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Tropical Cyclone Giovanna

tropical storm giovannaAs discussed and predicted yesterday, Invest 98S has formed quickly into Moderate Tropical Storm Giovanna. The development of this storm was a bit quicker than expected and looking at the intensity forecasts, it’s going to be a bit stronger than I expected too. It looks like we may well have a tropical cyclone making landfall in Madagascar in about 4 to 5 days. Tropical Storm Giovanna looks likely to reach wind speeds of around 90kt prior to approaching Madagascar, which would warrant it being titled an intense tropical cyclone, and then weaken slightly to around 80kt at landfall, though being almost a week out it is possible that Giovanna will be stronger or weaker than currently forecast.

Both the GFS and the EURO models are consistent in showing a Madagascar landfall, and the GFS has hinted at the possibility of Giovanna reforming into a tropical system again after passing over Madagascar, into the Mozambique Channel. The forecasts indicate rapid weakening once landfall is made and it will be interesting to see just how it does handle the island landfall and if it has enough to regain some strength when it reaches the channel.

I will continue to provide updates on tropical storm Giovanna as it moves across the South West Indian Ocean towards the south west over the coming days. This storm has the potential for severe flooding, tidal and wind related structural damage to Madagascar and warrants watching both for those in Madagascar and potentially Mozambique.

Latest from La Reunion:

RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER: 3/9/20112012
1.A MODERATE TROPICAL STORM 9 (GIOVANNA)
2.A POSITION 2012/02/09 AT 1800 UTC:
WITHIN 30 NM RADIUS OF POINT 14.1 S / 64.8 E
(FOURTEEN DECIMAL ONE DEGREES SOUTH AND SIXTY FOUR DECIMAL EIGHT
DEGREES EAST)

MOVEMENT : WEST-SOUTH-WEST 7 KT
3.A DVORAK ANALYSIS: 3.0/3.0/D 0.5/12 H
4.A CENTRAL PRESSURE: 996 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 40 KT
RADIUS OF MAXIMUM WINDS (RMW) :28 KM
6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 70 SE: 90 SW: 90 NW: 70
34 KT NE: 50 SE: 50 SW: 50 NW: 50
7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1008 HPA / 800 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : DEEP

1.B FORECASTS:
12H: 2012/02/10 06 UTC: 15.2 S / 63.0 E, MAX WIND=045 KT, MODERATE TROPICAL
STORM
24H: 2012/02/10 18 UTC: 16.4 S / 61.0 E, MAX WIND=055 KT, SEVERE TROPICAL STORM
36H: 2012/02/11 06 UTC: 17.3 S / 59.5 E, MAX WIND=065 KT, TROPICAL CYCLONE
48H: 2012/02/11 18 UTC: 17.7 S / 58.6 E, MAX WIND=080 KT, TROPICAL CYCLONE
60H: 2012/02/12 06 UTC: 17.8 S / 57.4 E, MAX WIND=085 KT, TROPICAL CYCLONE
72H: 2012/02/12 18 UTC: 17.5 S / 55.4 E, MAX WIND=090 KT, INTENSE TROPICAL
CYCLONE

2.B LONGER-RANGE OUTLOOK :
96H: 2012/02/13 18 UTC: 17.4 S / 51.3 E, MAX WIND=085 KT, TROPICAL CYCLONE
120H: 2012/02/14 18 UTC: 18.0 S / 47.6 E, MAX WIND=025 KT, INLAND

2.C ADDITIONAL INFORMATIONS:
T=CI=3.0

FOR LATEST HOURS, SYSTEM SHOWS AN IRREGULAR CDO PATTERN WITH A 100/120
NM DIAMETER (DT AT 3.0). AT 1530Z, SYSTEM HAS BEEN NAMED GIOVANNA BY
MAURITIUS METEOROLOGICAL SERVICE. WINDS EXTENSIONS HAVE BEEN
CALIBRATED THANKS TO 1738Z ASCAT SWATH. MSLP HAS BEEN ADJUSTED IN
RELATIONSHIP TO 23946 BUOY OBS AT 1710Z.

SYSTEM IS GENERALLY TRACKING WEST-SOUTHWESTWARD ON THE NORTHWESTERN
EDGE OF THE LOW-MID LEVEL SUBTROPICAL RIDGE SITUATED IN THE
SOUTH-EAST. WITHIN THE NEXT 36 HOURS, SYSTEM SHOULD KEEP THIS TRACK BY
SLIGHTLY ACCELERATING.

