United States: Water deficits to diminish in the SW, surpluses ahead for FL

25 June 2018

THE BIG PICTURE
The 12-month forecast indicates severe water deficits in the Northeast, relatively normal conditions in the Appalachian region south to the Gulf, primarily moderate deficits in the interior plains, intense surpluses in the Northern Rockies, and moderate to exceptional deficits in the southern Rockies, Southwest, and West.

Severe deficits are forecast for Vermont and Massachusetts, and deficits in central New Hampshire and southern Maine could be extreme to exceptional. Extreme to exceptional deficits are also forecast for southwestern Colorado and northeastern Utah, with deficits nearly as intense in Oregon and western Washington. Severe to exceptional surpluses are expected in Montana and Idaho, northwestern Wyoming, and central Nebraska, and are expected to be especially intense and widespread in the southeast quadrant of Montana and the east-west portion of the Salmon River across central Idaho. Generally less intense anomalies elsewhere include moderate surpluses in southern Michigan, western North Carolina, and Florida’s southeast coast and Gulf coast west of Gainesville. Primarily moderate deficits are forecast for eastern portions of the Carolinas and southeastern Georgia.

Outside the contiguous US, intense surpluses are forecast for Hawaii and for northwestern Alaska and the northern half of the Alaskan Peninsula trailing well into the interior. Deficits are forecast in patches of the eastern half of the state. Deficits are expected in Puerto Rico and will be severe in the west.

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

The near-term forecast through August indicates deficits in the Northeast which could be exceptional in southern Maine. Some deficits are forecast for eastern South Carolina and southeastern Georgia, but moderate to severe surpluses are expected in western South Carolina and northeastern Georgia, as well as in Virginia, North Carolina, southeastern Alabama, and Florida. Surpluses of equal intensity are forecast for southern Michigan.

Primarily moderate deficits are forecast for the vast Mississippi River Basin with areas of more intense deficit along the border of Iowa and Missouri. Severe deficits are forecast for central Indiana and along the Arkansas River to western Colorado, where deficits could be exceptional. Severe to exceptional deficits are expected in northern Utah, western Oregon, western Washington, and southernmost Texas. Primarily moderate deficits are forecast for California with pockets of greater severity scattered along the coast.

Surpluses in Idaho are forecast to diminish in extent and severity. Surpluses in Montana will downgrade from exceptional but will remain intense. Both deficits and surpluses are forecast for northwestern Montana, northern Idaho, and northeastern Washington.

From September through November surpluses will persist in Idaho, Montana, along the border of Wyoming and South Dakota, and central Nebraska, and some moderate surpluses will emerge at the central border of Arizona and New Mexico. Moderate deficits are forecast for the Mississippi River Basin, and deficits in the West and Northeast will moderate. However, severe to exceptional deficits will persist in northern Utah and western Colorado. Some mild deficits will emerge in the Ohio River Basin down to the Gulf. Aforementioned surpluses in middle and south Atlantic states will transition to mild deficits. Conditions in Florida and Michigan will transition from surplus to near-normal.

The forecast for the final months – December through February – indicates near-normal conditions east of the Mississippi, and the emergence of numerous areas of moderate surplus west of the Mississippi. Surpluses will persist in Idaho, Montana, the border of Wyoming and South Dakota, and central Nebraska, and will emerge in Wisconsin, southeastern Texas, southern Colorado, and many rivers in the southwest.

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

IMPACTS
A massive flash flood ravaged Ellicott City, Maryland last month when the Patapsco River rose 17.8 feet in two hours, sweeping away parked cars and destroying buildings. Governor Larry Hogan declared a state of emergency and announced that the flood was the second one-in-1000-year flood to hit the city in two years. Several weary business owners only recently finished repairing damages from the 2016 flood that devastated the area. One fatality was reported, a national guardsmen swept away while attempting to aid a woman in the flood-ravaged area.

Subtropical Storm Alberto, the first Atlantic storm of the 2018 hurricane season, made landfall in the United States in the Florida Panhandle late last month and pelted wide swaths of the southeastern United States before transitioning to a tropical depression, swinging up the Midwest, and finally dissipating in Canada. A downpour of up to ten inches transformed a docile Virginia creek into a raging river, engulfing a car and sweeping at least one person away. Mudslides in North Carolina caused a gas leak resulting in an explosion in one home, killing two people. Two journalists reporting on the storm in North Carolina died when a tree fell on their SUV. Total insured losses from Alberto to residential, commercial, and industrial properties, plus automobiles, were estimated at $50 million by a Boston-based catastrophe modeling agency.

Damages resulting from a heavy deluge on the Hawaiian Island of Kauai are expected to dramatically reduce production of taro, a staple root crop in the traditional Hawaiian diet. The United States Secretary of Agriculture designated the entire island a disaster area due to the heavy downpour, which also triggered dozens of landslides, destroyed homes and damaged a highway.

Farmers in Kansas and Oklahoma are abandoning wheat and other grains for cotton, a more drought-tolerant crop currently commanding relatively high prices. Global wheat prices have been gouged in recent years by increasing production from Russia, suggesting that the switch may be long-term.

Analysts are expecting some liquidation of US beef cattle in the coming grazing season due to months of drought stress in 70 percent of the beef cow herd states. Slaughter numbers were tracking 10 percent higher than 2017 late last month, and are expected to increase if seasonal rainfall in June and July is scarce.

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.

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