Event Timeline:
12:00 PM - 2:30 PM
Thunderstorm initiation occurred near Waco just before 12 PM on May 27th, right at the intersection of the cold front and meso-low. If you look closely at the radar loop, you’ll notice a speckled area of reflectivity extending to the southwest along I-35. This “fine line” is the radar sampling the density gradient (temperature contrast) along the cold front. Between 12 and 1 PM, this initial thunderstorm drifted southwestward along the cold front at perhaps 5 mph. Right around this time, the Storm Prediction Center issued Tornado Watch number 338 for the region due to the extreme amounts of instability present:
SEL8
MKC WW 271754 TXZ000-LAZ000-280000-
BULLETIN - IMMEDIATE BROADCAST REQUESTED TORNADO WATCH NUMBER 338 STORM PREDICTION CENTER NORMAN OK 1254 PM CDT TUE MAY 27 1997
THE STORM PREDICTION CENTER HAS ISSUED A TORNADO WATCH FOR PORTIONS OF
EAST TEXAS WESTERN LOUISIANA
EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 115 PM UNTIL 700 PM CDT.
TORNADOES...HAIL TO 3 1/2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
THE TORNADO WATCH AREA IS ALONG AND 125 STATUTE MILES EAST AND WEST OF A LINE FROM 25 MILES EAST OF COLLEGE STATION TEXAS TO 40 MILES NORTH NORTHWEST OF SHREVEPORT LOUISIANA.
REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNINGS.
OTHER WATCH INFORMATION... CONTINUE...WW 336...WW 337...
DISCUSSION...VERY LARGE HAIL/LOCALLY DAMAGING WINDS AND ISOLATED TORNADOES POSSIBLE THIS AFTERNOON IN VERY UNSTABLE AIR MASS /CAPE TO 5000 J/KG/ OVER REGION. ANY TORNADOES WILL LIKELY BE CONFINED TO BOUNDARY INTERSECTIONS GIVEN COMPARATIVELY WEAK VERTICAL SHEAR.
AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 3 1/2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
550. MEAN STORM MOTION VECTOR 27020.
This initial storm proceeded to rapidly intensify in the extremely unstable airmass. At 12:50 PM, the first Severe Thunderstorm Warning was issued for this storm for McLennan County (remember, the NWS issued “County Based Warnings” until October of 2007). As the storm approached the small town of Lorena, the radars in Fort Worth and Granger (not shown), indicated low-level rotation was increasingly rapidly, which warranted an upgrade to a Tornado Warning at 1:21 PM. Shortly thereafter, this storm produced its first tornado 5 miles southwest of Hewitt, or just outside of Lorena.
