Flash flood watches were in effect on Wednesday from eastern Texas to parts of West Virginia, as a slow-moving front and upper-level low drenched the corridor. It’s as if the atmosphere has hit the “repeat” button on the soggy pattern that brought record rains and flooding in February across much of this region.
The biggest threat for Wednesday into Thursday is localized flash flooding, especially where “training” bands of showers and thunderstorms may drop several inches of rain across a narrow strip. See the weather.com feature for regular updates.
One sign of the moisture-rich atmosphere flowing into the frontal zone: The 1.80” of precipitable water measured above Corpus Christi, TX, at 12Z Wednesday was the second-highest on record for any date in March across 65 years of radiosonde data. Another clue: the low temperature at Bush Intercontinental Airport on Tuesday was 73°F, which ties the warmest daily low ever recorded in Houston in March (a record set on March 19, 2012). Records in the Houston area go back to 1881.
Setting the (flood) stage
February’s rains helped lay the groundwork for the current flood threat by loading up the soil with moisture and filling many rivers and streams. The Mississippi’s Bonne Carré spillway near New Orleans was opened earlier this month for only the 12th time in its 87-year lifespan (see our related post). Moderate to major river flooding was affecting parts of eastern Louisiana on Wednesday. The Mississippi River at Baton Rouge crested at 43.48 feet last week, the ninth highest crest on record there and the highest water since May 2011.