National Weather Service United States Department of Commerce

Cold and Snow Pushing into South-Central U.S.; Fire Weather Concerns Persist in Northern California

An Arctic front will bring a wide swath of much below normal temperatures, snow, and chilly wind chills from the Rockies to the Mississippi Valley. Another cold front will bring more snow from the Great Lakes and Ohio Valley to the Northeast. Cold Arctic air in the Great Basin will continue to produce gusty winds and Critical Fire Weather threats to northern California. Read More >

 

WHAT IS FLASH FLOODING?

Flooding that begins within 6 hours, and often within 3 hours, of the heavy rainfall (or other cause).

Flash Floods can be caused by a number of things, but is most often due to extremely heavy rainfall from thunderstorms. Flash Floods can occur due to Dam or Levee Breaks, and/or Mudslides (Debris Flow).

The intensity of the rainfall, the location and distribution of the rainfall, the land use and topography, vegetation types and growth/density, soil type, and soil water-content all determine just how quickly the Flash Flooding may occur, and influence where it may occur.

Urban Areas are also prone to flooding in short time-spans and, sometimes, rainfall (from the same storm) over an urban area will cause flooding faster and more-severe than in the suburbs or countryside. The impervious surfaces in the urban areas do not allow water to infiltrate the ground, and the water runs off to the low spots very quickly.

Flash Flooding occurs so quickly that people are caught off-guard. Their situation may become dangerous if they encounter high, fast-moving water while traveling. If people are at their homes or businesses, the water may rise quickly and trap them, or cause damage to the property without them having a chance to protect the property.

 

WHERE DOES FLASH FLOODING STRIKE?

Flash Flooding is possible everywhere. The normally tranquil streams and creeks in your neighborhood or area can become raging torrents if heavy rain falls overhead -- or even upstream of your location! Flash Flooding can also occur on city streets and highway underpasses.

 T.A.D.D