ECMWF has been fairly consistent with a TC developing SE of PNG this weekend, then crossing the Qld central coast early next week. GFS not interested, but other models becoming more inline with EC. So yesterday the BoM upgraded this low's TC chances to 'medium'. JTWC also took note earlier this morning…
Australian Government Bureau of Meteorology
Queensland
Tropical Cyclone Outlook for Coral Sea
Issued at 2:30 pm EST on Wednesday 22 March 2017
for the period until midnight EST Saturday 25 March 2017.
Existing Cyclones in the Eastern Region:
Nil. Potential Cyclones:
A low pressure system southeast of the Papua New Guinea mainland is forecast to develop over the next few days while drifting slowly southwest. Conditions are expected to become more favourable for tropical cyclone development in the coming days, particularly from Saturday onwards.
At this stage, the likelihood for a tropical cyclone in the Eastern Region is moderate - this rating should continue into next week.
Likelihood of a tropical cyclone in the Eastern Region on:
Thursday: Very Low
Friday: Low
Saturday: Moderate
ABPW10 PGTW 221330
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND
/SOUTH PACIFIC OCEANS REISSUED/221330Z-230600ZMAR2017//
RMKS/
...
2. SOUTH PACIFIC AREA (WEST COAST OF SOUTH AMERICA TO 135 EAST):
A. TROPICAL CYCLONE SUMMARY: NONE.
B. TROPICAL DISTURBANCE SUMMARY:
(1) AN AREA OF CONVECTION (INVEST 91P) HAS PERSISTED NEAR
12.4S 154.0E, APPROXIMATELY 330 NM SOUTHWEST OF WILLIS ISLAND.
ANIMATED INFRARED SATELLITE IMAGERY DEPICTS A BROAD AREA OF
CONVECTION DISPLACED WEST OF THE LOW-LEVEL CIRCULATION CENTER (LLCC)
ASSOCIATED WITH STRONG DIFFLUENCE IN THE AREA. A
220827Z SSMIS 91GHZ IMAGE DEPICTS AREAS OF STRONG CONVECTION WITH
VERY LITTLE ORGANIZATION. A 221058Z ASCAT PASS INDICATES A SYMMETRIC
BUT WEAK 10-15 KNOT LLCC AT THE SURFACE. UPPER-LEVEL
ANALYSIS SHOWS AN UNFAVORABLE ENVIRONMENT WITH 20-25 KNOTS OF
VERTICAL WIND SHEAR SLIGHTLY OFFSET BY FAIR DIFFLUENCE ALOFT. GLOBAL
MODELS ARE SHOWING DEVELOPMENT BEYOND THE 72 HOUR TIMEFRAME AS IT
SLOWLY TRACKS SOUTHWESTWARD. MAXIMUM SUSTAINED SURFACE WINDS ARE
ESTIMATED AT 10 TO 15 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED
TO BE NEAR 1009 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS LOW.
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BoM going for a high risk chance of a Coral Sea TC on Sunday, moderate on Saturday
Australian Government Bureau of Meteorology
Queensland
Tropical Cyclone Outlook for Coral Sea
Issued at 2:30 pm EST on Thursday 23 March 2017
for the period until midnight EST Sunday 26 March 2017.
Existing Cyclones in the Eastern Region:
Nil. Potential Cyclones:
A tropical low pressure system is located southeast of the Papua New Guinea mainland. It is forecast to drift southward for the next 24 to 36 hours, before turning more westward towards the tropical Queensland coast late Friday or on Saturday.
Conditions are favourable for this system to develop, and the probability of it forming into a tropical cyclone will steadily increase into the weekend.
This system is likely to make landfall on the north tropical Queensland coast early next week.
Likelihood of a tropical cyclone in the Eastern Region on:
Friday: Low
Saturday: Moderate
Sunday: High
ABPW10 PGTW 230600
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND
SOUTH PACIFIC OCEANS/230600Z-240600ZMAR2017//
RMKS/
…
2. SOUTH PACIFIC AREA (WEST COAST OF SOUTH AMERICA TO 135 EAST):
B. TROPICAL DISTURBANCE SUMMARY:
(1) THE AREA OF CONVECTION (INVEST 91P) PREVIOUSLY LOCATED
NEAR 12.4S 154.0E, IS NOW LOCATED NEAR 13.5S 154.1E, APPROXIMATELY
290 NM NORTHEAST OF WILLIS ISLAND. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY AND A 222252Z AMSU-B METOP A MICROWAVE IMAGE SHOW PATCHES OF
CONVECTION BEGINNING TO WRAP INTO A SLIGHTLY ELONGATED LOW LEVEL
CIRCULATION CENTER (LLCC). THE DISTURBANCE IS CURRENTLY LOCATED IN
AN AREA OF GOOD POLEWARD OUTFLOW ALOFT, LOW VERTICAL WIND SHEAR (10-
15 KNOTS), AND WARM SEA SURFACE TEMPERATURES (29-30 C). GLOBAL
MODELS ARE IN AGREEMENT THAT THE DISTURBANCE WILL CONTINUE TO TRACK
TO THE SOUTHWEST WITH INTENSIFICATION GRADUALLY OCCURRING OVER THE
NEXT SEVERAL DAYS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT
10 TO 15 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR
1005 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL
CYCLONE WITHIN THE NEXT 24 HOURS REMAINS LOW.
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We did have fairly innocuous Bart further east in late Feb...
I think this developing low could be quite a beast by comparison. It's certainly ramped up this morning...
ABPW10 PGTW 231300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND
SOUTH PACIFIC OCEANS REISSUED/231300Z-240600ZMAR2017//
RMKS/
…
2. SOUTH PACIFIC AREA (WEST COAST OF SOUTH AMERICA TO 135 EAST):
B. TROPICAL DISTURBANCE SUMMARY:
(1) THE AREA OF CONVECTION (INVEST 91P) PREVIOUSLY LOCATED
NEAR 12.4S 154.0E, IS NOW LOCATED NEAR 14.7S 152.2E, APPROXIMATELY
161 NM NORTHEAST OF WILLIS ISLAND. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY AND A 230813Z SSMIS MICROWAVE IMAGE SHOW PATCHES
OF CONVECTION BEGINNING TO WRAP INTO A STILL SLIGHTLY ELONGATED LOW
LEVEL CIRCULATION CENTER (LLCC) WITH SOME BANDING BEGINNING TO FORM.
