nw australia Very Intense Tropical Cyclone Bruce

[Somerset Squall]

A tropical low is has developed a few hundred miles north of Cocos Island. The low, also known as invest 94S, is moving southwestwards, north of Cocos Island. The system is currently being affected by shear, and is currently quite broad natured, but the shear should ease as the low continues southwestwards, allowing development. BOM expects the system to become a tropical cyclone within the next 24hrs, and JTWC assess this risk as a MEDIUM risk. The cyclone should then move out of the Australian region of responsibility and into MeteoFrance's area of responsibility in the Southwest Indian Ocean in around 48hrs time, whilst continuing to intensify.

 

Edited December 16, 2013 by Somerset Squall

[Somerset Squall]

JTWC are about to issue their first advisory on this system. Organisation has improved markedly today, with a contracted and much better defined LLC covered with a small but deep area of convection. There is a hook/comma like appearance to the system, which does imply that it may be quite quick to strengthen. The shear from yesterday has eased, and with the good poleward outflow and warm waters along track, this system could become quite intense.

 

Edited December 17, 2013 by Somerset Squall

[Somerset Squall]

JTWC have issued their first warning, declaring the system Tropical Cyclone 04S. BOM should upgrade the system soon. As I've mentioned above, 04S should strengthen decently over the next few days. It's interesting to note however, that JTWC plump for 04S to reach an intensity of 70kts by day 4/5, wheras BOM are expecting a 90kt system (which would equate to about 100kts using a 1 min average wind measurement as JTWC does).

04S should move generally west-southwestwards along the northwestern periphery of a ridge to the southeast. In a few days time, an advancing trough should weaken the ridge, allowing 04S to take a more poleward turn.

Edited December 17, 2013 by Somerset Squall

[Somerset Squall]

Now named Bruce by BOM.

 

 

 

At 0000 UTC Tropical Cyclone Bruce was centred within 20 nautical miles of
Latitude ten decimal three south (10.3S)
Longitude ninety six decimal four east (96.4E)
Recent movement : southwest at 5 knots
Maximum winds: 35 knots
Central pressure: 995 hPa

Edited December 18, 2013 by Somerset Squall

[Coast]

Now named Bruce by BOM.

 

 

Well G'Day Bruce!

 

Tropical Cyclone Bruce threatening Cocos Islands

 

 

Tropical Cyclone Bruce is threatening to bear down on the Cocos Islands, the Bureau of Meteorology has warned. The BOM issued a Tropical Cyclone Advice at 5.34am on Wednesday morning after detecting the then tropical low moving southwest at 11km/h. At 7.15am the tropical low was declared Tropical Cyclone Bruce, a category 1 cyclone currently 215km north of the Cocos Islands moving southwest at 9km/h.

 

TC Bruce is expected to continue intensifying as it moves west southwest and passes to the northwest of the Cocos Islands on Wednesday. The Bureau predicts that gales with gusts of up to 100km/h will develop on the Cocos Islands during Wednesday morning, persisting into early Thursday morning, with gusts of 120km/h predicted if the cyclone moves closer to the island that expected. TC Bruce will be accompanied by heavy rain and squally thunderstorms, although it is predicted these should easy on Thursday depending on the movement of the system.

 

http://www.watoday.com.au/wa-news/tropical-cyclone-bruce-threatening-cocos-islands-20131218-2zk7d.html#ixzz2noG9odkd

[Coast]

000 

wtxs32 pgtw 172100

msgid/genadmin/joint typhoon wrncen Pearl Harbor hi//

subj/tropical cyclone 04s (four) warning nr 001//

ref/a/joint typhoon wrncen Pearl Harbor hi/170251z Dec 13//

ampn/ref a is a tropical cyclone formation alert//

rmks/

1. Tropical cyclone 04s (four) warning nr 001    

   02 active tropical cyclones in southio

   Max sustained winds based on one-minute average

   wind radii valid over open water only

    ---

   warning position:

   171800z --- near 9.6s 96.8e

     movement past six hours - 235 degrees at 05 kts

     position accurate to within 060 nm

     position based on center located by satellite

   present wind distribution:

   Max sustained winds - 035 kt, gusts 045 kt

   wind radii valid over open water only

   repeat posit: 9.6s 96.8e

    ---

   forecasts:

   12 hrs, valid at:

   180600z --- 11.1s 95.5e

   Max sustained winds - 040 kt, gusts 050 kt

   wind radii valid over open water only

   radius of 034 kt winds - 040 nm northeast quadrant

                            045 nm southeast quadrant

                            045 nm southwest quadrant

                            040 nm northwest quadrant

   vector to 24 hr posit: 235 deg/ 09 kts

    ---

   24 hrs, valid at:

   181800z --- 12.2s 94.0e

   Max sustained winds - 045 kt, gusts 055 kt

   wind radii valid over open water only

   radius of 034 kt winds - 050 nm northeast quadrant

                            055 nm southeast quadrant

                            055 nm southwest quadrant

                            050 nm northwest quadrant

   vector to 36 hr posit: 250 deg/ 10 kts

    ---

   36 hrs, valid at:

   190600z --- 12.9s 92.1e

   Max sustained winds - 050 kt, gusts 065 kt

   wind radii valid over open water only

   radius of 034 kt winds - 060 nm northeast quadrant

                            065 nm southeast quadrant

                            065 nm southwest quadrant

                            060 nm northwest quadrant

   vector to 48 hr posit: 255 deg/ 09 kts

    ---

   extended outlook:

   48 hrs, valid at:

   191800z --- 13.4s 90.3e

   Max sustained winds - 055 kt, gusts 070 kt

   wind radii valid over open water only

   radius of 050 kt winds - 025 nm northeast quadrant

                            025 nm southeast quadrant

                            025 nm southwest quadrant

                            025 nm northwest quadrant

   radius of 034 kt winds - 070 nm northeast quadrant

                            075 nm southeast quadrant

                            075 nm southwest quadrant

                            070 nm northwest quadrant

   vector to 72 hr posit: 255 deg/ 09 kts

    ---

   72 hrs, valid at:

   201800z --- 14.4s 86.6e

   Max sustained winds - 065 kt, gusts 080 kt

   wind radii valid over open water only

   radius of 050 kt winds - 035 nm northeast quadrant

                            035 nm southeast quadrant

                            035 nm southwest quadrant

                            035 nm northwest quadrant

   radius of 034 kt winds - 080 nm northeast quadrant

                            085 nm southeast quadrant

                            085 nm southwest quadrant

                            080 nm northwest quadrant

   vector to 96 hr posit: 250 deg/ 11 kts

    ---

   long range outlook:

    ---

   96 hrs, valid at:

   211800z --- 15.9s 82.1e

   Max sustained winds - 070 kt, gusts 085 kt

   wind radii valid over open water only

   vector to 120 hr posit: 230 deg/ 11 kts

    ---

   120 hrs, valid at:

   221800z --- 18.7s 78.5e

   Max sustained winds - 070 kt, gusts 085 kt

   wind radii valid over open water only

    ---

remarks:

172100z position near 10.0s 96.5e.

Tropical cyclone 04s (four), located approximately 150 nm

north of Cocos Island, Australia, has tracked southwestward at 05 

knots over the past six hours. Animated infrared satellite imagery 

depicts a consolidating low level circulation center (LLCC) with 

building deep convection while a 171851z trmm microwave image 

depicts an improving structure as convective banding has 

significantly improved along the southern semi-Circle as the LLCC 

has become tighter wrapped. The current position is based upon the 

aforementioned imagery with good confidence. Based on this increase 

in structure, the current intensity has been increased to 35 knots, 

with additional support from Dvorak intensity estimates of the same 

value from pgtw and aprf. Upper level analysis depicts a favorable 

environment as the system is experiencing low (05 to 10 knots) 

levels of vertical wind shear and has maintained excellent poleward 

outflow into an upper level low located over western Australia. Tc 

04s is currently tracking slowly to the southwest along a low- to 

mid-level subtropical ridge (str) located to the southeast of the 

system. This str will remain the dominant steering influence through 

the forecast period while the system's track becomes slightly more 

westward as the str is modified by a passing mid-latitude trough to 

the south. In the extended Taus, the system is expected to slow down 

and turn slightly more southwest as another transitory mid-latitude 

trough weakens the str. Good upper level support and warm along 

track SSTs (26 to 28 degrees celsius) will allow for general 

intensification reaching 70 knots near the end of the forecast. 

