Storm Australian Severe Weather Forum
Severe Weather Discussion => Tropical Cyclones, Typhoons and Hurricanes Worldwide => Topic started by: Mike on 30 December 2007, 07:01:32 PM
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It's official as of today Sunday 30th Dec. The low edging toward Gove is officially going to be called Helen. It's currently sitting over Jabiru and rapidly intensifying. A severe weather warning is being pre-issued to residents of Arnhem Land, Cape Don and Nhulunbuy to our east. We've got big tides and winds are currently gusting at Jabiru at 90kmh. As the low moves east it is dragging with it southerly winds filling the void left by the low as it moves. It's expected to move into the Gulf of Carpentaria by new years day into favourable conditions. It has a lot of moisture and thunderstorm activity to feed off from the northern parts. I don't know what the trade winds are doing at the moment and until it forms properly it will be a monitor situation on its path.
At the moment in Darwin we've just gotten our taste of the monsoon rains - absolutely pelting down with gusty winds for the last hour or so. Some debris is on the road from leaf litter from the winds and rain squalls. You can tell its monsoonal because the rain sheets come sideways at you!
BoM SWW #1 at http://www.bom.gov.au/cgi-bin/wrap_fwo.pl?IDD20040.txt
GIF wind stream also supplied - nice bit of circulation happening!
30 Dec....As for the low...things a little up in the air as to what it's going to do. From looking at the maps it's not showing much in the way of organisation later in the week, although BoM regard Tuesday coming as a moderate chance of forming. The computer models don't agree after that....:(
Mike
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Jeepers you'd never know it that we're under a cyclone watch! Awoke today to find this!
TROPICAL CYCLONE ADVICE NUMBER 2
Issued by the BUREAU OF METEOROLOGY, DARWIN
at 2:00 pm CST [1:30 pm WDT] Thursday 3 January 2008
A Cyclone WARNING is current for coastal and island communities from Mitchell
Plateau in Western Australia to Daly River Mouth in the Northern Territory.
A Cyclone WATCH is current for coastal and island communities from Daly River
Mouth to Goulburn Island, including Darwin and the Tiwi Islands.
At 12:30 pm CST [12:00 pm WDT] a Tropical Low was estimated to be
155 kilometres north of Wyndham and 345 kilometres west southwest of Darwin and
moving west at 11 kilometres per hour.
There is the possibility that the low will develop into a TROPICAL CYCLONE
tonight, and GALES could affect coastal and island communities between Mitchell
Plateau in Western Australia and Daly River Mouth in the Northern Territory
overnight or early tomorrow morning.
Heavy rain is expected to cause flooding in the north Kimberley region from
tomorrow.
Details of Tropical Low at 12:30 pm CST [12:00 pm WDT]:
.Centre located near...... 14.1 degrees South 128.2 degrees East
.Location accuracy........ within 55 kilometres
.Recent movement.......... towards the west at 11 kilometres per hour
.Wind gusts near centre... 80 kilometres per hour
.Severity category........ below cyclone intensity
.Central pressure......... 995 hectoPascals
Weather is pretty tame at the moment, overcast as usual mild winds and intermittent showers, but nothing associated with the pending cyclone at the moment. She's heading westerly at the moment beneath us - quite a contrast from the last few days as she was heading easterly all week. The low is around 995 but is expected to become a cyclone tonight to the west of Darwin, hence our watch issued. It's the first time I've actually not actively watched a system considering i'm always harping on about them!!! My interest is understandably sparked!
MIke
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See Mike, even the weather can catch us under our guard!
PJ
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Indeed it does. I had been watching the low as it was forming near Jabiru to our south, but with the lack of storms to chase - in fact lack of anything to chase - i've been doing other things and not really monitoring it. All expectations were for the low to track eastward toward the Gulf to Queensland - which it is still forecast to do - but this system has been a headache for the BoM to forecast. It is very erratic in its movements and as shown by the map posted it did a complete U-turn and decided to do other things.
I'm not too concerned at the moment with it as far as impact, the bureau advises that they still are waiting to see what it will do in the next day or two. There are no winds to speak of note and little rain. But as the low moves closer to us we'll see an increase in precip and winds as one would expect. It's small and just sorting itself out. A CAT1 will be its only fame for us unless it moves NE into a more expanse of water where things will dramatically change no doubt.
I'm hoping for some gusty storms with this system. It has the potential for 50kt gusts tomorrow or Saturday and will be out and about as soon as there's any hint of storm activity associated with this system as it moves east across us. The majority of the larger lightning borne storms have been to my south and east around 100km away of late. With some 'cleaner' air down these parts some excellent storm structure should be had.
