Laurence Dumping the NW Aussie Coast
Posted by JAC on 12/15/2009, 5:30 am

At Cat1

Relocation yesterday closer to land inhibited a strong RI.

Still, pretty amazing to see an eye form essentially along the shore.

Struture on 37GHz shows it may not be done strengthening.














REMARKS:
150900Z POSITION NEAR 14.6S 125.4E.
TROPICAL CYCLONE (TC) 06S (LAURENCE), LOCATED APPROXIMATELY 530 NM
NORTHEAST OF PORT HEDLAND, AUSTRALIA, HAS TRACKED SOUTHWESTWARD  
AT 06 KNOTS OVER THE PAST SIX HOURS. DESPITE ITS PROXIMITY TO THE
COAST, LAURENCE HAS INTENSIFIED TO NEAR 75 KNOTS (BASED ON 4.5
DVORAK FROM PGTW). OBSERVATIONS FROM TROUGHTON ISLAND INDICATE
SUSTAINED WINDS AS HIGH AS 74 KNOTS AS THE CYCLONE PASSED
APPROXIMATELY 12 HOURS AGO. IN CONTRAST TO THE PREVIOUS FORECAST,
THE SYSTEM IS NOW EXPECTED TO TRACK DEEPER INTO INTERIOR AUSTRALIA
AND DISSIPATE NEAR TAU 48 OVER LAND. AN UPPER LEVEL LONGWAVE TROUGH
POSITIONED ALONG 105E, AND EXTENDING AS FAR EQUATORWARD AS 10S, IS
EXPECTED TO AMPLIFY THE STEERING RIDGE TO THE EAST OF THE CYCLONE AS
IT APPROACHES. THIS WILL INHIBIT WESTWARD MOTION AS THE STEERING
FLOW STRENGTHENS OUT OF THE NORTH, DRIVING LAURENCE INLAND. ALL
AVAILABLE CONSENSUS MEMBERS, WITH THE EXCEPTION OF EGRR, INDICATE A
NOTICEABLE SOUTHWARD TURN INLAND BETWEEN TAU 24 AND 36, WITH MOST OF
THESE MEMBERS KEEPING THE CIRCULATION OVER LAND FOR 24 HOURS OR
GREATER. GFS, ECMWF, AND GFDN ATTEMPT TO PULL THE CIRCULATION BACK
OVER WATER, JUST NORTH OF PORT HEDLAND, AND SLOWLY REINTENSIFY THE
SYSTEM. IF THE CURRENT FORECAST TRACK VERIFIES, THEN THIS IS NOT
LIKELY TO OCCUR GIVEN THE DURATION THE CIRCULATION WILL BE OVER
LAND. HOWEVER, IF THE TROUGH FILLS PRIOR TO PASSAGE, THE CYCLONE
COULD CONTINUE TO TRACK ALONG THE COAST, MUCH STRONGER THAN
FORECAST, AND PROCEED BACK OVER WATER INTACT AND POSITIONED TO
REINTENSIFY. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 150600Z IS 16 FEET.
NEXT WARNINGS AT 152100Z AND 160900Z.




IDW24100
Australian Government Bureau of Meteorology
Western Australia

Media: Transmitters serving the area between Kalumburu and Kuri Bay are
requested to USE the Standard Emergency Warning Signal before broadcasting the
following warning.


TOP PRIORITY FOR IMMEDIATE BROADCAST

TROPICAL CYCLONE ADVICE NUMBER 34
Issued at 6:10 pm WST on Tuesday, 15 December 2009
BY THE BUREAU OF METEOROLOGY
TROPICAL CYCLONE WARNING CENTRE PERTH

A Cyclone WARNING continues for coastal areas from Kalumburu to Cockatoo Island,
extending inland to include Drysdale River and Mt Barnett.

A Cyclone WATCH continues for coastal areas from Cockatoo Island to Beagle Bay.

At 5:00 pm WST Severe Tropical Cyclone Laurence, Category 3 was estimated to be
160 kilometres west southwest of Kalumburu and
125 kilometres northeast of Kuri Bay and
moving southwest at 15 kilometres per hour.

Severe Tropical Cyclone Laurence is a small but intense tropical cyclone moving
southwest close to the Kimberley coast. VERY DESTRUCTIVE WINDS with gusts to 210
kilometres per hour are being experienced on the coast close to the system
centre and are expected to extend along the coast  to Kuri Bay overnight.

GALES with gusts to 110 kilometres per hour may extend further along the coast,
reaching Cockatoo and Koolan Islands during Wednesday and possibly to Beagle Bay
later on Thursday.

HEAVY RAIN is expected to continue over the north Kimberley region, extending
into the western Kimberley overnight. Daily rainfall totals in excess of 100mm
are possible near the coast with totals decreasing further inland.
FESA-State Emergency Service advises of the following community alerts:
YELLOW ALERT: People in or near the communities of Kuri Bay and Mitchell Plateau
should be taking action.
BLUE ALERT: People in or near the communities of Koolan Island and Cockatoo
Island
should start taking precautions.
ALL CLEAR: People in Kalumburu are advised that wind danger has passed but you
need to take care to avoid any danger caused by the heavy rain.

Details of Severe Tropical Cyclone Laurence at 5:00 pm WST:
.Centre located near...... 14.6 degrees South 125.2 degrees East
.Location accuracy........ within 30 kilometres
.Recent movement.......... towards the southwest at 15 kilometres per hour
.Wind gusts near centre... 205 kilometres per hour and weakening
.Severity category........ 3
.Central pressure......... 966 hectoPascals

The next advice will be issued by 9:00 pm WST Tuesday 15 December.Cyclone
advices and State Emergency Service Community Alerts are available by
dialling  1300 659 210


REMARKS:
Laurence is a small but intense system, as demonstrated by the observations at
Troughton Island earlier today, where a peak gust of 185 km/h was measured as
the system went directly over the island. An eye has been evident on IR and VIS
imagery during the day with its best presentation being at 0430Z. DT peaked at
6.0 but other images produced a DT of only 5.0 based on a Enum of 5.5 [B
surround] with an elongated eye adjustment -0.5. The FT is set at 4.5 in
agrement with the PAT.  ADT is running a little on the weak side having failed
to identify the eye signature.

The system is likely to weaken overnight due to the influence of land as it
tracks almost parallel to the coast toward Kuri Bay. On Wednesday the system is
likely to come under the influence of a mid-level trough to the west, leading to
a more south to southeasterly track; which will take it further inland and
continue the weakening trend.

Copyright Commonwealth of Australia


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Laurence Dumping the NW Aussie Coast - JAC, 12/15/2009, 5:30 am
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