BOB: VIYARU - Cyclonic Storm

[Meow]

IMD upgraded it to a cyclonic storm named Mahasen at 03Z.

[cycloneye]

WTIO31 PGTW 110900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 01B (ONE) WARNING NR 005//
RMKS/
1. TROPICAL CYCLONE 01B (ONE) WARNING NR 005
01 ACTIVE TROPICAL CYCLONE IN NORTHIO
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
110600Z --- NEAR 7.7N 90.2E
MOVEMENT PAST SIX HOURS - 310 DEGREES AT 11 KTS
POSITION ACCURATE TO WITHIN 060 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT
060 NM SOUTHEAST QUADRANT
070 NM SOUTHWEST QUADRANT
070 NM NORTHWEST QUADRANT
REPEAT POSIT: 7.7N 90.2E
---
FORECASTS:
12 HRS, VALID AT:
111800Z --- 8.9N 88.5E
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
025 NM SOUTHWEST QUADRANT
025 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT
070 NM SOUTHEAST QUADRANT
070 NM SOUTHWEST QUADRANT
080 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 310 DEG/ 08 KTS
---
24 HRS, VALID AT:
120600Z --- 9.9N 87.3E
MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 035 NM NORTHEAST QUADRANT
035 NM SOUTHEAST QUADRANT
035 NM SOUTHWEST QUADRANT
035 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 090 NM NORTHEAST QUADRANT
080 NM SOUTHEAST QUADRANT
085 NM SOUTHWEST QUADRANT
090 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 335 DEG/ 07 KTS
---
36 HRS, VALID AT:
121800Z --- 11.1N 86.7E
MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT
030 NM SOUTHEAST QUADRANT
030 NM SOUTHWEST QUADRANT
030 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 045 NM NORTHEAST QUADRANT
045 NM SOUTHEAST QUADRANT
045 NM SOUTHWEST QUADRANT
045 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 100 NM NORTHEAST QUADRANT
090 NM SOUTHEAST QUADRANT
090 NM SOUTHWEST QUADRANT
100 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 355 DEG/ 08 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
130600Z --- 12.7N 86.5E
MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT
035 NM SOUTHEAST QUADRANT
035 NM SOUTHWEST QUADRANT
035 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT
050 NM SOUTHEAST QUADRANT
050 NM SOUTHWEST QUADRANT
050 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 110 NM NORTHEAST QUADRANT
100 NM SOUTHEAST QUADRANT
100 NM SOUTHWEST QUADRANT
110 NM NORTHWEST QUADRANT
VECTOR TO 72 HR POSIT: 015 DEG/ 07 KTS
---
72 HRS, VALID AT:
140600Z --- 15.3N 87.1E
MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT
040 NM SOUTHEAST QUADRANT
040 NM SOUTHWEST QUADRANT
040 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 055 NM NORTHEAST QUADRANT
055 NM SOUTHEAST QUADRANT
055 NM SOUTHWEST QUADRANT
