GFS model simulation of heat dome parked over western United States. (WeatherBell.com)

A massive and intense heat dome has spread over the northern Plains and mountain West, sucking moisture out of the soil, and may persist for weeks. The scorching heat and absence of rain have spurred a rapidly intensifying drought that is decimating the region’s wheat crop.

Temperatures in Montana, Wyoming and the Dakotas surged into the 90s and 100s on Wednesday, about 15 to 20 degrees above normal. Forecast models predict the same general weather pattern that supported this heat to persist up to two more weeks.

The pattern is characterized by a sprawling heat dome or area of high pressure at high altitudes over the western third of the nation — resulting in simmering conditions not just in the Dakotas but all over the West. On Wednesday, Salt Lake City hit 105 degrees, its seventh-hottest reading recorded. It is expanding into the desert Southwest, resulting in searing 120-plus-degree heat in Death Valley and prolonging a 21-day streak of temperatures of at least 105 degrees in Las Vegas.

The sinking air underneath this heat dome has suppressed the formation of rain storms and rapidly dried out the land surface in the northern Plains and mountain West.

The dry pattern commenced in the spring but intensified in recent weeks as the western heat dome settled in. Glasgow, Mont., had its record-driest April-through-June period.

The suddenness of the drought’s onset and expansion has been remarkable.

In early May, the U.S. Drought Monitor classified neither the Dakotas nor Montana in a drought. Eight weeks later, drought covered 47 percent of North Dakota, 34 percent of South Dakota, and much of the eastern third of Montana — and its intensity is severe to extreme in many areas.


Change in drought conditions between early May and early July in north-central United States. (U.S. Drought Monitor)

“In northwestern South Dakota, South Dakota State University Extension staff reported poor pasture and range conditions as well as deteriorating crop conditions (corn),” the Drought Monitor said. “In eastern Montana, hot and dry weather continued to deteriorate pasture, rangeland, and crop conditions as temperatures soared above 90 degrees.”

In late June, the U.S. Department of Agriculture declared 15 North Dakota counties as agricultural disaster areas.

This week it rated two-thirds of the wheat crop in South Dakota as poor or very poor.

“Wheat conditions are at some of the lowest ratings in over a decade,” James Cordier, president and head trader at Optionsellers.com in Tampa, told CNBC.

“Spring wheat crop conditions have dropped about 40 percent in the last four weeks,” added Ted Seifried, chief marketing strategist with the Zaner Group in Chicago. “The crop is burning up, and it’s not going to produce anywhere near what we were expecting.”

This hit on the wheat crop means higher prices for high-protein breads, bagels and pizza crusts according to Bloomberg News.

Although prospects for rain in the region are grim in the next two weeks, the Climate Prediction Center does forecast drought improvement as the summer wears on.