THE DISTURBANCE IS CURRENTLY LOCATED IN AN AREA OF GOOD OUTFLOW
ALOFT, LOW VERTICAL WIND SHEAR (10-15 KNOTS), AND WARM SEA SURFACE
TEMPERATURES (29-30 C). GLOBAL MODELS ARE IN AGREEMENT THAT THE
DISTURBANCE WILL CONTINUE TO TRACK TO THE SOUTHWEST WITH
INTENSIFICATION GRADUALLY OCCURRING OVER THE NEXT SEVERAL DAYS.
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 10 TO 15 KNOTS.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1005 MB. THE
POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS UPGRADED TO MEDIUM.
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Yeah, particularly around the Townsville area at this stage…
BoM now going for a high risk chance of a Coral Sea TC by at least tomorrow.
JTWC also issued a TC Formation Alert for this low this arvo…
Australian Government Bureau of Meteorology
Queensland
Tropical Cyclone Outlook for Coral Sea
Issued at 1:36 pm EST on Friday 24 March 2017
for the period until midnight EST Sunday 26 March 2017.
Existing Cyclones in the Eastern Region:
Nil. Potential Cyclones:
At 10am, a tropical low pressure system is estimated to be 610 kilometres east of Cairns and 600 kilometres northeast of Townsville. The Coral Sea tropical low should develop into a tropical cyclone and move west towards the coast over the weekend.
For the latest, see tropical cyclone advices and forecasts tracks at http://www.bom.gov.au/qld/warnings/
Likelihood of a tropical cyclone in the Eastern Region on:
Friday:Moderate
Saturday:High
Sunday:High
WTPS22 PGTW 240130
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
090 NM EITHER SIDE OF A LINE FROM 15.5S 151.7E TO 17.9S 150.1E
WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 25 TO 30 KNOTS. METSAT
IMAGERY AT 240000Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 15.8S 151.5E. THE SYSTEM IS MOVING SOUTH-SOUTHWESTWARD AT 07
KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 91P) PREVIOUSLY LOCATED
NEAR 15.2S 151.8E, IS NOW LOCATED NEAR 15.8S 151.5E, APPROXIMATELY
100 NM EAST-NORTHEAST OF WILLIS ISLAND, AUSTRALIA. ANIMATED MULTI-
SPECTRAL SATELLITE IMAGERY AND A 232049Z MHS NOAA-18 89GHZ MICROWAVE
PASS SHOW CURVED BANDING WRAPPING INTO A RAPIDLY DEVELOPING LOW
LEVEL CIRCULATION CENTER. THE DISTURBANCE IS CURRENTLY LOCATED IN A
FAVORABLE ENVIRONMENT WITH EXCELLENT DUAL CHANNEL OUTFLOW, LOW
VERTICAL WIND SHEAR (10-15 KNOTS), AND WARM SEA SURFACE TEMPERATURES
(29-30 C). GLOBAL MODELS INDICATE DEVELOPMENT OF A TROPICAL CYCLONE
IS LIKELY WITHIN 12 TO 24 HOURS AS THIS DISTURBANCE TRACKS
SOUTHWESTWARD. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25
TO 30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1005
MB. BASED ON IMPROVED STRUCTURE AND FAVORABLE ENVIRONMENTAL
CONDITIONS, THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT
TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS HIGH.
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Good spiralling and rapid development today. BoM expects this low to be named by morning and aren't ruling out higher than Cat 3 before making landfall probably around Monday night at this stage…
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - EASTERN REGION
Issued by BRISBANE TROPICAL CYCLONE WARNING CENTRE
at: 0658 UTC 24/03/2017
Name: Tropical Low
Identifier: 24U
Data At: 0600 UTC
Latitude: 16.7S
Longitude: 151.8E
Location Accuracy: within 50 nm [95 km]
Movement Towards: southeast [143 deg]
Speed of Movement: 7 knots [13 km/h]
Maximum 10-Minute Wind: 25 knots [45 km/h]
Maximum 3-Second Wind Gust: 45 knots [85 km/h]
Central Pressure: 997 hPa
…
REMARKS:
Position fix is considered fair based on a combination of animated visible
imagery, Willis Island radar and peripheral surface observations. The tropical
low has been showing signs of development over the past 24 hours. Multiple
episodes of deep convection, showing some curvature, have developed near the
centre in the past 12 to 24 hours, although they have remained somewhat
transient in nature. Dvorak analysis was based on a curved band wrapping 0.4 to
0.5 in both Vis and IR imagery, yileding a DT of 2.5. Given the transient nature
of this convection though, the FT was biased towards the MET and PT of 2.0.
The low is currently being steered to the south-southeast by the combination of
a mid level ridge to the east, and an upper level trough moving eastwards across
the Tasman Sea. During the weekend, this trough is expected to move further
east, and a new mid level ridge should build to the south of the system, leading
to a change to a westerly track, taking the cyclone onto the Queensland coast.
All model guidance is in agreement with this scenario, although there are some
differences in forward speed amongst the guidance, which affects not only the
time of impact, but also the length of time available for the system to
intensify over the water.
The system is located in an area of weak vertical wind shear over SSTs of 29 to
30 deg C. Upper level outflow is good in all quadrants, and may become further
enhanced to the south due to the weak interaction with the upper trough.
Overall, the environment will remain supportive of intensification right up to
landfall on the Queensland coast, and it is reasonably likely that the system
will have sufficient time over water to reach category 3 status. A period of
more rapid intensification cannot be ruled out, which would lead to a higher
category system at landfall.
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Good bursts of convection around this monster's centre this morning.
BoM now expecting it to reach at least Cat 4 before making landfall…
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - EASTERN REGION
Issued by BRISBANE TROPICAL CYCLONE WARNING CENTRE
at: 1247 UTC 24/03/2017
Name: Tropical Low
Identifier: 24U
Data At: 1200 UTC
Latitude: 16.9S
Longitude: 151.9E
Location Accuracy: within 25 nm [45 km]
Movement Towards: south southeast [165 deg]
Speed of Movement: 2 knots [5 km/h]
Maximum 10-Minute Wind: 25 knots [45 km/h]
Maximum 3-Second Wind Gust: 45 knots [85 km/h]
Central Pressure: 996 hPa
…
REMARKS:
Position fair based on Willis Island radar imagery and peripheral surface
observations.
