Kevin Myatt is The Roanoke Times' weather columnist.

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Driving home at the end of vacation Tuesday, my wife and I were in rain pretty much all the way from Cookeville, Tenn., to Pulaski.

But in spite of that soaking, nearly all of that area is still in the throes of drought, or at least on the cusp of falling into drought, according to Thursday's updated map from the National Drought Mitigation Center in Lincoln, Neb.

Every drop helps, but it takes more than a single day of rain to free a region from a drought that is years in the making.

Much of the Southeast has seen below-normal rainfall for the past three years and intermittently back into the 1990s. The drought has intensified this year and is expanding into the Tennessee and Ohio river valleys, and now the mid-Atlantic as well.

In the past few weeks, a yellow patch denoting "abnormally dry" conditions has crept northward on the drought map and now covers much of Virginia. It's not quite a state of drought, but it's close. A few more weeks of dry weather could mean serious problems for agriculture and water tables.

The drought center uses a complex formula that includes rainfall deficits, soil moisture and stream flows to determine which areas are suffering drought.

Like areas to our south, Southwest Virginia's dryness did not develop all at once.

Roanoke is about 6 inches below normal in rainfall for the year to date. We finished 2005 almost 4 inches below normal and 2006 a little more than 5 inches below normal. We've been pretty dry since the surplus-rain years of 2003 and 2004, but not nearly as dry as 2001 (17¹₂ inches below normal) and most of 2002 (8¹₂ inches below normal after wet months late in the year).

But we have managed to get a few occasional periods of rain and more numerous thunderstorms than many of our neighbors to the south. As a result, the streams are running and the reservoirs are just full enough to keep us out of the dreaded "drought" territory, when crops wither and lakes begin to turn to cracked mud.

We were actually in a little worse shape this time a year ago, but widespread heavy rain over several days of late June 2006 pulled us out. It was a little too much rain all at once, with one fatality related to flooding in Alleghany County.

There is nothing like that on the horizon this year. In fact, it appears likely that strong high pressure will build in many layers of our atmosphere over the next several days. This will raise temperatures and deter rainfall, with only a few scattered thunderstorms.

Drastic situations require drastic actions. It takes big events to spring regions out of drought, such as last year's several-days deluge.

Tropical systems can help. Tropical Storm Barry earlier in the month helped parts of Georgia and Florida. It didn't end the drought in those areas, but it lessened the severity and put out some fires. The map now shows the drought centered more over northwest Alabama, which Barry missed, rather than over southern Georgia. Barry also spun out a needed rain over Southwest Virginia.

Better than big downpours, though, are long periods with moderate, widespread rain. It is uncommon to see those in July and August. With the jet stream retreating into the far northern U.S. and Canada, there is nothing that would indicate such a pattern of regular rain will be developing.

While droughts have a way of propagating themselves, as dry ground and vegetation lead to less moisture in the air, they are not unbreakable. Much of the central U.S. was colored yellow, orange and red on the drought map a year ago, but those regions are almost entirely clear of drought now. Some areas have even had serious flooding, thanks to months of snowstorms, large rain systems and numerous thunderstorms.

Until something big changes in the overall pattern, whether we slip from "abnormally dry" into drought depends on how many random thunderstorms we get, and whether the forecasted active tropical season in the Atlantic can spin some soakers into our area.

It might take a hurricane to keep us from drying up.