The future of flooding

By: Dr. Jeff Masters , 10:06 PM GMT on February 19, 2008

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Are storms getting more extreme due to climate change? That is a difficult question to answer, since reliable records are not available at all in many parts of the world, and extend back only a few decades elsewhere. However, we do have a fairly good set of precipitation records for many parts of the globe, and those records show that the heaviest types of rains--those likely to cause flooding--have increased in recent years. According to the United Nations' Intergovernmental Panel on Climate Change (IPCC) 2007 report, "The frequency of heavy precipitation events has increased over most land areas". Indeed, global warming theory has long predicted an increase in heavy precipitation events. As the climate warms, evaporation of moisture from the oceans increases, resulting in more water vapor in the air. According to the 2007 IPCC report, water vapor in the global atmosphere has increased by about 5% over the 20th century, and 4% since 1970. Satellite measurements (Trenberth et al., 2005) have shown a 1.3% per decade increase in water vapor over the global oceans since 1988. Santer et al. (2007) used a climate model to study the relative contribution of natural and human-caused effects on increasing water vapor, and concluded that this increase was "primarily due to human-caused increases in greenhouse gases". This was also the conclusion of Willet et al. (2007).

More water vapor equals more precipitation
This increase in water vapor has very likely led to an increase in global precipitation. For instance, over the U.S., where we have very good precipitation records, annual average precipitation has increased 7% over the past century (Groisman et al., 2004). The same study also found a 14% increase in heavy (top 5%) and 20% increase in very heavy (top 1%) precipitation events over the U.S. in the past century. Kunkel et al. (2003) also found an increase in heavy precipitation events over the U.S. in recent decades, but noted that heavy precipitation events were nearly as frequent at the end of the 19th century and beginning of the 20th century, though the data is not as reliable back then. Thus, there is a large natural variation in extreme precipitation events.

Pollution may contribute to higher precipitation
It is possible that increased pollution is partly responsible for the increase in precipitation and in heavy precipitation events in some parts of the world. According to Bell et al. (2008), summertime rainfall over the Southeast U.S. is more intense on weekdays than on weekends, with Tuesdays having 1.8 times as much rain as Saturdays during the 1998-2005 period analyzed. Air pollution particulate matter also peaks on weekdays and has a weekend minimum, making it likely that pollution is contributing to the observed mid-week rainfall increase. Pollution particles act as "nuclei" around which raindrops condense, increasing precipitation in some storms.

The future of flooding
It is difficult to say if the increase in heavy precipitation events in recent years has led to more flooding, since flooding is critically dependent on how much the landscape has been altered by development, upstream deforestation, and what kind of flood control devices are present. One of the few studies that did attempt to quantify flooding (Milly et al., 2002) found that the incidence of great floods has increased in recent decades. In the past century, the world's 29 largest river basins experienced a total of 21 "100-year floods"--the type of flood one would expect only once per 100 years in a given river basin. Of these 21 floods, 16 occurred in the last half of the century (after 1953). With the IPCC predicting that heavy precipitation events are very likely to continue to increase, it would be no surprise to see flooding worsen globally in the coming decades.

Jeff Masters

References
Bell, T. L., D. Rosenfeld, K.-M. Kim, J.-M. Yoo, M.-I. Lee, and M. Hahnenberger (2008), "Midweek increase in U.S. summer rain and storm heights suggests air pollution invigorates rainstorms," J. Geophys. Res., 113, D02209, doi:10.1029/2007JD008623.

Kunkel, K. E., D. R. Easterling, K. Redmond, and K. Hubbard, 2003, "Temporal variations of extreme precipitation events in the United States: 1895.2000", Geophys. Res. Lett., 30(17), 1900, doi:10.1029/2003GL018052.

Groisman, P.Y., R.W. Knight, T.R. Karl, D.R. Easterling, B. Sun, and J.H. Lawrimore, 2004, "Contemporary Changes of the Hydrological Cycle over the Contiguous United States: Trends Derived from In Situ Observations," J. Hydrometeor., 5, 64.85.