The system continues to become slowly organised, with increasing broad curvature
evident and transient bursts of curved convection near the centre. Dvorak
analysis based on a three hourly average of curved bands, averaging to
approximately an 0.35 wrap. DT is therefore 2.0. MET agrees. Final T 2.0.
The system is currently being steered to the south-southeast by the combination
of a mid level ridge to the east, and an upper level trough moving eastwards
across the Tasman Sea. During the weekend, this trough is expected to move
further east, and a new mid level ridge should build to the south of the system,
leading
to a change to a westerly track, taking the cyclone onto the Queensland coast.
All model guidance is in agreement with this scenario, although there are some
differences in forward speed amongst the guidance, which affects not only the
time of impact, but also the length of time available for the system to
intensify over the water.
The system is located in an area of weak vertical wind shear over SSTs of 29 to
30 deg C. Upper level outflow is good in all quadrants, and may become further
enhanced to the south due to the weak interaction with the upper trough.
Overall, the environment will remain supportive of intensification right up to
landfall on the Queensland coast. The intensity forecast is based on slightly
more than a standard rate of intensification; given the favourable environment
it is likely that there will be periods of more rapid intensification.
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JTWC already calling this low a TC with 40 kt 1-minute central mean winds…
WTPS31 PGTW 242100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 13P (THIRTEEN) WARNING NR 001//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/240121ZMAR2017//
AMPN/REF A IS A TROPICAL CYCLONE FORMATION ALERT.//
RMKS/
1. TROPICAL CYCLONE 13P (THIRTEEN) WARNING NR 001
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
241800Z --- NEAR 17.2S 152.0E
MOVEMENT PAST SIX HOURS - 150 DEGREES AT 04 KTS
POSITION ACCURATE TO WITHIN 050 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
...
REMARKS:
242100Z POSITION NEAR 17.4S 152.0E.
TROPICAL CYCLONE 13P (THIRTEEN), LOCATED APPROXIMATELY 356 NM EAST
OF CAIRNS, AUSTRALIA, HAS TRACKED SOUTH-SOUTHEASTWARD AT 04 KNOTS
OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS A
SYSTEM THAT IS WELL ORGANIZED WITH A BROAD BUT DEFINED LOW LEVEL
CIRCULATION CENTER (LLCC). THE CIRCULATION IS ALSO EVIDENT IN
SCATTEROMETRY AND THE WILLIS ISLAND RADAR LOOP. DESPITE MULTIPLE
IMAGERY SOURCES THE CONFIDENCE IN THE INITIAL POSITION IS FAIR DUE
TO THE BROAD NATURE OF THE LLCC. THE CURRENT INTENSITY IS HELD
HIGHER THAN DVORAK INTENSITY ESTIMATES OF T2.5 (35 KNOTS) BASED ON A
PREVIOUS 241156Z ASCAT PASS SHOWING 40KT WINDS TO THE SOUTH.
ENVIRONMENTAL CONDITIONS ARE VERY FAVORABLE WITH HIGH SEA SURFACE
TEMPERATURES (30 C) AND LOW VERTICAL WIND SHEAR. THE SYSTEM SHOWS
STRONG DUAL CHANNEL OUTFLOW AND A STRONG VORTICITY SIGNATURE. THE
SYSTEM IS CURRENTLY TRACKING SOUTHWARD ALONG A SUB TROPICAL RIDGE
LOCATED TO THE EAST TOWARD A TROUGH LOCATED TO THE SOUTH. DURING
THIS PERIOD, EXPECT A SLOW BUT STEADY INTENSIFICATION AS THE CYCLONE
CONTINUES TO CONSOLIDATE. AFTERWARDS, THE STORM WILL TURN TO THE
WEST AS IT BEGINS TO INTERACT WITH HIGH PRESSURE CURRENTLY BUILDING
OVER CENTRAL AUSTRALIA. VERY FAVORABLE ENVIRONMENTAL CONDITIONS WILL
PERSIST ALLOWING A PERIOD OF RAPID INTENSIFICATION PRIOR TO LANDFALL
JUST BEFORE TAU 72. THE PEAK INTENSITY WILL OCCUR NEAR TAU 60. AS
THE SYSTEM TRACKS OVER INLAND, THE FRICTIONAL EFFECTS OF LAND
INTERACTION WILL RAPIDLY ERODE THE CYCLONE LEADING TO ITS COMPLETE
DISSIPATION BY THE END OF THE FORECAST PERIOD. MODEL GUIDANCE FROM
THE PAST 48 HOURS SHOWED THE SYSTEM TRAVELING FURTHER SOUTH BEFORE
MAKING THE WESTWARD WITH EACH NEW MODEL RUN. THE SHIFT IS LIKELY DUE
TO THE SLOWED ARRIVAL OF THE HIGH PRESSURE SYSTEM. DESPITE THE
CONTINUAL SHIFT IN THE TAU AT WHICH THE STORM WILL TURN WEST, THE
MODELS ARE IN GENERAL AGREEMENT OF THE TRACK LENDING FAIR CONFIDENCE
IN THE FORECAST TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 241800Z IS
10 FEET. NEXT WARNINGS AT 250900Z AND 252100Z. THIS CANCELS AND
SUPERSEDES REF A (WTPS22 PGTW 240130).//
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - EASTERN REGION
Issued by BRISBANE TROPICAL CYCLONE WARNING CENTRE
at: 1854 UTC 24/03/2017
Name: Tropical Low
Identifier: 24U
Data At: 1800 UTC
Latitude: 17.0S
Longitude: 152.2E
Location Accuracy: within 20 nm [35 km]
Movement Towards: southeast [134 deg]
Speed of Movement: 2 knots [5 km/h]
Maximum 10-Minute Wind: 30 knots [55 km/h]
Maximum 3-Second Wind Gust: 45 knots [85 km/h]
Central Pressure: 992 hPa
...
