Red River rising: 18th consecutive year of flooding--why?

By: Dr. Jeff Masters , 3:08 PM GMT on March 19, 2010

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The Red River at Fargo, North Dakota continues to rise, with a peak expected Sunday at the 4th highest flood level observed in the past century. "Major" flood level is 30 feet, which the river surpassed on Wednesday, and the river is expected to crest near 38 feet on Sunday, just 2.8 feet below the record set last year. Flood stage is eighteen feet, and the Red River has now reached flood stage at Fargo for eighteen consecutive years, according to the U.S. Army Corps of Engineers. Prior to this remarkable stretch of flooding (which began in 1993), the river flooded in just 29 of 90 years. This year's flood is rated as somewhere between a 50-year and 100-year flood. Last year's record flood was a 100-year flood. The U.S. Army Corps of Engineers lists the 10-year flood level for the Red River at Fargo to be 10,300 cubic feet per second. A 10-year flood, historically, has a 10% chance of occurring in a given year. In the last twenty years, the Red River has had eight 10-year floods--one every 2.5 years, on average. This year is the fourth year out of the past five with a 10-year flood. Clearly, flooding has increased significantly along the Red River over the past twenty years.


Figure 1. Current and forecast flood stage for the Red River of the North at Fargo, ND. You can access images like these using our wundermap for Fargo with the "USGS River" layer turned on. Click on the icon for USGS station 05054000, then hit the "click for graph" link.

Reasons for flooding: landform factors
According the U.S. Geological Survey, the unique landform characteristics of the Red River Valley make it highly susceptible to flooding. These factors include:

1) A relatively shallow and meandering river channel--a shallow channel holds less water and the meandering can cause flow to slow down as the channel makes its turns, causing over-bank flooding.

2) A gentle slope (averaging 0.5 to 1.5 feet per mile) that inhibits channel flow and encourages overland flooding or water "ponding" (especially on even, saturated ground) in the basin.

3) The northerly direction of flow--flow in the Red River travels from south (upstream) to north (downstream). The direction of flow becomes a critical factor in the spring when the southern (upstream) part of the Red River has thawed and the northern (downstream) part of the channel is still frozen. As water moves north toward the still frozen river channel, ice jams and substantial backwater flow and flooding can occur.


Figure 2. Peak flow of the Red River at Fargo, North Dakota through time. The two largest flow rates occurred last year (2009), and in 1997. The projected crest for Sunday (red circle) would be fourth greatest flood since reliable records began in 1901. Image credit: U.S. Geological Survey.

Reasons for this year's flood: highly unfavorable weather conditions
The USGS also cites five weather factors that can act to enhance flooding along the Red River. All five of these factors occurred to a significant degree this year:

1) Above-normal amounts of precipitation in the fall of the year that produce high levels of soil moisture, particularly in flat surface areas, in the basin. North Dakota had its 22nd wettest fall in the 115-year record in 2009.

2) Freezing of saturated ground in late fall or early winter, before significant snowfall occurs, that produces a hard, deep frost that limits infiltration of runoff during snowmelt. Fargo had a November that was much warmer than average, followed by a sudden plunge to below-zero temperatures by the second week of December. This froze the saturated ground to a great depth.

3) Above-normal winter snowfall in the basin. North Dakota had a top 15% winter for precipitation, with the period December 2009 - February 2010 ranking 15th wettest in the past 115 years.

4) Above-normal precipitation during snowmelt. Precipitation for March 1 - 18 has been 1.41", compared to the average of 0.61".

5) Above-normal temperatures during snowmelt. High temperatures in Fargo have averaged 6°F warmer than normal for March 1 - 18.

Urbanization increases flooding
Urbanization has had a major impact on increasing flooding not only along the Red River, but in every river basin in the U.S. Many cities and developed areas are located in flood plains next to major rivers and their tributaries. Highways, streets, parking lots, sidewalks, and buildings now cover large areas of the ground that used to absorb excess rain water and slow the rate at which run-off from precipitation and melting snow reached rivers. By developing large portions of our flood plains, run-off now reaches rivers more quickly, generating higher floods.

