SIO: Dahlia - Post-Tropical

[Digital-TC-Chaser]

96S INVEST
As of 00:00 UTC Nov 24, 2017:

Location: 4.3°S 94.7°E
Maximum Winds: 20 kt
Minimum Central Pressure: 1006 mb






multi lpa's along the trough.

[Digital-TC-Chaser]

This invest maybe should have been classified as a TD on the 2017-11-24 18:51Z.

http://rammb.cira.colostate.edu/product ... 231404.GIF

[Digital-TC-Chaser]

IDW24010
Australian Government Bureau of Meteorology
Western Australia

TROPICAL CYCLONE INFORMATION BULLETIN
Issued at 3:58 pm WST on Tuesday 28 November 2017
BY THE BUREAU OF METEOROLOGY
TROPICAL CYCLONE WARNING CENTRE PERTH

A Tropical Low was located at 1:00 pm CXT near 8.2S 98.8E, that is 800 km west
northwest of Christmas Island and slow moving.
The system is expected to pass to the north of Christmas Island on Thursday as
a Tropical Low. While gales are not expected at Christmas Island, squally
conditions are likely over the next few days. During Friday the system is
expected to turn towards the southeast as it continues to intensify.

The next Information Bulletin will be issued at 8:00 am CXT.

[Digital-TC-Chaser]

IDW24010
Australian Government Bureau of Meteorology
Western Australia

TROPICAL CYCLONE INFORMATION BULLETIN
Issued at 2:56 pm WST on Wednesday 29 November 2017
BY THE BUREAU OF METEOROLOGY
TROPICAL CYCLONE WARNING CENTRE PERTH

A Tropical Low was located at 1:00 pm CXT near 8.3S 101.5E, that is 520 km west
northwest of Christmas Island and moving east at 11 kilometres per hour.
The system is expected to pass to the north of Christmas Island on Thursday as
a Tropical Low. While gales are not expected at Christmas Island, squally
conditions and heavy rain are likely on Thursday. On Friday the system is
expected to turn towards the southeast and intensify into a tropical cyclone
over open waters.

The next Information Bulletin will be issued at 8:00 pm CXT.

Looking like this will be a larger sprawling monsoonal type system.

In the Australian Region to qualify as a tropical cyclone a tropical
LOW must be accompanied by gales surrounding more than 50% of the center
of circulation for a period of at least six hours.

AUSTRALIAN REGION (longitude 90E eastward to longitude 160E)
MSW Averaging Period: 10 minutes

Tropical LOW - term is used to describe disturbances ranging from
diffuse, ill-defined low-pressure areas all the way to well-
organized tropical depressions with MSW up to 33 kts
Tropical Cyclone - MSW in range of 34-63 kts/ Dvorak rating ranging
from a strong T2.5/weak T3.0 to T4.0
Severe Tropical Cyclone - MSW exceeding 63 kts/ Dvorak T4.5 or
higher

http://australiasevereweather.com/cyclo ... nology.htm

WTXS22 PGTW 290430
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
155 NM EITHER SIDE OF A LINE FROM 8.5S 100.7E TO 10.3S 107.5E
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
290400Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 8.5S
101.0E. THE SYSTEM IS MOVING EASTWARD AT 06 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 96S) PREVIOUSLY LOCATED
NEAR 8.4S 101.2E IS NOW LOCATED NEAR 8.5S 101.0E, APPROXIMATELY
300NM WEST-NORTHWEST OF CHRISTMAS ISLAND, AUSTRALIA. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY DEPICTS A BROAD LOW-LEVEL
CIRCULATION CENTER (LLCC) WITH FORMATIVE CONVECTIVE BANDING OVER THE
WESTERN SEMI-CIRCLE. A 282328Z WINDSAT 37GHZ IMAGE SHOWS A
CONSOLIDATING LLCC WITH IMPROVED BANDING WRAPPING INTO A DEFINED
CENTER. A 290312Z ASCAT IMAGE SHOWS NUMEROUS 30-KNOT WINDS
ASSOCIATED WITH THE PRIMARY CONVECTIVE BAND. UPPER-LEVEL ANALYSIS
INDICATES A MARGINALLY-FAVORABLE ENVIRONMENT WITH MODERATE TO STRONG
(25 TO 35 KNOTS) VERTICAL WIND SHEAR OFFSET BY GOOD POLEWARD
OUTFLOW. GLOBAL DYNAMIC MODELS INDICATE THAT 96S WILL STEADILY
DEVELOP WHILE TRACKING EAST-SOUTHEASTWARD TO SOUTHEASTWARD INTO A
MORE FAVORABLE UPPER-LEVEL ENVIRONMENT OVER THE NEXT 2 DAYS. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KNOTS. MINIMUM SEA
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1000 MB. THE POTENTIAL FOR
THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS HIGH.

