Topic: Deadspots!

[striker92]

Hi guys
I'm new here so ill give you a rundown.
My names Mark I'm 15 and i love storms especially lightning, Ive seen one tornado and it was the same storm that inspired my passion for storms.
i was just wondering if anyone here has noticed the deadspots that seem to exist around NSW. Where i live in albion Park near shellharbour, we never seem to get good severe storms, only a few serious lightning shows and they are usually more in the general direction of shellharbour,cananyone tell me why this happens and as I'm very limited to my chasing potential id like to know any areas which seem to receive lots of good storms.
i do have some photos of a good lightning show, I'm not sure if they are anvil crawlers but there is one CG that was very close, seemed to travel horizontally and then decided to decimate a large tree near my house. unfortunately i dint know how to post them so could someone please tell me how thanks.
cheers for now, mark

[David Brodrick]

It's a very interesting question. Perhaps there are 'livespots' as well as deadspots. Over the past few years I've noticed that Rowena/Bellata seems to get a lot more action than we do in Narrabri and that's only about 50km away on similar terrain.

Someone emailed me the following question the other day, in reference to the effect of the 150,000 Ha bushfires that we had in the Pilliga Forest a couple of months ago. I haven't thought of a reply yet, what do others think?

We have noticed over a long period of years that after a major fire event in the forest, south and west of us, that the storms that normally come straight over us seem to  divert west and east around the fire areas, resulting ina  lower rainfall than usual as much of our summer rain is from storms.  We were wondering if anyone else has noticed this pattern?

[striker92]

I'm beginning to think that it may have something to do with the terrain of my area, where i live i have the great dividing range to the west, a large uplift area called stockyard mountain to the south and another large hill to the east, it would be best described as a closed end valley, what affect would this have on storm activity in my area,in regards to the second question posted were these storms occurring whilst the fires were burning or before and after, if they were occurring whilst the blazes were active the strong updrafts from the heat of the fire would repel all but the most powerfull of storms fires have been measured with updrafts of up to 200 kph!

[tohnanon]

I have been thinking the same thing, I am on a peninsula in NT, GOVE,and we get alot of cyclonic/ monsoonal weather, some old guy said we are safe here as it is on a penisula and all the cyclones go around. I have watched many storms reach land and form south of us, build up and go around and fade to almost nothing. This happened about 8-9 days straight we only got minor rain and some distant lightning/thunder. The first storms of the year were big enough to break thru and we got massive storm activity early morning, but I believe this area is a deadspot, and not to far from here is surely a wetspot.
Here is a build up of one of the drifting storms

[striker92]

hey again
with the monsoonal  weather systems, they seem to build quickly over the water then develop just of the coast, once these Storms hit land due to their (usually) high intensity they dissipate once isolated from their energy source, your description of the deadspot seems very similar to mine, it  seems to take a powerfull storm to break through the seemingly "dead " areas, its very frustrating as you probably already know!
cheers mark.

[Michael Bath]

Michael Thompson may have some comments about local conditions at Shellharbour !

Without doubt, topography plays a big role in where storms will form and how likely they are to survive once they move from that area. Conditions along the elevated terrain of the Great Divide are often quite different to the coastal areas. Convergence is quite common and will help develop storms that have no hope on the coastal plains. A storm moving off the ranges often encounters cooler sea breezes. This would be very pronounced where you live as the escarpment is so close to the sea.

You also have to consider the prevailing steering winds. Have there just been lots of days where windshear keeps the storms on the ranges ?   Certainly have been in NE NSW this season.

As to inland areas not influenced by hills and mountains... land use / vegetation type (or lack of) would create uneven heating and perhaps more favoured areas for initiation of convection. The storm setup takes over from there.

What do others think?

[Mike]

Howdy, firstly to Tohnanon re cyclones off Gove.  The tracks that northern cyclones are extremely erratic.  Gove and Nhulunbuy are MORE prone to being hit as you are on the outer coastline exposed to the Gulf of Carpentaria where the majority of the tropical lows develop once over water there.  (as you have one now!) 

Since 1970 there have been over 11 cyclones that have tracked around or through Gove and that part of the coastline and it was because of 'favorable' steering winds that these systems did not reach you head on.  That area has had 4 x Cat1, 6 x Cat2 or stronger and 1 x Cat5 (Monica last year).

The past cyclone tracks over the years actually show that Gove is in a very favourable position with cyclones that track westwards along our coastline, being in a peninsular does not mean cyclones will not pass through there or less prone - remember it's the steering winds and the monsoon trough movement that dictates where the cyclones track, not the shape of the coastline!

Gove is not really a 'deadspot' - in fact Nhulunbuy actually has a more constant rainfall average than Darwin because that area sees fairly good rain/showers even during the dry season.. A lot of the 'gulf lines'  form from the Gulf and drift westwards and then NW to us here in Darwin.  I will research some more and get some other info for you.

Mike

[Mike]

Hi  Michael.  Yes, absolutely i agree with your post re vegetation/topography affecting weather/storm/convection.  I was here in Darwin 18 years ago when there was little or no expansion of housing estates in the Palmerston area and without fail you would get afternoon storms from 4pm - that is Territory fact and legend!

