The great drought of 2011 may have started two months ago.

Since Tropical Storm Hermine drenched Central Texas in September, the state has been very dry, with large swaths receiving less than 10 percent of normal rainfall levels.

For instance, nearly all but the southeastern corner of Harris County has received less than 50 percent of normal rain.

A Texas corn field grows under a clear sky. Water reservoir levels in Texas are in good shape for now, but the National Weather Service’s Climate Prediction Center expects a “persistence and broad expansion” of drought in the Central Texas area during the next three months.

According to the National Climatic Data Center, the two-month period of October and November was the state’s eighth driest on record and second driest in 44 years. If Texas doesn’t receive at least 0.78 inch in December, it would be the driest October-December period since the 1950s.

The beginnings of drought conditions now trouble meteorologists because there’s little reason to expect relief during the next few months.

“Continuing dry weather is likely to persist at least into the spring,” said John Nielsen-Gammon, the state climatologist and a professor of atmospheric sciences at Texas A&M University. “It’s probably going to get worse before it gets better.”

The big concern is that, absent a wet spring, a large part of the state could experience a severe drought in 2011.

“For now it’s impossible to predict summer rainfall,” Nielsen-Gammon said. “But as things look right now, there will be very little subsurface moisture heading into late spring. These are hair-trigger conditions for a drought.”

The National Weather Service’s Climate Prediction Center expects a “persistence and broad expansion” of drought in the Central Texas area during the next three months.

More immediately, there’s the threat of wildfires as the state dries out.

Partly in response to the looming drought, the Texas Forest Service convened a workshop in College Station last week to alert state and federal fire agencies about the threat, and to prepare.

“There are important indicators, however, that at least an active fire season is at hand,” said Todd Lindley, a senior forecaster at the National Weather Service office in Lubbock.

Rainfall late in the state’s growing season fed the growth of grasslands that are now drying out, which will provide fuel for any fires sparked.

Wildfires are common in Texas during these months as strong winter systems bring gusty wind conditions that can easily spread fires.

Forecasters expect a dry fall to continue this winter because of strong La Niña conditions in the equatorial Pacific -— where sea surface temperatures are cooler than normal — that typically leads to drier and warmer winters.

The warmth matters, too, when it comes to drought as warmer daytime highs increase the rate of evaporation, further drying the soil.

“As one moves northward into northern Texas, the signal for dryness is somewhat muted,” said Victory Murphy, a climate expert with the National Weather Service’s Southern Region Headquarters in Fort Worth.

In response to the drying conditions, 80 Texas counties have enacted burn bans, including Robertson, Coryell and Bell counties. McLennan, Falls, Hill and Bosque counties are not under outdoor burn bans.

Murphy said the agricultural impacts could also be acute if the drought persists. During the last major state drought in 2008-09, farming losses were estimated to be $3.6 billion by Carl Anderson, of A&M’s Agriculture Extension Department.

“This impact will need to be monitored very closely by dry land farmers as well as pasture and rangeland producers starting in the springtime when planting begins,” Murphy said.

But there’s no immediate threat to stream or river flows. Widespread, heavy rains helped Texas emerge from a drought late in the summer of 2009 and, through this past June, have raised water reservoir levels into good shape.

But absent spring rains or a few good, soaking tropical systems next summer, impacts on water usage and pumping may arise next April and May, when homeowners seek to green their lawns and farmers their fields.