Tropical Cyclone Narelle

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Re: Tropical Cyclone Narelle (Technical Discussion Only)

Postby brayden » Fri Jan 11, 2013 9:04 pm

TROPICAL CYCLONE FORECAST TRACK MAP

Severe Tropical Cyclone Narelle

Issued at 8:50 pm WST Friday 11 January 2013. Refer to Tropical Cyclone Advice Number 16.

Image


Remarks:

Severe Tropical Cyclone Narelle is expected to continue moving to the southwest and pass west of the Northwest Cape over the weekend.

Gales with gusts to 100 kilometres per hour could develop in coastal areas between Mardie and Exmouth overnight Friday, then extend south to Cape Cuvier later on Saturday.

Winds are likely to increase in the Exmouth area on Saturday with damaging wind gusts to 125 kilometres per hour possible overnight Saturday if the cyclone takes a track closer to the coast.

On Sunday gales may extend south to Denham and winds along the west Pilbara coast should ease from the east later in the day.

Thunderstorm activity in western parts of the Pilbara could be squally with isolated heavy falls. This activity will extend into far northwestern Gascoyne over the weekend.

Tides along the west Pilbara coast are likely to rise above the normal high tide mark overnight Friday and Saturday night with flooding of low lying coastal areas possible. Higher than normal tides should extend along the west coast later Saturday and into early next week.

DFES-State Emergency Service advises of the following community alerts:

BLUE ALERT: Coastal and island communities from Mardie to Coral Bay including Onslow and Exmouth should be taking precautions.
Communities between Coral Bay and Carnarvon should listen for the next advice.

The next Forecast Track Map will be issued by 12:00 am WST Saturday


TOP PRIORITY FOR IMMEDIATE BROADCAST

TROPICAL CYCLONE ADVICE NUMBER 16
Issued at 8:50 pm WST on Friday 11 January 2013

A Cyclone WARNING is now current for coastal areas from Mardie to Cape Cuvier.

A Cyclone WATCH is now current for coastal areas from Cape Cuvier to Denham.

At 8:00 pm WST Severe Tropical Cyclone Narelle, Category 4 was estimated to be
460 kilometres north northwest of Exmouth and
770 kilometres north of Carnarvon and
moving southwest at 14 kilometres per hour.

Severe Tropical Cyclone Narelle is expected to continue moving to the southwest
and pass west of the Northwest Cape over the weekend.

Gales with gusts to 100 kilometres per hour could develop in coastal areas
between Mardie and Exmouth overnight Friday, then extend south to Cape Cuvier
later on Saturday.

Winds are likely to increase in the Exmouth area on Saturday with damaging wind
gusts to 125 kilometres per hour possible overnight Saturday if the cyclone
takes a track closer to the coast.

On Sunday gales may extend south to Denham and winds along the west Pilbara
coast should ease from the east later in the day.

Thunderstorm activity in western parts of the Pilbara could be squally with
isolated heavy falls. This activity will extend into far northwestern Gascoyne
over the weekend.

Tides along the west Pilbara coast are likely to rise above the normal high
tide mark overnight Friday and Saturday night with flooding of low lying
coastal areas possible. Higher than normal tides should extend along the west
coast later Saturday and into early next week.

DFES-State Emergency Service advises of the following community alerts:
BLUE ALERT: Coastal and island communities from Mardie to Coral Bay including
Onslow and Exmouth should be taking precautions.
Communities between Coral Bay and Carnarvon should listen for the next advice.

Details of Severe Tropical Cyclone Narelle at 8:00 pm WST:

.Centre located near...... 18.1 degrees South 112.5 degrees East
.Location accuracy........ within 35 kilometres
.Recent movement.......... towards the southwest at 14 kilometres per hour
.Wind gusts near centre... 260 kilometres per hour
.Severity category........ 4
.Central pressure......... 931 hectoPascals

The next advice will be issued by 12:00 am WST Saturday 12 January.

