Kevin Myatt is The Roanoke Times' weather columnist.

kevin.myatt
@roanoke.com
981-3341

Weather with Kevin Myatt

Recent columns

• Winter trying again to show up with snow
• We got graupel, but not on official record
• Moisture could get caught up in cold blast
• Column archive

Read the Weather Journal blog

• Many looking past mild, quiet week toward possibly wild weekend
• Sprinkles or flurries possible Tuesday, but maybe something bigger for the weekend?
• For now, it looks like a quiet, mostly mild week ahead for SW Virginia
• Weather Journal blog

#swvawx on Twitter

@KevinMyattWx

• Follow Kevin on Twitter at @KevinMyattWx

You just sweated through a record warm July in both Roanoke and Blacksburg, though not one record high temperature was set.

How is that possible? Take a look at the other end of the daily temperature cycle.

The July just finished had the warmest average low temperature in 57 years of record-keeping for Roanoke Regional Airport and tied with 1994 for the same distinction in 53 years or record-keeping at Blacksburg.

In a preliminary review of the data, Roanoke's average low temperature for the 31 days of July was 69.55 degrees. That made it a runaway winner where temperature records are concerned, with the second warmest July average minimum temperature being 69 in 1955. The average low in July over the previous 56 years at Roanoke Regional was 65.5 degrees.

This July had 19 days when the low temperature was 70 degrees or higher, including a record streak of 11 days with lows at or above 70 degrees.

Two days, July 12 and 22, set record high minimums, or the warmest low ever recorded on those dates. In each case, that low temperature was 74 degrees.

Roanoke's all-time record highest low temperature occurred on July 7, 1978, when the overnight low was 78 degrees.

Blacksburg's average low of 63.84 degrees was a statistical dead heat with 1994 for warmest average July low. Blacksburg's warmest low for the month was 70 degrees on July 12; its all-time warmest low on record was 72 on July 15, 1954, so that's pretty darn close.

The muggy nights were all about the tropical moisture that streamed in early in the month with the remnants of Tropical Storm Cindy, and were reinforced later by the leftovers of Hurricane Dennis that spun themselves out over the central and eastern United States. Moist air is much slower to cool, acting to buoy the temperatures at night. Roanoke's lowest temperature for the month, 63, occurred on July 24 when a brief infusion of dry air from the west moved in.

As for high temperatures, it may have felt hot to you many times, but it was actually a little cooler than average. Roanoke finished with an average very close to 86 degrees (85.97 is the number I come up with), more than a degree below the long-term average of 87.05. Roanoke had only three days that got hotter than 92. The highest temperature was 97 on July 25; the next two hottest days were July 26 and 27, both of which recorded 95.

It reached 90 or higher on only nine days in the month. All but one of the remaining 22 days were in the 80s; the clouds and showers caused by Cindy's remnants held the high to 74 on July 7.

Blacksburg, with an average high of 82.32 degrees in July, was a few decimal places below its long-term average of 82.63. Blacksburg had only one 90-degree day, July 26. Since its weather records began in 1952, Blacksburg has never had a high of 100 degrees, hitting 99 twice (July 15, 1954 and Aug. 23, 1983).

So July 2005 will not go down in the record books for its sizzling days, but rather, for its balmy nights.

Nasty wind storm in Rockbridge County

July has also been a month with some nasty thunderstorm-spawned winds.

The damage was so bad in Rockbridge County near Collierstown, west of Lexington, on Friday that the National Weather Service sent out a damage survey team.

The team concluded that the damage -- tin roofs removed, a shed dislodged from its foundation, windows blown out and numerous hardwood trees uprooted -- was most likely caused by a series of microburst winds rather than a tornado. Microburst winds blast downward from a thunderstorm, and then fan out from a central point, whereas tornadic winds spin rapidly.

While the weather service team concluded that a brief tornado touchdown was possible, it appeared that microburst winds were the culprit for most or all of the damage.

The team estimated winds of up to 100 mph occurred in the area. The wind also apparently propelled half-dollar size hail like bullets, adding to the damage.

There were other scattered reports of wind damage and hail on Friday as cooler air pushed the week's heat out of the way, spawning some powerful thunderstorms.