Well, here we go.
February 2009 is off to a warm and windy start. Sound familiar? Go back a year, and one will find a number of events between February 5th and the end of March. For reasons behind the "wind machine", click here. How are things shaping up through mid spring (February to April) in 2009? Read on!
It doesn't hurt. The last La Niña, which occurred generally from September, 2007, through May, 2008, likely contributed to a rapidly developing Texas drought, as well as an increasingly active spring storm track across the central United States, aiding what would be another busy tornado and severe thunderstorm season after one of the most active - and deadly - springs on record in 2008. Should the general storm track pan out as shown above, dangerous severe weather and tornadoes will likely stretch from north Texas and Oklahoma eastward through the lower Mississippi Valley, stretching northeast into the western Ohio Valley. Current indications suggest that a weak to moderate La Niña has developed this winter, and is forecast to continue through spring and perhaps linger into summer. Sound familiar?
U.S. Seasonal Drought Outlook, February through April, 2009.
For updated information on La Niña and El Niño any time of year, click here. For continuous updates of all things drought, from a national perspective, visit the U.S. Drought Portal.
- Drought. As seen in the figure at lower left, much of Texas will see drought persist, with the Lower Rio Grande Valley showing drought development. The potential storm track (above) would increase the speed of drought development by maintaining persistent strong winds, above normal temperatures, and frequent dry air intrusions behind associated frontal zones containing little rain. Combine these weather conditions with the Valley's low latitude (and high sun angle), as well as normally drier soils, and there is potential for extreme to exceptional drought to develop in some areas by March or April. Continue to monitor our drought information page throughout the spring for updates.
- Wildfire Growth Potential. Needless to say, the combination of strong winds, above average temperatures, and below average rainfall will continue the occasional threat for erratic and rapid wildfire growth. More worrisome is the expectation of occasional intrusions of very dry air behind weak cold fronts, which sharply reduce relative humidity, sometimes below 10 percent. This dry air can reduce fuel moisture levels toward the point of auto ignition, which, if combined with a period of gusty winds, can create explosive development and spread of a wildfire. Such a fire can begin with an innocent spark. March and April would be favored, as temperatures warm, allowing humidity to plummet more rapidly and frequently.
- Severe Weather. A fast moving storm track mainly across Oklahoma and points east and north, will tend to keep the necessary deep moisture and atmospheric energy well north of the Lower Rio Grande Valley, similar to the spring of 2008. However, one can never rule out a break in the pattern at an opportune time - allowing for a storm track to dip a bit farther south, providing an influx of deeper moisture into the area, and setting the stage for severe weather in the form large hail and perhaps a tornado. More likely, the primary severe weather threat will be from downburst winds along squall lines ahead of cold fronts.