Topic: NSW & SE QLD Rain, Flooding and Storms: 18-25 April 2008

[Michael Bath]

Rainfall totals for the 24 hours to 9am 21 April included a few over the 50mm mark at some Mid North Coast locations including Coffs Harbour and Taree. Noosa Heads in SE QLD topped the list with 72mm though heavy falls in that region were isolated.

Rainfall at my place for this event so far:

16/4  6.8
17/4  4.0
18/4  39.8
19/4  47.4
20/4  33.0
21/4  5.4

Total 136.4mm

April to date: 280.4mm on 12 days
YTD 983.4mm on 75 days.

GFS has unstable conditions over the NSW Northern Coast and SE QLD the next four days (CAPE around 1,000) though this is likely to change quite a bit if a low forms off the coast. We should see scattered thunderstorms over fairly wide areas.

[Matt Pearce]

Coffs Harbour's 56mm to 9am today was its heaviest April rainfall in nine years while Taree's 2-day total of 118mm is its highest 2-day total for April on record (records only go back 10 years though).

[Harley Pearman]

Overnight, further rainfall occurred across Sydney resulting in some large variations between suburbs. Some suburbs were drenched while others almost missed out.

Some comparison rainfall totals for the period from 9 am 20/4/2008 till 9 am 21/4/2008 (24 hour totals).

Bexley 56 mm (Highest for Sydney)
Canterbury 47 mm
Cronulla 33 mm
Bankstown 23 mm
Sydney city 22 mm
Parramatta 22 mm
Prospect 18 mm
Seven Hills 14 mm
Avalon 10 mm

The heaviest falls have not wholly been on the coastal suburbs. Instead the heaviest falls have been in a narrow band stretching from Cronulla and in a line NW through Bexley and Canterbury to an area just south east of Parramatta.

To highlight this further, Canterbury has had 90 mm of rain in the past 7 days from 9 am Monday 14/4/2008 until 9 am 21/4/2008 making this suburb the wettest in Sydney for the past 7 days.

Sydney's outer west missed out on most of these falls during this 24 hour period with Penrith receiving 6 mm, Warragamba dam 6 mm and Richmond 4 mm.

There are currently moderate to heavy rain cells on the NSW Central coast and lower to mid north coast which is likely to result in some reasonable rainfall totals over the coming few hours in the affected areas.

Harley Pearman

[Steven]

Quite a few updrafts have done up close to the coast today and tonight especially, dumping some large drops and the occasional thunder and lightning, so it looks as if the models are forecasting possible thunderstorms until Thursday at least.

[Michael Bath]

Spotted some lightning to my west early evening but the storms did not last long. A few cells reached a strong intensity on radar W and NW of Bris last night but again they did not last long. Could have been some small hail in those.

The Upper Low over NSW continues to produce interesting weather !

[Harley Pearman]

Moderate to heavy rainfall continues across the Lower North Coast and Central Coast and some reasonable rainfall totals have occurred.

In the 24 hours from 9 am - 21/4/2008 to 9 am - 22/4/2008, Mona Vale on Sydney's northern beaches scored the best rainfall for Sydney being 34 mm of rain.  Falls across the rest of Sydney were significantly lighter and concentrated more within the northern areas. Just beyond Sydney's northern fringe, some solid rainfall totals include (All from looking at BOM rain gauges and weather stations):-

Kangy Angy 80 mm (Highest in NSW).
Kincumber 58 mm
Peats Ridge 55 mm
Wyoming 53 mm
Gosford 52 mm.
Brooklyn 39 mm.

These are the highest falls and clearly the Gosford Wyong region scored the heaviest falls for this period.

Throughout the day, the showers have tapered off for Sydney and eased on the Central Coast. Showers and rain has contracted northwards. However, the Lower North Coast between Taree and Newcastle has scored the best falls from 9 am to 7 pm (22/4/2008) such as.

Wootton 38 mm.
Taree 35 mm.
Nabiac 32 mm.

Highest totals.

Other centres in this region have received anywhere between 20 mm and 38 mm for this period.

It is interesting to note that the rain band in this is rather narrow and approximately 100 to 150 km wide but continues to stream onto the coast in a regular fashion. The rain hits the Great Dividing Range only to leave a rain shadow on the western side. Very little if any of this rain is going inland. It is limited to the coastal areas only.

Harley Pearman

[Rodney Wallbridge]

Gyday all, observed a Thunderstorm 75kms away 45kms SSW of casino according to radar just after sunset.I set up my gear at home to try my luck. These images are resized, uncropped using a 70mm at F2.8 The cell appeared to be riding a convergence line along the Richmond Range.It was of medium size in height, I enjoyed the show!!!
 