[wxman57]

Now classified as Tropical Cyclone Dahlia by Jakarta. Second storm they've named within 48 hrs. Previously, they had only named 3 storms in the past 10 years.

[WAcyclone]

Dahlia could come quite close to the WA coast based on the models and the BOM's five day forecast. However, it would likely be a weakening or post-tropical system by that time...

[somethingfunny]

We have a system moving east along 8 degrees latitude?

Now classified as Tropical Cyclone Dahlia by Jakarta. Second storm they've named within 48 hrs. Previously, they had only named 3 storms in the past 10 years.

I can't remember the last time Jakarta had a cyclone to track before Cempaka. I have to say I'm impressed that they seem to be on top of the game noticing these and classifying them as they happen - I've seen other low-activity RSMCs (not naming names) drop the ball fairly often. This is interesting to watch. What was the last cyclone to significantly impact Indonesia, aside from the occasional WPAC or BOB system impacting northern Sumatra?

[Digital-TC-Chaser]

RSMC Initialized


Current Intensity Analysis



UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.2.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 29 NOV 2017 Time : 194000 UTC
Lat : 8:18:19 S Lon : 102:55:52 E


CI# /Pressure/ Vmax
2.9 / 992.2mb/ 43.0kt


Final T# Adj T# Raw T#
2.9 3.3 3.7

Latitude bias adjustment to MSLP : +0.0mb

Center Temp : -83.7C Cloud Region Temp : -83.9C

Scene Type : UNIFORM CDO CLOUD REGION

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : INDIAN
Dvorak CI > MSLP Conversion Used : PACIFIC

Tno/CI Rules : Constraint Limits : 0.2T/hour
Weakening Flag : OFF
Rapid Dissipation Flag : OFF

Satellite Name : HIM-8
Satellite Viewing Angle : 44.9 degrees

http://www5.bom.gov.au/files/2313/6799/ ... _table.pdf



A healthy monsoonal flow from the north with a southeasterly surge is driving this TC.

[mrbagyo]

looking healthy with a nice curved band.

[Digital-TC-Chaser]

