Flash flood warning
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Aflash flood warning(SAMEcode: FFW) is asevere weatherwarning product of theNational Weather Servicethat is issued by nationalweather forecastingagencies throughout the world to alert the public that aflash floodis imminent or occurring in the warned area. A flash flood is a sudden, violentfloodafter a heavyrain,or occasionally after a dam break. Rainfall intensity and duration, topography, soil conditions, and ground cover contribute to flash flooding.
Most flash floods occur when there is a heavy amount of precipitation falling in an area and that water is then channeled through streams or narrow gullies. Flash floods may take minutes or hours to develop. It is possible to experience a flash flood without witnessing any rain.[1][failed verification]
Flash flood alerts
[edit]There are two types of alerts for flash floods which are issued by theNational Weather Service.One is aflash flood watch,which means that conditions are favorable for flash flooding, and the other is aflash flood warning,meaning that a flash flood is occurring or one will occur imminently and is usually issued when there are strongweather radarechoes for an area that is prone to flash flooding.[2] Flash floods can also occur because of a dam or levee failure,[3]or because of a sudden release of water held by an ice jam.
Residents are usually urged to do the following when flash flooding is imminent:[4]
- Be aware of any signs of heavy rain
- Move to higher ground if rapidly rising water is seen or heard
- Not attempt to cross the flowing water
In addition, some NWS Weather Forecast Offices have instituted an enhanced flash flood warning, referred to as aflash flood emergency(or as termed by theAlbany, New Yorkoffice as aflash flood warning emergency[5]), which indicates a severe flooding situation in densely populated areas, similar to the procedure for declaring atornado emergency.
On August 27, 2017, asHurricane Harveybrought torrential rain to southeast Texas, the NWS issued a "Flash Flood Emergency for Catastrophic Life Threatening Flooding."[6]
On September 10, 2017, the NWS issued a Flash Flood Emergency for life-threatening storm surge because ofHurricane Irmain southwestern Florida at the eye landfall.[7][8]
On February 6, 2020, the NWS issued a Flash Flood Emergency forTazewell County, Virginiadue to a major storm moving through the area which caused theClinch Riverto rise to its highest crest in 40 years.[9]
On May 20, 2020, the NWS issued a Flash Flood Emergency for theTittabawassee RiverinMidland County, Michigandue to multiple dam failures causing the river to overflow and reach its highest crest since 1986.[10]
On July 6, 2020, the NWS issued a Flash Flood Emergency forTacony CreekandFrankford Creek,the former situated alongMontgomery CountyandNorth Philadelphia,Pennsylvania,and the latter along Philadelphia'sFrankfordneighborhood.[11]
On September 2, 2021, the NWS issued a first ever Flash Flood Emergency forNew York City,Philadelphia,FairfieldandNew HavenCounties inConnecticut,[12]and most of CentralNew Jerseya region that stretches over 200 miles, as the remnants ofHurricane Idatransitioned and intensified into apost tropical cyclonecausing torrential rains. Some areas reported up to 10 inches of rain in less than an hour. Although the region was forecasted to experience heavy rains, this event is considered unprecedented as such a warning has never been issued to the area. The region had already experienced above average precipitation for most of the Summer due to previous storm systems and tropical storms affecting the area.
On July 28, 2022, the NWS issued several Flash Flood Emergencies in eastern Kentucky for catastrophic and deadly flooding.[13]
On March 27, 2023, the NWS issued a Flash Flood Emergency for a dam break on the Head's Creek Reservoir in Spaulding County, Georgia. Astatementwas later posted on Twitter.
On September 27, 2024, a Flash Flood Emergency was issued forMetro AtlantaasHurricane Helenebrought catastrophic flooding to the area.[14]
On October 9, 2024, a Flash Flood Emergency was issued for several counties in the Tampa Bay and Big Bend areas of Florida asHurricane Miltonposed life-threatening flooding to a large portion of the West Coast.
