Australian Severe Storms, Weather Events and Storm Chasing

[Harley Pearman]

Useful rains fall in drought affected areas 10 and 11 April 2009

On Friday and Saturday 10 and 11 April some useful rainfall mainly in the form of shower and thunderstorm activity fell in some of the drought affected areas of the Murray Darling Basin. In particular, the better falls fell upstream of the Hume Reservoir and the upper catchments of the Murray River and nearby rivers. While individual shower and thunderstorm cells were hit and miss, enough activity occurred which resulted in a broader area receiving something from the weather event.

This is important because any runoff occurring can be captured by the Hume Reservoir for storage and later use. Given that the Hume Reservoir is holding 3.57% capacity as at 13/4/2009 (Goulburn Murray Water), this will help the water situation.

Some of the better falls to have fallen 10/4/2009 include:-

Albury Airport Borella Road - 8.4 mm, Dartmouth Reservoir - 14 mm, Falls Creek - 13 mm, Hume Reservoir - 17 mm, Hunters Hill - 12 mm, Jingellic - 20 mm, Jingellic Creek - 12 mm and Khancoban - 18 mm.

Rutherglen SW of Albury received 10 mm.

Charlottes Pass received 11 mm and Thredbo received 10 mm.

Areas west of Rutherglen and Howlong received much lighter totals or nothing from the weather event.

On 11/4/2009, the same region received further totals which has further wet the upper Murray Catchments including:-

Albury Airport Borella Road site - 6.4 mm. After sunset, a large thunderstorm cell collapsed over the Nail Can Hill Range west and north west of Albury which would have dropped higher rainfall totals over the hills and rural areas however there are no weather stations in the areas affected to record the event so actual totals will not be known.

Batlow - 17 mm, Cabramurra - 21 mm, Charlottes Pass - 22 mm, Dartmouth Reservoir - 6 mm, Hume Reservoir - 6 mm, Hunters Hill - 2 mm, Jingellic - 24 mm, Jingellic Creek - 28 mm, Khancoban - 18 mm and Thredbo 29 mm.

Many of these places are situated above the Hume Reservoir and the rainfall will help in this region.

Again, areas to the west received nothing and many places continue to await usefall rain.

The rain plot for the Murray Darling Basin is provided below for the week 5 to 12 April 2009. It has been generated from the Bureau of Meteorology site "Land and Water" at:-

http://www.bom.gov.au/cgi-bin/silo/rain_maps.cgi

The plot also shows another inland region of New South Wales within the same river basin receiving good rainfalls being central inland to northern inland New South Wales however the plot also shows the south west of the basin receiving nothing for the week.

Harley Pearman

[Michael Bath]

Some heavy falls have developed through parts of SE QLD in particular today - warning just issued by BoM:


SEVERE WEATHER WARNING
for Heavy Rain and Flash Flooding
For people in coastal areas of the Capricornia, Wide Bay, Burnett and Southeast
Coast districts
Issued at 2:35 pm on Monday 13 April 2009

Synoptic Situation: A surface trough lies near the Capricornia and southeast
Queensland coast, and is likely to deepen overnight before moving away from the
coast during Tuesday. An upper level trough lies over the southern Queensland
interior.

The combination of these two trough systems is expected to produce areas of
heavy rain with localised flash flooding and stream rises for the rest of today
and overnight for coastal and Hinterland areas of these districts. The rain is
expected to ease on Tuesday. 

Recent Events: 190 millimetres of rain has been reported in 3 hours around the
Bustard Heads area, near Bundaberg.

A Flood Warning has been issued for coastal streams between Rockhampton and the
Gold Coast.

[DanTheMan]

I'm in Nambour, and so far since 9am at 5.00pm we have had 47mm, but its still quite heavy outside and theres some heavier stuff heading my way on the radar, creek behind the house is flowing rather nicely! Plenty of thunder too.

[Michael Bath]

Latest charts have a low forming near Fraser Island tonight which moves south before a rapid SE heading during Tuesday. Mesolaps charts attached for +24, +30 and +36 hours

27mm here since 9am today with most of that falling between 3.30 and 4.30pm.

[Richary]

While Sydney has been relatively unaffected by this event there were some localised flooding problems on the roads this afternoon such as Artarmon, Green Square and the M5 tunnel. Originally the rain was supposed to start Saturday but apart from a few spits nothing really happened until this afternoon.