055 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 120 NM NORTHEAST QUADRANT
120 NM SOUTHEAST QUADRANT
110 NM SOUTHWEST QUADRANT
120 NM NORTHWEST QUADRANT
VECTOR TO 96 HR POSIT: 025 DEG/ 08 KTS
---
LONG RANGE OUTLOOK:
---
96 HRS, VALID AT:
150600Z --- 18.3N 88.6E
MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT
WIND RADII VALID OVER OPEN WATER ONLY
VECTOR TO 120 HR POSIT: 035 DEG/ 13 KTS
---
120 HRS, VALID AT:
160600Z --- 22.4N 91.8E
MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
---
REMARKS:
110900Z POSITION NEAR 8.0N 89.8E.
TROPICAL CYCLONE 01B (ONE), LOCATED APPROXIMATELY 880NM SOUTH OF
CHITTAGONG, BANGLADESH, HAS TRACKED NORTHWESTWARD AT 11 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI)
DEPICTS A LARGE AREA OF MULTIPLE BANDING FEATURES LEADING INTO A LOW-
LEVEL CIRCULATION CENTER (LLCC) WHICH IS CURRENTLY BEING OBSCURED BY
FLARING DEEP CENTRAL CONVECTION. THIS IS ALSO EVIDENT ON A 110403Z
AMSU-B MICROWAVE IMAGE. THE INITIAL POSITION IS BASED ON THE
AFOREMENTIONED IMAGERY WITH FAIR CONFIDENCE. THE INITIAL INTENSITY
IS ASSESSED AT 45 KNOTS BASED UPON CONGRUENT DVORAK INTENSITY
ESTIMATES OF THE SAME VALUE FROM PGTW AND KNES. UPPER-LEVEL ANALYSIS
INDICATES THAT FAVORABLE DIFFLUENCE ALOFT IS ASSISTING IN THE BUILD
UP OF DEEP CONVECTION WHILE VERTICAL WIND SHEAR HAS SLIGHTLY RELAXED
TO LOW TO MODERATE LEVELS (10 TO 20 KNOTS), OVERALL RESULTING IN A
FAVORABLE ENVIRONMENT. TC 01B IS FORECAST TO CONTINUE TRACKING
NORTHWESTWARD THROUGH TAU 36 ALONG THE WESTERN PERIPHERY OF THE
SUBTROPICAL RIDGE (STR) POSITIONED OVER THE NORTHEASTERN BAY OF
BENGAL. THEREAFTER, TC 01B IS EXPECTED SLOW AND TURN NORTHEASTWARD
AS THE STR WEAKENS DUE TO AN APPROACHING MIDLATITUDE SHORTWAVE
TROUGH CURRENTLY OVER NORTHERN INDIA AND THE NORTHEASTERN ARABIAN
SEA. TC 01B SHOULD INTENSIFY TO A PEAK OF 85 KNOTS BY TAU 96 AS
POLEWARD OUTFLOW INCREASES INTO THE WESTERLIES. BY TAU 120 THE
SYSTEM WILL MAKE LANDFALL AS A SIGNIFICANT TC AND BEGIN TO WEAKEN
DUE TO LAND INTERACTION. DYNAMIC MODEL GUIDANCE CONTINUES TO AGREE
ON THE RECURVE SCENARIO TOWARDS BANGLADESH, BUT HAS STARTED TO SLOW
AND SPREAD IN THE EXTENDED TAUS. THE JTWC FORECAST IS SLIGHTLY
FASTER THAN MULTI-MODEL CONSENSUS TO OFFSET WBAR, WHICH IS SLOWER
AND WEST OF THE OVERALL TIGHT GROUPING IN THE EARLY TAUS. HIGH
CONFIDENCE REMAINS IN THE FORECAST DUE TO THE WELL UNDERSTOOD
STEERING ENVIRONMENT AND TIGHT GROUPING OF THE DYNAMIC MODELS PRIOR
TO TAU 72. AFTER TAU 72, FORECAST CONFIDENCE IS LOW DUE TO THE
SPREAD AND DIFFERING SPEEDS OF THE MODELS. MAXIMUM SIGNIFICANT WAVE
HEIGHT AT 110600Z IS 14 FEET. NEXT WARNINGS AT 111500Z, 112100Z,
120300Z AND 120900Z.//
NNNN