 
 
 
  

[Richary]

Reminds me of the 3 years I spent at Coraki between 1979-81 (last 3 years of high school). Used to get some great storms, either close or off in the distance. And at the same time shows I am getting old :-)

[Michael Bath]

A couple of pics taken from home of storms that developed off the Tweed Coast after 10pm. The clouds were illuminated quite a bit by the moonlight. Lightning was fairly infrequent with only a few bolts spotted - and not much in-cloud lightning either.

[Michael Bath]

ABC report:


Wild weather hits Darling Downs
Wednesday April 23, 2008 - 08:38 EST
An aged care centre has been damaged, residents evacuated and power cut to thousands of homes after a wild storm lashed southern Queensland's Darling Downs last night.

Two residents were evacuated from the Blue Care aged care centre at Warwick when a lightning strike blew out windows and brought down a tree on the building.

Earlier, powerlines came down across houses at Mt Thysen west of Toowoomba, and at 10:00pm AEST a woman was injured when her car and a semi-trailer collided at a city intersection where traffic lights were out.

Ergon Energy spokesman Andrew Fox says 8,000 homes lost power.

"It was quite nasty last night from the number of outages that resulted," he said.

Residents are reporting rainfall totals up to 75 millimetres.

[Michael Bath]

Interesting cell on Gympie radar at present - this just issued:


SEVERE THUNDERSTORM WARNING - SOUTHEAST QUEENSLAND
for DAMAGING WIND and LARGE HAILSTONES

Issued at 2:46 pm Wednesday, 23 April 2008.

Thunderstorms are moving towards the east. They are forecast to affect Gympie and the area north of Gympie by 3:50 pm. Damaging winds and large hailstones are likely.

[Steven]

Quite interesting MB.

Currently there's an isolated cell just sitting in the same place for the last hour, it has gone into max intensity but haven't been hit by anything yet.

I think it moved slightly westwards but it's very isolated and I can see the stars just above me, I'll get back to you if something else arises.

Steve

[Michael Bath]

Should be some more thunderstorm action over SE QLD/ NSW NSW today though offshore seems more likely.

Some heavier falls have occurred over the Hunter and Mid North Coast regions the past 24 hours - the latest BoM warning:


NSW SEVERE WEATHER WARNING
for Flash Flooding
For people in
Midnorth Coast and Hunter Districts.

Issued at 9:15 am on Thursday 24 April 2008

Synoptic Situation: 6:00 am EST Thursday
A low pressure system is developing off the Mid North Coast of NSW. The low is expected to deepen further during today before beginning to move away to the southeast on Friday. Heavy rainfall is
expected to continue over the Mid North Coast and parts of the Hunter coast until Friday morning.

Currently the heaviest rain is falling from near Smoky Cape down to Seal Rocks, with some heavy showers also in parts of the Hunter. Laurieton has recently recorded over 50mm in an hour. This
rainfall combined with recent falls, is likely to cause flash flooding.

Since 9am Wednesday heaviest rainfall totals include: Laurieton 110mm, Port Macquarie 99mm, Cooranbong 100mm and Onley Forest 89mm [the last two are in the Hunter Valley].

A Flood Warning has been issued for the Williams River.

A Flood Watch is current for the NSW Mid North Coast from the Bellinger River to the Karuah River Valleys.

[Richary]

I'm hoping the flooding doesn't get bad as I am supposed to be driving up to Coffs Harbour tomorrow. Fingers crossed it won't cut the highway anywhere...

At this stage Minor to Moderate river flooding is possible along the following
river valleys between Thursday evening (24/4) and Friday evening (25/4):
 
1. Bellinger Valley
2. Nambucca Valley
3. Macleay Valley
4. Hastings Valley
5. Camden Haven Valley
6. Manning Valley
7. Karuah Basin

[Michael Bath]

Quite a few streams are in flood this morning though typically in the minor to moderate range: Hastings, Manning, Paterson and Williams Rivers, for Wyong/Tuggerah Lake and the Myall River at Bulahdelah.

Highest 24 hour rainfalls to 9am 25th April include:

Elands 134
Mt Seaview 137
Comboyne 176
Taree 139
Wootton 150
Upper Landsdowne 218

Further north some weak thunderstorms developed on the northern side of the low furing the afternoon and evening of the 24th. With 500hPa temps around -20 there was bound to be some more action. The most significant cell rapidly formed out to sea off Jacobs Well (SE Brisbane area).  I took these shots at home 120km to the south between 8.35pm and 8.40pm with the zoom lens at 200mm. F5.6 400 ISO.







(wasn't able to post last night due to the website being down)

MB