ON SATURDAY, IT IS EXPECTED TO SLOW DOWN DUE TO A WEAKNESS IN THE MID
LEVEL ANTICYCLONIC BELT IN THE SOUTH. BEYOND 60 TAU, TRACK SHOULD
RECURVE WESTWARD WITH THE REBUILDING OF HIGH PRESSURES SOUTH-EAST OF
MADAGASCAR. AVAILABLE NWP MODELS ARE IN RATHER GOOD AGREEMENT FOR
THIS TRACK. ECMWF FORECAST THAT SYSTEM WILL GO DOWN MORE TOWARD THE
SOUTH ON SATURDAY (RSMC OFFICIAL FORECAST TRACK).

ON THIS TRACK, ENVIRONMENTAL CONDITIONS ARE FAVOURABLE FOR A REGULAR
INTENSIFICATION UP TO SUNDAY. OCEANIC HEAT POTENTIAL IS VERY GOOD.
VERTICAL WIND SHEAR IS WEAK AND DIVERGENCE IS GOOD MAINLY SOUTHWARD.
POLEWARD OUTFLOW CHANNEL IS EXPECTED TO IMPROVE WITHIN THE NEXT 48
HOURS, AS THE SYSTEM IS APPROACHING OF AN UPPER LEVEL TROUGH
TRANSITING IN THE SOUTH.

ON SUNDAY AND AFTER, GIOVANNA SHOULD UNDERGO A WEAK TO MODERATE
EASTERLY VERTICAL WIND SHEAR ON THE NORTHERN SIDE OF REBUILDING UPPER
LEVEL HIGH PRESSURES. CONSEQUENTLY INTENSITY SHOULD LEVEL OFF AND
EVEN A BIT REDUCE BEFORE THE LANDFALL ON THE EASTERN COAST OF
MADAGASCAR THAT IS EXPECTED AT THE END OF FORECAST PERIOD.
INHABITANTS OF MASCARENES ISLANDS AND OF THE EASTERN COAST OF
MADAGASCAR ARE INVITED TO FOLLOW WITH ATTENTION THE EVOLUTION OF
THIS SYSTEM. OFFICIAL FORECAST TRACK BRING GIOVANNA VERY CLOSELY
SOUTH OF SAINT-BRANDON IN THE MORNING ON SATURDAY.

 

Update 10 February 2012 (19:30): Now Severe Tropical Storm Giovanna continued to intensify rapidly today as it moved to the south-west at around 08kt, an eye was visible on satellite already earlier in the day and forecast agencies amended their forecasts to show a much stronger cyclone in the short term, Giovanna is expected to continue it’s rapid strengthening over the next 36 odd hours where it will become a 110kt Intense Cyclone, but significant weakening is forecast to occur prior to landfall in Madagascar, as is often the case. Those in Mozambique are advised to keep a close eye on this storm as it’s quite possible that it will spin up again in the Mozambique channel as mentioned before, the latest forecast from the official agencies are as follows:

 

WTXS31 PGTW 101500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 12S (GIOVANNA) WARNING NR 003//
RMKS/
1. TROPICAL CYCLONE 12S (GIOVANNA) WARNING NR 003
01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY

WARNING POSITION:
101200Z — NEAR 15.6S 61.6E
MOVEMENT PAST SIX HOURS – 255 DEGREES AT 08 KTS
POSITION ACCURATE TO WITHIN 040 NM
POSITION BASED ON EYE FIXED BY SATELLITE
PRESENT WIND DISTRIBUTION:
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 – 065 NM NORTHEAST QUADRANT
075 NM SOUTHEAST QUADRANT
075 NM SOUTHWEST QUADRANT
065 NM NORTHWEST QUADRANT
REPEAT POSIT: 15.6S 61.6E

FORECASTS:
12 HRS, VALID AT:
110000Z — 16.2S 60.1E
MAX SUSTAINED WINDS – 085 KT, GUSTS 105 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 – 050 NM NORTHEAST QUADRANT
050 NM SOUTHEAST QUADRANT
050 NM SOUTHWEST QUADRANT
050 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS – 085 NM NORTHEAST QUADRANT
095 NM SOUTHEAST QUADRANT
095 NM SOUTHWEST QUADRANT
085 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 250 DEG/ 08 KTS

