Kevin Myatt

Latest entries from the Weather Journal blog

• A race against the rain on Sunday
• Sunday afternoon showers possible, but heavier rain likely overnight into Monday
• Sunnier, slowly warming weather on the way

About Kevin

Kevin Myatt grew up in Arkansas to the tune of tornado sirens and the rhythm of hailstones, aspiring to be a meteorologist before his studies and career were turned to journalism instead. Though he often chases storms, he prefers living in the cooler, more tranquil weather of the Blue Ridge. He moved to Roanoke in 1999 to take a job on the copy desk of The Roanoke Times; writing headlines and editing copy is his principal work for the newspaper today.

Each May, Kevin assists Pulaski County High School / Virginia Tech meteorology instructor Dave Carroll in leading college and high school students to the Plains to observe severe weather firsthand. The accounts of many of his storm chases can be found here on the storm chasing page of his weather blog on roanoke.com.

Kevin was an editor for "Hurricanes and the Middle Atlantic States," a book written by D.C.-area weather enthusiast Rick Schwartz and published by Blue Diamond Books that documents hurricanes striking the mid-Atlantic states since colonial times.

The Weather Journal column began in 2003 and appears on Friday's Virginia section front in The Roanoke Times. The Weather Journal blog began in 2006 and follows weather day-by-day between the larger columns.

Heat wave merely changes addresses

Follow the bouncing ball of heat.

Much of last week, the central United States experienced the core of the heat. Temperatures soared above 100 from the Rio Grande to the Canadian border, and beyond.

But things have shifted this week, and the cauldron of intense heat has moved to the western U.S., where locations all the way to the very coast of the usually cool, damp Pacific Northwest are experiencing roasting temperatures above 100 not often seen.

If it seems to you that it's the same heat wave as last week that merely changed addresses, you're largely correct.

Following the weather pattern in July and August is usually as simple as following the big ridge of high pressure and its lethargic movements over the U.S.

In summer, the main jet stream, which divides cool polar air from warmer subtropical air, retreats to the U.S.-Canada border area, sometimes well north into Canada. Without this 100-mph-plus river of air to steer things around, vigorous storm systems to stir the air are few and far between.

This often allows one particular area to heat day after day, frequently over an area of dry soil, like the Great Plains have been for several months. This mass of hot air, rising many miles in the atmosphere, usually becomes the key player in the U.S. weather pattern through midsummer.

Late last week, the "heat dome," as this mass of hot air with a high-pressure ridge is often called, shifted westward. A high-pressure system rotates clockwise in our hemisphere, so as it shifted westward, the clockwise flow around it began to pull cooler air down from Canada into the eastern U.S. and eventually even into the parched and baked central U.S.

As a general rule, if one side of the U.S. is unseasonably hot, the other side of the nation is unseasonably cool. This has to do with the rises and dips in the jet stream. If the jet stream is rising up over a ridge of high pressure in the west, it's probably dipping southward in the east.

The jet stream dipped all the way into the Ohio Valley over the weekend. This propelled a rather strong cold front well to the south, pushing away the heat, but also triggering mighty thunderstorms.

We've had some rather cool mornings after this turn of events, with lows in the mid-50s to near 60.

Slowly, this week, the high-pressure ridge that has been bringing excessive heat to the far west will shrink and also begin to build back toward the middle of the country.

One thing we have not seen this summer is the core of the hot air dome set up shop in the eastern U.S. Even when we started getting hot last week, we were on the eastern fringe of the high-pressure ridge, and it didn't take much to erode it as our mini-heat wave broke at midweek.

I would not be surprised to see the heat ridge build strong again over the central U.S. in the next couple of weeks. The ground and vegetation are extremely dry in much of that region, so turning it into an oven won't take long.

And once it does that, the potential is there for it to expand east again.

I think our chances are 50-50 that we'll have one day in August that becomes Roanoke's first 100-degree day in seven years.

See the latest tidbits on weather, locally and nationally, on Kevin Myatt's Weather Journal blog at blogs.roanoke.com/weatherjournal/