south indian ocean Tropical Cyclone Haruna

[Somerset Squall]

A tropical cyclone has formed in the Mozambique Channel this morning. Forecast to move southeastwards whilst intensifying, and strike southwest Madagascar in a few days time.

SUBJ/TROPICAL CYCLONE 16S (SIXTEEN) WARNING NR 001//

REF/A/JOINT TYPHOON WRNCEN PEARL HARBOR HI/180121Z FEB 13//

AMPN/REF A IS A TROPICAL CYCLONE FORMATION ALERT//

RMKS/

1. TROPICAL CYCLONE 16S (SIXTEEN) WARNING NR 001

01 ACTIVE TROPICAL CYCLONE IN SOUTHIO

MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE

WIND RADII VALID OVER OPEN WATER ONLY

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WARNING POSITION:

190000Z --- NEAR 20.0S 41.2E

MOVEMENT PAST SIX HOURS - 125 DEGREES AT 03 KTS

POSITION ACCURATE TO WITHIN 060 NM

POSITION BASED ON CENTER LOCATED BY SATELLITE

PRESENT WIND DISTRIBUTION:

MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT

WIND RADII VALID OVER OPEN WATER ONLY

REPEAT POSIT: 20.0S 41.2E

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FORECASTS:

12 HRS, VALID AT:

191200Z --- 20.6S 41.4E

MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT

WIND RADII VALID OVER OPEN WATER ONLY

RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT

040 NM SOUTHEAST QUADRANT

025 NM SOUTHWEST QUADRANT

025 NM NORTHWEST QUADRANT

VECTOR TO 24 HR POSIT: 170 DEG/ 03 KTS

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24 HRS, VALID AT:

200000Z --- 21.2S 41.5E

MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT

WIND RADII VALID OVER OPEN WATER ONLY

RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT

055 NM SOUTHEAST QUADRANT

045 NM SOUTHWEST QUADRANT

050 NM NORTHWEST QUADRANT

VECTOR TO 36 HR POSIT: 155 DEG/ 03 KTS

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36 HRS, VALID AT:

201200Z --- 21.8S 41.8E

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

035 NM SOUTHWEST QUADRANT

035 NM NORTHWEST QUADRANT

RADIUS OF 034 KT WINDS - 075 NM NORTHEAST QUADRANT

075 NM SOUTHEAST QUADRANT

065 NM SOUTHWEST QUADRANT

070 NM NORTHWEST QUADRANT

VECTOR TO 48 HR POSIT: 145 DEG/ 04 KTS

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EXTENDED OUTLOOK:

48 HRS, VALID AT:

210000Z --- 22.5S 42.3E

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 - 085 NM NORTHEAST QUADRANT

085 NM SOUTHEAST QUADRANT

070 NM SOUTHWEST QUADRANT

070 NM NORTHWEST QUADRANT

VECTOR TO 72 HR POSIT: 115 DEG/ 05 KTS

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72 HRS, VALID AT:

220000Z --- 23.3S 44.1E

MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT

WIND RADII VALID OVER OPEN WATER ONLY

DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND

VECTOR TO 96 HR POSIT: 120 DEG/ 07 KTS

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LONG RANGE OUTLOOK:

---

96 HRS, VALID AT:

230000Z --- 24.6S 46.6E

MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT

WIND RADII VALID OVER OPEN WATER ONLY

DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND

VECTOR TO 120 HR POSIT: 120 DEG/ 09 KTS

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120 HRS, VALID AT:

240000Z --- 26.3S 49.9E

MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT

WIND RADII VALID OVER OPEN WATER ONLY

DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER

---

REMARKS:

190300Z POSITION NEAR 20.2S 41.3E.

TROPICAL CYCLONE (TC) 16S, LOCATED APPROXIMATELY 335 NM WEST OF

ANTANANARIVO, MADAGASCAR, HAS TRACKED SOUTHEASTWARD AT 03 KNOTS OVER

THE PAST SIX HOURS. ANIMATED INFRARED (IR) SATELLITE IMAGERY DEPICTS

DEEP CONVECTIVE BANDING WRAPPING ALONG THE NORTHERN AND EASTERN

PERIPHERIES OF A CONSOLIDATING LOW LEVEL CIRCULATION CENTER (LLCC).