24 HRS, VALID AT:
111200Z — 16.7S 58.5E
MAX SUSTAINED WINDS – 100 KT, GUSTS 125 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 – 060 NM NORTHEAST QUADRANT
060 NM SOUTHEAST QUADRANT
060 NM SOUTHWEST QUADRANT
060 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS – 095 NM NORTHEAST QUADRANT
105 NM SOUTHEAST QUADRANT
105 NM SOUTHWEST QUADRANT
095 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 260 DEG/ 07 KTS

36 HRS, VALID AT:
120000Z — 16.9S 57.1E
MAX SUSTAINED WINDS – 110 KT, GUSTS 135 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS – 045 NM NORTHEAST QUADRANT
045 NM SOUTHEAST QUADRANT
045 NM SOUTHWEST QUADRANT
045 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS – 070 NM NORTHEAST QUADRANT
070 NM SOUTHEAST QUADRANT
070 NM SOUTHWEST QUADRANT
070 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS – 115 NM NORTHEAST QUADRANT
125 NM SOUTHEAST QUADRANT
125 NM SOUTHWEST QUADRANT
115 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 265 DEG/ 08 KTS

EXTENDED OUTLOOK:
48 HRS, VALID AT:
121200Z — 17.0S 55.4E
MAX SUSTAINED WINDS – 110 KT, GUSTS 135 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS – 045 NM NORTHEAST QUADRANT
045 NM SOUTHEAST QUADRANT
045 NM SOUTHWEST QUADRANT
045 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS – 070 NM NORTHEAST QUADRANT
070 NM SOUTHEAST QUADRANT
070 NM SOUTHWEST QUADRANT
070 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS – 115 NM NORTHEAST QUADRANT
125 NM SOUTHEAST QUADRANT
125 NM SOUTHWEST QUADRANT
115 NM NORTHWEST QUADRANT
VECTOR TO 72 HR POSIT: 265 DEG/ 11 KTS

72 HRS, VALID AT:
131200Z — 17.5S 50.9E
MAX SUSTAINED WINDS – 095 KT, GUSTS 115 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 – 065 NM NORTHEAST QUADRANT
065 NM SOUTHEAST QUADRANT
065 NM SOUTHWEST QUADRANT
065 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS – 105 NM NORTHEAST QUADRANT
115 NM SOUTHEAST QUADRANT
115 NM SOUTHWEST QUADRANT
105 NM NORTHWEST QUADRANT
VECTOR TO 96 HR POSIT: 255 DEG/ 11 KTS

LONG RANGE OUTLOOK:

96 HRS, VALID AT:
141200Z — 18.6S 46.3E
MAX SUSTAINED WINDS – 055 KT, GUSTS 070 KT
WIND RADII VALID OVER OPEN WATER ONLY
VECTOR TO 120 HR POSIT: 240 DEG/ 12 KTS

120 HRS, VALID AT:
151200Z — 21.0S 42.0E
MAX SUSTAINED WINDS – 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY

REMARKS:
101500Z POSITION NEAR 15.8S 61.2E.
TROPICAL CYCLONE (TC) 12S, LOCATED APPROXIMATELY 480 NM NORTHEAST OF
LA REUNION, HAS TRACKED WEST-SOUTHWESTWARD AT 08 KNOTS OVER THE PAST
SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY INDICATES THAT
TC 12S HAS RAPIDLY CONSOLIDATED AND HAS NOW FORMED AN INCIPIENT EYE.
ANIMATED WATER VAPOR IMAGERY INDICATES EXCELLENT RADIAL OUTFLOW WITH
STRONG POLEWARD OUTFLOW ENHANCED BY A DEEP UPPER-LEVEL TROUGH
POSITIONED SOUTHEAST OF MADAGASCAR. CONSEQUENTLY, DVORAK ESTIMATES
HAVE INCREASED TO 65 (PGTW/FMEE) TO 77 KNOTS (KNES). THE CURRENT
INTENSITY WAS ASSESSED AT 65 KNOTS BASED ON THE WEAK EYE IN VISIBLE
IMAGERY AND THE SIGNATURE IN THE 100919Z AMSU IMAGE. THERE IS HIGH
CONFIDENCE IN THE CURRENT POSITION BASED ON THE EYE. TC 12S IS
CURRENTLY TRACKING WEST-SOUTHWESTWARD (WSW) ALONG THE NORTHWESTERN
PERIPHERY OF THE DEEP SUBTROPICAL RIDGE (STR) AS A MIDLATITUDE
SHORTWAVE TROUGH PROPAGATES SOUTH OF THE SYSTEM. THIS WSW TRACK IS
EXPECTED TO BE SHORT-LIVED AS THE TROUGH MOVES EAST AND A STR BUILDS
INTO SOUTHERN MADAGASCAR PROVIDING A WESTWARD STEERING INFLUENCE.
THE AVAILABLE DYNAMIC GUIDANCE IS IN EXCEPTIONALLY TIGHT AGREEMENT
AND SUPPORTS THE JTWC TRACK, WHICH IS POSITIONED VERY CLOSE TO THE
MODEL CONSENSUS AS WELL AS THE ECMWF MODEL. DUE TO THE FAVORABLE
ENVIRONMENT, TC 12S IS FORECAST TO STRENGHTHEN TO A PEAK OF 110
KNOTS WITHIN THE NEXT 36 HOURS. THE SYSTEM IS EXPECTED TO WEAKEN
SIGNIFICANTLY AS IT TRACKS ACROSS MADAGASCAR; HOWEVER, RE-
DEVELOPMENT IS EXPECTED IN THE MOZAMBIQUE CHANNEL AFTER TAU 120.
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 101200Z IS 15 FEET. NEXT WARNINGS
AT 110300Z AND 111500Z.//
NNNN