The general attitude around Darwin is one of 'wait and see' and no-one is really too concerned about Helen at the moment. (something that is all too common even with larger systems I'm afraid to say...)
Satpic included with 4 very large storms in the southern parts and the low can be seen west of Darwin. I'd like a few of thos bigs cells closer to Darwin I must say and the low might just provide some beauty's. Radar imagery from wyndham where the low is situated just east, you can see the circulation and large rain bands.
UPDATES: Radar animation here http://radar.strikeone.net.au/?fuseaction=loops.main&radar=633&numberofImages=10&dateStart=1199327400&dateFinish=1199363400 for the last 10 or so hours. There have been regular monsoonal shower bands associated with the low to our east coming from the NW. If the low does reach CAT1 status and move in its anticapted eastward track then Darwin will be still feel the effects of it, but where I live and further down to Adelaide River about 90km to the southeast will feel the winds a little stronger i suspect. The rain bands are moving quickly through the region and dumping a lot of rain in the short bursts.
I'll attempt to keep everyone up to date as things happen. The watch is still in effect but no firm actions are being taken just yet, the bureau is advising within 48 hours but not before 24 hours for any immediate action by residents. The low is still very active and the central pressure is decreasing every three hours or so. Their biggest concern is if the low moves NE toward Darwin overnight.
Latest BoM advice:
TROPICAL CYCLONE ADVICE NUMBER 5
Issued by the BUREAU OF METEOROLOGY, DARWIN
at 11:00 pm CST [10:30 pm WDT] Thursday 3 January 2008
A Cyclone WARNING is current for coastal and island communities from Mitchell
Plateau in Western Australia to Daly River Mouth in the Northern Territory.
A Cyclone WATCH is current for coastal and island communities from Daly River
Mouth to Goulburn Island, including Darwin and the Tiwi Islands.
At 9:30 pm CST [9:00 pm WDT] a Tropical Low was estimated to be
145 kilometres north northwest of Wyndham and
390 kilometres west southwest of Darwin and
moving west southwest at 4 kilometres per hour.
The low remains slow moving and may develop into a TROPICAL CYCLONE later
tonight or tomorrow morning, before moving eastward towards the Top End of the
Northern Territory.
GALES could affect coastal and island communities between Mitchell Plateau in
Western Australia and Daly River Mouth in the Northern Territory later tonight
or early Friday morning.
If the system were to take a more northeast track, there is the possibility that
GALES could affect coastal and island communities between Daly River Mouth and
Goulburn Island, including Darwin and the Tiwi Islands late on Friday or on
Saturday.
Heavy rain is expected to cause flooding in the north Kimberley region tonight
and tomorrow.
Details of Tropical Low at 9:30 pm CST [9:00 pm WDT]:
.Centre located near...... 14.2 degrees South 127.8 degrees East
.Location accuracy........ within 46 kilometres
.Recent movement.......... towards the west southwest at 4 kilometres per hour
.Wind gusts near centre... 80 kilometres per hour
.Severity category........ below cyclone intensity
.Central pressure......... 990 hectoPascals
Mike
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I must admit Mike, I was a little surprised when it moved into the Timor Sea, since the BoM had been saying it had a high chance in the Gulf of Carpentaria. Ah well, as someone else said, the weather (especially Cyclones in Aus) can be unpredictable!
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2am advice has the low changing direction yet again, this time to the N/NW at 7km/h. Looks like it's wanting the warm waters in the Joseph Bonaparte Gulf/Timor Sea. Will be one to watch with the 5am advice.
Mike
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You can slightly see the centre of the system on the radar up in that area, it seems to still be heading northwest atm.
I looked at the SST's in the area, and wow - bloody warm....
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Seems our sneaky low pressure system has had the BoM guessing since it moved west. Information from the BoM reveals that this low has defied all the computer models as to where and when it would move, if at all. They have been scratching their heads for the last week trying to work out where it would go, but as nature has it, this low has not done what the computer models predicted.
Darwin is now included in a cyclone warning for a CAT1 system. Apparently the low has been under the influence of a ridge in central Australia which has been steering it westward. what the low wanted to do was to be under the influence of a very strong monsoonal flow. It is now taking advantage of the monsoon and has headed northwest and is expected to shift more easterly later this evening and move with the monsoon steering winds which would bring it right across the Darwin region or just below.
It is still under cyclone status at 80km/h winds near the centre, but this is set to increase to 120km/h later on as the low organises itself further now it is over water. It is what the low wanted to do all along but with a dominant easterly wind flow it was hindered from doing so.
