This long-lived mesoscale convective event exhibited several radar-detectable hazards including localized heavy rain, hail (reflectivities 55-65 dBZ), strong winds (radial velocities exceeding 25 m/s) as well as a large Mesoscale Convective Vortex (MCV).

• Composite surface and IR satellite images (0527.00Z, 0527.12Z, 0528.00Z, and 0528.12Z) from the Unisys Weather archive. These composites are intended to give only a brief sketch of the weather for this case. They include a color-filled radar summary, surface conditions, frontal locations (bold lines), and pressure contours (thin blue lines).

The May 26 afternoon convection which had formed over west Texas and southeast New Mexico merged into an extensive nocturnal squall line that continued eastward through the night. During its lifetime this squall line displayed three bow-shaped segments with enhanced stratiform precipitation behind the line. The southernmost bow-shaped segment continued east-southeastward and eventually dissipated by 1500 UTC on the 27th while the northernmost segment moved on into southeast Oklahoma where it first weakened, then developed into an MCV. This slow-moving MCV persisted on into Arkansas where it eventually dissipated around 0000 UTC on the 29th. The MCV was certainly responsible for extending this event into a long-lived sequence of convective weather.

Relevant images:

• Infrared satellite images for the period 0526.2000 to 0529.2300 UTC (The 0529.0600-1100 images are missing).

• Selected surface charts for the early period of convection initiation on May 26: 1900, 2000, 2100, and 2200.

• Upper air charts (see image archive).

• Severe Weather Reports from the NWS/NCEP/Storm Prediction Center archive. Each panel includes all reports of tornadoes, hail, and damaging winds for a convective day (Day.12Z-NextDay.12Z).

• Reflectivity swaths consist of the maximum reflectivity value that passed over each grid point, accumulated over time at one-hour intervals. The closed black contours indicate the current positions of the 2-km NIDS radar echoes (convective systems). Colored circles indicate the position of the centroid of enclosed reflectivities with the size of the circle proportional to the enclosed area of echo greater than 25 dBZ.

  Above each two-dimensional swath image is a histogram that represents the NS-averaged value of RainRate (mm/hr) within a series of narrow (0.25 deg wide) longitude strips.

• Hovmoller diagrams consist of NS-averaged (EW-averaged) values of PerCent Echo, RainRate, and Reflectivity plotted as a function of time (UTC).

• Topographic heights and WSR-88D radar locations within the case study area.

• Composites of gridded Level II radar reflectivity for the period 0526.2000 to 0529.1800 UTC. These composites were constructed by taking the maximum value of all available Level II gridded datasets within 4 km, 6 km, 8 km or 10 km (AGL) deep vertical slabs. The overlaid contours are minimum heights (km AGL) of the 0.5 deg elevation scan surfaces from all the available radars. These height contours tend to be concentric around each of the radars whose datasets were obtainable from the NCDC Level II data archive.