A MOSAIC OF RECENT MICROWAVE SATELLITE IMAGERY REVEALS THAT THE

CONVECTIVE ORGANIZATION HAS STEADILY IMPROVED OVER THE PAST 24

HOURS. THE INITIAL POSITION IS BASED ON THE ANIMATED IR LOOP AND A

182254Z AMSU 89GHZ MICROWAVE IMAGE. THE INITIAL INTENSITY IS

ASSESSED AT 35 KNOTS BASED ON THE PGTW DVORAK INTENSITY ESTIMATE.

UPPER LEVEL ANALYSIS INDICATES TC 16S IS LOCATED JUST SOUTH OF A

RIDGE AXIS, WITH A POINT SOURCE OVERHEAD PROVIDING GOOD RADIAL

OUTFLOW. THE SYSTEM IS CURRENTLY UNDER MODERATE (15-20 KNOT)

VERTICAL WIND SHEAR (VWS). TC 16S IS CURRENTLY TRACKING SLOWLY

SOUTHEASTWARD UNDER THE INFLUENCE OF LOW- TO MID-LEVEL SUB-TROPICAL

RIDGING TO THE NORTHEAST. A DEEP-LAYER MID-LATITUDE TROUGH IS

EXPECTED TO MOVE IN FROM THE WEST AFTER TAU 48, ADDING ADDITIONAL

VWS AND AMPLIFYING THE DEEP LAYER RIDGE TO THE EAST. THIS WILL

ACCELERATE THE SOUTHEASTERLY MOTION. THE FORECAST IS IN GOOD

AGREEMENT WITH THE ECMWF AND GFS MODELS, WHICH TRACK THE SYSTEM OVER

SOUTHERN MADAGASCAR, WHILE THE NOGAPS AND GFDN MODELS KEEP THE

SYSTEM UNREASONABLY STATIONARY DESPITE THE PASSING TROUGH. THIS

WARNING SUPERSEDES AND CANCELS REF A, JOINT TYPHOON WRNCEN PEARL

HARBOR HI 180121Z FEB 13 TROPICAL CYCLONE FORMATION ALERT (WTXS21

PGTW 180130). MAXIMUM SIGNIFICANT WAVE HEIGHT AT 190000Z IS 12 FEET.

NEXT WARNINGS AT 191500Z AND 200300Z.//

NNNN

[Somerset Squall]

Haruna is strengthening. Sustained winds are up at 45kts currently. Haruna has some deep convection near the LLC and very strong banding features. Haruna will continue to strengthen as it heads towards the south then southeast on the southwest side of a ridge northeast of Madagascar. Landfall is still expected in the southwest corner of Madagascar in a few days time.

[Somerset Squall]

Haruna has strengthened quickly today, and sustained winds are now at 70kts, cat 1 on the SS scale. Banding remains impressive around a solid central dense overcast encompassing a very large eye. Haruna has moved little over the last 12hrs, trapped in a weak steering environment. Haruna should begin the southeasterly motion towards SW Madagascar tomorrow as ridging builds to the northeast. Haruna should continue to strengthen up until landfall. Haruna is only expected to briefly cross land before emerging south of Madagascar. However, waters to the south of Madagascar are pretty cool at the moment, so Haruna is likely to begin extratropical transition as it clears southern Madagascar.

[Somerset Squall]

Haruna has rapidly intensified overnight, and sustained winds are now at 95kts, the upper reaches of cat 2 on the SS scale. The cyclone retains a well defined and very large eye surrounded by symmetrical banding. Haruna has started the eastward turn and is closing in on landfall, but should strengthen a little more today.

Edited February 21, 2013 by Somerset Squall

[Somerset Squall]

Haruna has attained cat 3 status on the SS scale, with sustained winds now at 100kts. Haruna retains a very large eye, which is not far off the coast of Madagascar currently.

[Somerset Squall]

Haruna has crossed Madagascar and emerged over water to the southeast of the country. Land interaction has weakened Haruna to 45kts, down from the 100kt peak. Convection is rebuilding near the LLC as Haruna is now over water. Haruna is forecast to maintain intensity over the next 24-36hrs as good outflow offsets moderate shear and marginally warm sea temps of 26C. Haruna will then encounter stronger shear and cooler water on the eastward track, causing the cyclone to dissipate beyond 48hrs.

Edited February 23, 2013 by Somerset Squall

[Somerset Squall]

Shear and cool waters have caused Haruna to degenerate to a remnant low. The fully exposed LLC is expected to continue to drift east then swing back northwestwards as ridging builds to the south of the system. Regeneration is not expected, but cannot be ruled out as the northwesterly motion may bring the remnant low back over warmer water.