Panic buying in the shopping centres as you would expect, they always leave it to the last minute up here...
Latest advice here (pending the 11am local time update) http://www.bom.gov.au/cgi-bin/wrap_fwo.pl?IDDP0002.txt and included is latest satpic and track map. JTWC gives a favourable environment for further development and agrees with BoM as to current scenarios at https://metocph.nmci.navy.mil/jtwc/warnings/sh1008web.txt
Mike
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It's named Helen now.
Looks like it moved a little north as well. Not really visible on the radar anymore.
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BoM have upgraded the rating to CAT2 by the time she nears the coast. She's certainly liking the warmer waters and has increased its track speed to the NE @ 16km/h. She should make landfall around 10pm tonight or early morning on 5 Jan. I'm out to tea this evening but will be keeping a close eye on what is going on and get some photos before then on the coast. Should be an interesting evening! Radar images farily messy, even the Wyndham radar is one mass of showers - but you'd expect that - she's compact! I'm waiting in anticipation for an eye to develop...
Mike
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Mike, I hope you get to your dinner reservation ok.
Also, if this current cyclone system heads further east into coral sea waters, could it go higher than Cat2 in rating? Is there enough warm waters to help it increase strength, IYO?
PJ
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Dinner will be fine - it's with another couple at their house but we'll be done by 10pm so i'll be out most of the morning trying to capture some shots and also any lightning in the outer bands. From what the bureau says it will cross over the NT and into the Gulf of Carpentaria where it will reform to cyclone status. This area is a breeding ground for big cyclones - depending on what happens with the monsoon and how long it takes to reach the gulf there's no reason why it should not track across to the Coral Sea. The monsoon is set to weaken somewhat by this time next week for us, but from the maps the trough will still be over QLD. Do you think QLD would want more rain!?
Currently compressing some pics I've just taken from the coast - unreal!
Mike
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BoM advice just issued states we'll feel the affects of Helen within the next 6 hours - most notably 100-130km/h winds. She is intensifying as she edges towards the Darwin-Daly region and Darwin itself.
http://www.bom.gov.au/cgi-bin/wrap_fwo.pl?IDDP0002.txt and loop with rain bands flowing through (another as I type!) http://radar.strikeone.net.au/?fuseaction=loops.main&radar=633&numberofImages=13&dateStart=1199413800&dateFinish=1199431800
The wind is gradually strengthening even in my area which is in the path of Helen, we're only 22km from Darwin but her track directs her wind range right over us. Radar imagery shows her on her way....
Mike
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Good luck with it, hope you get some great photos, have a fun time, and don't suffer any damage. Closest I have been to one was at Lismore years ago (about 1980) when it if had held it's track it would have come down over us in another 18 hours or so, but it turned NW and hit Maryborough in QLD instead. Still had winds getting up enough we tied down all the loose iron etc on the farm.
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Here's some technical data on shear, low level convergence, upper level divergence models from http://cimss.ssec.wisc.edu/tropic/real-time/shemi/winds/wgmsdvSW.html
Mike
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TC Helen chase report 5 January 2008
Summary:
TC Helen made landfall between 11pm and 1am on Friday morning near Port Keats to the southwest of Darwin. Its structure was a little weaker than I had expected given its CAT2 status. Rain bands were very widely spaced and the only major lightning was to the SE and NE of the actual system. The NE sector produced a lot of lightning for the first 3 hours as the convective band swept across the areas of Cape Don and Black Point some 400km away. I suspect that her entering a landmass had hindered her efforts to gain further strength and she was moving quite quickly between 16-20kts for most of her journey towards the NT coast.
There was no distinguishable eye throughout her movement on radar or satpics, the rainbands circulating around the centre were wide and seemed to detach somewhat from it. Given more time and more ocean she would have definitely gotten more organised. From about 5am there was little or no rain to speak of, although Batchelor and Adelaide River would have borne the brunt of the central winds of 130kmh as the 'eye' passed directly over Adelaide River which is a township around 90km to the SE.
Winds arrived in Darwin as she moved closer and she was only 180km away to the south of us. Heavy squalls and rain lashed Darwin itself and consistent wind gusts accompanied them. The winds lasted for approx 6 hours from 2am-6:30am when the there was only moderate winds and a graduall easing. The system was approx 80km to the south at 7am and still a CAT1. Observing the white low level clouds, they were just amazing to watch as they streaked across the sky under a blanket of blue/grey. Their movement was so fast I could not keep up with them even driving at 80kmh!!!