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TC Debbie was named around 01Z (2pm NZDT) by the BoM today…
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - EASTERN REGION
Issued by BRISBANE TROPICAL CYCLONE WARNING CENTRE
at: 0135 UTC 25/03/2017
Name: Tropical Cyclone Debbie
Identifier: 24U
Data At: 0000 UTC
Latitude: 17.4S
Longitude: 151.9E
Location Accuracy: within 20 nm [35 km]
Movement Towards: southwest [216 deg]
Speed of Movement: 5 knots [9 km/h]
Maximum 10-Minute Wind: 35 knots [65 km/h]
Maximum 3-Second Wind Gust: 50 knots [95 km/h]
Central Pressure: 992 hPa
…
REMARKS:
The tropical low has recently developed into Tropical Cyclone Debbie. The system
is associated with an impressive, very large circulation, but until recently has
shown little development near the centre. However, it continues to become slowly
organised, particularly near the centre, where convection is finally becoming
more sustained. The latest Dvorak analysis was based on a curved band pattern
with a 0.6 degree wrap, giving a DT of 3.0. MET and PAT were both 3.0. This
analysis was supported by observations of sustained gales from Marion Reef.
Confidence in the location of the system is considered good based on animated
visible imagery, Willis Island radar and surface observations from Lihou Reef.
Pressure observations have declined significantly at Lihou Reef over the last 24
hour with an MSLP observation of 991.8hPa at 18 UTC 24/3.
Until recently, the system was being steered to the southeast by the combination
of a mid level ridge to the east, and an upper level trough moving eastwards
across the Tasman Sea. In the last few hours, the expected shift onto a west
southwesterly track has been evident, as the upper trough moves further east,
and a new mid level ridge builds to the south of the system. The latter is
expected to remain the dominant steering mechanism over the next few days,
keeping the cyclone on a west-southwesterly track and taking the cyclone onto
the Queensland coast. Given such a large circulation, it can be expected that
the system will have some effect back onto the surrounding steering systems --
this is part of the reason for the drift to more southerly tracks recently. All
model guidance is in agreement with this scenario, although there remain some
differences in forward speed amongst the guidance, which affects not only the
time of impact, but also the length of time available for the system to
intensify over the water. It should also be noted that a significant proportion
of EC Ensemble tracks remain to the north of the current cluster of
deterministic forecasts, taking the system onto the coast north of Cardwell.
The system is located in an area of weak vertical wind shear over SSTs of 29 to
30 degrees celcius. Upper level outflow is excellent in all quadrants. Overall,
the environment will remain supportive of intensification right up to landfall
on the Queensland coast. The intensity forecast is based on slightly more than a
standard rate of intensification; given the favourable environment it is likely
that there will be periods of more rapid intensification.
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Yeah, 180,000 odd people in Townsville. Note that although the deterministic track-map still shows landfall a little further south towards Ayr at this stage, EC ensembles favour north of Cardwell…
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - EASTERN REGION
Issued by BRISBANE TROPICAL CYCLONE WARNING CENTRE
at: 0711 UTC 25/03/2017
Name: Tropical Cyclone Debbie
Identifier: 24U
Data At: 0600 UTC
Latitude: 17.5S
Longitude: 151.8E
Location Accuracy: within 30 nm [55 km]
Movement Towards: southwest [224 deg]
Speed of Movement: 1 knots [3 km/h]
Maximum 10-Minute Wind: 35 knots [65 km/h]
Maximum 3-Second Wind Gust: 50 knots [95 km/h]
Central Pressure: 992 hPa
…
REMARKS:
Tropical cyclone Debbie has a very large and impressive circulation featuring
spiral banding over much of the Coral Sea, but until recently has shown little
development near the centre. However, it continues to become slowly organised,
and convection has become a little more persistent near the centre over the past
few hours. This slow central development is fairly typical of very large
tropical lows. The latest Dvorak analysis was based on a curved band pattern
with a 0.6 degree wrap, giving a DT of 3.0. MET and PAT were both 3.0. This
analysis was supported by observations of sustained gales from Marion Reef.
Confidence in the location of the system is considered good based on animated
visible imagery, Willis Island radar and surface observations from Lihou Reef.
Pressure observations have declined significantly at Lihou Reef over the last 24
hour with an MSLP observation of 988.7hPa at 0230 UTC 25/3.
Until recently, the system was being steered to the southeast by the combination
of a mid level ridge to the east, and an upper level trough moving eastwards
across the Tasman Sea. The system has been fairly slow moving in the past few
hours, however there are signs that the expected shift onto a west southwesterly
track is occurring, as the upper trough moves further east, and a new mid level
ridge builds to the south of the system. The latter is expected to remain the
dominant steering mechanism over the next few days, keeping the cyclone on a
west-southwesterly track and taking the cyclone onto the Queensland coast. Given
such a large circulation, it can be expected that the system will have some
effect back onto the surrounding steering systems -- this is part of the reason
for the drift to more southerly tracks recently. All model guidance is in
agreement with this scenario, although there remain some differences in forward
speed amongst the guidance, which affects not only the time of impact, but also
the length of time available for the system to intensify over the water. It
should also be noted that a significant proportion of EC Ensemble tracks remain
to the north of the current cluster of deterministic forecasts, taking the
system onto the coast north of Cardwell.
The system is located in an area of weak vertical wind shear over SSTs of 29 to
30 degrees celcius. Upper level outflow is excellent in all quadrants. Overall,
the environment will remain supportive of intensification right up to landfall
on the Queensland coast. The intensity forecast is based on slightly more than a
standard rate of intensification; given the favourable environment it is likely
that there will be periods of more rapid intensification.
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Rapidly developing Debbie was upgraded to Cat 2 by the BoM at around 13Z (2am NZDT) this morning…
WTPS31 PGTW 250900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 13P (DEBBIE) WARNING NR 002//
RMKS/
1. TROPICAL CYCLONE 13P (DEBBIE) WARNING NR 002
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
250600Z --- NEAR 17.7S 152.1E
MOVEMENT PAST SIX HOURS - 180 DEGREES AT 02 KTS
POSITION ACCURATE TO WITHIN 020 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
…
REMARKS:
250900Z POSITION NEAR 17.8S 152.0E.