Milly, P.C.D., R.T. Wetherald, K.A. Dunne, and T.L.Delworth, Increasing risk of great floods in a changing climate", Nature 415, 514-517 (31 January 2002) | doi:10.1038/415514a.

Santer, B.D., C. Mears, F. J. Wentz, K. E. Taylor, P. J. Gleckler, T. M. L. Wigley, T. P. Barnett, J. S. Boyle, W. Brüggemann, N. P. Gillett, S. A. Klein, G. A. Meehl, T. Nozawa, D. W. Pierce, P. A. Stott, W. M. Washington, and M. F. Wehner, 2007, "Identification of human-induced changes in atmospheric moisture content", PNAS 2007 104: 15248-15253.

Trapp, R.J., N.S. Diffenbaugh, H.E. Brooks, M.E. Baldwin, E.D. Robinson, and J.S. Pal, 2007, Severe thunderstorm environment frequency during the 21st century caused by anthropogenically enhanced global radiative forcing, PNAS 104 no. 50, 19719-19723, Dec. 11, 2007.

Trenberth, K.E., J. Fasullo, and L. Smith, 2005: "Trends and variability in column-integrated atmospheric water vapor", Climate Dynamics 24, 741-758.

Willett, K.M., N.P. Gillett, P.D. Jones, and P.W. Thorne, 2007, "Attribution of observed surface humidity changes to human influence", Nature 449, 710-712 (11 October 2007) | doi:10.1038/nature06207.




Winter Flooding (Jmroh)
This is the result of extreme snowmelt and 4 inches of rain.
Winter Flooding
Yellow River Starke County Indiana (StarkeHistorian)
Kankakee Game Preserve, 10 Mile Road: The Yellow River crested this morning at 12.14' at the US35 bridge at 11:45AM. This was 2.14' over flood stage. The record is 15.3 Jan 1, 1991.
Yellow River Starke County Indiana

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450. TampaSpin
2:50 PM EST on February 26, 2008
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449. TampaSpin
2:09 PM EST on February 26, 2008
Very nasty stuff off shore Florida.
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448. TampaSpin
12:54 PM EST on February 26, 2008
BULLETIN - EAS ACTIVATION REQUESTED TORNADO WARNING NATIONAL WEATHER SERVICE TALLAHASSEE FL 1228 PM EST TUE FEB 26 2008 THE NATIONAL WEATHER SERVICE IN TALLAHASSEE HAS ISSUED A * TORNADO WARNING FOR... SOUTH CENTRAL LOWNDES COUNTY IN SOUTH CENTRAL GEORGIA... * UNTIL 1245 PM EST * AT 1224 PM EST...SKYWARN SPOTTERS REPORTED A TORNADO NEAR LAKE PARK...OR 7 MILES NORTHWEST OF JENNINGS...MOVING EAST AT 35 MPH. * OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO MELROSE
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447. TampaSpin
12:12 PM EST on February 26, 2008
SVR T-STORM WARNING JACKSONVILLE FL - KJAX 1207 PM EST TUE FEB 26 2008
SVR T-STORM WARNING TALLAHASSEE FL - KTAE 1206 PM EST TUE FEB 26 2008
SVR T-STORM WARNING JACKSONVILLE FL - KJAX 1202 PM EST TUE FEB 26 2008
SVR T-STORM WARNING JACKSONVILLE FL - KJAX 1201 PM EST TUE FEB 26 2008
SVR T-STORM WARNING TALLAHASSEE FL - KTAE 1155 AM EST TUE FEB 26 2008
SVR T-STORM WARNING PEACHTREE CITY GA - KFFC 1155 AM EST TUE FEB 26 2008
SVR T-STORM WARNING JACKSONVILLE FL - KJAX 1144 AM EST TUE FEB 26 2008
SVR T-STORM WARNING TALLAHASSEE FL - KTAE 1136 AM EST TUE FEB 26 2008
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444. TampaSpin
11:29 AM EST on February 26, 2008
Check these cloud tops out and getting higher it seems.
NEXRAD Storm Table = Tornado Vortex Signature = Mesocyclone = Hail Storm
ID Max Top VIL Chance of Severe Hail Chance of Hail Max Hail Size Speed Direction (from)
M3 61 dBZ 32,000 ft. 51 kg/m² 30% 100% 1.00 in. 40 knots WSW (255)