Example of a flash flood warning and emergency
[edit]Warning
[edit]
This warning was issued following a dam failure along theMinnesota-Wisconsinborder.
Flash Flood Warning MNC115-WIC013-031-192330- /O.NEW.KDLH.FF.W.0012.180618T2329Z-180619T2330Z/ /00000.U.DM.000000T0000Z.000000T0000Z.000000T0000Z.OO/ BULLETIN - EAS ACTIVATION REQUESTED Flash Flood Warning National Weather Service Duluth MN 1203 PM CDT SUN JUN 18 2018 The National Weather Service in Eastern Duluth MN has issued a * Flash Flood Warning for... A Dam Failure in... East central Pine County in east central Minnesota... Northwestern Douglas County in northwestern Wisconsin... North central Burnett County in northwestern Wisconsin... * Until 543 PM CDT * At 1201 PM CDT, local law enforcement reported the Radigan Flowage Dam west of Dairyland has failed, causing flash flooding downstream on the Tamarack River south of the Dam as it flows towards the Saint Croix River. * Locations impacted include... Town Rd T west of Dairyland. Swedish Highway at the Tamarack River. Highway T west of Cozy Corner. Markville Road east of Markville. PRECAUTIONARY/PREPAREDNESS ACTIONS... Turn around, don`t drown when encountering flooded roads. Most flood deaths occur in vehicles. Move to higher ground now. Act quickly to protect your life. Please report flooding to your local law enforcement agency when you can do so safely. && LAT...LON 4623 9218 4616 9226 4611 9228 4607 9229 4605 9234 4612 9234 4617 9230 4622 9225 $$ LE
This warning was issued for heavy rainfall.[15]
PAC051-102345- /O.NEW.KPBZ.FF.W.0017.200710T2142Z-200710T2345Z/ /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED Flash Flood Warning National Weather Service Pittsburgh PA 542 PM EDT Fri Jul 10 2020
The National Weather Service in Northern Pittsburgh has issued a
- Flash Flood Warning for...
Central Fayette County in southwestern Pennsylvania...
- Until 745 PM EDT.
- At 542 PM EDT, Doppler radar indicated thunderstorms producing
heavy rain across the warned area. Between 1 and 2.5 inches of rain have fallen. Flash flooding is ongoing or expected to begin shortly.
HAZARD...Flash flooding caused by thunderstorms.
SOURCE...Doppler radar.
IMPACT...Flooding of small creeks and streams, urban areas, highways, streets and underpasses as well as other drainage and low lying areas.
- Some locations that will experience flash flooding include...
Uniontown, South Connellsville, Dunbar, Vanderbilt and Dawson.
Additional rainfall amounts up to 1 inch are possible in the warned area.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flood deaths occur in vehicles.
&&
LAT...LON 4006 7967 3997 7982 3986 7972 3995 7955
FLASH FLOOD...RADAR INDICATED
$$
Emergency
[edit]Flash flood emergency in initial bulletin
[edit]This warning, containing both the "Flash Flood Emergency" wording and theParticularly Dangerous Situationwording, was issued in the wake of the devastating flooding that took place in westernNorth Carolinadue to theeffectsofHurricane Helene.
