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Irina Expected to Become Cyclone Off Mozambique

NOTE: This article is edited with updates pertaining to the latest information on Irina, scroll down to the bottom of the article for the latest.

The excitement continues in the South West Indian Ocean this year with another tropical storm located just off the Mozambique coast which has already brought heavy rains to the area with the bulk of the convection located on the West-Northwest side of the storm. This storm is forecast by the JTWC to move south in the Mozambique Channel while strengthening to cyclone strength by the end of tomorrow (Thursday).

The JTWC intensity guidance suggests that the storm will become cyclone Irina and will top out at 75kt sustained with 90kt gusts as it moves south and then west.

The track of Irina is certainly an interesting one and brings it very close to South Africa as a depression after making landfall in southern Mozambique. The JTWC track looks a bit further south than the GFS model has been showing, but based on the JTWC, heavy rains would be possible in Limpopo as a result of the storm. Currently it appears to be a very ‘wet’ storm with deep convection, which increases the possibility for rainfall effecting South Africa.

One will be able to get a better handle on both track and intensity in the next 36 hours, but it’s definitely another storm to keep an eye on. This is certainly a very active Indian Ocean year and may well see more to watch in the coming weeks.

The latest from the JTWC is as follows:

WTXS31 PGTW 290300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 14S (IRINA) WARNING NR 001//
REF/A/JOINT TYPHOON WRNCEN PEARL HARBOR HI/280121Z FEB 12//
AMPN/TROPICAL CYCLONE FORMATION ALERT//
RMKS/

1. TROPICAL CYCLONE 14S (IRINA) WARNING NR 001
01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY

WARNING POSITION:
290000Z — NEAR 16.2S 43.4E
MOVEMENT PAST SIX HOURS – 270 DEGREES AT 01 KTS
POSITION ACCURATE TO WITHIN 060 NM
POSITION BASED ON CENTER LOCATED BY A COMBINATION OF
SATELLITE AND SYNOPTIC DATA
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS – 035 KT, GUSTS 045 KT
WIND RADII VALID OVER OPEN WATER ONLY
REPEAT POSIT: 16.2S 43.4E

FORECASTS:
12 HRS, VALID AT:
291200Z — 16.8S 43.1E
MAX SUSTAINED WINDS – 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY


24 HRS, VALID AT:
010000Z — 17.6S 42.8E
MAX SUSTAINED WINDS – 050 KT, GUSTS 065 KT
WIND RADII VALID OVER OPEN WATER ONLY


36 HRS, VALID AT:
011200Z — 19.1S 42.2E
MAX SUSTAINED WINDS – 065 KT, GUSTS 080 KT
WIND RADII VALID OVER OPEN WATER ONLY


EXTENDED OUTLOOK:
48 HRS, VALID AT:
020000Z — 20.9S 41.0E
MAX SUSTAINED WINDS – 075 KT, GUSTS 090 KT
WIND RADII VALID OVER OPEN WATER ONLY


72 HRS, VALID AT:
030000Z — 22.9S 37.5E
MAX SUSTAINED WINDS – 075 KT, GUSTS 090 KT
WIND RADII VALID OVER OPEN WATER ONLY


LONG RANGE OUTLOOK:

96 HRS, VALID AT:
040000Z — 23.7S 34.5E
MAX SUSTAINED WINDS – 035 KT, GUSTS 045 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
VECTOR TO 120 HR POSIT: 250 DEG/ 04 KTS

120 HRS, VALID AT:
050000Z — 24.2S 32.8E
MAX SUSTAINED WINDS – 035 KT, GUSTS 045 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND

