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Hailstorm with spectacular shelf cloud: 26th March 2002
by Michael Bath

This was another day I had not paid much attention to until much later than I should have ! I guess the poor season in the Northern Rivers and a long time between decent storms contributed to the attitude.

An extensive trough system was through central NSW - part of an upper low that persisted over NSW for 5 days producing widespread rain and severe thunderstorms, eventually crossing the North Coast on the 30th. There was expectation for storms to form inland and possibly along the Great Divide today (and these did eventuate). AVN output indicated storms might form off the North Coast. Windshear was only marginal for assisting severe storms over the region, though upper temps were falling. There was reasonable backing of wind direction with height and the steering flow for storms was likely to be towards the ESE.

Thunderstorm cells developed in the Northern Rivers region from about 1pm and tracked slowly towards the ESE as was expected. At about 3pm I began to pay more attention to new development just west of Casino. Updrafts were persisting and strong, going up quite high and the anvil backshearing, though that was more an indication of the light winds aloft. Radar showed consolidation of a large thunderstorm over Casino, about 50km to my west.

McLeans Ridges 2.50pm McLeans Ridges 3.30pm McLeans Ridges 3.50pm

Dave Ellem was ready to go on chase but I was stuck home until 4pm. It was a tense time waiting to get the chance to head out as the storm cell grew larger and radar showed it had veered left - moving towards my location and Lismore. I eventually sped off to the lookout at Tregeagle about 10 minutes drive away and met up with Dave and his dad.

The storm was just to the SW and had developed a spectacular shelf cloud, the best I'd seen since October 2000 (apart from the Casino HP Supercell which is in a league of its own!). For a time, the shelf cloud base appeared to be circular with a partial inflow feature from the NE. This was prior to the onset of heavy precipitation. We watched the storm and base features evolve and slowly spread to fill the sky from S to N. The gust front was heading right for us. Intense precipitation was now falling along parts of the structure, but most intense near the centre. It was obvious this storm was producing hail. Thunder was becoming more frequent but only a few CGs were spotted. A spectacular arcus formation developed right near us minutes before the gusty strong winds hit from the SW (probably up to 75km/h - a gust of near 90km/h was measured in Goonellabah nearby). A funnel type structure was observed prior to the onset of intense rain and hail. A 2cm hail stone hit right next to me, so it was time to get in the car ! Dave's dad had left prior to the hail, so Dave and I positioned the chase vehicle to get some good footage. I estimate 30 to 40 millimetres of rain fell with continuous hail up to 3cm diameter, although most was around the 1 to 1.5 cm size. There was not enough hail for it to collect and form drifts so we headed off to keep within the intense precipitation area. We had only gone a couple of ks when the whole structure looked to be rapidly weakening. It was surprising to see the rapid weakening as the storm had been quite powerful just minutes earlier. We managed to keep near the leading edge of the storm and encountered some more bursts of heavy rain and hail in Lindendale and Wollongbar. Hail also occurred at my home at McLeans Ridges. By 5.30pm the cell had virtually dissipated.

Tregeagle 4.15pm Tregeagle 4.15pm Tregeagle 4.17pm Tregeagle 4.20pm Tregeagle 4.20pm Tregeagle 4.25pm Tregeagle 4.29pm Tregeagle 4.29pm Tregeagle 4.36pm Tregeagle 4.36pm Tregeagle 4.41pm Tregeagle 4.41pm Tregeagle 4.43pm Tregeagle 4.46pm

The following sequence was taken by Dave Ellem as the hail hit, and the funnel shaped feature was observed.

Tregeagle Tregeagle Tregeagle Tregeagle Tregeagle

These hail photos were taken at Lindendale, NE of Tregeagle

Lindendale Lindendale Lindendale Lindendale

The storm decays to the east:

McLeans Ridges 5.55pm

More storms approach from the WNW:

McLeans Ridges 6.25pm McLeans Ridges 6.50pm

During the evening, more storms moved in with brilliant lightning displays. These first three were taken by Owen Ellem at Wollongbar with a digital camera, the second group of three at McLeans Ridges by Michael Bath.

Wollongbar Wollongbar Wollongbar

McLeans Ridges 7.30pm McLeans Ridges 7.30pm McLeans Ridges 7.30pm

These photos were taken by John Bath at Ballina looking into the developing storm 20km to the west.

Ballina Ballina Ballina Ballina Ballina Ballina Ballina Ballina Ballina Ballina Ballina


Radar

From Bureau of Meteorology.

Looking at the radar is interesting as it illustrates nicely how the cell intensified near Casino, gathering up a nearby cell to its east, then veering markedly right of the other storms in the area. It also shows the slow overall movement of the storm. The 0550z to 0610z images show a very large storm cell with some supercell characteristics in the echo, though it very rapidly collapses into nothing.

  • Grafton local scale loop 0030z to 1230z 26/03/2002 (11.30am to 11.00pm local)
  • Grafton medium scale loop 0030z to 1300z 26/03/2002 (11.30am to midnight local)


    Satellite Images

    These image from CSIRO Marine Research

    Observed hailstorm is shown at 2.39pm and 5.39pm local at approximately 153E, 29S:

    NOAA satpic @ 2.39pm local NOAA satpic @ 5.39pm local


    Analysis Chart

    From Bureau of Meteorology.

    16/01/2002 06z


    AVN Model Analysis

    From NOAA 26/03/2002 06z analysis

  • Liftex Index
  • CAPE
  • Relative Humdity surface
  • Relative Humdity 850 hPa
  • Relative Humdity 700 hPa
  • Relative Humdity 600 hPa
  • Relative Humdity 500 hPa
  • Relative Humdity 400 hPa
  • Relative Humdity 300 hPa
  • Temperature (C) surface
  • Temperature (C) 850 hPa
  • Temperature (C) 700 hPa
  • Temperature (C) 500 hPa
  • Temperature (C) 300 hPa
  • Winds (knots) surface
  • Winds (knots) 925 hPa
  • Winds (knots) 850 hPa
  • Winds (knots) 700 hPa
  • Winds (knots) 600 hPa
  • Winds (knots) 500 hPa
  • Winds (knots) 300 hPa


    Document: 200203-01.html
    Updated: 30th April, 2002
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