Cyclone advices and State Emergency Service Community Alerts are available by
dialling 1300 659 210



TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by PERTH TROPICAL CYCLONE WARNING CENTRE
at: 1245 UTC 11/01/2013


Name: Severe Tropical Cyclone Narelle
Identifier: 05U
Data At: 1200 UTC
Latitude: 18.1S
Longitude: 112.5E
Location Accuracy: within 20 nm [35 km]
Movement Towards: southwest [233 deg]
Speed of Movement: 7 knots [14 km/h]
Maximum 10-Minute Wind: 100 knots [185 km/h]
Maximum 3-Second Wind Gust: 140 knots [260 km/h]

Central Pressure: 931 hPa
Radius of 34-knot winds NE quadrant: 180 nm [335 km]
Radius of 34-knot winds SE quadrant: 200 nm [370 km]
Radius of 34-knot winds SW quadrant: 180 nm [335 km]
Radius of 34-knot winds NW quadrant: 180 nm [335 km]
Radius of 48-knot winds NE quadrant: 60 nm [110 km]
Radius of 48-knot winds SE quadrant: 60 nm [110 km]
Radius of 48-knot winds SW quadrant: 60 nm [110 km]
Radius of 48-knot winds NW quadrant: 60 nm [110 km]
Radius of 64-knot winds: 30 nm [55 km]
Radius of Maximum Winds: 20 nm [35 km]
Dvorak Intensity Code: T6.0/6.0/D1.0/24HRS STT:D0.5/6HRS
Pressure of outermost isobar: 998 hPa
Radius of outermost closed isobar: 220 nm [405 km]
Storm Depth: Deep
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+12: 12/0000: 19.2S 111.7E: 045 [080]: 105 [195]: 925
+24: 12/1200: 20.4S 111.1E: 070 [130]: 105 [195]: 925
+36: 13/0000: 21.4S 110.3E: 090 [165]: 105 [195]: 925
+48: 13/1200: 22.7S 109.7E: 110 [200]: 090 [165]: 940
+60: 14/0000: 24.6S 109.0E: 130 [235]: 065 [120]: 963
+72: 14/1200: 27.0S 108.5E: 145 [270]: 045 [085]: 976

REMARKS:

Severe Tropical Cyclone Narelle has intensified during the day with a definitive
eye now evident on visible and infra-red imagery. Intensity of 100 knots based
on the three-hour average Dvorak DT of 6.0 [eye pattern]. the surrounding shade
has fluctated between black and white with an OW eye. At times the eye has been
quite elongated.

Further intensification is forecast with low [system relative] wind shear and
the system could reach category 5 intensity overnight based on its current
trend.
The cyclone should gradually weaken as it encounters cooler SSTs from
late Sunday and Monday but may remain at cyclone intensity to Tuesday well off
the west coast.

Expected motion persists to the southwest for the next 24 hours and then a more
south southwest track is likely in the following days. This leaves the cyclone
sufficiently off the coast that coastal areas will only experience the outer
edge of the cyclone and a severe impact is not expected.

Higher than normal tides are likely about the west Pilbara coast tonight and
Saturday, with a shelf wave moving down the west coast on the weekend and into
early next week.


Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 11/1900 UTC by Perth TCWC.
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Re: Tropical Cyclone Narelle (Technical Discussion Only)

Postby brayden » Fri Jan 11, 2013 11:51 pm

TROPICAL CYCLONE FORECAST TRACK MAP

Severe Tropical Cyclone Narelle

Issued at 11:44 pm WST Friday 11 January 2013. Refer to Tropical Cyclone Advice Number 17.

Image


Remarks:

Severe Tropical Cyclone Narelle is expected to continue moving to the southwest and pass west of the Northwest Cape over the weekend.

Gales with gusts to 100 kilometres per hour could develop in coastal areas between Mardie and Exmouth early Saturday, then extend south to Cape Cuvier later on Saturday.

Winds are likely to increase in the Exmouth area on Saturday with damaging wind gusts to 125 kilometres per hour possible overnight Saturday if the cyclone takes a track closer to the coast.

On Sunday gales may extend south to Denham and winds along the west Pilbara coast should ease from the east later in the day.

Thunderstorm activity in western parts of the Pilbara could be squally with isolated heavy falls. This activity will extend into far northwestern Gascoyne over the weekend.

Tides along the west Pilbara coast are likely to rise above the normal high tide mark early Saturday morning and again Saturday night with flooding of low lying coastal areas possible. Higher than normal tides should extend along the west coast later Saturday and into early next week.