REMARKS:
290300Z POSITION NEAR 16.3S 43.3E. TROPICAL CYCLONE (TC) 14S, (IRINA), LOCATED APPROXIMATELY 270 NM NORTHWEST OF ANTANANARIVO, MADAGASCAR, HAS TRACKED WESTWARD AT 01 KNOT OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS TC 14S IS OVERCOMING THE IMPEDIMENTS OF HIGH EASTERLY VERTICAL WIND SHEAR AND IS NOW INTENSIFYING OVER THE MOZAMBIQUE CHANNEL. THE CURRENT INTENSITY ANALYSIS IS BASED ON A COMBINATION OF AGENCY DVORAK ASSESSMENTS AND A PRESSURE REPORT FROM JUAN DE NOVA ISLAND, WHICH IS NEAR THE STORM CENTER. THE SYSTEM HAS BEEN DRIFTING WESTWARD OFF THE CAPE ST ANDRE REGION AND SLOWLY GATHERING STRENGTH. VERTICAL WIND SHEAR OVER THE LOW LEVEL CIRCULATION CENTER (LLCC) IS 20 TO 25 KNOTS, BUT ANIMATED WATER VAPOR IMAGERY SHOWS THE DEVELOPMENT OF A VIGOROUS OUTFLOW CHANNEL ON THE EQUATORWARD SIDE. POLEWARD OUTFLOW IS ALSO IMPROVING, ALTHOUGH THERE REMAINS A REGION OF PRONOUNCED SUBSIDENCE OVER THE SOUTHWEST QUADRANT. THAT IS ALSO REFLECTED IN TOTAL PRECIPITABLE WATER LOOPS, WHICH INDICATE A GENERAL LACK OF DEEP MOISTURE OVER THE CENTRAL AND SOUTHWEST MOZAMBIQUE CHANNEL. 28-29 DEGREE SEA SURFACE TEMPERATURES IN THE CHANNEL ARE SUPPORTIVE OF FURTHER INTENSIFICATION. PREVIOUS SCATTEROMETRY DATA INDICATED AN ELONGATED AND ILL-DEFINED LOW LEVEL CIRCULATION CENTER, BUT RECENT SATELLITE IMAGERY SHOWS BETTER ORGANIZATION AND TIGHTER BANDING. TC 14S IS IN A WEAK STEERING ENVIRONMENT BETWEEN A LOW- TO MID-LEVEL ANTICYCLONE NORTHEAST OF MADAGASCAR, WHICH IS ASSOCIATED WITH THE NEAR- EQUATORIAL RIDGE, AND THE NORTHWEST EXTENSION OF THE SUBTROPICAL RIDGE ALONG THE 30TH LATITUDE. THE NORTHERN ANTICYCLONE IS DEVELOPING INTO THE DOMINANT FORCE AND WILL DRIVE TC 14S ACROSS THE CHANNEL AND INTO MOZAMBIQUE, NORTH OF MAPUTO. PEAK INTENSITY WILL OCCUR BETWEEN TAU 48 AND 72 AS THE STORM MOVES THROUGH THE CENTER OF THE CHANNEL. THIS WARNING SUPERSEDES AND CANCELS REF A, JOINT TYPHOON WRNCEN 280121Z FEB 12 TROPICAL CYCLONE FORMATION ALERT
(WTXS21 PGTW 280130). MAXIMUM SIGNIFICANT WAVE HEIGHT AT 290000Z IS
12 FEET. NEXT WARNINGS AT 291500Z AND 010300Z.
//
NNNN

 

Update 1 March 2011 (08:00): Over the past 12 hours Irina has developed an impressive eye on microwave imagery and moved a bit further east than originally forecast, at 08:00 the center of Irina appeared to be just over the land of Madagascar, forecast to move away from the island over the next coming hours. Both the JTWC and La Reunion seem to indicate a similar track, bringing it into southern Mozambique. With the current forecast path from JTWC and La Reunion, it’s very possible that South Africa may witness flooding from this event. It’s still a way out and difficult to say, but the track is looking somewhat similar to Dando in regards to landfall location. I definitely think this warrants watching for those in northern KZN and Limpopo province. The current track path looks to be one of the closest to a direct South African landfall in quite some time. The intensity guidance is also suggesting that the storm will make landfall as a strong cyclone. Assuming it follows the current track forecast it would likely bring very large swells to KZN, possible strong winds and flooding for potentially KZN, Limpopo and Swaziland. La Reunion is forecasting then cyclone Irina to pass directly over Swaziland as a weakening tropical depression. The forecast does call for quick weakening after landfall, so assuming it does effect South Africa, one would assume heavy rain would be the issue.

