IDW27600
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE
at: 0058 UTC 27/02/2021
Name: Tropical Cyclone Marian
Identifier: 15U
Data At: 0000 UTC
Latitude: 14.8S
Longitude: 95.0E
Location Accuracy: within 20 nm [35 km]
Movement Towards: west southwest [249 deg]
Speed of Movement: 8 knots [15 km/h]
Maximum 10-Minute Wind: 60 knots [110 km/h]
Maximum 3-Second Wind Gust: 85 knots [155 km/h]
Central Pressure: 978 hPa
Radius of 34-knot winds NE quadrant: 100 nm [185 km]
Radius of 34-knot winds SE quadrant: 100 nm [185 km]
Radius of 34-knot winds SW quadrant: 140 nm [260 km]
Radius of 34-knot winds NW quadrant: 140 nm [260 km]
Radius of 48-knot winds NE quadrant: 40 nm [75 km]
Radius of 48-knot winds SE quadrant: 40 nm [75 km]
Radius of 48-knot winds SW quadrant: 70 nm [130 km]
Radius of 48-knot winds NW quadrant: 70 nm [130 km]
Radius of 64-knot winds:
Radius of Maximum Winds: 35 nm [65 km]
Dvorak Intensity Code: T4.0/4.0/D1.0/24HRS STT: D0.5/0,6HRS
Pressure of outermost isobar: 1002 hPa
Radius of outermost closed isobar: 240 nm [445 km]
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+06: 27/0600: 15.1S 94.2E: 040 [075]: 060 [110]: 978
+12: 27/1200: 15.5S 93.4E: 055 [105]: 060 [110]: 978
+18: 27/1800: 15.9S 92.8E: 070 [130]: 060 [110]: 978
+24: 28/0000: 16.3S 92.3E: 080 [150]: 070 [130]: 974
+36: 28/1200: 16.9S 91.3E: 105 [190]: 070 [130]: 969
+48: 01/0000: 17.4S 90.6E: 120 [220]: 070 [130]: 969
+60: 01/1200: 17.9S 90.1E: 140 [255]: 070 [130]: 968
+72: 02/0000: 18.1S 90.3E: 150 [280]: 070 [130]: 968
+96: 03/0000: 18.9S 92.5E: 225 [415]: 060 [110]: 975
+120: 04/0000: 20.8S 95.4E: 285 [525]: 055 [100]: 978
REMARKS:
At 21Z and 00Z no clear-cut DVK pattern. Unable to use embedded centre at 21Z
due to constraints, and curved banding no longer evident. Applying a shear
pattern yields a DT of 3.5. Applying a curved band analysis to microwave at 22Z
would give wrap of around 0.8, consistent with T3.5. Applying an Embedded Centre
pattern at 00Z [first allowable time under constraints] yields a T5.0
[discounted]. ADT has been steady at CI 3.7-3.8 overnight. SATCON at 1527
estimated 68 knots 1-min mean with ADT at 61 knots and CIMSS AMSU algorithm at
78 knots. AMSR2 pass at 1843Z indicated a small area of hurricane force winds in
the southwest quadrant. Final intensity estimate set at 60 knots 10-min mean.
Strong divergence in the southwest quadrant and moderate divergence in NW and SE
quadrants may be aided by split flow at high levels and a shear profile with
much of the shear at high levels.
The system has been tracking at a around 17 knots but has slowed overnight as it
intensified and the mid-level ridge weakens, and is now moving at a speed of
around 8 knots, consistent with NWP guidance.
CIMSS analysed shear at 22 knots from the east at 26/1800 UTC, consistent with
previous analysis and appearance in satellite imagery. Shear appears to be
mostly in the high levels with a noticeable shift in winds from 300hPa to
200hPa. The shear is expected to persist in the short term and dry air can be
seen wrapping around to the north and northeast of the system in animated TPW. A
strengthening trend is forecast that is slightly less than normal due to the
environment and large size
SST's are cooler to the south, with sub 26 degrees south of about 18S. This
could limit development on Monday and then assist in the system weakening as it
moves further south. The circulation is expected to remain at TC strength over
open waters for the next 5-7 days.
Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 27/0730 UTC.