DFES-State Emergency Service advises of the following community alerts:

BLUE ALERT: Coastal and island communities from Mardie to Coral Bay including Onslow and Exmouth should be taking precautions.
Communities between Coral Bay and Carnarvon should listen for the next advice.

The next Forecast Track Map will be issued by 3:00 am WST Saturday


TOP PRIORITY FOR IMMEDIATE BROADCAST

TROPICAL CYCLONE ADVICE NUMBER 17
Issued at 11:43 pm WST on Friday 11 January 2013


A Cyclone WARNING continues for coastal areas from Mardie to Cape Cuvier.

A Cyclone WATCH continues for coastal areas from Cape Cuvier to Denham.

At 11:00 pm WST Severe Tropical Cyclone Narelle, Category 4 was estimated to be
445 kilometres north northwest of Exmouth and
740 kilometres north of Carnarvon and
moving southwest at 14 kilometres per hour.

Severe Tropical Cyclone Narelle is expected to continue moving to the southwest
and pass west of the Northwest Cape over the weekend.

Gales with gusts to 100 kilometres per hour could develop in coastal areas
between Mardie and Exmouth early Saturday, then extend south to Cape Cuvier
later on Saturday.

Winds are likely to increase in the Exmouth area on Saturday with damaging wind
gusts to 125 kilometres per hour possible overnight Saturday if the cyclone
takes a track closer to the coast.

On Sunday gales may extend south to Denham and winds along the west Pilbara
coast should ease from the east later in the day.

Thunderstorm activity in western parts of the Pilbara could be squally with
isolated heavy falls. This activity will extend into far northwestern Gascoyne
over the weekend.

Tides along the west Pilbara coast are likely to rise above the normal high
tide mark early Saturday morning and again Saturday night with flooding of low
lying coastal areas possible. Higher than normal tides should extend along the
west coast later Saturday and into early next week.

DFES-State Emergency Service advises of the following community alerts:

BLUE ALERT: Coastal and island communities from Mardie to Coral Bay including
Onslow and Exmouth should be taking precautions.
Communities between Coral Bay and Carnarvon should listen for the next advice.

Details of Severe Tropical Cyclone Narelle at 11:00 pm WST:
.Centre located near...... 18.3 degrees South 112.3 degrees East
.Location accuracy........ within 35 kilometres
.Recent movement.......... towards the southwest at 14 kilometres per hour
.Wind gusts near centre... 260 kilometres per hour
.Severity category........ 4
.Central pressure......... 931 hectoPascals

The next advice will be issued by 3:00 am WST Saturday 12 January.

Cyclone advices and State Emergency Service Community Alerts are available by
dialling 1300 659 210
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Tropical Cyclone Narelle

Postby Fu Manchu » Sat Jan 12, 2013 12:20 am

The forecast from JTWC has been pretty consistent with this one
Image

Has been very similar to the BoM ones, which of course cover a much shorter time frame (of more certainty of sorts).

Both have Narelle making a Bline for cooler water.
Image

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Tropical Cyclone Narelle

Postby Fu Manchu » Sat Jan 12, 2013 12:23 am

So am I right in thinking the mid ridge has remained stronger and the approaching trough weaker than was a possibility a day or two ago, therefore steering it a bit further away from the coast line?

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Tropical Cyclone Narelle

Postby Fu Manchu » Sat Jan 12, 2013 12:47 am

Not much on radar available to the public. i.e.: Learmonth radar off line
Image

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Re: Tropical Cyclone Narelle

Postby Pete » Sat Jan 12, 2013 8:24 am

The southeastern quadrant of the cyclone seemed a bit unstable for a bit there, but she's sees to have reorganized herself. Now a cat 5 system.
http://www.ssd.noaa.gov/PS/TROP/floater ... -long.html

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Re: Tropical Cyclone Narelle

Postby von-Kármán » Sat Jan 12, 2013 8:26 am

As expected she's peaked at Cat 5 overnight.

While she's stalled a little she's unlikely to change direction (according to all the models) and should continue to track off the coast. THe question will be if she tracks back inland towards Perth in her final days.