 

Tropical Cyclone GiovannaUpdate 11 February 2012 (12:00): As expectedGiovanna continued rapid strengthening overnight and as of now, is a 120kt Intense Tropical Cyclone, the second one in 3 weeks, and both have been unusually close to the African continent. Intense tropical cyclone Giovanna is forecast to continue strengthening today and to reach around 135kt in 36 hours with wind gusts at an astonishing 165kt. Luckily for Madagascar, it still looks as though some weakening will take place prior to landfall, but don’t let that fool you, Giovanna is still extremely dangerous and Madagascar will likely take a bit of a beating regardless. The latest track takes Giovanna over Madagascar and into the Mozambique Channel, then heading for the Mozambique coast as a severe tropical storm. The reality of the situation though, is that it is very difficult to estimate the strength of a cyclone after making landfall – the important fact of whether the low level circulation can make it over the land in tact will determine the strength of landfall in Mozambique, should it occur. Regardless of wind speed, flooding will likely become an issue for both Madagascar and Mozambique.  Keep a close eye on this one.

 

Latest forecast data:

 

WTXS31 PGTW 110300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 12S (GIOVANNA) WARNING NR 005//
RMKS/
1. TROPICAL CYCLONE 12S (GIOVANNA) WARNING NR 005
01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY

WARNING POSITION:
110000Z — NEAR 16.7S 60.1E
MOVEMENT PAST SIX HOURS – 230 DEGREES AT 11 KTS
POSITION ACCURATE TO WITHIN 025 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS – 120 KT, GUSTS 145 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS – 030 NM NORTHEAST QUADRANT
035 NM SOUTHEAST QUADRANT
035 NM SOUTHWEST QUADRANT
030 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS – 060 NM NORTHEAST QUADRANT
065 NM SOUTHEAST QUADRANT
070 NM SOUTHWEST QUADRANT
060 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS – 095 NM NORTHEAST QUADRANT
100 NM SOUTHEAST QUADRANT
110 NM SOUTHWEST QUADRANT
095 NM NORTHWEST QUADRANT
REPEAT POSIT: 16.7S 60.1E

FORECASTS:
12 HRS, VALID AT:
111200Z — 17.5S 58.8E
MAX SUSTAINED WINDS – 125 KT, GUSTS 150 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 – 065 NM NORTHEAST QUADRANT
070 NM SOUTHEAST QUADRANT
075 NM SOUTHWEST QUADRANT
065 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS – 100 NM NORTHEAST QUADRANT
105 NM SOUTHEAST QUADRANT
115 NM SOUTHWEST QUADRANT
100 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 265 DEG/ 07 KTS

24 HRS, VALID AT:
120000Z — 17.6S 57.4E
MAX SUSTAINED WINDS – 130 KT, GUSTS 160 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 – 070 NM NORTHEAST QUADRANT
075 NM SOUTHEAST QUADRANT
080 NM SOUTHWEST QUADRANT
070 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS – 110 NM NORTHEAST QUADRANT
115 NM SOUTHEAST QUADRANT
125 NM SOUTHWEST QUADRANT
110 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 270 DEG/ 09 KTS