G4 61 dBZ 32,000 ft. 35 kg/m² 10% 100% 0.75 in. 38 knots WSW (251)

B4 61 dBZ 32,000 ft. 41 kg/m² 0% 90% 0.50 in. 54 knots WSW (256)

I6 60 dBZ 13,000 ft. 26 kg/m² 0% 0% 0.00 in. 84 knots WSW (255)

C3 59 dBZ 25,000 ft. 30 kg/m² 10% 70% 0.75 in. 34 knots WSW (244)

O5 58 dBZ 22,000 ft. 24 kg/m² 0% 0% 0.00 in. 47 knots W (260)

W4 58 dBZ 9,000 ft. 15 kg/m² 0% 0% 0.00 in. 36 knots W (264)

J6 56 dBZ 38,000 ft. 43 kg/m² 10% 100% 0.75 in. 44 knots WSW (255)

O6 55 dBZ 27,000 ft. 26 kg/m² 0% 50% <0.50 in. New Cell
V5 54 dBZ 37,000 ft. 33 kg/m² 0% 90% 0.50 in. 69 knots WSW (255)

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443. TampaSpin
11:20 AM EST on February 26, 2008
Tampa is at 79 degrees now.
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442. TampaSpin
11:16 AM EST on February 26, 2008
The storm over Tallahassee has a 35000 ft. top...boom.
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441. weathers4me
4:17 PM GMT on February 26, 2008
Sun shining bight and strong in Bradenton (a bit south of Tampa) Temp here in the shade 79. Perhaps we will get some much needed rain here this go around. Hopefully nothing too severe.
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439. TampaSpin
11:10 AM EST on February 26, 2008
StormW this sun is still shining in Tampa and i would suspect some very powerful storms late.
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436. Patrap
9:37 AM CST on February 26, 2008
GOM IR Loop of the Front pushing Ese.Link
Member Since: July 3, 2005 Posts: 414 Comments: 125476
435. lilmax
3:33 PM GMT on February 26, 2008
WATCH COUNTY NOTIFICATION FOR WATCH 77
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
948 AM EST TUE FEB 26 2008

GAC009-021-023-053-079-081-091-093-107-125-141-153-163-167-169-
175-193-197-207-209-215-225-235-249-259-261-269-271-279-283-289-
301-303-307-309-315-319-261700-
/O.CON.KFFC.SV.A.0077.000000T0000Z-080226T1700Z/

SEVERE THUNDERSTORM WATCH 77 REMAINS VALID UNTIL NOON EST TODAY
FOR THE FOLLOWING AREAS

IN GEORGIA THIS WATCH INCLUDES 37 COUNTIES

IN CENTRAL GEORGIA

BALDWIN BIBB BLECKLEY
CRAWFORD CRISP DODGE
DOOLY HOUSTON JONES
LAURENS MONROE MONTGOMERY
PEACH PULASKI TELFAIR
TWIGGS WHEELER WILCOX
WILKINSON

IN EAST CENTRAL GEORGIA

EMANUEL GLASCOCK HANCOCK
JEFFERSON JOHNSON TOOMBS
TREUTLEN WARREN WASHINGTON

IN WEST CENTRAL GEORGIA

CHATTAHOOCHEE MACON MARION
MUSCOGEE SCHLEY STEWART
SUMTER TAYLOR WEBSTER

THIS INCLUDES THE CITIES OF...ABBEVILLE...ALAMO...AMERICUS...
BUENA VISTA...BUTLER...COCHRAN...COLUMBUS...CORDELE...DUBLIN...
EASTMAN...ELLAVILLE...FORSYTH...FORT BENNING...FORT VALLEY...
GIBSON...GRAY...HAWKINSVILLE...JEFFERSONVILLE...LOUISVILLE...
MACON...MCRAE...MILLEDGEVILLE...MONTEZUMA...MOUNT VERNON...
PRESTON...RICHLAND...ROBERTA...SANDERSVILLE...SOPERTON...SPARTA...
SWAINSBORO...TOOMSBORO...VIDALIA...VIENNA...WARNER ROBINS...
WARRENTON AND WRIGHTSVILLE.

$$



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434. Patrap
9:32 AM CST on February 26, 2008
Is global warming causing an increase in Category 4 and 5 hurricanes?

