Rain sets record

Published 12:00 am Monday, December 6, 2004

[12/6/04] With Sunday’s rain, Vicksburg broke a 37-year record for annual rainfall and above-average precipitation is forecast for the year’s remaining 25 days.

Vicksburg recorded 1.37 inches of rain in the 24 hours that ended about 6 a.m. today, bringing the total for the year to 75.33 inches so far.

That’s .87 inch more than the National Weather Service-reported total for 1983, 74.46 inches, its highest yearly recorded total here since 1967.

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Rainfall measurements from gauges in various locations around the city have been kept since at least as far back as 1880, but are published only for the past 37 years.

Also, numbers differ on at least some monthly measurements and on the all-time record for rainfall in a year here.

For example, a set of records accessible through the U.S. Army Corps of Engineers’ Vicksburg District shows a gauge here received 87.03 inches in 1983, 12.57 inches more than the NWS’ total.

In order for this year’s total to break that record, 11.7 more inches of rain would have to fall in December. That amount would be shy by 0.8 inch of the NWS’ 37-year record for a December, so it’s possible but not likely, said Dr. Barry Keim of the Southern Regional Climate Center in Baton Rouge.

Based on the long-range weather forecast for December, “there’s a high probability that you will have more than” the 37-year average for December rainfall, 6.12 inches, said Keim, who’s primary job is climatologist for Louisiana.

The city has just completed its second-wettest November since 1967, according to the NWS, with 10 inches of rainfall during the month. That’s more than twice the average for the month since then, 4.83 inches, and within an inch of the 37-year record for the month, 10.85 inches, set in 1987.

The largest known all-time record rainfall for a November was 14.70 inches, set in 1970.

Monthly rainfall totals for the year had already included a near-record-setting June and one of the wettest Mays since 1967.

June rainfall measurements for Vicksburg have been reported as 11 inches, by Keim, and 11.31 inches, from previously accessed records. A previously reported all-time record for June was 9.96, from a measurement for 1909 on which data disagree.

Even the lower measurement for June 2004 would have also broken that record, but even the higher would not have broken the highest all-time high known to have been reported, 11.59 inches from 1957.

The highest rainfall total of this year was recorded in May, when 12.74 inches fell, Keim said. That was the second-wettest May on record since 1967, he added. The wettest was 13.23 inches, set in 1983, Keim said. Different data say May 1983 rainfall here was 15.35 inches.

If long-range forecasts are correct the city is in for an unusually wet December, January and February, Keim said.

“The long-term forecast for the winter is being influenced by a developing El Nio,” Keim said, referring to the weather system that the National Oceanic and Atmospheric Administration defines as “a disruption of the ocean-atmosphere system in the Tropical Pacific having important consequences for weather and climate around the globe.”

“It’s been building for the past four to five months,” Keim said. “It’s not strong yet, but it has the potential to develop into something stronger. Generally, under El Nio, the Southeast is wetter and colder than normal.”

And the heavy rainfall this year has not been just local. Mississippi, as a whole, averaged 9.83 inches of rainfall during June, making it the wettest such month since statewide records began being kept in 1885, Keim said.

Louisiana, a state that generally gets more rain than Mississippi, got 11.34 inches during that month, and Texas 6.23 inches, making June each of those states’ third-wettest June on record, Keim added.

For one city’s gauge to show record rainfall is common, but for the same to occur across “a vast area across Mississippi and Louisiana is just phenomenal,” Keim said. The phenomenon also played out across East Texas, he added.

Vicksburg’s official yearly average rainfall number is 57.99 inches, slightly different from the sum of the monthly averages, 57.47 inches, since complete data by month is not available for all years since 1967, Keim said.

Measurements have been taken from rain gauges in various Vicksburg locations through the years. Current official measurements are taken at the city water plant on the harbor.

Previously, the city’s official gauge had been in the Vicksburg National Military Park.