22S MARIAN 210227 1800 16.6S 92.4E SHEM 75 972
22S MARIAN 210227 1200 15.9S 93.3E SHEM 70 976
TPXS10 PGTW 271823
A. TROPICAL CYCLONE 22S (MARIAN)
B. 27/1745Z
C. 16.59S
D. 92.42E
E. THREE/GOES-IO
F. T4.5/4.5/D1.0/24HRS STT: D0.5/03HRS
G. IR/EIR
H. REMARKS: 09A/PBO RAGGED EYE/ANMTN. LG EYE SURROUNDED BY LG
YIELDS AN E# OF 5.0. SUBTRACTED 0.5 EYE ADJUSTMENT FOR B TO YIELD
A DT OF 4.5. MET AND PT AGREE. DBO DT.
IDW27600
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE
at: 0048 UTC 28/02/2021
Name: Severe Tropical Cyclone Marian
Identifier: 15U
Data At: 0000 UTC
Latitude: 16.8S
Longitude: 92.2E
Location Accuracy: within 20 nm [35 km]
Movement Towards: southwest [235 deg]
Speed of Movement: 7 knots [13 km/h]
Maximum 10-Minute Wind: 65 knots [120 km/h]
Maximum 3-Second Wind Gust: 90 knots [165 km/h]
Central Pressure: 970 hPa
Radius of 34-knot winds NE quadrant: 140 nm [260 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: 110 nm [205 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: 50 nm [95 km]
Radius of 64-knot winds:
Radius of Maximum Winds: 20 nm [35 km]
Dvorak Intensity Code: T4.5/4.5/D1.0/24HRS STT: D0.5/06HRS
Pressure of outermost isobar: 1002 hPa
Radius of outermost closed isobar: 280 nm [520 km]
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+06: 28/0600: 17.1S 91.6E: 035 [065]: 065 [120]: 970
+12: 28/1200: 17.3S 91.2E: 045 [080]: 070 [130]: 969
+18: 28/1800: 17.6S 90.8E: 050 [090]: 070 [130]: 969
+24: 01/0000: 17.8S 90.5E: 050 [095]: 075 [140]: 964
+36: 01/1200: 18.2S 90.0E: 060 [105]: 075 [140]: 960
+48: 02/0000: 18.4S 90.0E: 070 [130]: 070 [130]: 965
+60: 02/1200: 18.6S 90.5E: 085 [155]: 070 [130]: 966
+72: 03/0000: 18.9S 91.6E: 095 [180]: 065 [120]: 971
+96: 04/0000: 20.2S 94.2E: 135 [250]: 055 [100]: 979
+120: 05/0000: 21.9S 96.4E: 190 [350]: 050 [095]: 981
REMARKS:
Microwave satellite imagery overnight has given good confidence in the location
and structure of Severe Tropical Cyclone Marian. There is evidence of some
northeasterly shear over the system due to displacement of the upper level
circulation to the southwest. ASCAT passes overnight showed winds of at least 55
knots around the system, though it is possible that limitations to this sensor
analysing stronger winds is resulting in an underestimate.
DVK eye pattern with LG surrounding temperature of >=0.4 degrees, a MG eye with
a White surrounding ring yields T5.0 however the eye has been ragged and
elongated so an adjustment of -0.5 yields T4.5. This is consistent with PAT. CI
set to 4.5 with 10-min mean wind of 65 knots. SATCON estimates have spiked in
the past 6 hours due to CIMSS ATMS 1-min estimates - the latest of which 1902
UTC was 99 knots. ADT 1-min estimates of 72 knots are more in line with current
analysis and reasonable expectation of the system intensification rate.
The system continues to lie under northeasterly shear [CIMSS analysed shear at
27/1800 UTC was 17 knots from the east-northeast] though this shear appears to
be in the upper levels [above 400hPa]. The shear is expected to persist in the
short term, reducing in 12-24 hours as the system approaches 090E and the steady
SW motion slows. The system is likely to be slow moving for a period on Monday
before taking a track to the southeast on Tuesday.
A strengthening trend is forecast but is slightly less than normal due to the
environment and large size. SHIPS guidance indicates rapid intensification is
unlikely which is consistent with the synoptic environment.
SST's are cooler to the south, with sub 26 degrees south of about 18S. This
could limit development from Monday and then assist in the system weakening as
it moves further south. The circulation is expected to remain at TC strength
over open waters for the next 5-7 days.
Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 28/0730 UTC.
H. REMARKS: 11A/PBO RAGGED EYE/ANMTN. OW EYE SURROUNDED BY B
YIELDS AN E# OF 5.5. ADDED 0.5 EYE ADJUSTMENT FOR B, TO YIELD A DT
OF 6.0. MET AND PT YIELDS 5.0. DBO PT.