Link


Emanuel, K.A., "The dependence of hurricane intensity on climate"
Link
Member Since: July 3, 2005 Posts: 414 Comments: 125476
433. lawntonlookers
3:26 PM GMT on February 26, 2008
I just noticed that they added some features to the main page. WunderMap and weather stations. Today was the first day I noticed them. Rain in Harrisburg, PA, No snow.
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432. lilmax
3:20 PM GMT on February 26, 2008
Things should be getting pretty cold for SoFlo.

Wednesday: A chance of showers and thunderstorms before 1pm, then a slight chance of showers. Cloudy, then gradually becoming mostly sunny, with a high near 68. Windy, with a west wind 10 to 13 mph becoming north between 19 and 22 mph. Winds could gust as high as 29 mph. Chance of precipitation is 50%.

Wednesday Night: Mostly clear, with a low around 45. Northwest wind between 3 and 8 mph.

Thursday: Sunny, with a high near 69. North wind between 13 and 15 mph, with gusts as high as 20 mph.
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430. mgreen91
3:17 PM GMT on February 26, 2008
Thanks Storm W...
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429. TampaSpin
10:16 AM EST on February 26, 2008
Check out the new line developing in the GOM. compared to the imiage above.
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427. NEwxguy
3:04 PM GMT on February 26, 2008
I think most of the weather patterns this winter are directly attributed to the fairly strong La Nina. The La Nina is expected to last at least until June,so its probably going to be a turbulent spring like the winter has been.
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426. Patrap
8:54 AM CST on February 26, 2008
Bluejohn...Katrina was the Greatest Impact on any US Region..in History,from a 28 ft Storm Surge in Waveland Miss, to 17ft at the 17th St. Outfall Canal in New Orleans.

Using a Wind Loading based Saffir -Simpson Scale..isnt the best way to score impact.
Katrina at Landfall in Buras was a Cat-4..pushing the Large Cat-5 generated storm surge. And the Size of the Massive Hurricane..took an avg of 9 Hours to Move thru a Given area in the eyewall.
So your assessment of impact in New Orleans and the Cat-3 reference..is wrong, skewed..and tilted in your personal view of what occurred here.
Or have you visited and seen the Impact Zone that takes 3 hours to drive thru?

From Houma,LA. to The ALa/Fla Borders.

Its that Kinda posts that reinforce the General Knowledge and thinking that a New and Better Hurricane rating scale is needed.

Wind Loading on structures is what gave Birth to the H-scale as is.A new, better Surge to Size,Potential and Coastal shape ,..is what the public needs and deserves.

The Super Storms..large Cat-3 and Higher require more Public awareness of Surge and overall impact potential.

To many focus on a Cat # and less on Potential Impact. That can be a deadly and miscalculated risk.

They only make these Maps for the Super Impactors..Link

To clarify visually.
Cat-1 Hurricane Cindy,..July 2005 6 weeks before Katrina,local landfall Loop Link

Katrina Aug 2005 local landfall Loop Link

The Corps of Engineers and their Failure of Levee Protection.Link

Released June 4, the report The New Orleans Hurricane Protection System: What Went Wrong and Why focuses on the direct physical causes and contributing factors to the hurricane protection system failures during Hurricane Katrina. This report details the in-depth review by the ASCE Hurricane Katrina External Review Panel of the United States Army Corps of Engineers (USACE) Interagency Performance Evaluation Task Force (IPET) to better understand this tragedy and prevent similar disasters from happening again. It is a fascinating read, offering hope for not just the future of New Orleans, but for all other hurricane and flood-prone areas of the country.
Link



Member Since: July 3, 2005 Posts: 414 Comments: 125476
424. mgreen91
3:00 PM GMT on February 26, 2008
Good morning Storm W, has there been three years without a major cane hitting the US??


