Topic: Darwin and Top End Storms - mid to late December 2006

[Mike]

Greetings guys.  I thought I'd jump in and let you guys know about some sensational storms we've had here in Darwin over the past week - especially wed/friday just gone.  Initially here's some facts from wave of storms that hit us - total number of strikes for both storms in that week was around 1200+ -  624 alone in the 24 hours ending friday night!

We had storms roll through mid-afternoon coming in from the southeast.  This is where we generally get our cells from as they swing in from the gulf and sweep across Darwin on their way through. Although we've had some good storms develop toward the city, we've had NW sea breezes cut off any decent inflow to keep them aloft, but of late that hasn't affected them. On friday night we had an awesome display of lightning with multiple CGs and crawlers every 30 seconds.  My daughter and I witnessed an anvil crawler on the southern side of a storm over Darwin and it litteraly filled the entire base of the anvil and just kept discharged branches for at least 4 seconds.  My daughter and i could not beleive the amount of discharge, i was blwon away. The storm stayed to the north of darwin and lasted a good two hours.  The city did not receive too much rain but the light show was spectacular. I've got some photos, but as you guessed it, have not sent them to my work computer to post here, but i will!  Michael Bath has copies of them - so maybe he's posted them in the galleries, but haven't checked as yet.

We've had several low pressure troughs come up through NW W.A. and Central Australia and they're causing great instability for us in Darwin.  With the monsoon predicted early to mid-January we're being treated with some cool weather until it arrives (if it does!). There's increased convection to our north and over the next few weeks we'll see if that monsoon develops enough to come down.  We're in an el Nino stage for the development of cyclones this year which means we'll probably only see 3-5 develop and 60% chance of one developing near us - but most will be in the Gulf of Carpentaria.  Although you can't rule out anything because last year we had Monica and she was a cat5 and came on April 24 - generally late for cyclones to hit us!

Cheers 

[Jimmy Deguara]

Mike,

My friend Ray is also in Darwin and mentioned about the thunderstorm activity! Hope to see some of those pictures Michael Bath has - should post them in here.

Regards,

Jimmy Deguara

[Michael Bath]

Hope you can upload some of those photos soon Mike

It was very active - check the satpic loop from Friday 15th:



Nice overshoot on the last image in the sequence.

regards, Michael

[Jimmy Deguara]

Nice overshoot on second last and last image!

Good to see the north get some much needed action. The flow-on effect gets down to us as well.

Regards,

Jimmy Deguara

[David C]

Nice overshoot on second last and last image!

Good to see the north get some much needed action. The flow-on effect gets down to us as well.

Regards,

Jimmy Deguara

Good to see the Top-End firing up! As a general comment Jimmy, as you know overshoots are really not that uncommon. A persistent overshooting top is, however, a charactestic of an intense and more steady state updraft (usually mesocyclone). I doubt the updrafts with any of these Top-End storms would be long-lived.

[Jimmy Deguara]

David,

You are absolutely correct - definitely lacking windshear in northern Australia for persistent overshoots. I forgot to mention that the overshoots in each case were unlikely to be from the same cells in subsequent hourly satellite images.

Regards,

Jimmy Deguara

[Mike]

Here's a couple of photos i took in Darwin last Friday 15 December 2006 from Cullen Bay - about 2km from the city.  The lightning show lasted at least two hours and my only problem was deciding when to stop shooting!  I think we had around 1,120 strikes within the 24 hour period from Thurs night to Friday night - pretty cool i thought!

[Mike]

As you'd know we normally get single pulse storms here - litteraly - but now and then we get gulf lines that flow through from the Gulf of Carpentaria which give us a good rate of storm activity such as the ones last week.  Your'e correct about low wind shear - unfortunately there's just too many variables such as our evening sea breazes, weak shear that kill off our storms as they come close to Darwin.  I'd like some of the supercells you get in NSW, but that just won't happen.  I guess as a trade-off we get cyclones.  Appreciate everyone's input, learning a lot from it.

We are trying to discourage "we get this and you don't" in the discussions:) Easier to mention what you get. JD

[Mike]

My comment re 'trade off being we get cyclones' relates to the fact that we hardly ever see supercells in Darwin - not of the magnitude that NSW etc get. It's obvious that the NT is not the only one to get cyclones - that's fairly well known considering the unfortunate impact that Larry had in QLD. 