IDW27700
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by PERTH TROPICAL CYCLONE WARNING CENTRE
at: 1851 UTC 30/11/2017
Name: Tropical Cyclone Dahlia
Identifier: 03U
Data At: 1800 UTC
Latitude: 9.6S
Longitude: 108.7E
Location Accuracy: within 35 nm [65 km]
Movement Towards: east southeast [102 deg]
Speed of Movement: 12 knots [22 km/h]
Maximum 10-Minute Wind: 40 knots [75 km/h]
Maximum 3-Second Wind Gust: 55 knots [100 km/h]
Central Pressure: 993 hPa
Radius of 34-knot winds NE quadrant: 70 nm [130 km]
Radius of 34-knot winds SE quadrant: 30 nm [55 km]
Radius of 34-knot winds SW quadrant: 30 nm [55 km]
Radius of 34-knot winds NW quadrant: 70 nm [130 km]
Radius of 48-knot winds NE quadrant:
Radius of 48-knot winds SE quadrant:
Radius of 48-knot winds SW quadrant:
Radius of 48-knot winds NW quadrant:
Radius of 64-knot winds:
Radius of Maximum Winds: 30 nm [55 km]
Dvorak Intensity Code: T3.0/3.0/D1.0/24HRS STT:S0.0/06HRS
Pressure of outermost isobar: 1002 hPa
Radius of outermost closed isobar: 80 nm [150 km]
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+06: 01/0000: 10.2S 109.5E: 040 [080]: 045 [085]: 989
+12: 01/0600: 10.9S 110.0E: 055 [100]: 045 [085]: 989
+18: 01/1200: 11.5S 110.2E: 065 [125]: 050 [095]: 985
+24: 01/1800: 12.2S 110.2E: 080 [145]: 055 [100]: 982
+36: 02/0600: 13.6S 109.6E: 100 [185]: 060 [110]: 979
+48: 02/1800: 15.0S 109.2E: 120 [220]: 055 [100]: 982
+60: 03/0600: 16.7S 109.0E: 140 [255]: 050 [095]: 986
+72: 03/1800: 18.2S 109.0E: 155 [290]: 045 [085]: 988
+96: 04/1800: 20.2S 109.7E: 200 [370]: 025 [045]: 999
+120: 05/1800: 20.7S 111.6E: 290 [535]: 020 [035]: 1003
REMARKS:
TC Dahlia has continued to move east over the last few hours. Location was based
on IR satellite imagery, and a recent microwave pass.

Dvorak of the system was 3.0 based on shear pattern and MET.

SSTs continue to be very favourable north of 15S, favourable north of 20S and
become unfavourable south of 20S. Moisture is plentiful in the current region,
in the longer term however, mid level dry air is expected to wrap around to the
north and influence the system from Sunday.

Latest CIMMS wind shear product indicates a slight improvement with the shear
now between 15 and 20 knots from the east. Dahlia is expected to intensify
during Friday and Saturday as the system moves south into a low shear ridge.

[1900hurricane]

It's coming along.

[mrbagyo]

Dahlia now has a developing eye based on this microwave image

[Digital-TC-Chaser]

The money shot for the 30th.

TXXS29 KNES 010023
TCSSIO

A. 01S (DAHLIA)

B. 30/2330Z

C. 9.6S

D. 109.0E

E. THREE/HIMAWARI-8

F. T4.0/4.0/D1.5/24HRS

G. IR/EIR/VIS/SSMIS

H. REMARKS...SYSTEM IS CHARACTERIZED BY AN EIGHT-TENTHS WHITE BANDING
FEATURE OBSERVED IN 2240Z SSMIS MICROWAVE IMAGERY. THIS YIELDS A DT OF
4.0. MET IS 3.5 AND THE PT IS 4.0. FT IS BASED OFF THE DT.

I. ADDL POSITIONS

30/2240Z 9.5S 108.9E SSMIS


...GAETANO

[Digital-TC-Chaser]

01S DAHLIA 171201 0000 9.7S 109.0E SHEM 50 991


50 clicks also on ascat.

[Digital-TC-Chaser]

