West Texas wildfire. (Photo: Texas Forest Service)
(May 10, 2011) - National Weather Service forecast offices and River Forecast Centers have been gearing up for the third leg of a triple crown of disasters consisting of continuing drought and wildfires in the west, a record-breaking tornado outbreak in the South and record flooding along the Lower Mississippi River.
"The southern United States is widely known as having some of the world's most active and severe weather," said Bill Proenza, regional director, National Weather Service Southern Region. "But even in this region, the recent confluence of major, high-impact, back-to-back weather events is exceptional. While each event in itself presents major challenges, the combination has and is providing an extraordinary test of our field offices' capabilities. I am pleased to report our protection of life mission delivery has been outstanding due to their timely warnings."
More than a dozen forecast offices in Texas, Louisiana, Oklahoma and New Mexico have been providing numerous fire warning products and/or direct on-site weather support to incident commanders as drought-spawned wildfires continue to plague the region.
Particularly hard hit is Texas, where 75 percent of the state is in either extreme or exceptional drought as depicted by the latest U.S. Drought Monitor. Since November 2010, the Texas Forest Service has responded to 9,500 fires that destroyed hundreds of homes and burned more than 2.3 million acres and cost the lives of two firefighters. And there is little hope of quick relief as NOAA's Seasonal Drought Outlook indicates the drought is likely to persist at least through July.
Between April 25th and the 28th, more than 200 tornadoes, affecting eight southern states, were confirmed. During that period, at least 17 National Weather Service forecast offices issued more than 650 Tornado Warnings for portions of Texas, Arkansas, Louisiana, Tennessee, Mississippi, Alabama, Georgia and Florida.
The average warning lead time for the entire event was 21.6 minutes; and the lead time for April 27, the deadliest day of the outbreak, was 27.1 minutes, well above the national average of 12 minutes. Despite the exceptional warning times, more than 300 deaths were confirmed during the event. Following the outbreak, National Weather Service assessment teams conducted more than 80 damage surveys to determine the number, size and strength of the tornadoes. At least three EF-5 tornadoes, the strongest category, and 12 EF-4 tornadoes were among those identified. To view track map, visit: http://www.srh.noaa.gov/srh/ssd/mapping.
Heavy snowpacks in the Midwest resulted in higher than normal flooding on the upper Mississippi and Ohio Rivers. This flooding combined with numerous heavy rainfall events throughout April and led to major to record flooding on the lower portion of the Ohio and the middle Mississippi River valleys. As the flood crest continues to move downstream, severe main stem flooding is expected along the Lower Mississippi River; and major tributaries may also be impacted.
A new flood of record has already been recorded along the Mississippi River at Tiptonville, Tenn. with a crest of 48.4 feet; and at Caruthersville, Mo. which reached a crest of 48.1 feet - both topping records set back in 1937. Moving forward along the Mississippi:
- A crest of 48 feet (Flood Stage: 34 feet) was forecast for Memphis, Tenn. on May 10 (Flood of Record: 48.7 feet in 1937)
- A crest of 56.5 feet (Flood Stage: 44 feet) was forecast for Helena, Ark. on May 12 (Flood of Record: 60.2 feet in 1937)
- A crest of 53.5 feet (Flood Stage: 37 feet) was forecast for Arkansas City, Ark. on May 15 (Flood of Record: 59.2 feet in 1927)
- A crest of 64.5 feet (Flood Stage: 48 feet) was forecast for Greenville, Miss. on May 16 (Flood of Record: 65.4 feet in 1927)
- A record crest of 57.5 feet (Flood Stage: 43 feet) was forecast for Vicksburg, Miss. on May 19 (previous Flood of Record: 56.2 feet in 1927)
- A record crest of 64 feet (Flood Stage: 48 feet) was forecast for Natchez, Miss. on May 21 (previous Flood of Record: 58 feet in 1937)
- A record crest of 65.5 feet (Flood Stage: 48 feet) was forecast for Red River Landing, La. on May 22 (previous Flood of Record: 62.3 feet in 1997)
- A record crest of 47.5 feet (Flood Stage: 35 feet) was forecast for Baton Rouge, La. on May 22 (previous Flood of Record: 47.3 feet in 1927)
National Weather Service Hydrologic Services Chief Ben Weiger says the crests are not just one day events. "Crests along the Lower Mississippi River are expected to be broad multi-day crests and any future heavy rainfall could also prolong the flooding."
State and local emergency managers, officials and citizens living along the Lower Mississippi are likely to be dealing with the initial and post-flood impacts of this historic flood event for days and weeks to come.