Summer doldrums conundrum: Humid air, parched ground

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Summer, seemingly so simple compared to other seasons with its stagnant atmospheric patterns, can be confusing sometimes.

The air around us can be soaked with moisture, so much so that days with low to mid 90s highs suddenly garner heat advisories and even excessive heat warnings as the “heat index,” or estimated combined effect of heat and humidity on the human body, pushes into triple digits. Meanwhile, even though the air is moist, the ground can be hard and cracked, vegetation turning brown and rocks collecting dust in stream beds, from prolonged dryness.

On the U.S. Drought Monitor map , our region can be colored in shades of brown and orange signaling moderate to severe drought, yet sometimes small polygons overlapping those excessively dry areas can be painted green on National Weather Service maps for a flash flood warning. And when the next week rolls around, despite those torrents that triggered the flood warnings, the drought map won’t change much.

This is where we are as this summer moves toward mid-July.

It has been hot and dry on the whole — some triple-digit readings in Southside on the day after Independence Day — yet some have seen thunderous downpours in a few spots, at times. There was enough to flood streets and fill ditches and small streams beyond their banks in a few places. Some others got temporarily helpful rains for gardens of around ½ to 1 inch. A majority, though, have gotten less, even on the stormiest days.

Despite the spotty downpours, most streams in our region are running low, and even where beneficial rain fell, much of it ran off the drought-hardened ground or dried up quickly in subsequent days of hot sun.

That moisture returns to the air, and the cycle begins anew. But getting the moisture in the air back into our ground, vegetation and streams is problematic.

At mid-summer, we just don’t have the upper-air flow to bring in the kind of low pressure systems that can provide enough atmospheric lift for any type of widespread rain, as that has retreated into the northern U.S. and Canada. Even cold fronts that had been pushing through with a round of storms and then a day or two of cooler, drier air are starting to get stuck near us, not cleanly pushing through, hanging around as a weak trigger for scattered storms while not denting the heat much. That will be happening the next couple of days, in fact.

Some of this summer stagnation is fairly normal, but it has been hotter and drier in our region so far this summer, as we have been more under the high-pressure heat domes than in other recent years.

Last week’s heat-dome high pressure over the south-central U.S. split up, with a big chunk of it moving west and pushing Palm Springs, California (124) and Las Vegas (120) to their official hottest temperatures on record. The other part, not as intense, relocated eastward, more over us.

That allowed Hurricane Beryl to make a right turn in the western Gulf of Mexico bringing it into the Texas Gulf Coast with a lot of flooding and power-crashing mayhem around Houston, then inland as a weakened but still potent low-pressure system spawning tornadoes and torrential downpours even into the Ohio Valley.

Beryl stayed northwest of us, but its circulation has contributed to a low-pressure trough that is pulling a bit more Gulf of Mexico and western Atlantic moisture our way late this week. That will peak on Friday, when a disturbance moving northward will bring enough lift to trigger a greater coverage of showers and thunderstorms than we have seen most days, but more so east of the Blue Ridge than to the west.

There are indications of hot high pressure building back over us next week, perhaps infused with enough moisture for periods of showers and thunderstorms to erupt as highs climb into the 90s many days.

We appear to be stuck in the summer doldrums, with repeating periods of heat, sometimes excessive for our region, interspersed with scattered storms, sometimes.

There is no clear indication of this overall pattern breaking any time soon. Perhaps subtropical and tropical moisture will increase in time to allow more frequent and/or widespread showers and storms.

But the sticky air-dusty ground paradox looks likely to continue.

How hot has it been?

Last Friday, on July 5, Danville hit the 100-degree mark for the first time in three days short of 12 years, or 4,380 days, the longest streak between triple-digit temperatures in Danville’s weather history going back to the start of its records in 1917.

To the east, South Boston hit 102 on the same day and John H. Kerr Dam in Mecklenburg County topped out at 103 on the same day — though they get listed as July 6 with the 8 a.m. to 8 a.m. reporting cycle of co-op weather stations.

While Lynchburg and Appomattox have each reached 99, there appear to be no other regional sites that have hit 100 this summer. Wise and Burke’s Garden have yet to clip 90.

On the other end of daily temperature ledger, Roanoke recorded a low of only 78 degrees on June 30. Besides being the warmest low temperature on record for the date, it is only the 11 ^th time in 112 years of records that Roanoke has had a low of 78 or higher, the first time in 13 years.

Below are the locations I selected for the summer heat prediction contest last month, scattered fairly well across the region covered by Cardinal News, with the hottest temperature recorded so far and the date it was recorded. For many of the locations, aside from the major climate stations at Blacksburg, Roanoke, Lynchburg and Danville that report on a midnight-to-midnight cycle, the high temperature would have actually occurred on the afternoon before the reporting date. But for the purposes of hottest temperature of the summer so far, that doesn’t really matter much.

·        Abingdon: 94 (June 27)

·        Appomattox: 99 (July 6)

·        Blacksburg: 92 (June 23, July 6)

·        Burke’s Garden: 89 (July 6)

·        Clintwood: 90 (June 26)

·        Covington: 94 (July 6)

·        Danville: 100 (July 5)

·        Galax: 90 (June 27)

·        John H. Kerr Dam: 103 (July 6)

·        Lexington: 95 (July 1)

·        Lynchburg: 99 (June 22, June 26)

·        Martinsville: 97 (June 27)

·        Roanoke: 98 (June 26, July 5)

·        South Boston: 102 (July 6)

·        Wise: 89 (June 28)

·        Wytheville: 91 (June 27, July 5, July 6)

Journalist Kevin Myatt has been writing about weather for 20 years. His weekly column, appearing on Wednesdays, is sponsored by Oakey’s, a family-run, locally owned funeral home with locations throughout the Roanoke Valley.

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