Limited dynamic model guidance is slightly spread but in generally 

good agreement with the forecast track. The official jtwc forecast 

track is positioned close to multi-model consensus with low 

confidence due to the spread in the dynamic models. Maximum 

significant wave height at 171800z is 10 feet. Next warnings at 

180900z and 182100z. This warning supersedes and cancels ref a, 

joint typhoon wrncen Pearl Harbor hi 170251z Dec 13 tropical cyclone 

formation alert (wtxs21 pgtw 170300). Refer to tropical cyclone 03s 

(amara) warnings (wtxs31 pgtw) for twelve-hourly updates.//

Nnnn

 

 

http://www.wunderground.com/hurricane/southern-indian/2013/Tropical-Cyclone-Four?text=public

[Styx]

 

One of Australia's remotest offshore territories,  3600 miles from Tasmania.

It has a very very interesting history - which began in 1826. A unique Scotish-Malay hybrid culture.

http://en.wikipedia.org/wiki/Cocos_%28Keeling%29_Islands

 

Population of 600 of which 500 are Malay, and religion is predominantly Muslim.

 

------------

 

BOM reports 89mm in 24hrs from this system on Cocos, and peak wind speed 83kmhr/52mph.

[Vorticity0123]

Bruce appears to be intensifying at quite a rapid pace, considering the satellite picture. However, unlike Amara (which has a banding type eye), the 'eye' of Bruce isn't a real, well defined eye, which can be seen well in Water Vapor imagery.

 

WV imagery of Bruce.

 

Despite this slight disorganized feature, the current intensity of Bruce is already 50 kt. The system is forecast to strengthen up to 90 kt, and then weaken as it recurves into the midlatitudes. (as from the forecast of JTWC).

 

 

The steering winds also show the same picture, with a 'gap' in steering winds to the south of Bruce (though this isn't nessecarily the gap Bruce will take at the point of recurvature).

 

 

And finally, MIMIC TC image of Bruce (I really like those kind of images, as they show in a nice extent the amount of organization of tropical cyclones  ):

 

What can be seen here is that the Bruce hasn't yet got a well defined inner core, which could impede the chances of RI occuring. The core seems to be rather broad and not very symmetric. 

 

Sources:

http://www.usno.navy.mil/JTWC/

http://tropic.ssec.wisc.edu/real-time/dlmmain.php?&basin=austwest&sat=wgms∏=dlm3&zoom=&time=

http://www.ssd.noaa.gov/PS/TROP/floaters/04S/imagery/wv0-lalo.jpg

Edited December 18, 2013 by Vorticity0123

[Somerset Squall]

Bruce has strengthened fairly quickly today, and currently has winds of 60kts. The cyclone has strong banding features and a central dense overcast, in which a true eye appears to be now taking shape. Conditions appear to favour some further intensification as Bruce heads west-southwestwards. As Bruce turns to the south in a few days time, shear and cooler sea temps will begin to erode the cyclone. JTWC expect a peak of 90kts before this occurs.

 

 

 

[Somerset Squall]

Bruce now has a large eye, and winds have increased to 75kts according to JTWC, and BOM have classified Bruce as a severe tropical cyclone.

 

 

 

 

 

[Somerset Squall]

Bruce's intensity has continued to rocket up, and winds are now at 110kts, high end cat 3 on the SS scale, according to JTWC. Bruce has a large eye, which is slightly cloud filled, surrounded by a solid central dense overcast and strong banding. Bruce is expected to attain cat 4 status on the SS scale before a weakening trend sets in after 12 hours.

[Coast]

Sorry, couldn't resist

 

 

NASA sees Tropical Cyclone Bruce develop near Cocos Island

 

NASA's Aqua satellite flew overhead as the fourth tropical cyclone of the Southern Indian Ocean cyclone season developed today, December 18, while it was passing to the northwest of Cocos Island, Australia.

 

 

The MODIS or Moderate Resolution Imaging Spectroradiometer instrument that flies aboard NASA's Aqua satellite captured Tropical Cyclone Bruce's developing eye in a visible image taken on Dec. 18 at 07:30 UTC/2:30 a.m. EST. Animated multispectral satellite imagery showed that the low-level circulation center was consolidating and there was an improvement in the banding of thunderstorms around the elongated center. The Atmospheric Infrared Sounder instrument that also flies aboard Aqua more clearly showed the developing eye. The infrared data showed cloud top temperatures, and around the center cloud tops were as cold as -63F/-52C, while the center was devoid of high, cold clouds, providing a more clear indication of a developing eye.

