Today's storm surge is tomorrow's high tide, new report predicts

For the second time in just five days, the Northeast is facing a major coastal storm, or nor'easter, which is pushing...

Posted: Mar 7, 2018 10:41 AM
Updated: Mar 7, 2018 10:41 AM

For the second time in just five days, the Northeast is facing a major coastal storm, or nor'easter, which is pushing ocean water over storm walls and into the streets of many coastal cities.

The flooding comes as a major report released this week by the National Oceanic and Atmospheric Administration highlights a growing threat facing coastal communities in all parts of the United States.

The kind of floods we've only seen during storms might in the future be regular events

More frequent flooding likely due to seal level rise caused by global warming

As sea levels rise due to global warming, the kind of flooding currently experienced only in storms will happen during normal high tides. It's known as "sunny day flooding."

"Sunny day flooding, or high tide flooding, is flooding which is increasingly happening with no storm or rain in sight," William Sweet, report author and NOAA oceanographer told CNN.

"It is a direct response to years of local relative sea level rise," Sweet said.

That rise has been measured by NOAA's array of tide gauges that line every coast of the US mainland and territories including Alaska, Hawaii, and Pacific and Caribbean islands.

Examples of this storm-free flooding happening now include the "King-tide" floods in Miami and Charleston, which clog stormwater systems and flood some low-lying roads and vulnerable infrastructure.

"With sunny day flooding, we see a high tide on steroids," according to Erika Spanger-Siegfried, a senior climate analyst from the Union of Concerned Scientists. The group was not affiliated with the study.

"It can reach into our communities and leave us stranded in our cars, stuck at home, sloshing through water, unable to get to school and work ... not a catastrophic flood but it can disrupt our ability to go about our normal lives," said Spanger-Siefried.

But according to Sweet and his colleagues, this nuisance flooding is becoming a much greater and more frequent concern.

At a majority of the tide gauges analyzed on the East Coast, the rise in sea level was found to be accelerating -- and that trend is expected to continue.

By 2050, high-tide flooding would occur up to 130 days a year in cities along the Northeast Atlantic coastline, according to the "intermediate" scenario (considered a likely scenario based on current and projected greenhouse gas emissions) presented in the report. In the western Gulf of Mexico it would be 185 days per year and 80 days per year for the eastern Gulf. These locations currently see between three to six days of flooding in an average year.

The West Coast, while still seeing increases in sea level, is less vulnerable to high-tide flooding. That's because the rates of sea level rise have been generally lower and higher elevations and coastal geography make it less vulnerable.

Pacific coast locations would see around 30 to 35 days per year of high-tide floods by 2050 (compared with one to two days currently). El Ni-o years would likely see additional floods on the West Coast due to warmer waters and more storms.

But by 2100, high tide flooding will become daily flooding -- with nearly all regions experiencing high-tide flooding 365 days every year.

Current storms provide a look into the future

Recent nor'easters, such as the one currently hammering the region, show us the sea level rise path we are on, according to Spanger-Siefried.

Current tide heights have reached and even surpassed the famous blizzard of 1978, which saw tides rise more than 4 feet above normal, even though they were lesser storms, because they had the advantage of higher baseline sea levels.

As sea levels continue to rise, storm tides will climb even higher, bringing destructive floods even during not-so-extreme storms.

"With higher sea levels, the probability of such events causing minor-to-major [1.5 to 4 feet above current high tide levels] flooding is increasing," said Sweet.

But it won't take a storm to see pictures like we have seen from this winter's nor'easters. "The area of Boston that flooded during our January storm and sent dumpsters floating down the street is about the same area that will flood chronically, just with tides, in roughly four decades," said Spanger-Siegfried.

The Union of Concerned Scientists has produced maps, unaffiliated with the NOAA report, that show areas that will be routinely impacted by high-tide floods in the coming decades.

Greenland's melting glaciers may someday flood your city

Time to prepare is now

Even if the rosiest projections are used, where sea level rise continues at its current rate without accelerating -- considered extremely unlikely without swift and immediate action to curb greenhouse gas emissions -- high-tide flooding will still be a major problem in some of the largest cities in the country.