36 HRS, VALID AT:
121200Z — 17.6S 55.6E
MAX SUSTAINED WINDS – 135 KT, GUSTS 165 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 – 075 NM NORTHEAST QUADRANT
080 NM SOUTHEAST QUADRANT
085 NM SOUTHWEST QUADRANT
075 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS – 115 NM NORTHEAST QUADRANT
120 NM SOUTHEAST QUADRANT
130 NM SOUTHWEST QUADRANT
115 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 260 DEG/ 12 KTS

EXTENDED OUTLOOK:
48 HRS, VALID AT:
130000Z — 17.9S 53.2E
MAX SUSTAINED WINDS – 130 KT, GUSTS 160 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS – 045 NM NORTHEAST QUADRANT
045 NM SOUTHEAST QUADRANT
045 NM SOUTHWEST QUADRANT
045 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS – 070 NM NORTHEAST QUADRANT
070 NM SOUTHEAST QUADRANT
070 NM SOUTHWEST QUADRANT
070 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS – 115 NM NORTHEAST QUADRANT
125 NM SOUTHEAST QUADRANT
125 NM SOUTHWEST QUADRANT
115 NM NORTHWEST QUADRANT
VECTOR TO 72 HR POSIT: 255 DEG/ 11 KTS

72 HRS, VALID AT:
140000Z — 18.8S 48.7E
MAX SUSTAINED WINDS – 095 KT, GUSTS 115 KT
WIND RADII VALID OVER OPEN WATER ONLY
VECTOR TO 96 HR POSIT: 245 DEG/ 13 KTS

LONG RANGE OUTLOOK:

96 HRS, VALID AT:
150000Z — 20.8S 43.7E
MAX SUSTAINED WINDS – 055 KT, GUSTS 070 KT
WIND RADII VALID OVER OPEN WATER ONLY
VECTOR TO 120 HR POSIT: 245 DEG/ 12 KTS

120 HRS, VALID AT:
160000Z — 22.7S 38.9E
MAX SUSTAINED WINDS – 050 KT, GUSTS 065 KT
WIND RADII VALID OVER OPEN WATER ONLY

REMARKS:
110300Z POSITION NEAR 16.9S 59.8E.
TROPICAL CYCLONE (TC) 12S (GIOVANNA), LOCATED APPROXIMATELY 365 NM
NORTHEAST OF LA REUNION, HAS TRACKED SOUTHWESTWARD AT 11 KNOTS OVER
THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS THE
SYSTEM HAS MAINTAINED DEEP, HIGHLY-SYMMETRICAL AND VERY COMPACT
CONVECTIVE BANDING AROUND A 15-NM DIAMETER EYE. RECENT WATER VAPOR
SATELLITE ANIMATION DISPLAYS EXCELLENT RADIAL OUTFLOW WITH A VERY
EFFICIENT POLEWARD CHANNEL. THE INITIAL POSITION IS PLACED OVER THE
EYE FEATURE WITH HIGH CONFIDENCE AND THE INITIAL INTENSITY IS
SUPPORTED BY DVORAK ESTIMATES FROM FMEE, PGTW AND KNES. UPPER LEVEL
ANALYSIS INDICATES TC 12S IS IN A VERY FAVORABLE ENVIRONMENT OF LOW
VERTICAL WIND SHEAR IN A DIFFLUENT ZONE UNDER A RIDGE AXIS. IT IS
EXPECTED TO CONTINUE TRACKING ALONG THE NORTHWEST PERIPHERY OF A
DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE SOUTHEAST. AFTER TAU 12,
AN EXTENSION OF A SECONDARY STR CURRENTLY ANCHORED OVER MOZAMBIQUE
CHANNEL WILL ASSUME STEERING. THE TRANSITION WILL CAUSE A SLIGHTLY
MORE WESTWARD DIRECTION IN THE FORECAST TRACK. TC GIOVANNA WILL
CONTINUE TO INTENSIFY OVER THE NEXT 48 HOURS PEAKING AT 135 KNOTS
BEFORE MAKING LANDFALL IN MADAGASCAR AND EXITING INTO THE MOZAMBIQUE
CHANNEL JUST BEFORE TAU 96. THE AVAILABLE NUMERICAL GUIDANCE IS IN
VERY TIGHT AGREEMENT WITH THIS TRACK FORECAST WITH WBAR AS THE SOLE
LEFT OUTLIER AFTER TAU 36. MAXIMUM SIGNIFICANT WAVE HEIGHT AT
110000Z IS 26 FEET. NEXT WARNINGS AT 111500Z AND 120300Z.//
NNNN

 

Tropical Cyclone Giovanna Track

 

Update 12 February 2012 (10:30): Tropical Cyclone Giovanna has been going through an eyewall replacement cycle since yesterday evening and is currently forecast to weaken into a 70kt storm before making landfall in Madagascar. It is still then expected to reform in the Mozambique Channel and make landfall in southern Mozambique. This storm has the potential to cause flooding to northern South Africa if it makes landfall in southern Mozambique as forecast.