Damage
I keep telling people up here that are pretty complacent (long time locals also) that even a CAT2 can cause serious damage. Driving around in the early hours I could see major damage to some properties from very large Mahogany trees, which being shallow rooted and with the aid of two weeks of wet weather, really did cause the major damage as the toppled over. Some of these trees were over 20m tall and just as wide - death traps in reality. A strong band embedded with thunderstorm outflows aided the strong gusts in this area.
Powerlines were down in the suburbs Nightcliff and Parap. Nightcliff sustained the most carnage. Being right on the coastal areas it is open to stronger winds coming off the ocean. Many trees were felled across the roads in this area and other areas towards Darwin that are on the coastal fringe also sustained lots of debris and felled trees. Most traffic lights in the northern areas were out and i believe power was lost to most of the areas here also.
Surveying the damage I could not help to wonder what if this cyclone was stronger - CAT4 perhaps - there would be just chaos. The trees that Darwin has are just minefields for damage to occur. People still parked their cars on the roads next to big trees that were accidents waiting to happen! Trees in Darwin are large, old and really the wrong type whoever planted them. Palms were all still standing, it was the gums, mahogany and other species that got flattened even with 100kmh winds on the coast. I dread to think what would have happened if the winds reached 250+.
All in all a great chase experience. A sureal sensation as one sits in the open hearing the relentless howl of the wind, knowing that it won't let up for a very long time until daylight. The rain was nothing out of the ordinary, I've actually seen heavier falls with severe storms in Darwin, it was just coming in waves as you'd expect with the bands flowing through.
I hope I've given some interesting facts and accounts during the cyclone for members.
'When's the next one'!!!
* Photos of damage I will post here simply because the event is over and for simplicity of viewing members. Am compressing them now to attach....
Mike
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Some more photos. Not too much structural damage to houses, but the ones that the big trees hit did so. I'm sure there's some cars that got hit in other side streets considering the amount of large tree types that were pushed over.
Mike
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Mike,
It certainly must be a case of large trees, wet and weight of water in leaves and soggy ground -the combination - uprooted trees. Still you have to have severe winds to do this much damage.
Regards,
Jimmy Deguara
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Indeed. I've just been out for another drive-by sussing out the damage around the city - the coastal areas by far have been hammered. The only other time I can remember whilst living here with this much damage to trees was TC Gretel way back in 84-85 and she also was a CAT1-2.
I told a fib earlier about no palms being uprooted - just found a 15 metre Cuban Royal palm upended onto a fence!! These things are sturdy as and it has shifted 2 metres from where it was planted! Insane stuff.
Honestly, anyone who lives in Darwin and is complacent about cyclones - especially CAT3-5's should think again how dangerous these winds can be from the amount of downed trees. If Monica had hit last year in the cross-hairs on Darwin with 360kmh winds it would be a wakeup call to everyone here, the amount of damage would be terrible.
Mike
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Last lot of shots that i took yesterday along the coast, These trees were obliterated by the winds - BoM think some of the gusts may have been 140kmh near her centre - these trees were not uprooted, simply blown apart! Helen is expected to form in the Gulf as a CAT1-2 cyclone again by Tuesday. She's hiking along at a rate of knots just east of Gove now.
My favorite shot is the busted stump and limbs in the foreground to the proud palm still standing - kinda looks like a cathedral!
Mike
* some info just in via email courtesy Greg Browning, Severe Weather Section, Bom here in Darwin re Helen. (it's Queensland's baby now they say!)
Extra details
Helen crossed the coast 130 km southwest of Darwin near Channel Point.
Channel Point Observers recorded 975 hPa at 10:47 pm Friday night, their maximum wind estimate was 60-70 km/hr.
At 09:13 AM 5/01/2008, Lori Chappel wrote:
TC Helen crossed the coast as a Category 2 last night (Friday night) near 10pm.
Gales were experienced at Charles Point lighthouse from 7pm to 4 am (8-9 hours), max wind gust 120 km/hr at 130am.
Darwin airport experienced gales intermitantly from 1030pm, then consistently from midnight to 3 am. Max gust 102 km/hr at about 2am.
Point Fawcett on the Tiwi Island experience gales briefly 9-10pm.
Rainfall in the Darwin area has been 30-50 mm ( 24 hrs to 9am Sat)
Highest rainfalls have been in the path of the TC, Adelaide River Township area and the Douglas Daly area have been 150-200 mm. ( 24 hrs to 9am Sat)
Kakadu (Jabiru, Central Arnhem) has recorded 100+ mm ( 24 hrs to 9am Sat)
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Lori Chappel
Weather Services Co-ordinator Ph (08) 8920 3810