Dark streaks of cirrus clouds begin to fill the western sky in southern Botetourt County on Thursday, Sept. 12. This was the leading edge of clouds associated with former Hurricane Francine that made landfall on the coast of Louisiana last week, a forerunner to the development of a low-pressure system off the Carolinas affecting Virginia weather this week. Photo by Kevin Myatt.
Dark streaks of cirrus clouds begin to fill the western sky in southern Botetourt County on Thursday, Sept. 12. This was the leading edge of clouds associated with former Hurricane Francine that made landfall on the coast of Louisiana last week, a forerunner to the development of a low-pressure system off the Carolinas affecting Virginia weather this week. Photo by Kevin Myatt.

Potential Tropical Cyclone 8 never realized that tropical potential, but it was plenty potent, with some hurricane-force wind gusts and up to a foot and a half of rain in North Carolina’s Cape Fear region.

PTC8 never developed the tight circulation feeding off warm ocean waters indicative of a tropical cyclone that would garner a name, but rather remained a broader, open, comma-like swirl spun by contrasting air masses along a frontal boundary — a baroclinic low-pressure system, or as non-weather-involved people might call it, a plain old low-pressure system.

The ghost of PTC8 has been wandering inland over the Carolinas, circulating Atlantic moisture westward across Virginia. That resulted in streaky bands of moderate to heavy rain Monday night and Tuesday, with widely varying rainfall amounts depending on terrain effects (upslope flow enhanced amounts in many locations on and near the Blue Ridge) and the location of heavy banding.  Some thunderstorms occurred early Tuesday evening near the Virginia-North Carolina state line.

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Scattered showers with a possibility of some afternoon thunderstorms are expected to continue through this Wednesday afternoon and into Thursday before the system clears out. All of the rain is needed, considering how dry the state has become in recent weeks, with Thursday’s U.S. Drought Monitor map update not likely to show much improvement for Virginia since it doesn’t include Tuesday data.

It also brought on a cloudy, foggy, misty gloom over much of Virginia that kept Tuesday’s high temperatures well below mid-September norms that range from the mid 70s in the mountainous west to lower 80s in lower elevations. Much the same was expected Wednesday, though some sun peeks in the afternoon east of the Blue Ridge were possible and could enhance instability for thunderstorms.

Low rainy clouds stream over the mountains along Interstate 81 in Montgomery County on Tuesday, Sept. 17, as moisture from a coastal low that had moved inland brought significant and much-needed rain to many locations in Southwest and Southside Virginia. Photo by Kevin Myatt.
Low rainy clouds stream over the mountains along Interstate 81 in Montgomery County on Tuesday, Sept. 17, as moisture from a coastal low that had moved inland brought significant and much-needed rain to many locations in Southwest and Southside Virginia. Photo by Kevin Myatt.

PTC8, however clumsy its name may be and understanding that it was a big problem for some of our neighbors to the south, forestalled what would have otherwise probably been a warm, almost hot, week that would have broken up what has thus far been one of the coolest Septembers in many years.

Within Cardinal News’ generally Southwest and Southside coverage area, the first 15 days of September were:

  • The fifth coolest in 108 years at Danville, averaging 68.5 degrees, and the second coolest since 1976.
  • The sixth coolest in 94 years at Wytheville, averaging 62.8 degrees, and the second coolest since 1997.
  •  The 11th coolest in 132 years at Lynchburg, averaging 67.2 degrees, and the third coolest since 1986.
  • The 11th coolest in 127 years at Burke’s Garden, averaging 58.9 degrees, and the second coolest since 1994.
  •  The 12th coolest in 53 years at Abingdon, averaging 67.0 degrees, and the fourth coolest since 1997.
  • The 13th coolest in 113 years at Roanoke, averaging 67.4 degrees, and the third coolest since 1988.
  • The 18th coolest in 132 years at Blacksburg, averaging 63.6 degrees, and the third coolest since 1988.

In each of those cases, the first half of September just seven years ago in 2017 was even cooler than this one on average, and for some of them, early September 2006 was also cooler.

Recent cool, dry weather has brought on spectacular mountain views, such as this one of Cahas Mountain from the Blue Ridge Parkway in Franklin County on Sept. 2. Photo by Kevin Myatt.
Recent cool, dry weather has brought on spectacular mountain views, such as this one of Cahas Mountain from the Blue Ridge Parkway in Franklin County on Sept. 2. Photo by Kevin Myatt.

The recent cool spate is all the more notable given a summer that saw the region’s most persistent extremely hot weather in a dozen years through much of late June to mid-July, and was among the hottest on record at several locations, including tied for the hottest in 113 years of records at Roanoke. Globally, July was the hottest month on record dating to 1850, and the 14th consecutive month that rated as the warmest on record for that particular month.

There are generally two ways to sandbag September average temperatures in our region: cool, clear, dry mornings that drop into the 30s and 40s, or cloudy, damp afternoons that keep temperatures below seasonal norms.

The first half of September brought a couple of waves of unseasonably cool, dry air from Canada resulting in many 30s and 40s lows across our region, in some cases the coldest early September temperatures of the 21st century to date. (See last section of last week’s weather column, linked here.)

So now when signals several days ago had been pointing to a week of 80s highs and maybe even a few spots scraping 90, along comes PTC8 to buy a few more days of cooler afternoons (though muggy nights) to keep September averages among the coolest in over a century of records.

The backside circulation of the departing offshore low containing some of PTC8’s influence (which in turn was partially influenced by Hurricane Francine’s remnants) will help circulate a somewhat cooler, drier air mass that will wedge from the northeast along and east of the Appalachians by the weekend.

After a day or two that may be a little warmer with some 80s highs, that will bring on 40s-50s lows and 60s-70s highs across our region by early next week.

Tropical systems often help fall happen, but so do not-quite-tropical cyclones.

Long-range forecasts suggest warmer than normal temperatures covering much of the U.S. and even edging back into Virginia by the end of a September that has been dominated by some of the coolest temperatures for this time year thus far in the 21st century. Courtesy of Climate Prediction Center, NOAA.
Long-range forecasts suggest warmer than normal temperatures covering much of the U.S. and even edging back into Virginia by the end of a September that has been dominated by some of the coolest temperatures for this time of the year thus far in the 21st century. Courtesy of Climate Prediction Center, NOAA.

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. Sign up for his weekly newsletter:

Kevin Myatt has written about Southwest and Southside Virginia weather for the past two decades, previously...