freezing Rain/Freezing Drizzle

Rain or drizzle which falls as liquid then freezes when it strikes the ground or other surface.

 Frost

The formation of thin ice crystals on the ground or other surfaces.

 Wind Chill

A cooling effect caused when wind blows across exposed skin.