Image
She's looking decidedly lopsided and surprisingly asymmetric for a Category 5 ... and I suspect (emphasis on the suspect) this is because of some dry air injection.

the WV shows the dry air spiriling towards the eye, and this could cause a partial eyewall collapse if it becomes severe enough ...
Image

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Re: Tropical Cyclone Narelle (Technical Discussion Only)

Postby brayden » Sat Jan 12, 2013 9:27 am

TROPICAL CYCLONE FORECAST TRACK MAP

Severe Tropical Cyclone Narelle

Issued at 9:12 am WST Saturday 12 January 2013. Refer to Tropical Cyclone Advice Number 20.

Image


Remarks:

Severe Tropical Cyclone Narelle is expected to move to the south southwest and pass well west of the Northwest Cape on Sunday.

Gales with gusts to 100 kilometres per hour may develop in coastal areas between Onslow and Exmouth later Saturday, extending south to Cape Cuvier on Sunday. Gales may extend south to Denham late on Sunday or Monday if the cyclone takes a track closer to the coast than expected.

Thunderstorm activity in western parts of the Pilbara could be squally with isolated heavy falls.

Tides along the west Pilbara coast are likely to rise above the normal high tide mark with flooding of low lying coastal areas possible. Higher than normal tides should extend along the west coast overnight tonight and continue into early next week.

DFES-State Emergency Service advises of the following community alerts:

BLUE ALERT: Coastal and island communities from Mardie to Coral Bay including Onslow and Exmouth should be taking precautions.
Communities between Coral Bay and Carnarvon should listen for the next advice.

The next Forecast Track Map will be issued by 12:00 pm WST Saturday


TOP PRIORITY FOR IMMEDIATE BROADCAST

TROPICAL CYCLONE ADVICE NUMBER 20
Issued at 9:12 am WST on Saturday 12 January 2013


A Cyclone WARNING continues for coastal areas from Onslow to Cape Cuvier,
including Exmouth.

A Cyclone WATCH continues for coastal areas from Cape Cuvier to Denham
including Carnarvon.

The Cyclone WARNING from Mardie to Onslow has been cancelled.

At 8:00 am WST Severe Tropical Cyclone Narelle, Category 4 was estimated to be
435 kilometres northwest of Exmouth and
720 kilometres north northwest of Carnarvon and
moving southwest at 9 kilometres per hour.

Severe Tropical Cyclone Narelle is expected to move to the south southwest and
pass well west of the Northwest Cape on Sunday.

Gales with gusts to 100 kilometres per hour may develop in coastal areas
between Onslow and Exmouth later Saturday, extending south to Cape Cuvier on
Sunday. Gales may extend south to Denham late on Sunday or Monday if the
cyclone takes a track closer to the coast than expected.

Thunderstorm activity in western parts of the Pilbara could be squally with
isolated heavy falls.

Tides along the west Pilbara coast are likely to rise above the normal high
tide mark with flooding of low lying coastal areas possible. Higher than normal
tides should extend along the west coast overnight tonight and continue into
early next week.

DFES-State Emergency Service advises of the following community alerts:
BLUE ALERT: Coastal and island communities from Mardie to Coral Bay including
Onslow and Exmouth should be taking precautions.
Communities between Coral Bay and Carnarvon should listen for the next advice.

Details of Severe Tropical Cyclone Narelle at 8:00 am WST:
.Centre located near...... 18.7 degrees South 111.8 degrees East
.Location accuracy........ within 30 kilometres
.Recent movement.......... towards the southwest at 9 kilometres per hour
.Wind gusts near centre... 260 kilometres per hour
.Severity category........ 4
.Central pressure......... 935 hectoPascals

The next advice will be issued by 12:00 pm WST Saturday 12 January.

Cyclone advices and State Emergency Service Community Alerts are available by
dialling 1300 659 210
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Tropical Cyclone Narelle

Postby Fu Manchu » Sat Jan 12, 2013 9:39 am

Convection on her eastern side not the greatest at the moment.
The mid ridge still steering her in a consistent track. Hasn't really moved all over the place like we often see with cyclones.

Water vapour animation showing a pretty solid area of dry air on its way in as VonKarmen mentioned.
This shows it pretty well.
http://realtime2.bsch.au.com/wv_sat.htm ... &stop=#nav

She is a beautiful cyclone.

How long before we see significant structural weakening do you think?
I'm thinking late today, early tomorrow.