IDW27700
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by PERTH TROPICAL CYCLONE WARNING CENTRE
at: 0716 UTC 01/12/2017
Name: Tropical Cyclone Dahlia
Identifier: 03U
Data At: 0600 UTC
Latitude: 10.2S
Longitude: 109.6E
Location Accuracy: within 25 nm [45 km]
Movement Towards: south southeast [149 deg]
Speed of Movement: 6 knots [12 km/h]
Maximum 10-Minute Wind: 50 knots [95 km/h]
Maximum 3-Second Wind Gust: 70 knots [130 km/h]
Central Pressure: 987 hPa
Radius of 34-knot winds NE quadrant: 90 nm [165 km]
Radius of 34-knot winds SE quadrant: 50 nm [95 km]
Radius of 34-knot winds SW quadrant: 60 nm [110 km]
Radius of 34-knot winds NW quadrant: 80 nm [150 km]
Radius of 48-knot winds NE quadrant: 30 nm [55 km]
Radius of 48-knot winds SE quadrant:
Radius of 48-knot winds SW quadrant:
Radius of 48-knot winds NW quadrant: 30 nm [55 km]
Radius of 64-knot winds:
Radius of Maximum Winds: 20 nm [35 km]
Dvorak Intensity Code: T3.5/3.5/D0.5/24HRS STT:D0.5/06HRS
Pressure of outermost isobar: 1004 hPa
Radius of outermost closed isobar: 140 nm [260 km]
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+06: 01/1200: 10.7S 109.8E: 030 [055]: 050 [095]: 986
+12: 01/1800: 11.4S 109.8E: 040 [075]: 055 [100]: 981
+18: 02/0000: 12.0S 109.6E: 055 [100]: 065 [120]: 978
+24: 02/0600: 12.6S 109.3E: 065 [120]: 065 [120]: 977
+36: 02/1800: 13.8S 108.8E: 085 [155]: 065 [120]: 980
+48: 03/0600: 15.2S 108.6E: 105 [195]: 055 [100]: 988
+60: 03/1800: 16.7S 108.8E: 125 [230]: 045 [085]: 993
+72: 04/0600: 18.2S 109.1E: 145 [270]: 035 [065]: 995
+96: 05/0600: 19.9S 110.2E: 195 [360]: 030 [055]: 999
+120: 06/0600: 21.8S 111.9E: 255 [470]: 025 [045]: 1000
REMARKS:
TC Dahlia has started taking a more south southeasterly track in the last six
hours. It now appears the low level circulation centre has moved further under
the deep convection after previously being exposed to the east of the deepest
convection. This is consistent with a decrease in easterly wind shear.
Intensity now at 50kn [category 2] determined from:
Dvorak analysis: FT/CI=3.5 based on shear pattern and MET [slight development
over 24hours].
ASCAT at 0230UTC has maximum of 45kn to the northeast.
SATCON also is 45kn [10min average].

The forecast intensity and track is made more difficult by the influence of the
remnants of TC Cempaka to the south and another vortex currently well to the
east which is expected to pass to the south of Dahlia over the weekend. Some
models do not resolve these weaker circulations and these tend to move Dahlia
faster than the forecast track. While the general environment [ocean
temperatures, low-mid level moisture and moderate wind shear, upper level
divergence] remains conducive to intensification over the weekend, it is
possible these other circulations will disrupt the flow preventing much if any
development of Dahlia. At this stage a conservative development policy to
develop the system to category 3 intensity remains until the influence of these
circulations becomes clearer.

On Monday the system encounters cooler water south of 18S and possibly dry air
wraps around from the west. Gales may persist to the southwest for a period as
the system interacts with the synoptic SE'ly flow associated with the
sub-tropical ridge.

[euro6208]