TROPICAL CYCLONE 13P (DEBBIE), LOCATED APPROXIMATELY 364 NM EAST
OF CAIRNS, AUSTRALIA, HAS TRACKED SOUTHWARD AT 02 KNOTS OVER THE
PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY AND A
250558Z SSMIS 37 GHZ IMAGE DEPICT A RAPIDLY CONSOLIDATING LOW-LEVEL
CIRCULATION CENTER WITH IMPROVED CONVECTIVE BANDING, AND A LARGE
MICROWAVE EYE. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
BASED ON THE ABOVE IMAGERY. THE INITIAL INTENSITY OF 55 KNOTS IS ON
THE HIGH END OF AGENCY DVORAKS OF T3.0 (45 TO 55 KNOTS) BASED ON THE
RAPIDLY IMPROVING STRUCTURE OF THE SYSTEM. UPPER-LEVEL ANALYSIS
INDICATES A VERY FAVORABLE ENVIRONMENT WITH RADIAL OUTFLOW AND LOW
VERTICAL WIND SHEAR. TC DEBBIE IS CURRENTLY TRACKING SLOWLY
SOUTHWARD TOWARD A WEAKNESS BETWEEN A NER TO THE EAST AND A STR TO
THE SOUTHWEST. THE NER WILL TAKE OVER AS THE DOMINANT STEERING
FEATURE THROUGH THE FORECAST PERIOD AS IT BEGINS TO BUILD AND
MIGRATE WESTWARD, CAUSING TC DEBBIE TO CHANGE COURSE TO THE
SOUTHWEST. THIS SYSTEM IS FORECAST TO UNDERGO RAPID INTENSIFICATION
OVER THE NEXT 48 HOURS AS SSTS AND THE UPPER-LEVEL ENVIRONMENT
REMAIN EXTREMELY FAVORABLE. PEAK INTENSITY WILL OCCUR JUST PRIOR TO
LANDFALL, SHORTLY AFTER TAU 48. AS THE SYSTEM TRACKS INLAND, THE
FRICTIONAL EFFECTS OF LAND INTERACTION WILL RAPIDLY ERODE THE
CYCLONE LEADING TO ITS COMPLETE DISSIPATION BY THE END OF THE
FORECAST PERIOD. DYNAMIC MODEL GUIDANCE CONTINUE TO CONSOLIDATE ON
THE FORECAST TRACK LENDING HIGH CONFIDENCE TO THE JTWC FORECAST
TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 250600Z IS 13 FEET. NEXT
WARNINGS AT 252100Z AND 260900Z.//
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - EASTERN REGION
Issued by BRISBANE TROPICAL CYCLONE WARNING CENTRE
at: 1310 UTC 25/03/2017
Name: Tropical Cyclone Debbie
Identifier: 24U
Data At: 1200 UTC
Latitude: 17.7S
Longitude: 151.9E
Location Accuracy: within 30 nm [55 km]
Movement Towards: south [180 deg]
Speed of Movement: 2 knots [3 km/h]
Maximum 10-Minute Wind: 55 knots [100 km/h]
Maximum 3-Second Wind Gust: 75 knots [140 km/h]
Central Pressure: 985 hPa
…
REMARKS:
Tropical cyclone Debbie has been slow moving for the past 12 hours. It has
continued to improve in organisation, and is currently undergoing a significant
convective burst near the centre. This has been reflected in the steady increase
of peripheral wind observations.
Confidence in the centre position is fair to good based on animated IR satellite
imagery, imagery from Willis Island radar, and peripheral observations.
Intensity is analysed at 55 knots [10 minute mean]. Dvorak analysis using curved
bands has averaged DT3.0 over the previous three hours, but this average has
increased to DT3.5 during the hour and a half prior to the 12UTC analysis
[0.65-0.7 wrap with +0.5T for the band being white or colder]. MET and PAT are
3.0. Final T is 3.5. Automatic weather stations at Marion Reef [approximately 90
nautical miles south of the system] and at Lihou Reef [approximately 40 nautical
miles north] have peaked at 50 and 46 knots respectively [10 minute mean],
supporting the analysed intensity. The intensity is also supported by ADT
values. The observations and surrounding convection suggest an asymmetric wind
structure at present, which is forecast to become more symmetrical as the system
increases its organisation. The pressure at Lihou Reef is dropping against the
diurnal trend [991.8hPa at 12UTC].
Steering has been weak for the past 12 hours, however CIMSS satellite winds
suggest a mid-level ridge building to the south of the system as forecast. This
will steer the system to the west-southwest for the next several days until
landfall on the Queensland coast, expected overnight Monday or Tuesday morning.
Deterministic NWP models all follow this scenario with landfalls occurring
broadly between Lucinda and Mackay on the Queensland coast. MOGREPS and GFS
ensembles are consistent with this, although a number of 00Z ECMWF ensemble
members have landfalls further north between Cairns and Lucinda.
The system remains located in an area of weak vertical wind shear over SSTs of
29 to 30 degrees celsius. Upper level outflow is excellent in all quadrants.
Conditions will remain favourable for development right up until landfall, and
this has been reflected in an intensity forecast at slightly above the standard
rate. This is generally on the high end of the objective guidance spectrum,
although HWRF and recent SHIPS guidance are similar. Given the supportive
environment, it is likely that there will be periods of more rapid
intensification, and the intensity may be higher than forecast.
You do not have the required permissions to view the files attached to this post.
REMARKS:
Tropical cyclone Debbie has continued to show improved signs of development on
satellite imagery over the last 24 hours. The latest Dvorak intensity analysis
was based on a curved band pattern with a 0.7 degree wrap, giving a DT of 3.5.
MET is 4.0 and PAT 3.5. FT was baed on DT and PT. This analysis is supported by
observations from Marion Reef and Lihou Reef and a recent Ascat pass over the
system; the Ascat pass was also useful for confirming wind radii. SATCON
estimates have been suggested a system with an intensity of 65 knots [1-minute
mean], which roughly matches the analysed intensity when converted to a
10-minute mean.
Confidence in the centre position is rated as good based on a combination of
imagery from Willis Island radar, animated visible satellite imagery and
peripheral surface observations.
Steering has been weak for the past 12 to 18 hours, however CIMSS satellite
winds suggest a mid-level ridge building to the south of the system as forecast.
This will steer the system to the west-southwest for the next several days until
landfall on the Queensland coast, which is currently expected during Tuesday
morning, or at earliest overnight Monday. Deterministic numerical weather
prediction models all follow this scenario with landfalls occurring broadly
between Lucinda and Mackay along the Queensland east coast.
The system remains located in an area of weak vertical wind shear over sea
surface temperatures of 29 to 30 degrees Celsius. Upper level outflow is
excellent in all quadrants. Conditions will remain favourable for development
right up until landfall, and this has been reflected in an intensity forecast at
slightly above the standard rate. This is generally on the high end of the
objective guidance spectrum, although HWRF and recent SHIPS guidance are
similar. Recent SSMIS microwave pass combined with SHIPS RI guidance suggest a
period of rapid intensification is possible in the next 24 hours. Given this
evidence, the intensity may be higher than forecast approaching landfall.
