Link to NWS Louisville Science and Technology Homepage WSR-88D Images of the April 16, 1998 Large Hail and Tornado Event
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During the afternoon of April 16, 1998, a cluster of thunderstorms developed and moved east across south-central Kentucky. One particular storm, a large severe supercell, produced wind damage, very large hail, and tornadoes across parts of Logan, Warren, Barren, Metcalfe, and Adair counties. Baseball size (2.75 inch diameter) hail was reported over Logan and Warren counties. The hail produced major widespread damage to many cars, homes, and other structures in the city of Bowling Green with damage estimated in the hundreds of millions of dollars. Tornadoes also occurred in several counties. F1 intensity tornadoes were reported in Logan and Warren counties with F3 (major) tornadoes in Barren and Adair counties. Many homes and other structures were damaged or destroyed in Barren and Adair counties with some damage in Metcalfe county as well. The following series of Doppler radar images from the NWS Louisville WSR-88D shows the evolution of this severe supercell thunderstorm.
WSR-88D Image 1 of April 16, 1998 Severe Weather Event

This image is a reflectivity vertical cross-section of a large severe thunderstorm in northwest Logan county in south-central KY (about 85 miles southwest of the radar site). Cross-sections show the vertical structure and distribution of heavy rain and any hail within thunderstorms. In this case, the storm exhibited a deep, large mass of very high reflectivity values (dark red, pink, and small purple colors) suspended aloft (15000 to 35000 ft) in the storm. This is indicative of a strong, cyclonically rotating updraft (mesocyclone) and large hail within the storm. This large hail later reached the ground with baseball size hail reported.
WSR-88D Image 2 of April 16, 1998 Severe Weather Event Ten minutes later, base reflectivity data at the lowest radar elevation showed the large severe thunderstorm over northern Logan county. Very heavy rain and hail were occurring in this area (in the red colors). Although the storm already was a supercell, some classic low-level traits were not clearly evident at this time. Nevertheless, the storm possessed a mesocyclone at this time which was associated with an F1 tornado.
WSR-88D Image 3 of April 16, 1998 Severe Weather Event The storm moved east into Warren county (just west of the city of Bowling Green). Dark red and pink colors indicated that large hail was in progress at the surface. On the southern edge of the storm, a weak echo region (blue and green colors) started to appear coincident with the rotating updraft. Large hail was occurring just north of the weak echo region/mesocyclone.
WSR-88D Image 4 of April 16, 1998 Severe Weather Event Fifteen minutes later, the storm tracked across Warren county and Bowling Green. Widespread large hail, some baseball size, was occurring in the city coincident with the pink colors on the reflectivity image. In addition, a "hook echo" and weak echo region now had become clearly evident on the southern flank of the supercell storm, just south and east of the large hail (pink color) area. An tornado that produced F1-F2 damage was reported in this county.
WSR-88D Image 5 of April 16, 1998 Severe Weather Event As the storm moved into eastern Warren and western Barren counties, it continued to exhibit classic supercell characteristics. A well-defined hook echo was present on the southwest side of the storm with very heavy rain and large hail just north and east of this area. Lighter rain extended well to the northeast of the severe portion of the storm. A tornado was in progress at this time.
WSR-88D Image 6 of April 16, 1998 Severe Weather Event This storm-relative velocity (SRM) image shows wind flow directed toward (green) and away (red) from the radar located about 70-75 miles to the north of the area shown. A strong mesocyclone was indicated along the Warren, Barren, and Allen county border (i.e., bright red colors immediately next to light green colors). This location was coincident with the hook echo/weak echo region in the reflectivity image above. The tornado was in progress in this region. Across southwest Barren county, a broad light green area was indicative of strong storm-relative flow into the mesocyclone, which is important for enhancing the severity of the storm.
WSR-88D Image 7 of April 16, 1998 Severe Weather Event The supercell moved east across Barren county still showing a hook echo and curved appearance along its southern edge. Storm-relative flow into the storm continued from the south. A strong mesocyclone (not shown) was present within the hook echo's weak echo region (yellow and small green colors). An F3 tornado was reported in Barren county near the city of Glasgow. Hail continued just north of this area (darker red colors).
WSR-88D Image 8 of April 16, 1998 Severe Weather Event As the storm moved across northern Metcalfe county, it appeared to weaken temporarily as the hook became more diffuse. Nevertheless, the storm remained severe with wind, hail, and an F1 tornado reported.
WSR-88D Image 9 of April 16, 1998 Severe Weather Event As the supercell moved into Adair county, the areal extent of red colors lessened giving the appearance of a weakening storm. However, forecasters are aware that radar sampling issues must be considered for more distant storms. Also, a closer inspection again showed a definitive hook echo and weak echo region on the southwest side of the storm in north-central Adair county. The storm generated a tornado with up to F3 damage in Adair county.
WSR-88D Image 10 of April 16, 1998 Severe Weather Event The corresponding storm-relative velocity (SRM) data at this time showed a strong mesocyclone in existence over north-central Adair county (red/outbound colors immediately next to the light green/inbound colors). The mesocyclone was coincident with the hook in the reflectivity image above and with the tornado on the ground at this time. The storm slowly weakened as it continued east during the evening of April 16.

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