The rain has mainly been coastal rather than over the catchments, Sydney Airport was probably the pick with 71mm since 2pm and about 60mm of that falling in 3 hours. By contrast here at Rydalmere I have only had 12mm though it was raining heavy enough from about 5:30 until recently that you wouldn't have wanted to be outside.

Interestingly the current RTA warnings include flooding on the Harbour bridge between the toll plaza and southern pylon, it must be bucketing down in town if it can't run off the bridge with that slope. Hope it doesn't drown our radio gear on top of the pylon, too many steps to climb for that one!

NEW 8:12pm
Dawes Point - Sydney Harbour Bridge between Southern Toll Plaza and Southern Pylon
Adverse weather - Flooding
Initial report
Lanes Affected:    Northbound
RTA advice:    Exercise caution
Other advice:    Water is affecting lanes 1 and 2.

[Antonio (stormboy)]

a huge mass of clouds are cluttering together to form this...

[Shaun Galman]

Hi all,
Great to see a few good totals around the states (other then the annoying flash floods here and there).

I had a check of the rain gauge at my mums place and for Sunday (12th of April 2009) we received a nice 21mm and for yesterday (Monday, 13th of April 2009) we had a further 36mm in town, much to the dismay of the 6000+ tourists that came for the Easter Goat Races.

Totals varied out on the fields however. The Four Mile (West of town) only had 25mm yesterday and Grawin (45k's West of town) only had 6mm in total!

Nice to see but it is still very warm this afternoon, also extremely humid. Feels very stormy now, the skies are clearing fast now. I guess a storm might pop up in the coming days if all goes well.

Kindest regards,
Shauno.

[Richary]

Nice lightning active storm to my SW currently (down near Liverpool I would guess), mainly seems ICs with a few bolts shooting out. Unfortunately low cloud between me and it is obscuring the view somewhat, though the radar track looks like it might be intensifying and heading my way. Only to yellow on the radar at the moment though.

[DanTheMan]

That bit of cloud ended up giving me 134mm, not bad, that brings this months total to 470mm!! And its only the 14th! Lets see if we can hit the half a meter mark.

[Richary]

The Sydney storm is staying to my south, still very lightning active but unfortunately the low cloud is still hanging around in the way of it. It has now been severe warned as well, occasionally touching red on the radar loop.

DETAILED SEVERE THUNDERSTORM WARNING
for LARGE HAILSTONES, FLASH FLOODING and DAMAGING WIND

For people in parts of the
Sydney Metropolitan area.

Issued at 6:49 pm Tuesday, 14 April 2009.

The Bureau of Meteorology warns that, at 6:50 pm, severe thunderstorms were detected on weather radar near Holsworthy and Liverpool. These thunderstorms are moving towards the east. They are forecast to affect Sutherland, Bankstown and Hurstville by 7:20 pm and Sydney City, Sydney Airport and Sydney Olympic Park by 7:50 pm.

Large hailstones, very heavy rainfall, flash flooding and damaging winds are likely.


Could be fun at the Easter Show!

[Harley Pearman]

Sydney rainfall totals

Late Monday 13/4/09 some moderate to heavy rainfalls occurred over South East Sydney. The big falls occurred on suburbs close to the coast with some coastal suburbs receiving over 60 mm. Further inland falls tapered. Around 16 mm fell where I live in Blacktown.

Further west from Blacktown, rainfall totals were below 10 mm.

The rainfall plot below taken from the Bureau of Meteorology site 'Land and Water"shows where the rain fell across Sydney. It shows the heaviest falls being concentrated to the south east of the city. The plot is for the 24 hours 9 am 13/4/09 to 9 am 14/4/09.

http://www.bom.gov.au/hydro/flood/nsw/sydney_metro.shtml

The thunderstorm occurring over Sydney 14/4/09 is well to the south east of Blacktown and the cloud tower is well hidden by low cloud. I have seen lightning flickering in the top part of the cloud before it became obscured. It will not be possible to take photos of it due to the amount of low cloud in the area. The storm is moving ENE mainly across the southern parts of Sydney.

A friend of mine reported to me some rain (no hail) starting to fall at Ashfield at around 7.10 pm plus a thunderclap but nothing significant.


Harley Pearman

[Richary]

Hmmm, just got the edge of the rain here. But looking at the bureau 24mm in 17 minutes at Bankstown and 18mm in 9 minutes at Sydney Airport. Shame about the low cloud as it is still lighting up the sky pretty well but nothing to see directly. Various local flooding issues on the RTA website.