WTPS31 PGTW 252100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 13P (DEBBIE) WARNING NR 003//
RMKS/
1. TROPICAL CYCLONE 13P (DEBBIE) WARNING NR 003
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
251800Z --- NEAR 17.9S 151.7E
MOVEMENT PAST SIX HOURS - 240 DEGREES AT 02 KTS
POSITION ACCURATE TO WITHIN 020 NM
POSITION BASED ON CENTER LOCATED BY A COMBINATION OF
SATELLITE AND RADAR
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT
…
REMARKS:
252100Z POSITION NEAR 18.0S 151.5E.
TROPICAL CYCLONE 13P (DEBBIE), LOCATED APPROXIMATELY 343 NM EAST
OF CAIRNS, AUSTRALIA, HAS TRACKED WEST-SOUTHWESTWARD AT 02 KNOTS
OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY AND A
251711Z SSMIS 37 GHZ IMAGE DEPICT A CONSOLIDATING LOW-LEVEL
CIRCULATION CENTER (LLCC) WITH AN EYE VISIBLE ON THE MICROWAVE
IMAGE. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON
THE MICROWAVE IMAGERY. THE INITIAL INTENSITY OF 65 KNOTS IS HEDGED
SLIGHTLY ABOVE THE AGENCY DVORAKS OF T3.5 (55 KNOTS) BASED ON THE
PREVIOUS SATCON VALUE OF 64 KTS AND THE STRUCTURAL IMPROVEMENT.
UPPER-LEVEL ANALYSIS INDICATES A FAVORABLE ENVIRONMENT FOR CONTINUED
DEVELOPMENT WITH GOOD OUTFLOW, BOTH POLEWARD AND EQUATORWARD, AND
LOW VERTICAL WIND SHEAR VALUES. TC DEBBIE HAS BEEN TRACKING SLOWLY
SOUTHWARD ALONG A SUBTROPICAL RIDGE LOCATED TO THE EAST AND HAS
BEGUN TO SHIFT DIRECTION TO THE WEST DUE TO THE INFLUENCE OF THE
RIDGE LOCATED OVER CENTRAL AUSTRALIA. THE RIDGE OVER CENTRAL
AUSTRALIA WILL REMAIN AS THE DOMINANT STEERING FEATURE FOR THE
DURATION OF THE FORECAST PERIOD. THIS SYSTEM IS FORECAST TO UNDERGO
RAPID INTENSIFICATION OVER THE NEXT 24 TO 48 HOURS AS THE SEA
SURFACE TEMPERATURE AND THE UPPER-LEVEL ENVIRONMENT REMAIN
FAVORABLE. PEAK INTENSITY WILL OCCUR JUST PRIOR TO
LANDFALL, WHICH WILL OCCUR SHORTLY AFTER TAU 48. AS THE SYSTEM
TRACKS INLAND, THE FRICTIONAL EFFECTS OF RUGGED TERRAIN WILL RAPIDLY
ERODE THE CYCLONE LEADING TO COMPLETE DISSIPATION BY THE END OF THE
FORECAST PERIOD. MODEL GUIDANCE HAS CONTINUED TO CONSOLIDATE ON
THE FORECAST TRACK LENDING HIGH CONFIDENCE TO THE JTWC FORECAST
TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 251800Z IS 16 FEET. NEXT
WARNINGS AT 260900Z AND 262100Z.//
You do not have the required permissions to view the files attached to this post.
REMARKS:
Tropical cyclone Debbie has continued to show improved signs of development on
satellite imagery over the last 24 hours. The latest Dvorak intensity analysis
was based on a curved band pattern on Vis imagery with a 1.1 degree wrap, giving
a DT of 4.0. MET and PAT agree, hence FT set to 4.0. Ascat pass over the system
at 22:45 UTC 25/3 was also useful for confirming wind radii. SATCON estimates
have been suggested a system with an intensity of 65 knots [1-minute mean],
which roughly matches the analysed intensity when converted to a 10-minute mean.
Confidence in the centre position is rated as good based on a combination of
imagery from Willis Island radar, animated visible satellite imagery and
peripheral surface observations.
Steering has been weak for the past 12 to 18 hours, however CIMSS satellite
winds suggest a mid-level ridge building to the south of the system as forecast.
This will steer the system to the west-southwest for the next several days until
landfall on the Queensland coast, which is currently expected during Tuesday
morning, or at earliest overnight Monday. Deterministic numerical weather
prediction models all follow this scenario with landfalls occurring broadly
between Lucinda and Mackay along the Queensland east coast.
The system remains located in an area of weak vertical wind shear over sea
surface temperatures of 29 to 30 degrees Celsius. Upper level outflow is
excellent in all quadrants. Conditions will remain favourable for development
right up until landfall, and this has been reflected in an intensity forecast at
slightly above the standard rate. This is generally on the high end of the
objective guidance spectrum, although HWRF and recent SHIPS guidance are
similar. Recent SSMIS microwave pass combined with SHIPS RI guidance suggest a
period of rapid intensification is possible in the next 24 hours. Given this
evidence, the intensity may be higher than forecast approaching landfall.
You do not have the required permissions to view the files attached to this post.
Latest remarks from JTWC. Some entrained dry continental air slowed intensification a little today, so not quite Cat 3 yet, but convection seems to be stepping up…
WTPS31 PGTW 260900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 13P (DEBBIE) WARNING NR 004//
RMKS/
1. TROPICAL CYCLONE 13P (DEBBIE) WARNING NR 004
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
260600Z --- NEAR 18.3S 151.2E
MOVEMENT PAST SIX HOURS - 250 DEGREES AT 03 KTS
POSITION ACCURATE TO WITHIN 020 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT
WIND RADII VALID OVER OPEN WATER ONLY
...
REMARKS:
260900Z POSITION NEAR 18.4S 151.0E.
TROPICAL CYCLONE 13P (DEBBIE), LOCATED APPROXIMATELY 320 NM EAST-
SOUTHEAST OF CAIRNS, AUSTRALIA, HAS TRACKED WEST-SOUTHWESTWARD AT
03 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY DEPICTS AN ORGANIZED LOW-LEVEL CIRCULATION CENTER WITH
FLARING DEEP CONVECTION WRAPPING INTO THE SYSTEM. A 260545Z SSMIS 37
GHZ IMAGE REVEALS TIGHTLY CURVED CONVECTIVE BANDING, A LARGE
MICROWAVE EYE, AND SUPPORTS THE CURRENT JTWC BEST TRACK POSITION
WITH HIGH CONFIDENCE. THE INITIAL INTENSITY OF 70 KNOTS IS SUPPORTED
BY MULTI-AGENCY DVORAKS OF T3.5 (55 TO 70 KNOTS) LATEST SATCON
ESTIMATES AROUND 65 KNOTS, AND THE IMPROVED CONVECTIVE ORGANIZATION.