[Alyono]

shear is quite strong over this from the SE and it may not let up. Latest GFS nearly dissipates the system prior reaching Bangladesh

[SouthDadeFish]

A view under the cirrus canopy...

[Macrocane]

TROPICAL CYCLONE ADVISORY
RSMC – TROPICAL CYCLONES, NEW DELHI
TROPICAL STORM ‘MAHASEN’ ADVISORY NO. FOUR ISSUED AT 1800 UTC OF 11TH MAY
2013 BASED ON 1500 UTC CHARTS OF 11TH MAY 2013.

THE CYCLONIC STORM MAHASEN OVER SOUTHEAST BAY OF BENGAL MOVED
NORTHWESTWARDS AND LAY CENTRED AT 1500 TC OF 11TH MAY 2013 NEAR LATITUDE 08.50
N AND LONGITUDE 89.00 E, ABOUT 420 KM SOUTHWEST OF CAR NICOBAR (43367), 880 KM
EAST-SOUTHEAST OF TRINCOMALEE (43418), 1080 KM SOUTHEAST OF CHENNAI (43279) AND
1560 KM SOUTH-SOUTHWEST OF CHITTAGONG (41977). THE SYSTEM WOULD INTENSIFY
FURTHER INTO A SEVERE CYCLONIC STORM DURING NEXT 24 HOURS. IT WOULD MOVE
INITIALLY NORTHWESTWARDS DURING NEXT 36 HOURS AND RECURVE THEREAFTER
NORTHEASTWARDS TOWARDS BANGLADESH-MYANMAR COAST.
ACCORDING TO SATELLITE IMAGERIES, THE INTENSITY OF THE SYSTEM IS T 2.5. IT IS A
CURVED BAND PATTERN. INTENSE TO VERY INTENSE CONVECTION SEEN OVER SOUTH BAY
OF BENGAL, ADJOINING INDIAN OCEAN BETWEEN 4.50N AND 13.00N EAST OF LONG 82.00E.
THE LOWEST CLOUD TOP TEMPERATURE (CTT) IS ABOUT -700C.
SUSTAINED MAXIMUM SURFACE WIND SPEED IS ESTIMATED TO BE ABOUT 40 KNOTS
GUSTING TO 50 KNOTS AROUND SYSTEM CENTRE. THE STATE OF THE SEA IS HIGH AROUND
THE SYSTEM CENTRE. THE ESTIMATED CENTRAL PRESSURE IS ABOUT 996 HPA.
BASED ON LATEST ANALYSIS WITH NWP MODELS AND OTHER CONVENTIONAL TECHNIQUES,
ESTIMATED TRACK AND INTENSITY OF THE SYSTEM ARE GIVEN IN THE TABLE BELOW:

Date/Time(UTC) Position (Lat. 0N/ Long. 0E) Sustained maximum surface wind speed (kmph) Category
11-05-2013/1500 08.5/89.0 65-75 gusting to 85 Cyclonic Storm
11-05-2013/1800 09.0/88.2 70-80gusting to 90 Cyclonic Storm
12-05-2013/0000 09.6/88.1 80-90 gusting to 100 Cyclonic Storm
12-05-2013/0600 10.3/87.4 90-100 gusting to 110 Severe Cyclonic Storm
12-05-2013/1200 11.0/86.7 90-100 gusting to 110 Severe Cyclonic Storm
13-05-2013/0000 12.5/86.0 100-110 gusting to 120 Severe Cyclonic Storm
13-05-2013/1200 13.5/86.2 100-110 gusting to 120 Severe Cyclonic Storm
14-05-2013/0000 15.0/86.7 110-120 gusting to 130 Severe Cyclonic Storm
14-05-2013/1200 16.5/87.5 110-120 gusting to 130 Severe Cyclonic Storm
15-05-2013/0000 18.5/89.0 110-120 gusting to 130 Severe Cyclonic Storm
15-05-2013/1200 20.5/90.5 110-120 gusting to 130 Severe Cyclonic Storm
16-05-2013/0000 22.0/92.0 110-120 gusting to 130 Severe Cyclonic Storm
16-05-2013/1200 24.0/94.0 55-65 gusting to 75 Deep Depression

