Heat Wave and Severe Weather July 2006

Largest Power Outage in the History of St. Louis

PHOTOS COURTESY OF KMOV-4 AND POST DISPATCH

The Heat Wave

A deadly heat wave built across the United States during the third week of July 2006. Temperatures each afternoon topped out near or above the century mark with heat indices reaching above 115 F in some locations. In all, 22 deaths in 10 states were blamed on the excessive heat during that week.

Temperature and Heat Index Plot for St. Louis, Missouri

Highest Heat Index Readings During July 2006 Heat Wave

19 July 2006: Round One of Severe Weather

View a loop of radar reflectivity (4 MB)

View a loop of radar velocity (3 MB)

On July 19th, after reaching a high temperature of 100 degrees, a cluster of thunderstorms, also known as a mesoscale convective system, formed across Northern Illinois and propogated southwest across West Central Illinois and Eastern Missouri. The outflow boundary and the thunderstorm complex produced straight line winds or downbursts that created widespread wind damage from Central Illinois across the St. Louis Metropolitan Area and into the Eastern Ozarks. The damage sustained in the St. Louis Metropolitan Area was consistent with wind speeds between 70 and 80 mph. Areas of damage across Illinois suggested that wind speeds could have approached 90 mph. Two tornado tracks were also uncovered across Southwest Illinois near the towns of Bunker Hill and Edwardsville. Over 500,000 customers were left without power, and thus no air conditioning.

A State of Emergency was declared for the St. Louis Area, and Governor Matt Blunt called in the National Guard to help with heat evacuations and clean-up efforts from the severe thunderstorms. The temperature rose near 100 degrees once again on Thursday and heat index values were as high as 115 degrees in the affected region.

Wind gusts of 58 mph or greater on July 19, 2006

TIME (CDT) GUST (MPH) LOCATION COUNTY SOURCE

6:35 PM 92 1 NW Bunker Hill Macoupin, IL Trained Spotter

6:35 PM 88 2 NW Bunker Hill Macoupin, IL Trained Spotter

6:53 PM 63 Alton Airport Madison, IL Official NWS Observation

7:09 PM 62 Bethalto Madison, IL Emergency Manager

7:19 PM 59 Cahokia, Parks Airport St. Clair, IL Official NWS Observation

8:25 PM 92 Hillsboro Jefferson, MO Trained Spotter

STORM DAMAGE MAP: Wednesday July 19, 2006. M represents locations of microbursts and T signifies locations of
tornado touchdowns.

STORM DAMAGE PHOTOS FROM 19 JULY 2006

21 July 2006: Round Two of Severe Weather

View a loop of radar reflectivity (4 MB)

View a loop of radar velocity (3 MB)

Another complex of severe thunderstorms formed across Central Missouri during the morning of July 21st on the trailing end of an outflow boundary from overnight convection across Southern Iowa and Northern Missouri. This cluster of thunderstorms formed into a bow echo as they pushed across the St. Louis Metropolitan Area producing another swath of wind damage from Central Missouri to Central Illinois. To the north of the apex of the bow a strong circulation produced several tornadoes. This led to many additional power outages and complicated clean up efforts from the July 19th storm damage. Some people who had just gotten their power back from the previous storm suddenly found themselves in the dark once again. Power outages once again rose above 500,000.

STORM DAMAGE MAP: Friday 21 July 2006. M represents Microbursts and T Represents Tornado Touchdown.

STORM DAMAGE PHOTOS FROM 21 JULY 2006

National Weather Service Weather Forecast Office