Flash Flood Warning NCC023-027-111-291800- /O.NEW.KGSP.FF.W.0113.240927T2323Z-240929T1800Z/ /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/ BULLETIN - EAS ACTIVATION REQUESTED Flash Flood Warning National Weather Service Greenville-Spartanburg SC 723 PM EDT Fri Sep 27 2024 ...FLASH FLOOD EMERGENCY FOR CATAWBA RIVER FROM LAKE JAMES TO LAKE RHODHISS... The National Weather Service in Greenville-Spartanburg has issued a * Flash Flood Warning for... Central Burke County in western North Carolina... Southeastern Caldwell County in western North Carolina... East Central McDowell County in western North Carolina... * Until 200 PM EDT Sunday. * At 723 PM EDT, Devastating rainfall of 6-25 (twenty-five) inches occurred from Wednesday evening through Friday morning from Lake Hickory to the Catawba River headwaters, with the highest totals exceeding 2 feet along the Blue Ridge Escarpment across the upper Catawba River watershed. This is resulting in catastrophic and historic inflows into Lake James, and releases from Lake James are causing catastrophic flooding along the Catawba River into Lake Rhodhiss. * The latest pool elevations for the upper Catawba River lakes are as follows (Full Pool is 100.0 feet): Lake James: 110.3 feet and rising steadily. RECORD BROKEN. Lake Rhodhiss: 108.1 feet and rising steadily. * The former record pool elevation at Lake James is 107.36 feet which occurred in September 8, 2004 during Hurricane Frances. Major Flood Stage is 110.0 feet. * The current record pool elevation at Lake Rhodhiss is 110.10 feet which occurred in August 1940. Major Flood Stage is 110.0 feet. * This is an unprecedented and extremely dangerous event. Residents are urged to heed guidance from emergency management and law enforcement on any potential impacts to property. We are pleading with drivers to heed any barricades and avoid all flooded areas. There have been numerous swift water rescues because people are choosing to risk their lives and the lives of others by failing to Turn Around Don`t Drown. Please do the right thing and protect your life, the life of your family, and the lives of those who risk theirs to save you. This is a FLASH FLOOD EMERGENCY for Catawba River from Lake James to Lake Rhodhiss. This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND NOW! HAZARD...Life-threatening flash flooding from historic rainfall and resultant dam floodgate releases. SOURCE...Duke Energy and Burke County Emergency Management. IMPACT...This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND NOW! Life-threatening flash-flooding of Lake James, the Catawba River, and Lake Rhodhiss is ongoing. Structural flooding along Lake James continues and is developing along Lake Rhodhiss. Downstream of Bridgewater Dam on the Catawba River, several structrues are damaged or destroyed, with some single-level homes submerged by floodwaters. These floodwaters are causing numerous swift-water rescues. Backwater effects are causing significant inundation along tributaries, including flooding exceeding 4 ft deep at the NC 18/US 64 bridge, blocking a primary roadway connecting Morganton and Lenoir. * Please stay weather aware and monitor lake levels and Duke Energy projections closely for any changes. * For more information on lake levels or dam releases, people are encouraged to visit https://lakes.duke-energy or call 1-800-829-5253. * Residents along the Catawba River are encouraged to stay aware of the latest updates from Burke County by signing up for alerts at: http://smart911 * McDowell County Emergency Management, Burke County Emergency Management, Caldwell County Emergency Management, and Duke Energy are closely monitoring these high flows and pool levels and additional updates will be provided as new information becomes available. PRECAUTIONARY/PREPAREDNESS ACTIONS... Move to higher ground now! This is an extremely dangerous and life-threatening situation. Do not attempt to travel unless you are fleeing an area subject to flooding or under an evacuation order. If you are in low-lying areas along the Catawba River you should move to higher ground immediately. && LAT...LON 3583 8188 3577 8179 3584 8164 3581 8159 3581 8146 3578 8135 3573 8139 3574 8143 3574 8159 3571 8176 3572 8194 3568 8202 3572 8206 3580 8191 FLASH FLOOD...OBSERVED FLASH FLOOD DAMAGE THREAT...CATASTROPHIC $$ JMP
Flash flood emergency in follow-up statement
[edit]This particular Flash flood emergency also includes the enhanced wording "Particularly Dangerous Situation".