UPPER-LEVEL ANALYSIS CONTINUES TO INDICATE A VERY FAVORABLE
ENVIRONMENT FOR DEVELOPMENT WITH RADIAL OUTFLOW AND LOW VERTICAL
WIND SHEAR. HOWEVER, RECENT TPW IMAGERY SHOWS SOME DRY CONTINENTAL
AIR BEING ENTRAINED INTO THE SYSTEM, WHICH HAS SLOWED THE
INTENSIFICATION OVER THE PAST 12 HOURS. TC DEBBIE HAS BEEN TRACKING
SLOWLY SOUTHWESTWARD BETWEEN THE WESTERN PERIPHERY OF A NER AND A
STR TO THE SOUTHWEST. THIS SYSTEM WILL REMAIN UNDER THE SHARED
STEERING INFLUENCE OF BOTH FEATURES THROUGH THE FORECAST PERIOD,
WHICH WILL MAINTAIN ITS SOUTHWESTWARD TRAJECTORY. FAVORABLE
ENVIRONMENTAL CONDITIONS WILL PERSIST UNTIL TC 13P MAKES LANDFALL
SHORTLY AFTER TAU 36, ALLOWING FOR A PERIOD OF STEADY
INTENSIFICATION. AS THE SYSTEM TRACKS INLAND, THE FRICTIONAL EFFECTS
OF RUGGED TERRAIN WILL RAPIDLY ERODE THE CYCLONE LEADING TO COMPLETE
DISSIPATION BY THE END OF THE FORECAST PERIOD. DYNAMIC MODEL
GUIDANCE HAVE CONTINUED TO CONSOLIDATE ON THE FORECAST TRACK LENDING
HIGH CONFIDENCE TO THE JTWC FORECAST TRACK. MAXIMUM SIGNIFICANT WAVE
HEIGHT AT 260600Z IS 18 FEET. NEXT WARNINGS AT 262100Z AND 270900Z.//
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Debbie still at Cat 2 this morn. Convection a little erratic overnight, although some recent improvement...
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - EASTERN REGION
Issued by BRISBANE TROPICAL CYCLONE WARNING CENTRE
at: 1313 UTC 26/03/2017
Name: Tropical Cyclone Debbie
Identifier: 24U
Data At: 1200 UTC
Latitude: 18.4S
Longitude: 150.7E
Location Accuracy: within 20 nm [35 km]
Movement Towards: west southwest [247 deg]
Speed of Movement: 4 knots [7 km/h]
Maximum 10-Minute Wind: 60 knots [110 km/h]
Maximum 3-Second Wind Gust: 85 knots [155 km/h]
Central Pressure: 976 hPa
…
REMARKS:
The amount of convection near the centre of tropical cyclone Debbie has
continued to wax and wane during the past 24 hours. Little improvement in the
cloud signature has been seen over the past 6 hours or so. Currently the system
has less deep convection than 24 hours ago, although association with the centre
and curvature have improved.
Intensity remains estimated at a 10 minute mean of 60 knots [category 2]. Dvorak
technique gives DT4.0 based on both curved band and embedded centre patterns.
MET and PAT are 3.5. Final T is 4.0. This is supported by the 0859UTC SATCON of
66 knots. NESDIS and CIMSS ADT are slightly lower at 57 knots and 55 knots [1
minute mean].
Confidence in the centre position is rated as good based on radar imagery from
Willis Island and Bowen radars. The fix is consistent with IR satellite imagery.
The mid-level ridge building to the south of the system has become the dominant
steering influence, and this will maintain the system on a west-southwest track
for the next several days until landfall on the Queensland coast, which is
currently expected during Tuesday morning. There is high confidence in this
track given the simple environment and excellent consistency amongst
deterministic and ensemble numerical weather prediction models.
The system remains located in an area of weak vertical wind shear over sea
surface temperatures of 29 to 30 degrees Celsius. Conditions will remain
favourable for development right up until landfall, and this has been reflected
in an intensity forecast at above the standard rate. This is above most
objective guidance, with the ECMWF deterministic model being an exception. The
forecast allows for a period of rapid intensification to occur before landfall
in the favourable environment, which recent SHIPS guidance suggests is a
possibility.
You do not have the required permissions to view the files attached to this post.
Entrained dry air and less organised equatorward outflow continues to slow Debbie's intensification. JTWC seems to think that she may only barely make Cat 3. Currently about 285 km ENE of Bowen.
WTPS31 PGTW 262100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 13P (DEBBIE) WARNING NR 005//
RMKS/
1. TROPICAL CYCLONE 13P (DEBBIE) WARNING NR 005
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
261800Z --- NEAR 18.6S 150.3E
MOVEMENT PAST SIX HOURS - 250 DEGREES AT 06 KTS
POSITION ACCURATE TO WITHIN 050 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT
…
REMARKS:
262100Z POSITION NEAR 18.7S 150.1E.