REMARKS:
THE UPPER TROPOSPHERIC RIDGE RUNS ALONG 120N AND IS PROVIDING POLEWARD OUT
FLOW IN ASSOCIATION WITH THE ANTICYCLONIC CIRCULATION OVER SOUTH ANDAMAN
SEA. UPPER LEVEL DIVERGENCE IS FAVOURABLE FOR INTENSIFICATION. THE LOW LEVEL
CONVERGENCE ALONG WITH LOW LEVEL RELATIVE VORTICITY REMAINED UNCHANGED
DURING PAST 12 HRS. THE SEA SURFACE TEMPERATURE IS ABOUT 30-320C AND OCEAN
THERMAL ENERGY IS ABOUT 100 KJ/CM SQUARE OVER STORM AREA. THE VERTICAL WIND
SHEAR OF HORIZONTAL WIND IS ABOUT 10-20 KNOTS (MODERATE) IN THE NORTHWEST
SECTOR. THE MJO NOW LIES OVER PHASE 3 WITH AMPLITUDE GREATER THAN 2. IT IS
FAVOURABLE FOR INTENSIFICATION.
MOST OF THE NWP MODELS SUGGEST INITIAL NORTHWESTWARD MOVEMENT DURING NEXT
36 HRS AND THEN RECURVING NORTHEASTWARDS TOWARDS BANGLADESH-MYANMARCOAST. HOWEVER, ECMWF MODEL SHOWS SLOW MOVEMENT AND DOES NOT SHOW
LANDFALL. THERE IS LARGE DIVERGENCE IN THE NWP GUIDANCE WITH RESPECT TO
INTENSIFICATION OF THE SYSTEM. WHILE SOME MODELS LIKE JMA SUGGEST
INTENSIFICATION OF THE SYSTEM TO SEVERE CYCLONIC STORM, THE MODELS LIKE ECMWF
UKMO & NOW GFS DO NOT SUGGEST SUCH SEVERITY IN INTENSITY RATHER THEY
SUGGEST GRADUAL WEAKENING DURING RECURVATURE OF THE SYSTEM.
CLIMATOLOGICALLY, THE SYSTEM IS LIKELY TO INTENSIFY FURTHER.

[Alyono]

The latest OSCAT pass shows that Mahasen may have weakened quite a bit. I did not see anything more than 30 KT on the OSCAT. The latest SSM/I also indicates that the center is east of the convection.

[SouthDadeFish]

The latest OSCAT pass shows that Mahasen may have weakened quite a bit. I did not see anything more than 30 KT on the OSCAT. The latest SSM/I also indicates that the center is east of the convection.

The most recent TRMM pass continues to show the displaced center:

[SouthDadeFish]

I have a feeling we may see a round of intensification begin soon. A large convective burst is occurring:



Also, the latest CIMSS analysis shows wind shear is starting to drop as Mahasen nears an upper-level anticyclone:



A new microwave pass would be very helpful.

[Alyono]

shear does look to be dropping.

However, forecast confidence is non existent. Models take the system anywhere from india to Myanmar. It's like forecasting 20 years ago

Also, even a cat 1 could cause major problems in Bangladesh

[Macrocane]