844 WGUS71 KBOX 282143 FFSBOX Flash Flood Statement National Weather Service Boston/Norton MA 543 PM EDT Sun Jun 28 2020 MAC005-017-021-023-027-282300- /O.CON.KBOX.FF.W.0003.000000T0000Z-200628T2300Z/ /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/ Norfolk MA-Worcester MA-Middlesex MA-Plymouth MA-Bristol MA- 543 PM EDT Sun Jun 28 2020 ...THIS IS A FLASH FLOOD EMERGENCY FOR THE TOWN OF NORWOOD AND SURROUNDING TOWNS... ...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 700 PM EDT FOR NORFOLK...EASTERN WORCESTER...SOUTH CENTRAL MIDDLESEX...WEST CENTRAL PLYMOUTH AND NORTH CENTRAL BRISTOL COUNTIES... At 537 PM EDT, law enforcement reported heavy rain falling including the towns of Norwood and Dedham where up to 3.5 inches have already fallen. Flash flooding is already occurring. Some evacuations may be necessary. Listen to local officials. THIS IS A FLASH FLOOD EMERGENCY FOR NORWOOD AND SURROUNDING TOWNS! This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND NOW! HAZARD...Life threatening flash flooding. Heavy rain producing flash flooding. SOURCE...Law enforcement. IMPACT...This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND NOW! Life threatening flash flooding of low water crossings, small creeks and streams, urban areas, highways, streets and underpasses. Some locations that will experience flooding include... Brockton, Quincy, Randolph, Franklin, Norwood, Milford, Milton, Stoughton, Dedham, Walpole, Mansfield, Easton, Canton, Sharon, Foxborough, Bellingham, Abington, Westwood, Holliston and Medway. PRECAUTIONARY/PREPAREDNESS ACTIONS... Move to higher ground now. This is an extremely dangerous and life-threatening situation. Do not attempt to travel unless you are fleeing an area subject to flooding or under an evacuation order. && LAT...LON 4210 7096 4204 7114 4203 7151 4219 7152 4223 7114 4223 7113 4224 7108 FLASH FLOOD...OBSERVED FLASH FLOOD DAMAGE THREAT...CATASTROPHIC EXPECTED RAINFALL...1-2 INCHES IN 1 HOUR $$ NOCERA
See also
[edit]
References
[edit]- ^"NOAA".
- ^"Stormwarn".
- ^"New Orleans Levee Breach Flash Flood Warning".
- ^"NOAAWatch Home".Archived fromthe originalon 23 January 2014.Retrieved17 January2014.
- ^NWGeek on YouTube."NWS Albany Flash Flood Warning Emergency EAS - Newfane, VT".NWRGeek.NWRGeek Productions.Retrieved1 August2012.[dead YouTube link]
- ^"IEM Valid Time Extent Code (VTEC) App".Mesonet.agron.iastate.edu.Retrieved2017-08-27.
- ^"National Weather Service Watch Warning Advisory Summary".forecast.weather.gov.Archived fromthe originalon 10 September 2017.Retrieved12 January2022.
- ^"IEM:: Valid Time Event Code (VTEC) App".
- ^Clay, Alayna (2020-02-06)."Rare Flash Flood Emergency issued for Tazewell County".WCYB.Retrieved2020-02-06.
- ^Fedschun, Travis (2020-05-20)."Michigan flood hits record level, dam breaches 'historic event' playing out in midst of coronavirus, Whitmer says".Fox News.Retrieved2020-05-22.
- ^Cappucci, Matthew (2020-07-06)."Flash flood emergency in Philadelphia as storms dump half a foot of rain in two hours".Washington Post.Retrieved2020-07-11.
- ^"Significant Flooding in Parts of CT After 1st Ever Flash Flood Emergency Issued".NBC Connecticut.September 2021.Retrieved2021-09-02.
- ^"IEM:: Valid Time Event Code (VTEC) App".
- ^"FFC Flash Flood Warning 65".mesonet.agron.iastate.edu.National Weather Service Peachtree City, Georgia. 27 September 2024.
- ^Herzmann, Daryl."IEM:: Valid Time Event Code (VTEC) App".mesonet.agron.iastate.edu.Retrieved2020-07-11.