Update 13 February 2012 (07:00): Despite calls from the official agencies of Tropical Cyclone Giovanna to weaken as it approaches Madagascar after the eye-wall replacement cycle, Giovanna repeated history when it underwent more rapid intensification. It’s looking at the moment like Madagascar may get a real pounding from this one, a category 4 landfall is possible, something very rare for the SW Indian Ocean. Landfall is only a few hours away and Giovanna is looking good as ever. This storm has the potential for devastation as it packs winds of 145mph. What happens after landfall is not clear right now, but it’s best to focus on Madagascar at this point.

Update 13 February 2012 (21:00): Tropical Cyclone Giovanna remains a dangerous cyclone with winds of 100kt according to the latest from La Reunion. The storm is currently around 5 or 6 hours from landfall and stations along the Madagascan coast have already reported winds in excess of 70km/h, long before landfall. The area it is set to make landfall in is said to be quite sparsely populated and thus the damage will be less than it could be, with that said though, both winds and rain as well as storm surge will be extremely dangerous as we head into the night and night time storms are always the worst for those in them as it’s difficult to see breaking or leaning trees or tree limbs that may pose a threat. The next update from me will likely come at around 6am tomorrow morning, where those in Madagascar should have a clear view of the damage caused and the cyclone should be near to the capital. If you’re a resident along the east coast of Madagascar, near the storm path – stay indoors and preferably in an area safest from possible falling tree limbs.

Update 14 February 2012 (08:00): Reports are somewhat slow coming in from Giovanna, and it’s still too early for any reliable reports on damage. More information should be coming in through the day as the locals begin the clean up process in the wake of the storm. Giovanna is currently over land now and is expected to continue a SW heading and emerge off the island in the early hours of tomorrow morning. It is unknown how strong Giovanna will be when it leaves land, but strengthening is likely once in the Mozambique Channel. The models seem to indication that Giovanna may make a U-turn in the channel and slip south of Madagascar heading east without making landfall in Mozambique, one run even had the storm making a second landfall in Madagascar, this time the far SW corner of the island. Will update again when accurate damage reports are received.

Update 15 February 2012 (08:00): Images have started surfacing over the past 24 hours of the destruction in Madagascar and the damage looks quite bad, widespread flooding was present as well as quite a lot of structural damage, billboards were bent like tin foil, trees were blown down onto houses and housing structures themselves were damaged. The surprising thing is that it seems there were very few fatalities, the last I heard there was only 1 fatality reported from Madagascar, though this may climb a bit. Giovanna is now a weak storm in the Mozambique Channel but is clearly looking to fight it’s way back to cyclone status. The models have been a bit back and forth on track lately, with the GFS back to showing a southern Mozambique landfall with the remnant low heading into Limpopo, which would bring some heavy rain. Hopefully over the next 24 hours or so a track will become better defined.

Update 16 February 2012: Giovanna is still located off the coast of Madagascar in the Mozambique Channel and is slowly strengthening again. There is an extremely large amount of uncertainty when it comes to the track of Giovanna. As discussed before, the models have been flip flopping between 2 primary tracks, one being where Giovanna will move slowly westwards and meander a bit in low steer currents before then moving ashore and making landfall in southern Mozambique. The other scenario is one where Giovanna will meander a bit allowing for a low to the east to pull Giovanna back east and actually has the potential for a second landfall on Madagascar, though there have been some alternate runs where strangers things happen. It remains a ‘wait and see’ situation and more details can be provided once the models cling onto a particular scenario better. Right now, as always, follow the official track forecasts.

Update 17 February 2012: As expected, the official forecasts moved in line with the model guidance over the past day and they are now on board with the models for Giovanna no longer threatening Mozambique, but rather heading east towards the Madagascan coast. Looks like Madagascar may get a second landfall from this system, though shouldn’t be very strong, maybe 60kt at best when landfall is made. The storm is then likely to head south east and die off as it loses it’s tropical characteristics. It’s been interesting tracking this storm, but I did see that the death toll was moved up to around 10 fatalities.

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