With a powerful early-season heat dome dominating in recent weeks, repeated rounds of hot conditions and a general lack of other weather have led the way to a speedy expansion of drought in the eastern United States.

June is typically one of the wettest months in the Ohio Valley, Mid-Atlantic and parts of the Southeast, so weeks without much rain will drive up any precipitation deficits. The addition of peak summer sun and minimal cloud cover have also fueled speedy drying and browning of grasses, shrubs and trees.

The Mid-Atlantic to parts of the Southeast have suffered the brunt of recent drying. Virginia, and parts of surrounding states have jumped into moderate drought — the lowest of four drought categories that is also one step above the first alert category of abnormal dryness, as defined by the U.S. Drought Monitor. Portions of the Midwest, Ohio Valley and Southeast have also experienced drought expansion.

“Several rounds of hot temperatures along with several weeks of dry weather has led to rapidly deteriorating conditions across the upper Ohio Valley and Mid-Atlantic,” wrote the Drought Monitor in its latest update, adding that this warrants “the broad expansion of abnormal dryness (D0) and moderate drought (D1) conditions."

There’s little sign the widespread month-to-date rainfall deficits of 2 to 4 inches will soon let up. In fact, after a brief respite that allowed for a few rounds of storms, the heat dome is likely to shift east again — and the Weather Service is favoring drier than normal conditions for most spots in the impacted region during weeks to come.

How much drought expanded in just three weeks

The change in drought conditions over recent weeks is stark. At the start of the month, only a few splotches east of the Mississippi River were characterized as abnormally dry by the Drought Monitor.

Three weeks later, much of the region, especially in and east of the Appalachians, is abnormally dry or worse.

According to statistics from the Drought Monitor, Virginia went from zero percent in moderate drought on June 5 to 91 percent as of this week’s update. West Virginia moved from zero to 59 percent, North Carolina went from zero to 57 percent coverage and Ohio bumped from zero to 21 percent.

As far south as north Florida, large swaths have gone from no drought to notable drought over the course of several weeks.

This appears to be the early stages of a flash drought, defined by federal forecasters as the “rapid onset or intensification of drought.” They also point out that lack of precipitation, in addition to high temperatures and intense solar radiation, are key factors in its development.

A major flash drought occurred over the South last summer, leading to lengthy feedback loops of historically hot and dry until winter set in.

What happens when June lacks rain

June is typically a wet month in much of the area with growing drought. It often comes in the way of hit-or-miss heavy thunderstorms, but they are usually consistent enough to get the job done.

With part of the heat dome focused on the East Coast, stormy weather has mainly remained west and northwest of the Mississippi River Valley. On the flip side of drought in the east, there have been extensive and historic floods in parts of the northern Plains and Upper Midwest.

Much of the area where drought has expanded has seen less than 50 percent normal rainfall this month, often well less, with locations in Georgia and the Mid-Atlantic as low as single digits as a percent of normal. This translates to June totals that are 5.4 inches below normal in Valdosta, Ga.;, 3.55 inches below in Cincinnati and 3.46 inches below in Richmond, among many other similar tallies.

A dry loop

Once a dry pattern is established, it often makes it that much harder for conditions to improve. That’s in part because dry ground will typically allow for surface temperatures to heat more readily, leading to additional drying of the landscape.

While some spots did see a decent dousing of rain with a recent cold front, and additional storms are forecast in days ahead, it likely won’t be enough to move the needle much in the big picture.

With dry conditions tending to prevail for now, the table is set for the next wave of substantial heat.

And heading into the Fourth of July holiday period, it appears the heat dome will migrate back to the east. This would bring another extended period of high heat and seemingly limited storm potential compared to usual.

What to expect ahead

Resilient summertime heat domes have been common in recent years across the globe. In the months following after a planet torching El Niño, hotter than average tends to rule.

Plus the stage is increasingly set for warm streaks thanks to human caused climate change. The locations may vary but the trend is now familiar: Heat sets in early in the warm season, builds upon itself, causes drought and fires and relents once the monsoon or cool season arrives. That’s been the recent case in places including Mexico, China, Spain, Greece, Canada, north Africa and Russian Siberia.

Scientists have found that heat domes are becoming stronger and more persistent as a result of climate change. Droughts and floods are also becoming more extreme.

Forecasts by professionals and weather modeling strongly suggests July will tend hot and dry in much of the Eastern U.S., in a continued preview of what’s on the way in the years ahead.