United States: Exceptional water surpluses in SE Texas & the Gulf

20 September 2017

The Big Picture

The 12-month forecast above shows intense water deficits in the Northern Plains states, intense water surpluses in southeastern Texas and coastal Mississippi, and both deficits and surpluses in the northern Rockies.

The general pattern for the period indicates primarily deficits in the western half of the US. Specifically, this includes widespread, exceptional deficits in Montana and moderate to severe deficits in North Dakota into northwestern Minnesota. Pockets of moderate deficits are evident from South Dakota down through southernmost Texas where the intensity increases to exceptional south of Laredo. Moderate to severe deficits are forecast for central and southern Iowa. Both deficits and surpluses are expected in the northern Rockies, along with intense surpluses in southern Idaho along the Snake River from Idaho Falls to Twin Falls. Deficits of varying intensity are forecast for California, western Oregon, and western Washington.

The dark blue block in southeastern Texas indicates a large pocket of exceptional water surplus through Houston, Galveston, and Beaumont – clearly the footprint of unprecedented rainfall levels dumped by Hurricane Harvey in late August. Water surplus is also indicated eastward along the Gulf through southern Louisiana, southern Mississippi, and southern Alabama, with exceptional intensity in coastal Mississippi. Moderate to occasionally severe surpluses are forecast for Wisconsin, Indiana, western Ohio, New York, and eastern Pennsylvania.

Primarily moderate deficits are expected in the coastal Southeast.

Outside the contiguous US, deficits are forecast for most of Alaska, though surpluses are indicated for the Juneau area. Surpluses are forecast for Hawaii.

Estimated overall economic losses from Hurricanes Harvey and Irma which struck in August and September are running between $200 and $300 billion, say analysts. Only about $70 billion of those losses are insured, with the current breakdown between $20 and $35 billion for Harvey, which devastated Houston and the Gulf Coast, and between $30 and $40 billion for Irma, which affected nearly every corner of Florida along with the US Virgin Islands and many other parts of the Caribbean.

As Harvey swamped Houston it took about 25 percent of US Gulf oil output offline and threatened to create a toxic stew of carcinogenic benzene runoff from the area's many refineries and petrochemical plants. Environmental agencies are also in the process of assessing whether a myriad of hazardous materials has migrated into the water from dozens of Superfund sites, including liquid mercury, a neurotoxin, which washed ashore east of Houston. Flaring from refineries and chemical plants has released more than a million pounds of dangerous air pollutants.

The hurricane left more than 70 people dead. On September 8 Congress approved a $15.25 billion relief package for Texas and Louisiana.

In Florida, the death toll currently stands at 42 from Hurricane Irma, including drownings, blunt force trauma, auto accidents, heart attacks, electrocution, and carbon monoxide poisoning from faulty generators. Eight additional deaths occurred in a nursing home where elderly patients succumbed to heat when the facility lost power to its air conditioning system. 

Hurricane Irma knocked out power to 15 million people across the state, according to the Department of Homeland Security, and left 10,000 homeless in the Florida Keys. More than 1.3 million customers in Georgia were without power, 161,000 in South Carolina, 62,000 in North Carolina, and 20,000 in Alabama.

Flooding and subsequent power outages have caused more than 28 million gallons of treated and untreated sewage to spew across the Sunshine State, creating a health hazard and threatening the state's waterways.

Four deaths were reported in the US Virgin Islands, where emergency federal funding was made available by a disaster declaration issued by President Trump, and the Department of Interior expedited $223 million advance payment for estimated FY 2018 rum excise taxes.

Forecast Breakdown
The 3-month maps (below) show the evolving conditions in more detail.

Please note that we are well aware of the recent devastation wrought by Hurricanes Harvey and Irma. The forecast that follows indicates water deficits in Florida, a forecast at odds with recent observed precipitation. Readers are advised that inputs used in our Water Security Indicator Model (WSIM), the model used to generate “Global Water Monitor and Forecast Watch List,” have proven reliable in forecasting broad precipitation patterns, but are not effective for predicting singular events such as tropical storms. For more information on WSIM, see https://www.isciences.com/water-security-indicator-model.

From September through November exceptional water surpluses are forecast to persist in southeastern Texas along with surpluses of lesser severity along the Gulf. Exceptional deficits in the Northern Plains States, particularly Montana, are forecast to retreat, leaving some moderate deficits along the Yellowstone River in Montana and in the western part of the state, and in northwestern Minnesota. In the West, conditions of both deficit and surplus will transition to surplus in Idaho, northern Nevada, northwestern Utah, eastern Oregon, and isolated small pockets of central California.

Moderate to severe deficits will persist in northern Colorado and Iowa; moderate deficits will emerge in greater extent in Nebraska and Kansas and will persist in northeastern and southernmost Texas. Moderate to severe deficits are also forecast for: southern Michigan, northwestern Pennsylvania, northern Maine, southern West Virginia, North Carolina, southern Georgia, and Florida. Moderate surpluses are expected in Michigan’s Upper Peninsula, eastern Pennsylvania, and central Tennessee.

From December through February primarily moderate water surpluses are forecast for the Ohio River Valley, Pennsylvania, and western New York. Small pockets of surplus will continue to emerge in Idaho and surrounding states which may reach exceptional intensity. Primarily moderate surpluses are forecast in southern Colorado and tracing a path along the Colorado River through Utah and the Rio Grande through New Mexico. Deficits in the southern states of the Eastern Seaboard are expected to persist.

The forecast for the final months of the forecast period – March through May – indicates surpluses in the Rocky Mountain States and along the Missouri, Yellowstone, and Platte Rivers.

(It should be noted that forecast skill declines with longer lead times.)

Note on Administrative Boundaries
There are numerous regions around the world where country borders are contested. ISciences depicts country boundaries on these maps solely to provide some geographic context. The boundaries are nominal, not legal, descriptions of each entity. The use of these boundaries does not imply any judgement on the legal status of any territory, or any endorsement or acceptance of disputed boundaries on the part of ISciences or our data providers.


Many analyses reported in ISciences-authored blog posts are based on data generated by the ISciences Water Security Indicator Model (WSIM). Other sources, if used, are referenced in footnotes accompanying individual posts. WSIM is a validated capability that produces monthly reports on current and forecast global freshwater surpluses and deficits with lead times of 1-9 months at 0.5°x0.5° resolution. This capability has been in continuous operation since April 2011 and has proven to provide reliable forecasts of emerging water security concerns in that time-frame. WSIM has the ability to assess the impacts of water anomalies on people, agriculture, and electricity generation. Detailed data, customized visualizations, and reports are available for purchase.

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