 

The latest text from JTWC and image from La Reunion below.

Cyclone Irina

WTXS31 PGTW 010300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 14S (IRINA) WARNING NR 003//
REFER TO TROPICAL CYCLONE 15S (FIFTEEN) WARNINGS (WTXS32 PGTW)
RMKS/
1. TROPICAL CYCLONE 14S (IRINA) WARNING NR 003
02 ACTIVE TROPICAL CYCLONES IN SOUTHIO
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY

WARNING POSITION:
010000Z — NEAR 17.0S 43.6E
MOVEMENT PAST SIX HOURS – 195 DEGREES AT 04 KTS
POSITION ACCURATE TO WITHIN 060 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS – 060 KT, GUSTS 075 KT
WIND RADII VALID OVER OPEN WATER ONLY


FORECASTS:
12 HRS, VALID AT:
011200Z — 18.7S 43.2E
MAX SUSTAINED WINDS – 070 KT, GUSTS 085 KT
WIND RADII VALID OVER OPEN WATER ONLY


24 HRS, VALID AT:
020000Z — 20.9S 42.4E
MAX SUSTAINED WINDS – 085 KT, GUSTS 105 KT
WIND RADII VALID OVER OPEN WATER ONLY


36 HRS, VALID AT:
021200Z — 22.7S 40.7E
MAX SUSTAINED WINDS – 090 KT, GUSTS 110 KT
WIND RADII VALID OVER OPEN WATER ONLY


EXTENDED OUTLOOK:
48 HRS, VALID AT
:
030000Z — 23.6S 38.6E
MAX SUSTAINED WINDS – 090 KT, GUSTS 110 KT
WIND RADII VALID OVER OPEN WATER ONLY


72 HRS, VALID AT:
040000Z — 24.2S 35.8E
MAX SUSTAINED WINDS – 080 KT, GUSTS 100 KT
WIND RADII VALID OVER OPEN WATER ONLY


LONG RANGE OUTLOOK:

96 HRS, VALID AT:
050000Z — 25.2S 33.9E
MAX SUSTAINED WINDS – 050 KT, GUSTS 065 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
VECTOR TO 120 HR POSIT: 255 DEG/ 03 KTS

120 HRS, VALID AT:
060000Z — 25.5S 32.5E
MAX SUSTAINED WINDS – 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND

REMARKS:
010300Z POSITION NEAR 17.4S 43.5E.
TROPICAL CYCLONE (TC) 14S (IRINA), LOCATED APPROXIMATELY 225 NM WEST-NORTHWEST OF ANTANANARIVO, MADAGASCAR, HAS TRACKED SOUTH- SOUTHWESTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY DEPICTS A RAPIDLY CONSOLIDATING SYSTEM WITH TIGHTLY-CURVED DEEP CONVECTIVE BANDING. TC 14S HAS INTENSIFIED RAPIDLY OVER THE PAST 12 HOURS, INCREASING FROM 35 KNOTS TO 60 KNOTS. THE CURRENT INTENSITY IS BASED ON AN AVERAGE OF DVORAK CURRENT INTENSITY ESTIMATES RANGING FROM 55 (KNES/FMEE) TO 65 (PGTW) KNOTS. THERE IS POOR CONFIDENCE IN THE CURRENT POSITION DUE TO THE LACK OF MICROWAVE IMAGERY AND THE CENTRAL DENSE OVERCAST OBSCURING THE CENTER. TC 14S IS TRACKING SOUTHWARD ALONG THE WESTERN PERIPHERY OF A DEEP SUBTROPICAL STEERING RIDGE BUT IS FORECAST TO TURN WESTWARD AS AN EXTENSION OF THE SUBTROPICAL RIDGE BUILDS TO THE SOUTH OF THE SYSTEM. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT UNTIL AFTER TAU 96 WHEN THERE IS INCREASING UNCERTAINTY DUE TO AN APPROACHING DEEP MIDLATITUDE SHORT-WAVE TROUGH. THIS FORECAST IS POSITIONED CLOSE TO THE MODEL CONSENSUS AND INDICATES A SIGNIFICANT DECREASE IN TRACK SPEEDS IN THE EXTENDED TAUS. TC 14S IS EXPECTED TO INTENSIFY TO A PEAK INTENSITY OF 90 KNOTS BY TAU 36 DUE TO FAVORABLE ENVIRONMENTAL CONDITIONS. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 010000Z IS 16 FEET. NEXT WARNINGS AT 011500Z AND 020300Z. REFER TO TROPICAL CYCLONE 15S (FIFTEEN) WARNINGS (WTXS32 PGTW) FOR TWELVE-HOURLY UPDATES.//