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Re: Tropical Cyclone Narelle (Technical Discussion Only)

Postby brayden » Sat Jan 12, 2013 9:43 am

TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by PERTH TROPICAL CYCLONE WARNING CENTRE
at: 0139 UTC 12/01/2013


Name: Severe Tropical Cyclone Narelle
Identifier: 05U
Data At: 0000 UTC
Latitude: 18.7S
Longitude: 111.8E
Location Accuracy: within 15 nm [30 km]
Movement Towards: southwest [229 deg]
Speed of Movement: 5 knots [9 km/h]
Maximum 10-Minute Wind: 100 knots [185 km/h]
Maximum 3-Second Wind Gust: 140 knots [260 km/h]
Central Pressure: 935 hPa
Radius of 34-knot winds NE quadrant: 180 nm [335 km]
Radius of 34-knot winds SE quadrant: 160 nm [295 km]
Radius of 34-knot winds SW quadrant: 160 nm [295 km]
Radius of 34-knot winds NW quadrant: 150 nm [280 km]
Radius of 48-knot winds NE quadrant: 60 nm [110 km]
Radius of 48-knot winds SE quadrant: 60 nm [110 km]
Radius of 48-knot winds SW quadrant: 60 nm [110 km]
Radius of 48-knot winds NW quadrant: 60 nm [110 km]
Radius of 64-knot winds: 30 nm [55 km]
Radius of Maximum Winds: 20 nm [35 km]
Dvorak Intensity Code: T5.5/6.0/D0.5/24HRS STT: W 0.5/6HRS
Pressure of outermost isobar: 1002 hPa
Radius of outermost closed isobar: 300 nm [555 km]
Storm Depth: Deep
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+12: 12/1200: 19.6S 111.3E: 040 [070]: 090 [165]: 946
+24: 13/0000: 20.7S 110.6E: 065 [120]: 075 [140]: 960
+36: 13/1200: 22.1S 110.0E: 085 [155]: 065 [120]: 969
+48: 14/0000: 24.1S 109.3E: 105 [190]: 055 [100]: 978
+60: 14/1200: 26.3S 108.7E: 120 [225]: 045 [085]: 985
+72: 15/0000: 28.6S 108.2E: 140 [265]: 035 [065]: 991

REMARKS:

Severe Tropical Cyclone Narelle appears to have peaked in intensity overnight,
but recent imagery shows a weakness in the eastern eye wall, most evident on
microwave. Dvorak DT estimates have fluctuated between 5.0 and 6.5 from 17 to
23UTC with recent images trending down. The most recent three hour average would
indicate a FT of 5.5 although a CI of 6.0 is maintained suggesting an intensity
of 100 knots. AMSU/SATCON estimates are slightly lower.

Moderate easterly shear may be having an impact on the system and as the cyclone
moves south of 20S it should encounter sea surface temperatures less than 26C on
Sunday. Hence a weakening trend is forecast, but may remain at cyclone intensity
to Tuesday well off the west coast.

Expected motion is south southwest for the next 48 hours and then a more
southerly track is likely in the following days. This leaves the cyclone
sufficiently off the coast that a coastal impact is not the likely scenario. The
greatest risk period for gales on the coast is during Sunday in the
Exmouth-Ningaloo area, as models suggest a slight expansion of gales on the
eastern side. There is still sufficient uncertainty on how far off the coast
Narelle will be off the west coast later on Sunday and Monday to maintain a
precautionary watch for west coastal areas south to Denham.

Higher than normal tides are likely about the west Pilbara coast Saturday night
and Sunday, with a shelf wave moving down the west coast likely to push tides
above the highest astronomical tide at least towards Shark Bay at least.

Although widespread heavy rain is not expected in the Pilbara, the remnants of
the system may bring some rain to the Gascoyne and southern parts of the state
from Sunday to Tuesday.



Copyright Commonwealth of Australia
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The next bulletin for this system will be issued by: 12/0700 UTC by Perth TCWC.
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Re: Tropical Cyclone Narelle

Postby von-Kármán » Sat Jan 12, 2013 10:10 am

Fu Manchu wrote:Convection on her eastern side not the greatest at the moment.
The mid ridge still steering her in a consistent track. Hasn't really moved all over the place like we often see with cyclones.

Water vapour animation showing a pretty solid area of dry air on its way in as VonKarmen mentioned.
This shows it pretty well.
http://realtime2.bsch.au.com/wv_sat.htm ... &stop=#nav

She is a beautiful cyclone.