Building levees and flood defenses increases flood peaks
Defending ourselves against floods has made floods worse. Every time a new levee is built, or an old floodwall raised in height to prevent overtopping, more and more water is forced into the river bed, which raises the height of the flood. Flood waters that used to be able to spread out over their natural flood plains are now forbidden from spilling out over newly developed land in flood plains. For example, proposed improvements to the flood defense system in Fargo could cause a 4 - 10 inch rise in floods immediately downstream from the city, according to the Army Corps of Engineers.

Precipitation is increasing
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). 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). Precipitation over the Red River drainage basin increased by about 10 - 20% during the 20th Century (Figure 3.) 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. These are the type of events most likely to cause flooding. 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.


Figure 3. Change in precipitation over the U.S. between 1900 - 2000, from the U.S. Cooperative network. Precipitation in the Red River drainage area increased by 10 - 20% over the 20th century. Image credit: Contemporary Changes of the Hydrological Cycle over the Contiguous United States: Trends (Groisman et al., 2002).

The future of flooding
As the population continues to expand, development in flood plains and construction of new levees and flood protection systems will continue to push floods to higher heights. With global warming expected to continue and drive ever higher precipitation amounts--falling preferentially in heavy precipitation events--it is highly probable that flooding in the Red River Valley--and over most of the northern 2/3 of the U.S. where precipitation increases are likely--will see higher and more frequent floods. With these higher and more frequent floods comes the increased risk of multi-billion dollar disasters, when a record flood event overwhelms flood defenses and inundates huge areas of developed flood plains. Obviously, we need to make smart decisions to limit development in flood plains to reduce the cost and suffering of these future flooding disasters.

References
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.

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.

Links
A good way to track the flooding event is to use our wundermap for the Red River with the USGS River layer turned on.

The Fargo Flood webpage of North Dakota State University, Fargo, has some excellent links.

I'll have a new post on Monday or Tuesday.

Jeff Masters

Red River Flood 2006 (mw25)
The water level of the Red River when I took this photo was 47.2 feet, 19.2 feet above flood stage and the 6th highest level in Grand Forks' history. The river is expected to crest at 47.4 feet on Wednesday morning. Luckily, no homes have been lost in the Grand Forks area as of yet due to the flooding.
Red River Flood 2006
Fargo Flood 2009 - Elm & 15th Ave. N. (tliebenow)
Picture says it all. Clay dike built to contain the Red River in North Fargo.
Fargo Flood 2009 - Elm & 15th Ave. N.

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Quoting plywoodstatenative:


So what does that mean then when we come to hurricane season. Will we see the same frequency and amounts of troughs?


Can't really say what will happen absolutely. Climate model pressures indicate a weak Azores-Bermuda High which suggests a negative NAO which would allow the ridge axis to extend further westward preventing the recurvature of storm. Also low pressures in the Caribbean and MDR region suggest higher pressure over the CONUS.
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Quoting Drakoen:


The GFS shows it continuing but lessening in frequency as we head into April featuring transient high pressure ridges and flatter troughs.


So what does that mean then when we come to hurricane season. Will we see the same frequency and amounts of troughs?
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no problem, altest....it's all good....

:)
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Here's an interesting analog trend pertaining to this spring.

Here are the U.S. temperature anomalies for February and March during the 5 hurricane analog years that occurred during a cold PDO. Notice how cold it was in the south and east, like this year:



Now check out the same years for April and May:



Notice the big warm-up in the central U.S. and the gulf coast states. This same kind of warm-up is expected to turn winter right around into spring next month, and this is what will warm the GOM up.
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Quoting jeffs713:

Nor do i. But the similarities are striking.


JFV wants a Hurricane to strike him in Florida and altesticstorm10 wants a Hurricane in Texas.
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thanks jeffs.....

:)
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altest...I'm not 25....I'm almost 42....

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193. Dude, really? A weather blog is not the place to be picking up women. Especially happily married women. Keep thy hormones in check.
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Pat,or Elvis sightings.
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Quoting plywoodstatenative:
Drak, when is this current spanse of troughs going to subside? Because we are supposed to be on the verge of spring, yet we have temps forecast to be way below normal this coming week.


The GFS shows it continuing but lessening in frequency as we head into April featuring transient high pressure ridges and flatter troughs.
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Quoting plywoodstatenative:
Jeffs, reference the name plywoodstatenative, I live in Hurricane alley.

