SPAC: TC's Ului & Tomas

[Willoughby Owen]

Hi,

Tropical cyclone ULUI is a currently a cat 4 ranging slowly in the NE Coral Sea, with tops cooling tonight. It's a beautiful, symmetrical cyclone with excellent poleward outflow. It went from a tropical disturbance to category 5 in less than 24 hours, so very impressive how quickly it gathered strength.

Satellite loop: http://www.goes.noaa.gov/sohemi/sohemiloops/shirgmscol.html
(Can't forget also about TC Tomas, which is currently getting ripped apart as it quickly becomes extra-tropical now passing 30 degrees S.)

Tomas battered the small northeastern islands of Fiji with winds up to 200 km/h early morning on Tuesday, with a state of emergency declared.

Not close enough for the Fujiwara effect...

Major models show a weakening trend late just before it crosses the coast northwest of Rockhampton, on Queensland's central coast.

JTWC seems to agree,

IDQ20018
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - EASTERN REGION
Issued by BRISBANE TROPICAL CYCLONE WARNING CENTRE
at: 0705 UTC 17/03/2010
Name: Severe Tropical Cyclone Ului
Identifier: 09U
Data At: 0600 UTC
Latitude: 14.1S
Longitude: 157.8E
Location Accuracy: within 10 nm [20 km]
Movement Towards: south [180 deg]
Speed of Movement: 3 knots [6 km/h]
Maximum 10-Minute Wind: 90 knots [165 km/h]
Maximum 3-Second Wind Gust: 125 knots [230 km/h]
Central Pressure: 950 hPa
Radius of 34-knot winds NE quadrant: 150 nm [280 km]
Radius of 34-knot winds SE quadrant: 150 nm [280 km]
Radius of 34-knot winds SW quadrant: 150 nm [280 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: 40 nm [75 km]
Radius of Maximum Winds: 15 nm [30 km]
Dvorak Intensity Code: T5.0/5.5/W0.5/24HRS
Pressure of outermost isobar: 1002 hPa
Radius of outermost closed isobar: 180 nm [335 km]
Storm Depth: Deep
FORECAST DATA
Date/Time   : Location    : Loc. Accuracy: Max Wind   : Central Pressure
[UTC]       : degrees     :      nm  [km]: knots[km/h]: hPa
+12: 17/1800: 14.7S 157.9E:     040 [075]:  090  [165]:  950
+24: 18/0600: 15.9S 158.0E:     070 [130]:  090  [165]:  950
+36: 18/1800: 17.2S 157.4E:     100 [190]:  090  [165]:  950
+48: 19/0600: 18.7S 156.0E:     135 [250]:  090  [165]:  950
+60: 19/1800: 19.9S 154.0E:     180 [340]:  090  [165]:  950
+72: 20/0600: 20.6S 151.5E:     230 [425]:  090  [165]:  950
REMARKS:
Recent imagery shows Severe Tropical Cyclone Ului as a symmetric system,
although cloud tops have warmed in the past 12 hours, indicating some weakening.
Dvorak analysis based on Eye pattern DT=5.0 based on LG surround with LG/OW eye
[5.0 with no adjustment] supported by PAT. CI kept at 5.5. The upper level
pattern generally remains favourable with strong poleward outflow associated
with an upper level trough to the south. Possibly the recent weakening trend is
due to ocean upwelling resulting from the slow movement in the past 48 hours. 

Steering remains light with forecast slow southerly movement expected in the
next 24 hours. From this time Ului should accelerate and track to the southwest
then to the west southwest towards the Queensland coast on Friday as a mid-level
ridge develops south of the system. 

While some weakening may continue in the next 24 hours as Ului tracks slowly to
the south, forecast intensity is held at 90 knots [category 4] through the
forecast period. In general the upper level pattern should remain conducive for
Ului to remain at severe classification through to landfall. 

At this stage a severe impact on the Queensland coast is likely later on
Saturday and/or Sunday.

 

[Willoughby Owen]

TC Ului has equalled Hurricane Wilma for the fastest ever recorded intensification of a cyclone from tropical storm strength to Category 5.

Between 13 and 14 March, Cyclone Ului underwent an unusually explosive phase of rapid intensification. During a 24 hour span, the system intensified from a tropical storm to a Category 5 equivalent cyclone, tying Hurricane Wilma in 2005 for the fastest intensification of a system from tropical storm to Category 5. According to the JTWC, maximum sustained winds increased from 100 km/h (65 mph) to 260 km/h (160 mph). They also estimated that the storm's minimal central pressure had decreased from 982 mbar (hPa) to 918 mbar (hPa), a drop of 64 mbar (hPa), during this span." -wiki