WTIO31 PGTW 122100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 01B (MAHASEN) WARNING NR 011//
RMKS/
1. TROPICAL CYCLONE 01B (MAHASEN) WARNING NR 011
01 ACTIVE TROPICAL CYCLONE IN NORTHIO
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
121800Z --- NEAR 10.7N 86.7E
MOVEMENT PAST SIX HOURS - 330 DEGREES AT 06 KTS
POSITION ACCURATE TO WITHIN 060 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 075 NM NORTHEAST QUADRANT
070 NM SOUTHEAST QUADRANT
070 NM SOUTHWEST QUADRANT
075 NM NORTHWEST QUADRANT
REPEAT POSIT: 10.7N 86.7E
---
FORECASTS:
12 HRS, VALID AT:
130600Z --- 11.9N 86.4E
MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 085 NM NORTHEAST QUADRANT
075 NM SOUTHEAST QUADRANT
070 NM SOUTHWEST QUADRANT
080 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 005 DEG/ 07 KTS
---
24 HRS, VALID AT:
131800Z --- 13.3N 86.5E
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
025 NM SOUTHWEST QUADRANT
025 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 090 NM NORTHEAST QUADRANT
080 NM SOUTHEAST QUADRANT
075 NM SOUTHWEST QUADRANT
085 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 015 DEG/ 07 KTS
---
36 HRS, VALID AT:
140600Z --- 14.7N 86.9E
MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT
030 NM SOUTHEAST QUADRANT
030 NM SOUTHWEST QUADRANT
030 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 100 NM NORTHEAST QUADRANT
095 NM SOUTHEAST QUADRANT
090 NM SOUTHWEST QUADRANT
095 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 035 DEG/ 07 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
141800Z --- 15.9N 87.7E
MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT
040 NM SOUTHEAST QUADRANT
040 NM SOUTHWEST QUADRANT
040 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 105 NM NORTHEAST QUADRANT
100 NM SOUTHEAST QUADRANT
095 NM SOUTHWEST QUADRANT
100 NM NORTHWEST QUADRANT
VECTOR TO 72 HR POSIT: 035 DEG/ 09 KTS
---
72 HRS, VALID AT:
151800Z --- 18.7N 89.8E
MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT
025 NM SOUTHEAST QUADRANT
025 NM SOUTHWEST QUADRANT
025 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT
050 NM SOUTHEAST QUADRANT
045 NM SOUTHWEST QUADRANT
045 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 110 NM NORTHEAST QUADRANT
105 NM SOUTHEAST QUADRANT
100 NM SOUTHWEST QUADRANT
105 NM NORTHWEST QUADRANT
VECTOR TO 96 HR POSIT: 040 DEG/ 09 KTS
---
LONG RANGE OUTLOOK:
---
96 HRS, VALID AT:
161800Z --- 21.5N 92.3E
MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
VECTOR TO 120 HR POSIT: 040 DEG/ 06 KTS
---
120 HRS, VALID AT:
171800Z --- 23.4N 94.0E
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
---
REMARKS:
122100Z POSITION NEAR 11.0N 86.6E.
TROPICAL CYCLONE 01B (MAHASEN), LOCATED APPROXIMATELY 721 NM
SOUTHWARD OF CALCUTTA, INDIA, HAS TRACKED NORTH-NORTHWESTWARD AT
06 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY
SHOWS THE SYSTEM HAS REGAINED A CENTRAL DENSE OVERCAST FEATURE THAT
HAS, ONCE AGAIN, OBSCURED THE LOW LEVEL CIRCULATION CENTER (LLCC).
THE INITIAL POSITION, EXTRAPOLATED FROM A 121345Z SSMI/S MICROWAVE
IMAGE, HAS BECOME DIFFICULT TO LOCATE AS IT HAS BECOME BROAD AND
ILL-DEFINED. THE INITIAL INTENSITY IS BASED ON THE DVORAK ESTIMATE
FROM PGTW. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS 07 DEGREES
SOUTH OF THE RIDGE AXIS IN AN AREA OF MODERATE (20 KNOT) EASTERLY
VERTICAL WIND SHEAR (VWS); HOWEVER, THE VWS IS OFFSET BY ROBUST
WESTWARD OUTFLOW, AS EVIDENCED ON ANIMATED WATER VAPOR IMAGERY. THE
CYCLONE IS BEGINNING TO ROUND THE WESTERN EDGE OF THE SUBTROPICAL
RIDGE TO THE EAST. IT IS EXPECTED TO SLOW DOWN OVER THE NEXT 24 HOURS
AS IT MAKES THE TURN BEFORE RECURVING NORTHEASTWARD ON THE POLEWARD
SIDE OF THE RIDGE AXIS. TC 01B WILL GRADUALLY INTENSIFY AS THE VWS
RELAXES ALONG THE RIDGE AXIS. ADDITIONALLY, THE POLEWARD OUTFLOW IS
EXPECTED TO OPEN UP AS THE SYSTEM BECOMES EXPOSED TO THE PREVAILING
WESTERLIES. AFTER TAU 72, TC MAHASEN WILL GRADUALLY WEAKEN AS VWS
INCREASES BEFORE MAKING LANDFALL NEAR CHITTAGONG, BANGLADESH. LAND
INTERACTION WILL RAPIDLY ERODE AND DISSIPATE THE SYSTEM BEFORE THE
END OF THE FORECAST. THE AVAILABLE NUMERICAL GUIDANCE IS IN AGREEMENT
WITH THE RECURVE SCENARIO BUT THE MODELS OFFER VARYING SPEEDS AND
TRAJECTORIES AFTERWARDS. THE JTWC FORECAST IS LAID CLOSE TO MODEL
CONSENSUS WITH POOR CONFIDENCE IN VIEW OF THE LARGE VARIANCES IN THE
MODEL MEMBERS. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 121800Z IS 17 FEET.
NEXT WARNINGS AT 130300Z, 130900Z, 131500Z AND 132100Z. //
NNNN

