Published: July 10,2017
A long-lived heat wave from the northern Plains to parts of the northern Rockies and Great Basin shows little sign of relenting over the next week or more, and that's likely to exacerbate the nation's most rapidly worsening drought in parts of the Dakotas and Montana.
Known as a flash drought for its relatively rapid development, this northern Plains drought developed quickly by late May over a sizable swath of eastern Montana, North Dakota and South Dakota.
Animation of the drought monitor analysis from May 16 through July 4, 2017, indicating the development of the northern High Plains flash drought. More dire areas of drought are denoted by the darker orange and red contours.
A drought emergency was declared in eastern Montana by Gov. Steve Bullock in late June. Local ranchers and farmers told KRTV-TV this is the worst drought in northeast Montana since 1988.
Glasgow, Montana, in the state's northeast corner, shattered its previous record-driest April-through-June period – a record that stood for 99 years.
This is the most widespread occurrence of "extreme drought" in North Dakota in almost nine years, the second worst category on the Drought Monitor analysis.
Fifteen North Dakota counties were designated as agricultural disaster areas at the end of June, KFYR-TV reported. The declaration by the U.S. Department of Agriculture made emergency loans available for affected farmers and ranchers.
"There are some areas of western North Dakota into Montana that haven't had good rain going on three months, other than isolated spots," Daryl Ritchison, executive director of the North Dakota Agricultural Weather System, told the Williston Herald.
Some farmers in McIntosh County, North Dakota, resorted to "hauling water" and some pastures had "zero growth," according to the June 27 U.S. national drought summary.
(MORE: State of Emergency Declared As Numerous Wildfires Burn Out of Control in British Columbia; Thousands Evacuated)
Extended Heat WaveOverall, there's little relief on the horizon for this parched area. In general, an expansive dome of high pressure aloft will remain anchored over the Rockies into next week.
Therefore, highs well into the 90s or low 100s are likely to persist in the northern High Plains drought area, as well as lower elevations of the northern Rockies and Great Basin, not to mention parts of the southern Canadian prairie.
There will be a brief period Tuesday when temperatures will retreat closer to average, but then the heat will intensify, once again, from Thursday onward as the ridge rebuilds.
Forecast Highs Late Week
Billings, Montana, topped out at 100 degrees on Saturday, a threshold the city hadn't crossed in almost three years. More highs near the century mark are likely late this week into the weekend.
One location in South Dakota topped 110 degrees Sunday – hotter than Needles, California.
Sunday marked the sixth consecutive day Salt Lake City had been in the 100s, and several daily records were set or tied during that time. Last Wednesday, Utah's capital city soared to 105 degrees, the third hottest temperature on record there. Afternoon readings in the upper 90s and low 100s are likely to continue through this weekend.
Numerous other daily record highs have been set across the West to start July. Even Death Valley tied a daily record high on Friday when the mercury soared to 127 degrees.
(MORE: July is Warmest Time of Year in Much of U.S.)
Environment Canada warned of an "unusually long-duration high-temperature event ... expected to last for longer than a week" in southern Alberta.
(MORE: Summer 2017 Outlook)
As mentioned before, the ridge is expected to grow in size and intensity once again by the end of this week, which means heat will once again amplify across the West.
In fact, some forecast guidance suggests the excessive heat may persist in this general area into the third week of July.
Little Rain Relief, EitherWhile the chance of rain isn't zero in the drought-suffering northern High Plains, the kind of soaking, mid-summer thunderstorm complexes don't appear to be in the cards, either, through this week.
Rainfall Outlook Over the Drought Area: Next 7 Days
A low-pressure system moving through the northern Plains through Tuesday may actually raise fire weather concerns in parts of Montana and the Dakotas by increasing trailing winds as the system passes through.
(MORE: Why Dry Thunderstorms are a Danger)
Another concern is the feedback that often occurs during flash droughts. Namely, a lack of soil moisture to transfer to the atmosphere means less rain generated by either scattered thunderstorms or any larger-scale weather system that moves in.
This dry ground then heats up faster than moist ground, essentially sucking any scant moisture out of the soil, leading to hotter temperatures and helping to reinforce the large-scale pattern that created the heat in the first place.
Throw in the ability for strong large-scale winds to occur in the northern High Plains in the summer and you have a worrisome scenario for the nation's current most dire drought to intensify in the weeks ahead.
Jonathan Erdman is a senior meteorologist at weather.com and has been an incurable weather geek since a tornado narrowly missed his childhood home in Wisconsin at age 7. Follow him on Facebook and Twitter.
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