I know you do. :)
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AMEN!!!!!!!!!!!!!Apocalypse-induced misanthropic environmetal nervousness!!!
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Quoting StSimonsIslandGAGuy:
I don't think altesticstorm10 is JFV.

Nor do i. But the similarities are striking.
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Drak, when is this current spanse of troughs going to subside? Because we are supposed to be on the verge of spring, yet we have temps forecast to be way below normal this coming week.
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Jeffs, reference the name plywoodstatenative, I live in Hurricane alley.
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Quoting StSimonsIslandGAGuy:
I don't think altesticstorm10 is JFV.


Me neither.
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GFS 12z on the south central Winter Storm:


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MAN, I love North Central TX!! It's 74F now and LOOK what's coming!!
Member Since: August 25, 2009 Posts: 20 Comments: 6785
altest...no deal...not in this lifetime...I'm married...not available....

You can marry my purple hippo though...
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168. Dodabear 1:56 PM PDT on March 19, 2010
Quoting altesticstorm10:


Where, exactly do you live????


In a bathroom in South Florida...


;)
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181. HadesGodWyvern (Mod)
Tropical Cyclone Warning Center Brisbane
Tropical Cyclone Warning
Tropical Cyclone Ului, CAT 2
5:00 AM EST March 20 2010
=====================================

At 18:00 PM UTC, Tropical Cyclone Ului, Category 2 (980 hPa) located at 18.4S 155.1E or 690 kms east northeast of Mackay and 880 kms east of Townsville has 10 minute sustained winds of 55 knots with gusts of 75 knots. The cyclone is reported as moving southwest at 7 knots.

Tropical Cyclone Ului, category two intensity, is moving to the southwest towards the Queensland coast.

The most likely scenario is for the cyclone to cross the coast Sunday morning between Cardwell and Mackay and it may remain at category 2 intensity by landfall.

Damaging winds should develop between Townsville and Yeppoon later today, then increase further and extend to Cardwell and to adjacent inland parts on Sunday morning as the cyclone nears the coast.

Heavy rainfall and flooding are likely to develop about coastal and adjacent inland areas between Bowen and St Lawrence early Sunday.

Seas and swell are expected to increase along much of the Queensland east coast. Dangerous surf conditions are expected to continue about exposed beaches south of the cyclone until later on Sunday. A separate Severe Weather Warning is current for these conditions.

Dvorak Intensity: T3.5/3.5/W0.5/24hrs

Storm Force Winds
==================
30 NM from the center in northern quadrant
60 NM from the center in southern quadrant

Gale Force Winds
================
70 NM from the center in northern quadrant
150 NM from the center in southeastern quadrant
210 NM from the center in southwestern quadrant

Forecast and Intensity
=======================
12 HRS: 19.2S 153.2E - 60 knots (CAT 2)
24 HRS: 19.6S 150.1E - 55 knots (CAT 2)
48 HRS: 20.0S 144.7E - 25 knots (Tropical Low)
72 HRS: 17.7S 137.9E - 25 knots (Tropical Low)

Tropical Cyclone Watches
===========================
A Cyclone WARNING has been declared for coastal areas from Townsville to Ayr.

A Cyclone WARNING continues for coastal areas from Ayr to Yeppoon.

A Cyclone WATCH continues for coastal areas from Cardwell to Townsville

Additional Information
==========================
Tropical Cyclone Ului has weakened in the last 24 hours due to northwesterly wind shear, however shear has weakened over the past 6-12 hours. Dvorak analysis still based on shear pattern, the low level circulation being within 0.3 degrees of convection yielding a DT=PT=MET=FT=3.5.

Models remain very consistent with the forecast track shifting more to the west southwest on today and crossing the coast between Townsville and Mackay on Sunday morning, steered by the mid-level ridge to the south. As a result, there is a higher than normal confidence in the track forecast.

Forecast intensity is held at category two through to landfall based on the prospect of the shear continuing to ease, arresting the weakening trend.
Member Since: May 24, 2006 Posts: 54 Comments: 48877
Quoting jeffs713:

How about this... when you have to live through a strong hurricane, then you can talk about hoping for an active season. Until then, I would strongly suggest that wishes for a strong season be kept to yourself.


agreed 100%
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Quoting Patrap:
National Ice Core Laboratory.