WTXS31 PGTW 010900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
1. TROPICAL CYCLONE 01S (DAHLIA) WARNING NR 006
01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
010600Z --- NEAR 10.2S 109.6E
MOVEMENT PAST SIX HOURS - 130 DEGREES AT 08 KTS
POSITION ACCURATE TO WITHIN 040 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 035 NM NORTHEAST QUADRANT
025 NM SOUTHEAST QUADRANT
025 NM SOUTHWEST QUADRANT
035 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT
050 NM SOUTHEAST QUADRANT
050 NM SOUTHWEST QUADRANT
070 NM NORTHWEST QUADRANT
REPEAT POSIT: 10.2S 109.6E
---
FORECASTS:
12 HRS, VALID AT:
011800Z --- 11.1S 110.2E
MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT
040 NM SOUTHEAST QUADRANT
025 NM SOUTHWEST QUADRANT
030 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT
045 NM SOUTHEAST QUADRANT
075 NM SOUTHWEST QUADRANT
075 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 185 DEG/ 05 KTS
---
24 HRS, VALID AT:
020600Z --- 12.0S 110.1E
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
020 NM SOUTHWEST QUADRANT
030 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT
055 NM SOUTHEAST QUADRANT
065 NM SOUTHWEST QUADRANT
060 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 190 DEG/ 06 KTS
---
36 HRS, VALID AT:
021800Z --- 13.1S 109.9E
MAX SUSTAINED WINDS - 060 KT, GUSTS 075 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
030 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT
070 NM SOUTHEAST QUADRANT
065 NM SOUTHWEST QUADRANT
060 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 190 DEG/ 08 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
030600Z --- 14.6S 109.6E
MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 035 NM NORTHEAST QUADRANT
035 NM SOUTHEAST QUADRANT
030 NM SOUTHWEST QUADRANT
030 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 075 NM NORTHEAST QUADRANT
080 NM SOUTHEAST QUADRANT
065 NM SOUTHWEST QUADRANT
055 NM NORTHWEST QUADRANT
VECTOR TO 72 HR POSIT: 175 DEG/ 08 KTS
---
72 HRS, VALID AT:
040600Z --- 17.9S 109.9E
MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT
065 NM SOUTHEAST QUADRANT
060 NM SOUTHWEST QUADRANT
050 NM NORTHWEST QUADRANT
VECTOR TO 96 HR POSIT: 140 DEG/ 08 KTS
---
LONG RANGE OUTLOOK:
---
96 HRS, VALID AT:
050600Z --- 20.3S 111.9E
MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT
060 NM SOUTHEAST QUADRANT
060 NM SOUTHWEST QUADRANT
050 NM NORTHWEST QUADRANT
VECTOR TO 120 HR POSIT: 115 DEG/ 06 KTS
---
120 HRS, VALID AT:
060600Z --- 21.4S 114.3E
MAX SUSTAINED WINDS - 020 KT, GUSTS 030 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
---
REMARKS:
010900Z POSITION NEAR 10.4S 109.7E.
TROPICAL CYCLONE 01S (DAHLIA), LOCATED APPROXIMATELY 771 NM
NORTH-NORTHWEST OF LEARMONTH, AUSTRALIA, HAS TRACKED
SOUTHEASTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY DEPICTS FLARING AND CONSOLIDATING
CONVECTION ASSOCIATED WITH THE LOW LEVEL CIRCULATION CENTER (LLCC).
THE INITIAL POSITION WAS PLACED WITH GOOD CONFIDENCE BASED ON A
010232Z METOP-B ASCAT IMAGE. THE INITIAL INTENSITY IS 50 KNOTS, BASED
ON DVORAK ESTIMATES OF T4.0 (65 KNOTS) FROM KNES AND T3.0 (45 KNOTS)
FROM PGTW. VERTICAL WIND SHEAR IS FAVORABLE (5 TO 10 KNOTS) AND BOTH
POLEWARD AND EQUATORWARD OUTFLOW REMAIN GOOD. SEA SURFACE
TEMPERATURES ARE FAVORABLE FOR DEVELOPMENT IN THE SHORT TERM (28 TO
29 DEGREES CELSIUS) BUT WILL BECOME UNFAVORABLE (25 DEGREES CELSIUS)
BY TAU 72. TC 01S WILL TRACK SOUTHWARD ALONG THE WESTERN PERIPHERY OF
THE SUBTROPICAL RIDGE LOCATED OVER NORTHWEST AUSTRALIA. AS TC 01S
TRACKS SOUTHWARD OVER THE COOLER SEA SURFACE TEMPERATURES IT WILL
DECREASE IN INTENSITY BEFORE DISSIPATING. NUMERICAL MODEL GUIDANCE IS
IN GOOD AGREEMENT LENDING TO HIGH OVERALL CONFIDENCE IN THE JTWC
FORECAST TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 010600Z IS 18
FEET. NEXT WARNINGS AT 011500Z, 012100Z, 020300Z, AND 020900Z.//
NNNN

[1900hurricane]

Like Ockhi, it appears that Dahlia is currently experiencing some dry air woes. Recent microwave imagery shows a degraded system structure and a wedge of low RH air entering into the system's circulation.

[wxman57]

Looks like Dahlia has dissipated.