 

When NASA's Tropical Rainfall Measuring Mission or TRMM satellite passed over Bruce on Dec. 18 at 407 UTC/Dec. 17 at 11:07 p.m. EST, data showed that the bands of thunderstorms were fragmented, but tightly wrapped into the center. On December 18 at 0900 UTC/4 a.m. EST, Tropical Cyclone Bruce had maximum sustained winds near 50 knots/57.5 mph/92.6 kph making it a tropical storm. Bruce is expected to strengthen over the next several days and reach hurricane/typhoon strength before weakening. Bruce was centered just 108 nautical miles/124.3 miles/200 km northwest of Cocos Island, near 10.9 south latitude and 95.5 east longitude. It was moving to the southwest at 9 knots/10.3 mph/16.6 kph. The Australian Bureau of Meteorology noted on December 18 at 11:00 a.m. EST, that winds affecting the Cocos Islands eased below gale force as Tropical Cyclone Bruce continues moving away. Bruce is expected to track to the west-southwest and intensify over the next couple of days as it moves over open ocean.

 

http://phys.org/news/2013-12-nasa-tropical-cyclone-bruce-cocos.html#jCp

Edited December 20, 2013 by Coast

[Somerset Squall]

Bruce has continued to intensify, and is now a 125kt cat 4 on the SS scale. The eye has cleared out this afternoon and has become more defined. Bruce could intensify a little more.

[Somerset Squall]

MeteoFrance has now upgraded Bruce to a "Very Intense Tropical Cyclone", the highest on their scale. They estimate the pressure to be 915mb! What a beast!

[Styx]

 

http://tropic.ssec.wisc.edu/real-time/mosaic/images/mossir.jpg

 

Bruce and Amara not too long ago.

Edited December 21, 2013 by Styx

[Somerset Squall]

Bruce is on the cusp of becoming a cat 5 on the SS scale and is expected to over the next 24hrs. Winds are at 135kts according to JTWC. If Bruce d0es become a cat 5, it'll be the first in the south indian 0cean since Edzani in 2010, and the 6th worldwide this year

[Sainsbo]

Bruce is now a Category 5 with sustained winds of 160mph, and gusts of up to 195mph. It looks like Bruce is forecast to slowly weaken throughout the day

 

 

Though I must say, he doesn't look very impressive on satellite for a Cat. 5

 

[Somerset Squall]

Yes, Bruce became a cat 5 on the SS scale overnight with winds of 140kts. I think now however, that Bruce may be weakening and almost certainly will have lost cat 5 status next JTWC advisory. In fact, Navy/NRL tropical cyclone page suggests winds may have dropped back to 130kts currently. Bruce and Amara have been two very impressive systems for the start of the South Indian Ocean season, I wonder if it is a sign of things to come?

Edited December 22, 2013 by Somerset Squall

[Somerset Squall]

Bruce has weakened through the day as it curves south. Winds are down to 110kts, making Bruce a cat 3 now on the SS scale. The eye remains fairly well defined but the central dense overcast is eroding and becoming less convectively deep. This is due to cooling sea temps and increasing shear, two factors which are set to become even more unfavourable over the coming days, leading to further weakening as Bruce accelerates southeastwards.

[Styx]

Bruce is on the cusp of becoming a cat 5 on the SS scale and is expected to over the next 24hrs. Winds are at 135kts according to JTWC. If Bruce d0es become a cat 5, it'll be the first in the south indian 0cean since Edzani in 2010, and the 6th worldwide this year

 

How does that compare to recent years, and is it close to a record?

[crikey]

 

If you can watch this convergence now.. AWESOME

http://tropic.ssec.wisc.edu/real-time/indian/movies/m5wv/m5wvjava.html

[Somerset Squall]

Bruce has weakened further, with winds now down to 75kts. The eye has gone, and the convective canopy is evaporating as the warm water fuelling the cyclone has now been replaced by rather cold water. Shear and dry air also are adding to the mix to further weaken Bruce. Bruce will begin extratropical transition soon, and should have completed this process in a day or so.