Tried some shots early on while it was still half light before the other cloud got in the way but nothing worthwhile.

[Matthew Piper]

I was right in the path of the severe storm that crossed southwest Sydney this evening. Most notable for me was the duration of the hail which lasted at least 10 minutes or so. It was however only small, around marble size at best. The wind and rain was also intense and I am not surprised at the 27mm which Holsworthy reported from the storm. The thunder from this storm was almost all very short and sharp and without the long rumblings most storms have. This I would say would indicate it had almost 100% CG type lightning at the time it was passing over me. All in all a nice surprise to have at this time of the year and an apt way to mark the 10th anniversary of the April 1999 Sydney hailstorm.

[vrondes]

Yes Matt and Richary, it certainly was a decent storm for this time of the year. Some nice base and cumuliform structure photographed before outflow terminated any further shots. Some nice greenage observed and non stop but short duration lightning, had to keep the mossie repellant packed on, so many mossies being next to the parramatta River, even more alert now with reports of Ross River virus found in mosquito traps on the Georges river at Alfords point,

1st photo showing some pileus as it started firing up,



2nd and 3rd shots showing some nice intra cloud lightning illuminating the convective towers





4th shot of a cg on the southern boundary



5th shot showing the hailshaft



last two shots with cgs illuminating the base





Cheers, Con.

[Harley Pearman]

The thunderstorm passing over the Bankstown Airport (Southern Sydney) has given a good snapshort as to what happened in the Bankstown area. The data from it is sourced from Weatherzone and it reveals how intense the thunderstorm was:-

Bankstown Airport Readings 14/4/2009 during the thunderstorm event

Time             Wind speed     Wind gust         Temperature           Rainfall

7.00 pm         28 km/h          44 km/h            18.1C                    Nil
7.02 pm         30 km/h          63 km/h            17.4C                   1.6 mm
7.05 pm         57 km/h          78 km/h            16C                      6.8 mm
7.10 pm         50 km/h          78 km/h            15.1C                   Not available
7.11 pm         30 km/h          78 km/h            15.1C                   20.8 mm
7.13 pm         30 km/h          76 km/h            15.9C                   23.2 mm
7.17 pm         41 km/h          65 km/h            16.6C                   24.4 mm
7.20 pm         35 km/h          65 km/h            16.3C                   Not available
7.21 pm         35 km/h          65 km/h            16.4C                   24.6 mm

The thunderstorm was over by 7.21 pm at this weather station but when looking at this it reveals that:-

The storm lasted approximately 19 minutes and 24.6 mm fell giving a rainfall intensity of approximately 74 mm per hour.

Between 7.05 pm and 7.13 pm, 16.4 mm fell in 8 minutes giving a rainfall intensity of 2.05 mm per minute which equates to a rainfall intensity of 123 mm / hour albeit briefly.

Between 7.05 and 7.11 pm, 14 mm fell in 6 minutes giving a peak intensity in this period of 2.3 mm per minute which would result in a peak rainfall intensity of 138 mm per hour. That would co incide with the peak intensity of the storm over this weather station.

Maximum peak wind gusts reached 78 km/h between 7.05 and 7.11 pm at this weather station site.

Given that hail was reported in some locales, this storm did have an impact on parts of Sydney and the Bankstown Airport Weather Station has captured it well.

The details are from Weatherzone (Information lifted from the Bankstown Airport Weather Station Database)

The rainfall plot below provided from the Bureau of Meteorology further shows rainfall from the event across Sydney. Rainfall is limited largely to southern Sydney with the heaviest totals around Glenfield, Bankstown then onto the Airport and La Peruse. The highest rainfall overall occurred around the Glenfield - Bankstown area (25 mm to 29 mm).

Some showers occurred after the storm hence the other totals. Another shower occurred over Bankstown after the storm and the total topped out at near 26 mm. Generally the path of the thunderstorm is reasonably clear. Some light shower activity occurred around the Blacktown to Parramatta area but northern and much of Western Sydney completely missed out.

The rainfall plot provided is found at http://www.bom.gov.au/hydro/flood/nsw/sydney_metro.shtml
Bureau of Meteorology "Land and Water site" for the 24 hours from 9 am 14/4/2009 to 9 am 15/4/2009.

Harley Pearman