[Macrocane]

TROPICAL CYCLONE ADVISORY NO.13
RSMC – TROPICAL CYCLONES, NEW DELHI
TROPICAL STORM ‘MAHASEN’ ADVISORY ISSUED AT 1800 UTC OF 12TH MAY 2013 BASED
ON 1500 UTC CHARTS OF 12TH MAY 2013.
THE CYCLONIC STORM MAHASEN OVER SOUTHEAST BAY OF BENGAL MOVED SLIGHTLY
WESTWARDS AND LAY CENTRED AT 1500 UTC OF 12TH MAY 2013 NEAR LATITUDE 10.50 N AND
LONGITUDE 86.50 E, ABOUT 700 KM NORTHWEST OF CAR NICOBAR (43367), 610 KM
NORTHEAST OF TRINCOMALEE (43418), 750 KM SOUTHEAST OF CHENNAI (43279) AND 1420
KM SOUTH-SOUTHWEST OF CHITTAGONG (41977). IT WOULD MOVE INITIALLY
NORTHWESTWARDS DURING NEXT 24 HOURS AND RECURVE THEREAFTER
NORTHEASTWARDS TOWARDS BANGLADESH-MYANMAR COAST.
ACCORDING TO SATELLITE IMAGERIES, SATELLITE ESTIMATED INTENSITY IS T-2.5.
ASSOCITED INTENSE TO VERY INTENCE CONVECTION OVER SOUTH BAY ADJOINING INDIAN
OCEAN BETWEEN LAT 6.00N TO 15.00N LONG 80.00E TO 89.00E ADJOINING SRILANKA PALK
STRAIT. THE LOWEST CLOUD TOP TEMPERATURE (CTT) IS ABOUT -700C.
SUSTAINED MAXIMUM SURFACE WIND SPEED IS ESTIMATED TO BE ABOUT 40 KNOTS
GUSTING TO 50 KNOTS AROUND SYSTEM CENTRE. THE STATE OF THE SEA IS HIGH AROUND
THE SYSTEM CENTRE. THE ESTIMATED CENTRAL PRESSURE IS ABOUT 996 HPA.
BASED ON LATEST ANALYSIS WITH NWP MODELS AND OTHER CONVENTIONAL TECHNIQUES,
ESTIMATED TRACK AND INTENSITY OF THE SYSTEM ARE GIVEN IN THE TABLE BELOW:

Date/Time(UTC) Position (Lat. 0N/ Long. 0E) Sustained maximum surface wind speed (kmph) Category
12-05-2013/1500 10.5/86.5 65-75 gusting to 85 Cyclonic Storm
12-05-2013/1800 10.8/86.3 65-75 gusting to 85 Cyclonic Storm
13-05-2013/0000 11.2/86.2 65-75 gusting to 85 Cyclonic Storm
13-05-2013/0600 11.5/86.2 65-75 gusting to 85 Cyclonic Storm
13-05-2013/1200 12.0/86.4 65-75 gusting to 85 Cyclonic Storm
14-05-2013/0000 13.5/87.0 65-75 gusting to 85 Cyclonic Storm
14-05-2013/1200 15.1/87.6 65-75 gusting to 85 Cyclonic Storm
15-05-2013/0000 16.8/88.4 65-75 gusting to 85 Cyclonic Storm
15-05-2013/1200 18.4/89.4 65-75 gusting to 85 Cyclonic Storm
16-05-2013/0000 19.6/90.6 65-75 gusting to 85 Cyclonic Storm
16-05-2013/1200 21.0/92.0 50-60 gusting to 70 Deep Depression
17-05-2013/0000 23.2/93.8 50-60 gusting to 70 Deep Depression

REMARKS:
THE UPPER TROPOSPHERIC RIDGE RUNS ALONG 150N AND IS PROVIDING POLEWARD OUT
FLOW IN ASSOCIATION WITH THE ANTICYCLONIC CIRCULATION OVER SOUTH ANDAMAN
SEA. UPPER LEVEL DIVERGENCE IS FAVOURABLE FOR MAINTAINING THE INTENSITY. THE
LOW LEVEL CONVERGENCE ALONG WITH LOW LEVEL RELATIVE VORTICITY SHOWS NO
CHANGE DURING PAST 12 HRS. THE SEA SURFACE TEMPERATURE IS ABOUT 30-320C ANDOCEAN THERMAL ENERGY IS MORE THAN 100 KJ/CM SQUARE OVER STORM AREA. THE
VERTICAL WIND SHEAR OF HORIZONTAL WIND CONTINUES TO BE ABOUT 05-10 KNOTS (LOW
TO MODERATE) IN THE NORTHEAST SECTOR. THE MJO NOW LIES IN THE BORDER OF PHASE
3 WITH AMPLITUDE GREATER THAN 2. IT IS FAVOURABLE FOR INTENSIFICATION AND
NORTHWARD MOVEMENT OF THE SYSTEM. DYNAMICAL PARAMETERS SHOW THE
INTENFICATION OF THE SYSTEM AFTER RECURVATURE.

MOST OF THE NWP MODELS SUGGEST INITIAL NORTHWESTWARD MOVEMENT DURING NEXT
12-24 HRS AND THEN RECURVING NORTHEASTWARDS TOWARDS BANGLADESH ADJOINING
MYANMAR COAST. HOWEVER, THERE IS LARGE DIVERGENCE IN THE NWP GUIDANCE WITH
RESPECT TO INTENSIFICATION OF THE SYSTEM. ECMWF AND HWRF MODEL MAINTAIN
INTENSITY TILL RECURVATURE AND WEAKENING THEREAFTER. UKMO MAINTAINS
INTENSITY TILL LANDFALL. WHILE JMA AND GFS INDICATE WEAKENING OF THE SYSTEM.
DYNAMICAL STATISTICAL MODELS OF IMD SUGGEST SLIGHT WEAKENING DURING NEXT 36
HRS AND THEN INTENSIFICATION FURTHER DURING SUBSEQUENT 24 HRS.

[Alyono]

its known IMD is bad... but there is flat out wrong info.

12Z GFS does NOT decrease the winds before landfall. The winds actually increase in the BOB when one looks at the 10m winds in the high res GFS

[senorpepr]

A 0451Z MODIS pass over Mahasen shows the exposed circulation:

http://www.nrlmry.navy.mil/tcdat/tc13/I ... .100pc.jpg

Caution, image is 1.6 MB.

