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Floods & Flash Floods: NWS Products

Introduction
NWS Products
Current Conditions
Staying Safe

 


How the National Weather Service Keeps You Informed

It is important to understand the different types of information available to be able to take full advantage of these critical weather information services. The tables below briefly explain the primary ways the NWS informs you of upcoming and current flood threats.

**For detailed information on how to stay safe in a flood, please see our Staying Safe page**


Flash Flooding Products

Product What It Means You Should...
Hazardous Weather Outlook Will there be any threat of flash flooding in the next several days?

If there is a threat of flash flooding, check back later for updated forecasts and possible watches and warnings.

Latest Hazardous Weather Outlook

Flash Flood Watch

There is a threat of flash flooding within the next 48 hours, either as a result of heavy rain, ice jams, or the threat of a dam break.

Monitor weather conditions closely, especially if you live in an area prone to flash flooding.
Flash Flood Warning

There is an immediate threat for flash flooding in the warned area, especially in low-lying and poor drainage areas.

These warnings are updated frequently with Flash Flood Statements.

If you live in an area susceptible to flash flooding, be prepared to evacuate and head to higher ground. Be very cautious when driving in the warned area, especially at night or while it is still raining. You may not be able to see a flooded road until it is too late!

A Flash Flood Emergency may be declared when a severe threat to human life and catastrophic damage from a flash flood is imminent or ongoing. The declaration of a Flash Flood Emergency would typically be found in either a Flash Flood Warning or Flash Flood Statement. People are strongly encouraged to avoid the geographic area of concern in a Flash Flood Emergency. The Flash Flood Emergency wording is used very rarely and is reserved for exceptionally rare and hazardous events.
Areal Flood Warning

The threat of flash flooding is over, but there is still significant standing water in the affected area.

Areal flood warnings will typically list locations and roads impacted by the flooding. Try to avoid these locations until the water has receded.

 


River Flooding Products

Product What It Means You Should...
Hazardous Weather Outlook

Will any of the rivers reach  moderate flood stage or greater during the next week?

If there is a threat of river flooding in your area, be prepared to take the necessary precautions to protect yourself and your property. Check back later for updated forecasts and possible warnings.

Latest Hazardous Weather Outlook

Hydrologic Outlook

The affected location on the river may rise above flood stage in the next couple of days, but is dependent on future rainfall.

This product contains more detail about the expected intensity of the flood than a Hazardous Weather Outlook.

If you live near the affected river, assess how much of an impact the flood will have on you. Check back later for updated forecasts and possible watches or warnings.

Flood Watch

There is high confidence that the affected location on the river will rise above flood stage in the next one to two days.

If you live near the affected river, assess how much of an impact the flood will have on you. Start taking necessary precautions in case the river will impact you and stay tuned for possible warnings.

Flood Warning

The affected location on the river is expected to reach flood stage within the next two to three days. The flood warning remains in effect until the river falls back below flood stage.

Flood warnings are updated at least every six hours with a Flood Statement.

If you live near the affected river, ensure that you are not in danger of being flooded. The text of the warning will contain the expected crest of the river (out to seven days). If you are in danger, take the necessary precautions to protect yourself and your property.

If you are traveling through a region that is under a flood warning, make sure that none of the roads are impacted.

Note: In March of 2012, the flood stages of many rivers in central Iowa were changed to more accurately reflect the true definition of a minor, moderate, and major flood. More information about this change and how it affects each river forecast point can be found here.

 


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