Why Study Ice Cores?

Ice cores contain an abundance of climate information --more so than any other natural recorder of climate such as tree rings or sediment layers. Although their record is short (in geologic terms), it can be highly detailed. An ice core from the right site can contain an uninterrupted, detailed climate record extending back hundreds of thousands of years. This record can include temperature, precipitation , chemistry and gas composition of the lower atmosphere, volcanic eruptions, solar variability, sea-surface productivity and a variety of other climate indicators. It is the simultaneity of these properties recorded in the ice that makes ice cores such a powerful tool in paleoclimate research.



Greenland Ice Core Temperature Data:



Vostok, Antarctica Ice Core Temperature Data:



Notice how it has been much warmer than it is now on multiple occasions in history, according to the ice cores. Also notice the fairly consistent climate cycles with rapid warming peaks and then slower falls into colder periods.
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Quoting altesticstorm10:

Dallas, TX...

How about this... when you have to live through a strong hurricane, then you can talk about hoping for an active season. Until then, I would strongly suggest that wishes for a strong season be kept to yourself.
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Quoting altesticstorm10:

LOL at going by climatology to back up your arguments...might as well jump out of a plane without a parachute, I say.

2005 wasn't the only recent season to have at least 5 storms by July...see 2008. A strong July is a staple of an active season in this active period.

2004.
2001.
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Quoting altesticstorm10:

LOL at going by climatology to back up your arguments...might as well jump out of a plane without a parachute, I say.

2005 wasn't the only recent season to have at least 5 storms by July...see 2008. A strong July is a staple of an active season in this active period.


Altestic all he's saying is that climatologically July is pretty much never the height of the hurricane season, and your post seemed to state that you think July will be the peak of this year's season. Maybe that's not what you meant, but he's just pointing out the facts there. September is almost always the peak.
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Quoting altesticstorm10:

Dallas, TX...


Not exactly in hurricane alley, eh?
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Quoting KEEPEROFTHEGATE:
most dangerous time in the tropics mid august till mid sept


Unfortunately I think with the way the temps are rising in the CATL we are going to be proven wrong once again when it comes to what time is the most dangerous with storms. It only takes one storm to make a day or week that is normally quiet, a dangerous one.

Andrew proved that in 1992 when he became a menace to the Homestead area, before that storm formed there were no dangers in the months that people are talking about. Each year we hear about people talking about how this month or that month is dangerous. It just takes one system to wipe away all those questions. Just ask those in the New Orleans, Bridge City, and Homestead about what month is most dangerous.
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Quoting altesticstorm10:


Where, exactly do you live????
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Quoting Patrap:
Factors that Lead to Hurricane Intensification
Factors that Lead to Hurricane Intensification

Why did Hurricane Isabel - a powerful 2003 Atlantic hurricane - remain a Category 5 for as long as 3 consecutive days?

This is nearly unprecedented. Much of this has to do with the very warm ocean water that Isabel encountered, and complete lack of destructive winds high in the atmosphere.
who knows maybe this season we will see a cat 5 for 5
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Keeper, unfortunately thats what altes has been good at lately. When the season truly starts to ramp up, we will see the blog rules being enforced and therefore you will see people who normally are in here stirring up nonsense become quiet. Right now this is all just wishcasting as to whats going to happen.
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Quoting StormChaser81:


Lot's factors could kill you early forecast of the heart of hurricane season being in July. Like historical data suggest that rarely ever happens and probably will not happen. We might get one or two more storms than normal. but doubt will see a huge spike in activity. I'll go with September being the heart considering it is the heart of hurricane seasons on the past.
most dangerous time in the tropics mid august till mid sept
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Quoting altesticstorm10:

The heart of hurricane season begins in early July this year.


SC81, I mean for the Gulf to warm up closer to normal, not to warm up to 85%uFFFD in March. Of course, when April and May come and the sun begins to beat down directly on the Gulf, it shouldn't take too long to warm to normal or slightly above normal SSTs providing that there isn't too much cloudiness.


Lot's factors could kill you early forecast of the heart of hurricane season being in July. Like historical data suggest that rarely ever happens and probably will not happen. We might get one or two more storms than normal. but doubt will see a huge spike in activity. I'll go with September being the heart considering it is the heart of hurricane seasons of the past.

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

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