[SouthDadeFish]

Center is still sheared off from deepest convection. Here is an 11Z pass:

[Alyono]

Still badly sheared. I am really doubting this intensifies at all now. Shear is not letting up as was forecast

[mrbagyo]

the easterly wind shear is just getting worse, almost displacing the whole convective cloud from the low level cirulation

[Meow]

Shamelessly naked Mahasen

[euro6208]

WTIO31 PGTW 150300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 01B (MAHASEN) WARNING NR 020//
RMKS/
1. TROPICAL CYCLONE 01B (MAHASEN) WARNING NR 020
01 ACTIVE TROPICAL CYCLONE IN NORTHIO
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
150000Z --- NEAR 16.4N 87.3E
MOVEMENT PAST SIX HOURS - 030 DEGREES AT 09 KTS
POSITION ACCURATE TO WITHIN 060 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
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
055 NM NORTHWEST QUADRANT
REPEAT POSIT: 16.4N 87.3E
---
FORECASTS:
12 HRS, VALID AT:
151200Z --- 18.1N 88.4E
MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 075 NM NORTHEAST QUADRANT
075 NM SOUTHEAST QUADRANT
070 NM SOUTHWEST QUADRANT
065 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 040 DEG/ 10 KTS
---
24 HRS, VALID AT:
160000Z --- 19.6N 89.8E
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
040 NM SOUTHWEST QUADRANT
040 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT
080 NM SOUTHEAST QUADRANT
075 NM SOUTHWEST QUADRANT
075 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 045 DEG/ 10 KTS
---
36 HRS, VALID AT:
161200Z --- 21.1N 91.3E
MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 045 NM NORTHEAST QUADRANT
045 NM SOUTHEAST QUADRANT
045 NM SOUTHWEST QUADRANT
045 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 085 NM NORTHEAST QUADRANT
085 NM SOUTHEAST QUADRANT
080 NM SOUTHWEST QUADRANT
080 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 045 DEG/ 10 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
170000Z --- 22.5N 92.7E
MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
VECTOR TO 72 HR POSIT: 040 DEG/ 09 KTS
---
72 HRS, VALID AT:
180000Z --- 25.3N 95.3E
MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
---
REMARKS:
150300Z POSITION NEAR 16.8N 87.6E.
TROPICAL CYCLONE 01B (MAHASEN), LOCATED APPROXIMATELY 377 NM SOUTH
OF KOLKATA, INDIA, HAS TRACKED NORTH-NORTHEASTWARD AT 09 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
INDICATES A LOW LEVEL CIRCULATION CENTER (LLCC) LOCATED UNDER THE
EASTERN PERIPHERY OF A LARGE AREA OF DEEP CONVECTION. A 142339Z
SSMIS MICROWAVE IMAGE REVEALS THE POSITION OF THE LLCC UNDER THE
EASTERN EDGE OF THE SYSTEM. A CURVED BAND OF DEEP CONVECTION IS
PRESENT IN THE NORTHERN SEMICIRCLE, INDICATING DECREASING EASTERLY
VERTICAL WIND SHEAR. THE INITIAL POSITION IS ESTIMATED WITH FAIR
CONFIDENCE BASED ON THE MICROWAVE IMAGE. THE INITIAL INTENSITY IS
ESTIMATED AT 45 KNOTS BASED ON THE 142330Z PGTW DVORAK INTENSITY
ESTIMATE. THE STORM IS FORECAST TO CONTINUE TO TRACK NORTHEASTWARD
ALONG THE POLEWARD ORIENTED SUBTROPICAL RIDGE UNTIL WESTERLY FLOW
ADVECTS THE SYSTEM OVERLAND. AGREEMENT BETWEEN THE DYNAMICAL MODEL
GUIDANCE IS TIGHT LEADING THE JTWC FORECAST TO BE POSITIONED CLOSE
TO MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE. WESTERLY FLOW WILL
INCREASE THE SYSTEM TO A MAXIMUM INTENSITY OF 60 KNOTS BY TAU 36.
STORM DISSIPATION IS EXPECTED OVER LAND BY TAU 72. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 150000Z IS 12 FEET. NEXT WARNINGS AT
150900Z, 151500Z, 152100Z AND 160300Z.//
NNNN

[Rezwanur]

is it a category 3 cyclone?

[Hurricane_Luis]

is it a category 3 cyclone?

No, it is a Cyclonic Storm (SSHS Tropical Storm)