Abstract: Between 1525 and 1610, a thunderstorm developed northeast of Broadford.  This storm appeared to become severe between 1530 and 1600, exhibiting characteristics similar to that of a supercell, which included strong inflow tail on the south side and a weaker inflow tail on the north side.  During this period this storm was rotating possibly anticyclonically. At approximately 1545, what appeared to be suction vortices developed below the main concentrated updraft area, effectively becoming a tornado.  The vortices appeared to touch down briefly at this time.  Still photos and video analysis show evidence of this.  After approx 1605, the storm rapidly weakened, leaving a narrow rotating column between the surface and middle levels.  This updraft column disappeared rapidly after this time, although the remaining anvil continued to produce precipitation.  The development took on the appearance of what could be described as a hybrid LP / HP supercell.

Location: The updraft core appeared to be located near Vicroads Country Directory Map 61E6, southeast of Broadford, west of Flowerdale.

Synoptic Description: At the time of the storm occurrence, a trough and associated complex low was traversing across Victoria.  It appears the Broadford storm developed near to the southwest or southern quadrant of the low.  The low pressure system itself was complex, with centres separated from the surface low in the middle and higher levels.  The low pressure system was slow moving and appeared to be cut off by a high pressure belt from the Bight to the Tasman Sea.

Broadford supercell from the east - Andrew McDonald

      

Left: Victorian visible image 4pm

Left: BoM enhanced satpic (time uncertain)  Right: BoM Victorian infrared 6.30pm

  

    AVN analysis chart 10pm

10am sounding text                                    10pm sounding text

Times appear when you hold your mouse over the image.