TROPICAL CYCLONE 13P (DEBBIE), LOCATED APPROXIMATELY 277 NM EAST-
SOUTHEAST OF CAIRNS, AUSTRALIA, HAS TRACKED WEST-SOUTHWESTWARD AT
06 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE
IMAGERY DEPICTS A WELL ORGANIZED STORM WITH FLARING CONVECTION
WRAPPING INTO THE SYSTEM. A 261500Z GCOMW1 36GHZ IMAGE REVEALS THAT
THE LOW LEVEL CIRCULATION CENTER IS OFFSET SLIGHTLY TO THE NORTH OF
THE UPPER LEVEL CIRCULATION CENTER AND LENDS HIGH CONFIDENCE IN THE
INITIAL POSITION. THE INITIAL INTENSITY OF 70 KNOTS IS SUPPORTED BY
MULTI-AGENCY DVORAKS OF T4.0 (65KTS) AND THE LATEST SATCON
ESTIMATE OF 68 KNOTS. THE STORM IS CURRENTLY LOCATED IN AN AREA OF
LOW VERTICAL WIND SHEAR. UPPER-LEVEL ANALYSIS SHOWS STRONG POLEWARD
OUTFLOW WITH LESS ORGANIZED EQUATORWARD OUTFLOW. THE SYSTEM IS ALSO
BEGINNING TO ENTRAIN DRY AIR ON THE EQUATORWARD SIDE FROM
CONTINENTAL AUSTRALIA, EVIDENT IN TOTAL PERCEPTIBLE WATER LOOPS,
WHICH HAS SLOWED THE RATE OF INTENSIFICATION. TC DEBBIE IS
CONTINUING TO TRACK SLOWLY TO THE SOUTHWEST UNDER THE INFLUENCE OF A
SUBTROPICAL RIDGE LOCATED TO THE EAST AND A RIDGE POSITIONED OVER
CENTRAL AUSTRALIA. THESE TWO RIDGES WILL CONTINUE TO STEER THE
SYSTEM TO THE SOUTHWEST AS IT MAKES LANDFALL SHORTLY AFTER TAU 24,
AND FOR THE REMAINDER OF THE FORECAST PERIOD. ENVIRONMENTAL
CONDITIONS WILL REMAIN FAVORABLE HOWEVER, AS SYSTEM BEGINS TO
INTERACT WITH LAND THE RUGGED TERRAIN OF EASTERN AUSTRALIA WILL
RAPIDLY DISSIPATE THE CYCLONE BY THE END OF THE FORECAST PERIOD.
MODEL GUIDANCE CONTINUES TO BE IN GOOD AGREEMENT ON THE FORECAST
TRACK LENDING HIGH CONFIDENCE TO THE JTWC FORECAST TRACK. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 261800Z IS 18 FEET. NEXT WARNINGS AT
270900Z AND 272100Z.//
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - EASTERN REGION
Issued by BRISBANE TROPICAL CYCLONE WARNING CENTRE
at: 1844 UTC 26/03/2017
Name: Tropical Cyclone Debbie
Identifier: 24U
Data At: 1800 UTC
Latitude: 18.6S
Longitude: 150.6E
Location Accuracy: within 20 nm [35 km]
Movement Towards: southwest [231 deg]
Speed of Movement: 3 knots [5 km/h]
Maximum 10-Minute Wind: 55 knots [100 km/h]
Maximum 3-Second Wind Gust: 75 knots [140 km/h]
Central Pressure: 983 hPa
...
REMARKS:
Tropical cyclone Debbie has shown little signs of development on satellite
imagery over the last 24 hours. Deep convective clouds with low cloud top
temperatures continue to wrap around the system centre. The latest Dvorak
analysis was therefore based on a curved band pattern with a 0.7 degree wrap and
an additional 0.5 for white band, which yielded a DT of 3.5. MET and PAT were
both 3.5. FT was based on MET as the DT was not completely clear. CI maintained
at 4.0 as per the Dvorak rules. SATCON evidence suggests a system intensity of
62 knots [1-minute mean], which when converted to a 10-minute mean roughly
matches the currently analysed intensity inferred from Dvorak.
Confidence in the centre position is rated as good based on a combination of
radar imagery from Willis Island and Bowen radars and animated infrared
satellite imagery.
The mid-level ridge building to the south of the system has become the dominant
steering influence, and this will maintain the system on a west-southwest track
until landfall on the Queensland coast, which is currently expected during
Tuesday morning. There is high confidence in this track given the simple
environment and excellent consistency amongst deterministic and ensemble
numerical weather prediction models.
The system remains located in an area of weak vertical wind shear over sea
surface temperatures of 29 to 30 degrees Celsius. Conditions will remain
favourable for development right up until landfall, and this has been reflected
in an intensity forecast at above the standard rate. This is above most
objective guidance, with the ECMWF deterministic model being an exception. The
forecast allows for a period of rapid intensification to occur before landfall
in the favourable environment, which recent SHIPS guidance suggests is a
possibility. However, CIMSS satellite winds and animated water vapour satellite
imagery indicate that the outflow channel to the north of the system has
weakened over the last 12 hours and therefore it is possible that the window for
any rapid intensification may be diminishing.
You do not have the required permissions to view the files attached to this post.
The BoM upgraded Debbie to Cat 3 around 01z (2pm NZDT) today. She's become a lot better organised in the last few hours, good convection and also sporting a ragged eye. Currently about 250 km ENE of Bowen…
REMARKS:
Tropical cyclone Debbie showed little signs of development through the previous
24 hours to sunrise this morning. However in the past few hours, the long
expected rapid development appears to be taking place. Deep convection has
rapidly dveloped around the system centre, with possibly a ragged eye feature
appearing. The latest Dvorak analysis was therefore based on an eye pattern in
IR, with a DG surround and OW eye, subtracting 0.5 for ragged eye yielded a DT
of 4.0. MET and is 5.0 and PT is 4.5. FT was based on PT as the DT was not
completely clear. SATCON has jumped dramatically over the past 6 hours from 62
knots to 90 knots. ADT from both agencies are around 5.0 System will be upgraded
to a severe category 3.
Confidence in the centre position is rated as good based on a combination of
radar imagery from Willis Island and Bowen radars and animated visible satellite
imagery.
The mid-level ridge building to the south of the system has become the primary
steering influence. However, animated WV imagery suggests that the shortwave
trough moving north into SE Queensland may have a little more amplitude than the
models are suggesting, leading to a slight weakening of the ridge and a slightly
more southerly track which has been evident over the past 12 hours. There may
also be some influence from internal processes within the cyclone core, where it
remains somewhat disorganised. Overall, the system is most likely to remain on a
general west-southwest track for the next 24 hours up to landfall on the
Queensland coast. There is still reasonably high confidence in this track,
although there is more uncertainty on the southern side.
The system remains located in an area of weak vertical wind shear over sea
surface temperatures of 29 to 30 degrees Celsius. Conditions will remain
favourable for development right up until landfall, and this has been reflected
in an intensity forecast at above the standard rate, reinforced by the recent
fairly rapid development. This is above most objective guidance at this time.
The forecast allows for a period of rapid intensification to occur before
landfall in the favourable environment, which recent SHIPS guidance suggests is
a possibility.
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Once it has died, it will form into another low system moving across the Tasman Sea towards NZ later this week.
More wet weather to come for the country, NZ country that is..