However, since moving here six years ago again there has been a definite reduction in the amount of storms following the same track they did back then - which is due to many, many houses being built within the same areas those storms came through on.

 My friend in Humpty Doo, about 40km from Darwin, has always mentioned that there are less storms passing 'though' his property since they started clearing land and building.  Vegetation releases oxygen into the atmosphere - we've all seen the affects of rainforest decimation and the impact it has on the weather in those areas.

Certainly mountanous areas would benefit evaporation due to the air masses flowing up the sides of the mountains and condensing thus forming rain droplets, but with flat areas with vegetation cleared it does - and has- had a reduction in convection certainly up here.

So yes, i'm all for that argument and will defend it as I've seen the weather patterns change since housing estates popped up. 

Certainly the worst thing that these housing estates create is their own 'weather patterns'.  Cities create their own weather simply by the fact that they generate an enormous amount of heat into the atmosphere around them - that can either be beneficial or detrimental.  One such housing estate is built here in a sloping area facing where the storms come through and these new houses get absolutely hammered by wind as they've built the houses in a natural terrain 'tunnel' and the wind just howls through there from storms.

Mike.

[striker92]

Thanks alot guys this is really interesting.
The main thing i have noticed is the seeming "corridor" if you like that occurs in my area, from just south of Wollongong to just north of kiama there is a pronounced area of stunted storm activity. I have also noticed some massive storms building, then as if to further frustrate me shift away and realease their fury elsewhere. Certainly though in my area it is very rare to get a large amount of storms, but the ones we do get are very powerfull, they seem to hit the uplift zone behind my house backbuild then spill over With amazing speed and ferocity. More then once i have watched transfixed as a huge cell or once or twice the odd squall line marches over the ranges or mountains. The majority though as Michael said they seem to spill over and die in no uncertain terms.
Still its a blessing as well as a curse, when a storm does roll through i know I'm in for a show, it sort of increases the excitement to look forward and forward and forward until finally you get the "big one"

Cheers and thanks for the posts guys keep em coming
Mark

[striker92]

Also
Regarding housing and cities generating their own climates and conditions:
Observations made in one of the hangars where NASA service their fleet of shuttles have been found to indicate the development of Microclimates and weather patterns withing the hangar.
So a development like housing,roads and land clearing all expose more nice flat thermodynamic areas for lots of solar energy to be stored and eventually released, want proof. Go outside at about 9 at night after a warm day and feel the bricks or road surface. I can guarantee that even if you have been lucky enough for a storm to come through and soak you, there will be heat stored in the surfaces, now imagine thousands of houses and roads, with nice heat absorbant tiles and beautiful black surfaces. The heat transmission would be huge, and the dynamics of the areas weather would most definatley be altered. Imagine the strength of the thermal currents over these areas. There is no doubt that this sort of topographic alteration would affect local weather systems.

[Mike]

And just for more proof - we have an LNG gas plant and a electricity plant near each other and at night the LNG plant has a cloud over it that is produced by the vapour and heat generated from the generators!!!  Although non-toxic of course, they're making their own clouds at night when the air temperature is cooler but they're pushing warm moist air above them - whala - clouds!

Mike

[striker92]

He He
That's amazing but still very possible, i observed the same affect from our hot water system, albeit on a much smaller scale, just think of the microscopic storms we could be causing every day.......
the same applies to your breath on a cold night the mist when you open the freezer and of course those great storm clouds

[Mike]

Re deadspots for Gove...

The storms that form in those are generally formed and steered from the SE during 'break-in' periods during the monsoon.  Unless they form over land right over Gove they will generally be steered away to the coast by these winds.  As i said, the Gulf Lines are probably the more common storm lines that produce rain and storms right over Gove as they're travelling from the East to the West across that part of the country.  The dead spot you refer to is generally the lull between the monsoon - we get them here in Darwin - no sun, lack of warming, too much moisture - ie no 'single' storms!


Mike

[tohnanon]

The storms, not monsoonal, I have observed build up south of us as they hit a greater land mass then the peninsula and move west over land and into a bay area and then further to another area that has frequent storms. I see the build up over the bauxite plant here from the steam power station that supplies power to the plant and the surrounding towns, its an interesting point about how industry creates its own climate. I dont think this effects the greater powers of mother nature but in some ways influences as the amount of heat produced to convert bauxite to alumina is great. I believe the land mass of the area is less than the areas that gather these smaller storms and the winds blow them across the land as the winds tend to blow in from the water and being cooler than the red dirt that provides natural heat. Alot of these formations have been very interesting to watch and to see them only 10ks away and we dont get a drop of rain at the plant. At the moment we are in typical monsoonal weather and the clouds have so many layers and tend to go along way into the sky with 4 -5 different layers of brilliant formations, will try get some photographic examples.

[Mike]

Tohnanon, yep that's exactly what I meant.  Gulf line storms - forming in the south and moving to the west.  These storms actually continually to mature as they pass over land to us here in Darwin.  A lot of our midnight or early morning showers/storms come from those gulf lines - even in the dry we get some, but not often. 

But I know what your'e saying - even with no monsoon the storms you observe are just convecting away from where you are that's all.  We get storms all the time out in the rural area and you can see them going off, but as they do they travel East-West.