How long before we see significant structural weakening do you think?
I'm thinking late today, early tomorrow.

It is already happening, as I suspected the eyewall in the south eastern quadrant has already collapsed, and you can now see this on the Vis sat imagry ... although it willbecome more apparant over the next few hours. You can see it very clearly on the microwave images as below (and this was about 2 hours ago!)

Image

I think this will become a great example of how a bit of dry air can kill a cyclone ...

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Re: Tropical Cyclone Narelle

Postby von-Kármán » Sat Jan 12, 2013 10:17 am

I suspect that this could lead to an entire eyewall replacement, (if it rebuilds at all) but certainly a significant weakening. Pity, she was such a nice storm!

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Re: Tropical Cyclone Narelle

Postby von-Kármán » Sat Jan 12, 2013 11:15 am

No more good MW sensor satellite passes until TRMM in about 3 hours (so no data for about 5 hours) so we have to rely on the vis and IR imagery to deduce what is happening to the eyewall for the moment.

Certainly latest Vis appears to show a complete collapse of the eye, but the next update (due any second) will confirm (or otherwise) that.
http://www.weatherzone.com.au/satellite ... a2/visible

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Re: Tropical Cyclone Narelle (Technical Discussion Only)

Postby brayden » Sat Jan 12, 2013 11:57 am

TROPICAL CYCLONE FORECAST TRACK MAP

Severe Tropical Cyclone Narelle

Issued at 11:53 am WST Saturday 12 January 2013. Refer to Tropical Cyclone Advice Number 21.

Image


Remarks:

Severe Tropical Cyclone Narelle is expected to move to the south southwest and pass west of the Northwest Cape on Sunday.

Gales with gusts to 100 kilometres per hour may develop in coastal areas between Onslow and Exmouth later Saturday, extending south to Cape Cuvier on Sunday. Gales may extend south to Denham late on Sunday or Monday if the cyclone takes a track closer to the coast than expected.

Thunderstorm activity in western parts of the Pilbara could be squally with isolated heavy falls.

Tides along the west Pilbara coast are likely to rise above the normal high tide mark with flooding of low lying coastal areas possible. Higher than normal tides should extend along the west coast overnight tonight and continue into early next week.

DFES-State Emergency Service advises of the following community alerts:

BLUE ALERT: Coastal and island communities from Onslow to Coral Bay including Exmouth should be taking precautions.
Communities between Coral Bay and Carnarvon should listen for the next advice.

The next Forecast Track Map will be issued by 3:00 pm WST Saturday


TOP PRIORITY FOR IMMEDIATE BROADCAST

TROPICAL CYCLONE ADVICE NUMBER 21
Issued at 11:50 am WST on Saturday 12 January 2013


A Cyclone WARNING continues for coastal areas from Onslow to Cape Cuvier,
including Exmouth.

A Cyclone WATCH continues for coastal areas from Cape Cuvier to Denham,
including Carnarvon.

At 11:00 am WST Severe Tropical Cyclone Narelle, Category 4 was estimated to be
410 kilometres northwest of Exmouth and
690 kilometres north northwest of Carnarvon and
moving south southwest at 7 kilometres per hour.

Severe Tropical Cyclone Narelle is expected to move to the south southwest and
pass west of the Northwest Cape on Sunday.

Gales with gusts to 100 kilometres per hour may develop in coastal areas
between Onslow and Exmouth later Saturday, extending south to Cape Cuvier on
Sunday. Gales may extend south to Denham late on Sunday or Monday if the
cyclone takes a track closer to the coast than expected.

Thunderstorm activity in western parts of the Pilbara could be squally with
isolated heavy falls.

Tides along the west Pilbara coast are likely to rise above the normal high
tide mark with flooding of low lying coastal areas possible. Higher than normal
tides should extend along the west coast overnight tonight and continue into
early next week.

DFES-State Emergency Service advises of the following community alerts:
BLUE ALERT: Coastal and island communities from Onslow to Coral Bay including
Exmouth should be taking precautions.
Communities between Coral Bay and Carnarvon should listen for the next advice.

