November 13, 2023
3 min learn
The Nationwide Climate Service has launched the primary flood forecasting system with exact, real-time knowledge exhibiting spots that are at imminent danger of inundation
Floodwater from the Mississippi River surrounds houses and covers streets on Might 3, 2023, in Rapids Metropolis, Illinois.
CLIMATEWIRE | A brand new authorities forecasting system reveals for the primary time roads, streets and properties which can be more likely to be flooded by ongoing or upcoming rainstorms, offering unprecedented element for preparations.
The Nationwide Climate Service enterprise gives the primary real-time forecasting service that reveals exact areas similar to metropolis blocks more likely to expertise no less than an inch of flooding over the following 5 days, shading the areas blue on an online map.
A number one NWS scientist referred to as the forecasting system “a revolutionary advance” for offering detailed, street-level flood prediction in actual time.
“We’re not just trying to say that the flood is at 10 feet. We’re trying to say your street can be flooded,” stated Mark Glaudemans, the chief of NWS’s Water Assets Companies Department. “With this five-day forecast, local authorities, emergency managers and the public can now make preparations to be ready.”
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The NWS system, dubbed a Flood Inundation Map, now covers about 10 % of U.S. households, exhibiting elements of japanese Texas, western Pennsylvania and upstate New York. By October 2025, the flood forecast will cowl all the nation — together with Alaska and Hawaii — reporting five-day flood danger for all 3.4 million miles of rivers within the U.S., according to NWS.
Glaudemans stated NWS’s current advisories — flood surge maps and flood watches — are rather more restricted than the inundation maps launched in September. The advisories warn residents in a a lot wider area about surging water ranges of close by rivers fairly than predicting actual areas going through excessive flood dangers within the subsequent hours and days.
The brand new forecasting system solely tasks inundations from riverine flooding and doesn’t account for coastal flooding, storm surges or sewer overflows.
“Saying that there’s going to be this many feet [of water] above the flood stage doesn’t mean much” to most residents, stated John Nielsen-Gammon, the state climatologist of Texas. Speaking flood danger “in a graphic way that people understand will be a tremendous advance.”
The brand new flood forecast reveals how flooding will have an effect on small areas “by putting water on the map,” Glaudemans stated. Native authorities and catastrophe responders will acknowledge the exact areas that demand consideration when heavy rain pushes up water ranges to harmful heights, serving to them put together for floods extra shortly and effectively, he added.
The brand new on-line forecast additionally differs from the flood maps created by the Federal Emergency Administration Company that present areas with the best flood danger, Glaudemans stated.
Local weather scientists say world warming will gas extra intense and frequent storms that inundate neighborhoods and key infrastructure similar to roads, bridges and energy grids. With rising sea temperatures, hurricanes are also rising in power and are more likely to reach inland areas and dump inches of rain in a matter of hours.
The flood forecast combines floor elevation knowledge with fashions predicting river-level rises to mark areas on interactive maps that might submerge after rain, Glaudemans stated. Decrease lands begin flooding first when rivers overflow. A contour map that reveals elevation each 30 toes lets NWS make street-by-street flood projection for sure ranges of rainfall.
However the brand new flood forecast additionally has weaknesses and limitations.
The nationwide flood forecast depends on estimates fairly than noticed knowledge for native components, affecting its accuracy, Glaudemans stated. Knowledge exhibiting components similar to riverbed shapes and the quantity of rain absorbed by soil and vegetation isn’t obtainable for “99% of the country,” Glaudemans wrote in an e mail.
“This information is expensive to collect and is simply not possible to obtain for the 3.4 million miles of rivers covered by” the brand new flood forecast, Glaudemans added.
The brand new forecast doesn’t show projected flood depth and ignores the probabilities of levees failing, says an NWS webpage answering frequently asked questions.
If a home or a avenue is shaded blue on the flood map, “it does not necessarily mean you are or will experience flooding,” the webpage says. Nevertheless it does imply “that heightened attention and awareness is needed.”
“We know from weather forecasting that models can be wrong,” stated Nielsen-Gammon, the Texas climatologist. “We’ll need to really see how they perform over a period of time to get a better sense of their accuracy.”
Reprinted from E&E News with permission from POLITICO, LLC. Copyright 2023. E&E Information offers important information for power and surroundings professionals.