 

Update 1 March 2012 (21:00): The South African Weather Service has put together an excellent press release on Irina that provides some good information regarding rainfall totals and a look at the track models over the next coming days. It is good to see that they have put an effort into creating an informative product and credit must be given where credit is due, hopefully we will see more press releases like this in future from the SAWS in regards to severe weather activities. CLICK TO VIEW PRESS RELEASE

 

Update 2 March 2012 (14:00): Tropical storm Irina continues to move away from Madagascar and westward through the Mozambique Channel. The storm is weaker than was previously forecast, but is still expected to become a tropical cyclone as it approaches the far southern Mozambique coast over the next couple of days. It looks as though the effects will be felt in South Africa as early as tomorrow as the outer bands of the cyclone approach Mozambique. By Saturday evening it looks like heavy rainfall will begin to affect parts of KZN and Swaziland. The rainfall will then likely continue for Sunday and Monday and possibly Tuesday too. This prolonged period of heavy rainfall is likely to cause vast areas of flooding and precautions should be taken, remember to monitor water levels and be sure to bring any pets inside should the water begin to submerge your garden. I don’t want to ‘over hype’ the scenario, but I don’t want to downcast either, there is the potential for severe flooding. Keep an eye on the official forecasts and warnings from La Reunion, JTWC and the South African Weather Service.

 

Update 3 March 2012 (18:00): Continuing with the trend of being weaker than forecast tropical storm Irina now looks unlikely to reach tropical cyclone strength in the short term, and as with some of the other cyclones this year, a large change in the track forecast was issued today. The storm is now expected to turn and do a loop off the north east coast of South Africa as a 50kt storm before then strengthening somewhat and heading towards the coast of extreme southern Mozambique near to where the original landfall forecast point was. There is currently no landfall forecast in the forecast period but the previously mentioned potential landfall area is based on extrapolation. The new track forecast would suggest rain would be more limited in the area to the far west and more present on the eastern parts of northern KZN. The prolonged period of tracking off the coast could pose a larger flood threat, and if it were to make a landfall later into this week as forecast it could pose a larger flooding threat than before assuming the outer bands already saturate the grounds while it loops off the coast. The SAWS has issued a new press release on the system today which can be viewed here. Below is the latest track as per La Reunion.

 

 

Tropical storm Irina track

 

Follow the discussion on Irina in the forums: Tropical Storm Irina Forum Thread

Update 4 March 2012 (11:00): Tropical storm Irina has started to have an impact on weather in the eastern and northern parts of South Africa. There was a large area of cirrus and moderate convection associated with the bands of this storm which moved as far south as East London, with some deep convection moving over Durban, causing some heavy showers. Heavy rain has been reported from several north eastern parts. Latest satellite imagery seems to show this large band diminishing slightly and continue moving south. The deep convection around the center of the storm seems to have lightened slightly over the past few hours too. There were reports of several hundred houses being flooded already by Sunday morning, with the collapse of a house in Kwazulu Natal. The Umhlangeni River was reported to be near flooding level by eyewitnesses just an hour ago. There were reports of the Durban beaches already being closed too in a precautionary measure, which is a wise thing to do considering people often end up thinking surfing or swimming is wise during a cyclone. The current track remains very similar to the above track but no longer expected to reach cyclone strength before landfall which looks destined to make landfall on Thursday, in what still appears to be far southern Mozambique. For current satellite imagery you can view weatherphotos.co.za.

Update 5 March 2012 (08:00): NEW ARTICLE ON IRINA

Experiencing conditions related to Irina? Feel free to comment with details.

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