Kevin Myatt is The Roanoke Times' weather columnist.

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• We got graupel, but not on official record
• Moisture could get caught up in cold blast
• Forecast for Weather Journal: Partly print, with frequent Internet
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• 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
• Coldest morning of winter so far likely across much of Southwest Virginia; Tuesday precipitation looking doubtful
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Today, autumn gets its first jab in on summer, using a winterlike technique to pull its punch.

Today's high temperatures are expected to be in the low to mid 70s, little more than a week after temperatures were struggling toward 100 here in Roanoke and were in the 90s throughout most of Southwest Virginia.

In fact, today's highs will be lower than many of our nighttime lows during the recent week of heat.

Sunday morning's low temperatures will likely be in the 50s to about 60.

A strong cold front moved through the area on Friday. That was the cause of early Friday morning's rumbles and downpours ... the cooler, drier air from Canada slamming into the warm, moist air that has hung with us, in varying intensity, for about the past month.

What will make today so refreshingly cool and dry is something more common during winter. Then, we would call it cold air damming; this isn't really cold, so perhaps "cool air damming" is the appropriate description, or as it is often called by meteorologists, a wedge.

High pressure circulating clockwise near the Great Lakes will be pushing northeast winds into the area from New England and eastern Canada.

These winds will bring cooler, drier air at the surface, wedging the mass of cool air against the eastern slopes of the Appalachians.

Just three months from now, this phenomenon would be a prescription for the threat of snow and ice if moist air from the Gulf of Mexico were to overrun the cold air trapped at the surface.

But for now, it will just mean unseasonably cool weather, with daytime highs about 15 degrees below normal ... quite likely further below normal that the hottest temperatures of the heat wave were above normal.

Being August and not January, the wedge will not hold the cool air in long.

The hot August sun will begin to heat the air mass, and temperatures will steadily warm through the coming week, likely topping 80 again in Roanoke by Sunday and possibly challenging 90 sometime during the next week.

The high-pressure area bringing the cooldown will also slip eastward, and may become positioned later in the week where its circulation brings a southerly flow of warm, moist air.

But this brief taste of cooler weather does remind us that fall is not far away, and as time goes along, it will become easier for these kinds of cool snaps to win out against summer's fading heat, and easier for them to hang around longer.

Weather town hall meeting

On Sept. 12, the National Weather Service in Blacksburg will host a "town hall meeting" at the Roanoke Civic Center from 7 to 9 p.m.

Weather service meteorologists will show videos of weather phenomena, including violent storms, and give an overview of the weather service's mission. They will also be there to answer questions from the public.

The event is free and open to anyone, but the weather service asks those who expect to attend to register in advance, by Sept. 8. To register, send an e-mail to Phil Hysell, warning coordination meteorologist with the weather service, at phil.hysell@noaa.gov, or by calling (540) 552-0084.