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422. LakeShadow
2:43 PM GMT on February 26, 2008
So we have a wild spring in store for us, eh?
I'm already seeing signs of an early spring here.
Flu bug has hit hard all over...I'm thinking another ripple effect of this climate change is the propogation and mutations of viruses...these viruses didnt get really "killed off" at all in the freezing cold, due to all those warm Pacific air bursts that have been pumping in from the West all winter long. Normally a few months of below freezing temps would weaken the epidemics.
Any one with thoughts?

Thanks for all the folks who posted lots of great stuff lately! Storm, you, especially Rock! Thanks for all your efforts! Wea ll learn soooooooooo much!

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421. bluejohn
2:51 PM GMT on February 26, 2008
The latest research shows that there has not been any increase in storm number or ferocity. Katrina was only cat 3 when it struck New Orleans. The problem there was one of poor maintenance not the ferocity of the storm. River flooding is due to dredging being ignored. All rivers silt up their beds and subsequent rains force water to overbank due to the silting up. The problem with this sort of maintenance is it is extreemly expensive so tends to get forgotten.
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420. TampaSpin
9:26 AM EST on February 26, 2008
Nasty storms over Ga. and Alabama
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419. mgreen91
2:34 PM GMT on February 26, 2008
I don't think there have been three years without a major hitting the US, right??

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418. LakeShadow
2:31 PM GMT on February 26, 2008
guten morgen!

Looking at Warner Robins Base radar and spotted a line of 5 hailstorms. What a squall line that is!!! its huge!

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416. NEwxguy
1:55 PM GMT on February 26, 2008
Its been really amazing how much convective activity there has been this month,does not bode well for the spring.
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415. TampaSpin
8:53 AM EST on February 26, 2008
StormW with the sun currently shining in Tampa now, the instability could rise as the front approaches.
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411. TampaSpin
8:43 AM EST on February 26, 2008
hello there chowder....lol
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410. NEwxguy
1:34 PM GMT on February 26, 2008
Gm storm,and to all
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409. TampaSpin
8:32 AM EST on February 26, 2008
I would suggest if we get much sun shine in Tampa the worse this evenings weather will be.
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408. Patrap
7:17 AM CST on February 26, 2008
HAil is a BAd thing ...those Hail Indicators on the radar usually Ping on the real deal. Hope all is well with them StormW.
Member Since: July 3, 2005 Posts: 414 Comments: 125476
407. weathers4me
1:06 PM GMT on February 26, 2008
As always, thanks Storm and Pat for all the information. After reading the posts on La Nina as it relates to the upcoming tropical atlantic season, the severity and probability of any land falling storms will, and has always been hinged on at least two important factors; wind shear and where the BH will set up. Are there things that can be predicted with any acccuracy this year as compared to last?
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405. CybrTeddy
12:58 PM GMT on February 26, 2008
T-4 months 6 days and counting in till the atlantic Hurricane season begins, all is looking good in the control rooms at this time and we are still go, around the 3 month mark pre-forcast predictions will come in. This is weatherunderground control.
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404. Patrap
6:46 AM CST on February 26, 2008
Morning surfmom,StormW. The Line passing thru here now,not much weather with it,looking forward to the cool down real soon. Its Muggy here this am.
Member Since: July 3, 2005 Posts: 414 Comments: 125476
403. Patrap
6:41 AM CST on February 26, 2008
Dupage severe Weather warnings Page Link

Best source for Warnings ...and storm reports
Member Since: July 3, 2005 Posts: 414 Comments: 125476
401. surfmom
12:36 PM GMT on February 26, 2008
Well I am zooming off to get kid to school and myself to work. See you guys later.
Member Since: July 18, 2007 Posts: 30 Comments: 26536

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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.