Details of Severe Tropical Cyclone Narelle at 11:00 am WST:
.Centre located near...... 18.9 degrees South 111.9 degrees East
.Location accuracy........ within 35 kilometres
.Recent movement.......... towards the south southwest at 7 kilometres per hour
.Wind gusts near centre... 260 kilometres per hour
.Severity category........ 4
.Central pressure......... 934 hectoPascals

The next advice will be issued by 3:00 pm WST Saturday 12 January.

Cyclone advices and State Emergency Service Community Alerts are available by
dialling 1300 659 210
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Re: Tropical Cyclone Narelle

Postby von-Kármán » Sat Jan 12, 2013 2:23 pm

While there was definitely a partial collapse, it is very hard to tell if the eyewall fully collapsed (pity we dont have any radar). IR indicates that an eye is still present but it is much cooler than it was before indicating it has probably filled in a bit. Vis images are not high enough resolution to tell (and the sun is to high to cast relief properly. TRMM overpassed within 194 km about 20min ago and data should be down in the next hour or so, and that should show what has happened to her.

She still has a lot of momentum, but that dry air combined with the warmer SSTs shes coming over and increasing shear will have mortally wounded her I'm afraid

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Re: Tropical Cyclone Narelle (Technical Discussion Only)

Postby brayden » Sat Jan 12, 2013 3:02 pm

TROPICAL CYCLONE FORECAST TRACK MAP

Severe Tropical Cyclone Narelle

Issued at 2:57 pm WST Saturday 12 January 2013. Refer to Tropical Cyclone Advice Number 22.

Image


Remarks:

Severe Tropical Cyclone Narelle is expected to move to the south southwest and pass west of the Northwest Cape on Sunday.

Gales with gusts to 100 kilometres per hour may develop in coastal areas between Onslow and Cape Cuvier on Sunday. Gales may extend south to Denham late on Sunday or Monday if the cyclone takes a track closer to the coast than expected.

Tides along the west Pilbara coast are likely to rise above the normal high tide mark with flooding of low lying coastal areas possible. Higher than normal tides should extend along the west coast overnight tonight and continue into early next week.

DFES-State Emergency Service advises of the following community alerts:

BLUE ALERT: Coastal and island communities from Onslow to Coral Bay including Exmouth should be taking precautions.
Communities between Coral Bay and Denham should listen for the next advice.

The next Forecast Track Map will be issued by 6:00 pm WST Saturday


TOP PRIORITY FOR IMMEDIATE BROADCAST

TROPICAL CYCLONE ADVICE NUMBER 22
Issued at 2:56 pm WST on Saturday 12 January 2013


A Cyclone WARNING continues for coastal areas from Onslow to Cape Cuvier,
including Exmouth.

A Cyclone WATCH continues for coastal areas from Cape Cuvier to Denham,
including Carnarvon.

At 2:00 pm WST Severe Tropical Cyclone Narelle, Category 4 was estimated to be
390 kilometres northwest of Exmouth and
660 kilometres north northwest of Carnarvon and
moving south southwest at 10 kilometres per hour.

Severe Tropical Cyclone Narelle is expected to move to the south southwest and
pass west of the Northwest Cape on Sunday.

Gales with gusts to 100 kilometres per hour may develop in coastal areas
between Onslow and Cape Cuvier on Sunday. Gales may extend south to Denham late
on Sunday or Monday if the cyclone takes a track closer to the coast than
expected.

Tides along the west Pilbara coast are likely to rise above the normal high
tide mark with flooding of low lying coastal areas possible. Higher than normal
tides should extend along the west coast overnight tonight and continue into
early next week.

DFES-State Emergency Service advises of the following community alerts:

BLUE ALERT: Coastal and island communities from Onslow to Coral Bay including
Exmouth should be taking precautions.
Communities between Coral Bay and Denham should listen for the next advice.

Details of Severe Tropical Cyclone Narelle at 2:00 pm WST:
.Centre located near...... 19.2 degrees South 111.8 degrees East
.Location accuracy........ within 35 kilometres
.Recent movement.......... towards the south southwest at 10 kilometres per hour
.Wind gusts near centre... 250 kilometres per hour
.Severity category........ 4
.Central pressure......... 938 hectoPascals

The next advice will be issued by 6:00 pm WST Saturday 12 January.

