A river flood watch is issued by the
National Weather Service
The National Weather Service (NWS) is an agency of the United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weather-related products to organizations and the public for the ...
of the
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...
when flooding at formal forecast points with
river
A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of w ...
gaging sites and established flood stages is possible. Flooding may be caused by various reasons, such as heavy rain in the vicinity of the river, melting
snow
Snow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes.
It consists of frozen crystalline water throughout ...
, and/or
ice jam
Ice jams occur when a topographic feature of the river causes floating river ice to accumulate and impede further progress downstream with the river current. Ice jams can significantly reduce the flow of a river and cause upstream flooding—som ...
s.
Example
The following is an example of a river flood watch issued by the National Weather Service office in
Seattle, Washington
Seattle ( ) is a seaport city on the West Coast of the United States. It is the seat of King County, Washington. With a 2020 population of 737,015, it is the largest city in both the state of Washington and the Pacific Northwest region ...
.
ZCZC SEAFFASEW
WGUS66 KSEW 151139
URGENT - IMMEDIATE BROADCAST REQUESTED
FLOOD WATCH
NATIONAL WEATHER SERVICE SEATTLE WA
339 AM PST THU NOV 15 2007
...THE NATIONAL WEATHER SERVICE IN SEATTLE HAS ISSUED A FLOOD WATCH
FOR THE FOLLOWING RIVERS IN WESTERN WASHINGTON...
SKOKOMISH RIVER NEAR POTLATCH AFFECTING MASON COUNTY.
.FLOOD BULLETIN NO. 1
HEAVY RAIN OVER THE OLYMPIC MOUNTAINS COULD DRIVE THE SKOKOMISH RIVER
ABOVE FLOOD STAGE LATE TONIGHT OR FRIDAY MORNING.
A VIGOROUS FRONTAL SYSTEM WILL PRODUCE PERIODS OF HEAVY RAIN OVER THE
OLYMPIC PENINSULA TONIGHT...AND SOME SPOTS ON THE SOUTH SLOPES OF
THE OLYMPIC MOUNTAINS COULD RECEIVE MORE THAN THREE INCHES OF RAIN.
THE RAINFALL COULD BE HEAVY ENOUGH TO PRODUCE FLOODING ON THE
SKOKOMISH RIVER.
A FLOOD WATCH MEANS THAT FLOODING IS POSSIBLE BUT NOT IMMINENT OR
CERTAIN. BE READY TO ACT QUICKLY IF THE NATIONAL WEATHER SERVICE
ISSUES A FLOOD WARNING.
WAC045-151839-
/O.NEW.KSEW.FL.A.0004.071115T1139Z-000000T0000Z/
/SRPW1.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
339 AM PST THU NOV 15 2007
THE NATIONAL WEATHER SERVICE IN SEATTLE HAS ISSUED A
* FLOOD WATCH FOR
THE SKOKOMISH RIVER NEAR POTLATCH
* UNTIL FURTHER NOTICE.
* AT 2:45 AM THURSDAY THE STAGE WAS 13.0 FEET.
* MINOR FLOODING IS POSSIBLE.
* FLOOD STAGE IS 16.0 FEET.
* FORECAST...FLOOD STAGE MAY BE REACHED BY LATE TONIGHT OR FRIDAY
MORNING.
$$
MCDONNAL
WEATHER.GOV/SEATTLE
See also
*
Severe weather terminology (United States)
This article describes severe weather terminology used by the National Weather Service (NWS) in the United States. The NWS, a government agency operating as an arm of the National Oceanic and Atmospheric Administration (NOAA) branch of the United ...
References
External links
National Weather Service
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Weather warnings and advisories