New York, under the low-end scenario, is still looking at 130 high-tide flooding days per year by the end of this century, while Miami and San Francisco would experience 60 and 30 days per year, respectively.

With this report, Sweet and his team from NOAA's National Ocean Service hope to inform coastal community managers and policy makers of the significant and imminent threat they are facing from rising seas.

"Understanding the risk to communities from relative sea level rise is important to mitigating and preparing for flooding impacts," Sweet said.

But the time to prepare is now, and some cities such as Norfolk, Virginia, Miami Beach, Florida, and Charleston, South Carolina, which are already seeing sunny day flooding a few days every year, are planning or implementing large-scale engineering solutions to deal with the rising sea levels.

But there are still ways we can all help to "stem the tide."

"There are real differences in the flooding that is projected under different future sea level rise scenarios," according to Spanger-Siegfried.

"By reducing global warming emissions and slowing the rate at which sea level rise accelerates, we can buy ourselves time to adapt to the change that's already in the pipeline."

Mississippi Coronavirus Cases

Data is updated nightly.

Cases: 343505

Reported Deaths: 7543
CountyCasesDeaths
Hinds23932444
DeSoto23229283
Harrison20527329
Rankin15411291
Jackson15232252
Madison10959227
Lee10719179
Jones9047169
Forrest8723159
Lauderdale7884244
Lowndes7054151
Lamar702989
Lafayette6548124
Washington5595139
Pearl River5196152
Bolivar4954134
Oktibbeha494398
Panola4771112
Warren4728128
Marshall4701106
Pontotoc447773
Union433279
Monroe4330137
Neshoba4281181
Hancock428088
Lincoln4176116
Pike3667113
Leflore3627125
Tate353388
Alcorn350974
Sunflower347694
Scott341176
Adams340988
Yazoo339376
Copiah324968
Simpson322891
Itawamba314680
Coahoma314085
Tippah306568
Prentiss298863
Covington293484
Leake285475
Marion284181
Wayne277543
George272251
Grenada269488
Newton262364
Tishomingo239770
Winston236784
Jasper230648
Stone229637
Attala226373
Chickasaw219060
Holmes200174
Clay197654
Clarke186880
Tallahatchie183742
Calhoun181332
Smith179235
Yalobusha171540
Walthall145748
Lawrence142826
Greene140134
Amite137543
Noxubee135235
Perry133538
Montgomery133044
Carroll126431
Webster121232
Jefferson Davis116734
Tunica114227
Benton106725
Claiborne105331
Kemper102429
Humphreys100133
Franklin87923
Quitman84719
Choctaw82619
Wilkinson78032
Jefferson71328
Sharkey51618
Issaquena1736
Unassigned00

Alabama Coronavirus Cases

Cases: 587405

Reported Deaths: 11536
CountyCasesDeaths
Jefferson853851591
Mobile48932864
Madison37517533
Shelby27280257
Tuscaloosa27171465
Montgomery26172627
Baldwin25399329
Lee17224181
Calhoun15401334
Morgan15170291
Etowah14954370
Marshall13116235
Houston12077293
Elmore10915219
St. Clair10763252
Limestone10725158
Cullman10546205
Lauderdale10255254
DeKalb9508192
Talladega8949188
Walker7793288
Autauga7563114
Jackson7400117
Blount7362139
Colbert6703142
Coffee6365132
Dale5650117
Russell480243
Chilton4771117
Covington4749125
Franklin458181
Tallapoosa4519156
Escambia441383
Chambers3949125
Dallas3743163
Clarke371263
Marion3463107
Pike332579
Lawrence3263100
Winston298773
Bibb290465
Geneva283983
Marengo262467
Barbour250961
Pickens245562
Butler240872
Hale235578
Fayette227065
Henry213945
Monroe202141
Randolph201144
Cherokee199248
Washington185239
Macon170552
Crenshaw168358
Clay166259
Cleburne161345
Lamar151038
Lowndes145455
Wilcox132331
Bullock126542
Conecuh121332
Coosa118329
Perry110528
Sumter110333
Greene99137
Choctaw64425
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The heat wave that controlled our area over the past several days is now behind us. The forecast for the next week looks a bit cooler & less humid.
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