Cyclone advices and State Emergency Service Community Alerts are available by
dialling 1300 659 210
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Tropical Cyclone Narelle

Postby Fu Manchu » Sat Jan 12, 2013 3:10 pm

The view from Exmouth
Photo from @GianDP
Gian De Poloni who is an ABC NW reporter.
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Tropical Cyclone Narelle

Postby Fu Manchu » Sat Jan 12, 2013 3:13 pm

Von Karman, it really looks to have collapsed. It's not going to hold up much longer even if it turns out it has.
She was beautiful for her moment of fame though.
Clearly it's been a quiet news week though.

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Re: Tropical Cyclone Narelle (Technical Discussion Only)

Postby brayden » Sat Jan 12, 2013 3:23 pm

TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by PERTH TROPICAL CYCLONE WARNING CENTRE
at: 0716 UTC 12/01/2013


Name: Severe Tropical Cyclone Narelle
Identifier: 05U
Data At: 0600 UTC
Latitude: 19.2S
Longitude: 111.8E
Location Accuracy: within 20 nm [35 km]
Movement Towards: south southwest [201 deg]
Speed of Movement: 5 knots [10 km/h]
Maximum 10-Minute Wind: 95 knots [175 km/h]
Maximum 3-Second Wind Gust: 135 knots [250 km/h]
Central Pressure: 938 hPa
Radius of 34-knot winds NE quadrant: 180 nm [335 km]
Radius of 34-knot winds SE quadrant: 160 nm [295 km]
Radius of 34-knot winds SW quadrant: 160 nm [295 km]
Radius of 34-knot winds NW quadrant: 180 nm [335 km]
Radius of 48-knot winds NE quadrant: 60 nm [110 km]
Radius of 48-knot winds SE quadrant: 60 nm [110 km]
Radius of 48-knot winds SW quadrant: 60 nm [110 km]
Radius of 48-knot winds NW quadrant: 60 nm [110 km]
Radius of 64-knot winds: 30 nm [55 km]
Radius of Maximum Winds: 20 nm [35 km]
Dvorak Intensity Code: T5.5/6.0/S0.0/24HRS STT: W0.5/6HRS
Pressure of outermost isobar: 1000 hPa
Radius of outermost closed isobar: 240 nm [445 km]
Storm Depth: Deep
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+12: 12/1800: 20.0S 111.3E: 045 [080]: 085 [155]: 949
+24: 13/0600: 21.3S 110.6E: 070 [130]: 070 [130]: 961
+36: 13/1800: 22.9S 110.0E: 090 [165]: 060 [110]: 970
+48: 14/0600: 24.9S 109.5E: 110 [200]: 050 [095]: 979
+60: 14/1800: 27.0S 109.3E: 130 [235]: 040 [075]: 986
+72: 15/0600: 28.9S 109.7E: 145 [270]: 030 [055]: 992

REMARKS:

Severe Tropical Cyclone Narelle peaked in intensity overnight and has weakened
in the last -9h with the effects of some easterly shear and restricted outflow
on the eastern flank apparent. Dvorak DT estimates have fluctuated between 5.0
and 5.5 in the past 5h, with the CI held at 6.0, consistent with ADT.
The effects of moderate easterly shear and cooler sea surface temperatures [<26C
south of 20S] on Sunday. Hence a weakening trend is forecast, but may remain at
cyclone intensity to Tuesday well off the west coast.

Expected motion is generally to the south southwest on Sunday and Monday. The
greatest risk period for gales on the coast is during Sunday in the
Exmouth-Ningaloo area. There is still sufficient uncertainty on how far off the
coast Narelle will be later on Monday to maintain a precautionary watch for west
coastal areas south to Denham.

Higher than normal tides are likely about the west Pilbara coast tonight and on
Sunday, with a shelf wave moving down the west coast likely to push tides above
the highest astronomical tide at least towards Shark Bay at least.

Although widespread heavy rain is not expected in the west Pilbara, upslide to
the southeast of the cyclone may bring some rain to the Gascoyne and southern
parts of the state from Sunday to Tuesday.

Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 12/1300 UTC by Perth TCWC.
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Re: Tropical Cyclone Narelle

Postby von-Kármán » Sat Jan 12, 2013 3:39 pm

Microwave has come in, and shows no distinct eyewall as I suspected ... a little dry air goes a long way to destroying a cyclone!
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