Our main aim is to keep the forum content informative - no explantions required:) So what else has happened up there in recent days? We'll give the title some dates. JD

[Mike]

Hey there Jimmy.  Well we've had quite a bit of rain over the past 48 hours.  We've had a trough hovering above the coast which is keeping the temperature down a little, but has created a nice dose of rain.  The occasional storm about, but nothing to be noteworthy.  Over the last 24 hours the northern suburbs have received the most rain - ranging from 40mm to 92mm.  We had one shower that produced 40mm in one hour yesterday in our suburb.  There is generous convective activity to our north which reflects the monsoon is building nicely for us.  The Met bureau predict that we'll get the monsoon probably as early as Monday 1 Jan or just after.  It was due early January at any rate, it's just a matter of waiting. 

It's been a very 'dry' buildup for us, but our average rainfall for the 3 month period to date is on cue with what we're supposed to get, thanks to a couple of lows hovering to our south and moving upward to us and now the trough.  So all in all we're expecting some decent rains for January with the monsoon.

[Jimmy Deguara]

Mike,

That's great news that the monsoon has begun to fire. I am assuming that the recent rains occurred over the past 24 to 48 hours? Be good to mention dates in your post.

What are the Bureau using as a guide to determine with such accuracy the start of the monsoon as being January 1st or soon anyway. What I am getting at is what determines when it is the actual monsoon or not given there was heavy rain recently?

Regards,

Jimmy Deguara

[Mike]

Hey there, sorry about the dates - they would be from 25 December to 27 December inclusive - you might as well add tonight also - steady rain again 27th December.

I've been trying to keep track on the tropical charts as to where the monsoon is.  Our weather explanations and satphotos show active convection gradually building and has been for about three days thus far.  The rain we're experiencing at the moment is not from the monsoon.  We usually get 'dry spells prior to the monsoon coming down and get the occasional afternoon storms, so i would suggest that this rain we're having now is just favorable conditions from other sources!

From what I have read in the media about the recent rain we've experienced and what the bureau says, quotes from the bureau to the media stated that the monsoon was due early to mid January because of the El Nino effect. Normally our monsoon would be with us by now in La Ninya or neutral phases - but all I can say is what I've said.  I used to have a contact within the met bureau but he is now down in Melbourne so I can't converse with him up here anymore.  He is aparty to the new maps, warnings pages you're now seeing on-line - so he's being kept busy.

The rain also here is not typical of monsoon activity anyway.  There's no squalls accompanying the rain which does happen with monsoon showers/storms.  From what the radar shows the rain is coming from the direction of the Gulf of Carpentaria but we do have a good NW wind flow which is typical when the monsoon is 'near' us but not 'with' us!


Hope that was help to you.  Unfortunately the monsoon troughs are very fickle in El Nino phases, but if the bureau says it's coming, then I'm with them.

Mike

[Mike]

Just an update for you re the monsoon.  There's more and more thunderstorm activity in the Indonesian archepelago to our north which indicates the monsoon is still gathering momentum. Indonesia is being hounded by flooding rains, so hopefully we'll see some of that rain and hopefully spread at least the the eastern states - they surely need the rain.  Most of the NW/NE flow is converging towards a LOW just outside Oz waters off the NW W.A. coast.  It's expected (with "") to develop into a tropical low within three or so days with the favorable conditions.  So far only a strong wind warning is current for that area, but windflow suggests that most of the moisture is heading towards it.



Cheers.

[Mike]

[attachthumb=#]

Another update for your re our monsoon.  Both WA and NT met offices say that there's ever increasing thunderstorm activity to our northern region.  The monsoon yesterday was posted as 'weak' but developing - but today the met office says the:

'monsoon trough is developing' which is always nice to read.

 We've had substantial prolonged showers - that means 'heavy' compared to normal storm showers - and only this afternoon in one hour we've had significant mm's of rain with several periods of strong downpours - yet another sign of the monsoon.  You can always tell up here when the monsoon is developing as the skies are blueish in colour and covered with immature storms.  The effect of a blue-grey background with white/grey Cbs hanging in the foreground - different but exciting!  From the tropical charts the flow is still NW/NE right across the Top End which is an indicator of monsoonal flow.

The only problem with the monsoon is that although you get storms - they're embedded within the rain bands and no good for photographing unless you like shots of blue green skies with lots of rain curtains - nuh!

No lows present thus far although the one off WA is still drawing most of the NW wind feed from Indonesia. That will no doubt hinder our monsoon as it sucks all the decent weather toward it - as always!

Oh, just on another point...heard on radio today from senior long range forcaster in NSW that the El Nino is waining.  He said the indicators are that the southern oscillation is weakening across the pressure trough from the Top End to Indonesia and this may indicate an early end to the drought affecting QLD/NSW.  He said probably within a week or so.   Let's hope indicators are on par and the eastern states get some much needed rain. 

Regards! Mike