Joalane (was 22S - Southern Indian Ocean)

The RapidScat instrument that flies aboard the International Space Station (ISS) provided data about Tropical Cyclone Joalane's surface winds that showed how the strongest sustained winds consolidated as the tropical cyclone intensified and developed an eye. As of April 9, warnings were in effect at Rodrigues Island in the Southern Indian Ocean as Joalane approached.

RapidScat measured the surface winds within Tropical Cyclone Joalane late on April 7 and on April 8, revealing that the strongest winds consolidated over a 24 hour period. RapidScat measured Joalane's winds on April 7 from 23:19 to 00:52 (7:19 p.m. to 8:52 p.m. EDT) and April 8 from 10:07 to 11:40 UTC (6:07 p.m. to 11:40 p.m. EDT).

The strongest sustained winds up reached up to 30 meters per second (67.1 mph/108 kph). During the earlier pass on April 7, those strongest wind speeds were north and east of the developing eye, and extending south and east in a wide band of thunderstorms. On April 8, the strongest surface winds became more concentrated and circled the entire center (which was an eye at that time). Sustained winds of 30 meters per second (67.1 mph/108 kph) were also seen in occurring bands of thunderstorms south and east of the center. The data was generated into images at NASA's Jet Propulsion Laboratory in Pasadena, California.

On April 9 at 05:50 UTC (1:50 a.m. EDT), the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA's Aqua Satellite captured visible-light data of Tropical Cyclone Joalane. That data was made into an image by the MODIS Rapid Response Team at NASA's Goddard Space Flight Center in Greenbelt, Maryland. The image showed banding of thunderstorms in the southwestern and northeastern quadrants of the storm, wrapping into the storm's center. The eye of the storm now just 7 nautical miles (8.0 miles/12.9 km) wide according to microwave data was obscured by clouds in the visible MODIS imagery.

A Class I tropical cyclone warning was posted on April 9 at Rodrigues. For updated forecasts for Rodrigues Island, visit the Mauritius Meteorological Services website at: http://metservice.intnet.mu/.

By 1500 UTC (11 a.m. EDT), Joalane's maximum sustained winds were still at 80 knots (92 mph/148.2 kph), just where they were 24 hours before. Joalane is still a strong Category 1 hurricane on the Saffir-Simpson hurricane wind scale. Joalane's center was near 17.0 south latitude and 65.7 east longitude, about 513 nautical miles (590.3 miles/ 950.1 km) east-northeast of Port Louis, Mauritius. As it was 24 hours before, Joalane was still moving at 6 knots (6.9 mph/11.1 kph) but shifted its path from the south-southeast to due south.

Joalane is moving south into an area of cooler sea surface temperatures and increased vertical wind shear. It is expected to start weakening in a day while transitioning into an extra-tropical storm.

Rob Gutro
NASA's Goddard Space Flight Center

South Indian Ocean: NASA Sees Tropical Cyclone 15S Meandering in Mozambique Channel

Tropical Cyclone 15S continued to meander in the Mozambique Channel of the Indian Ocean when NASA's Aqua satellite passed overhead and captured a picture of it. The storm's lack of direction is short-lived, however, as forecasters at the Joint Typhoon Warning Center or JTWC expect that the storm will move in a southwesterly direction and landfall in west central Madagascar by March 9.
The Moderate Resolution Imaging Spectroradiometer or MODIS instrument that flies aboard NASA's Aqua satellite captured a visible image of Tropical Cyclone 15S on March 5 at 11:25 UTC (6:25 a.m. EST) when it was hugging the coast of eastern Mozambique. The MODIS image showed that the bulk of clouds and rain were north and west of the center of circulation, extending over the Mozambique coastline, while the center of Tropical Cyclone 15S remained over the open waters of the Mozambique Channel.

On March 6 at 1500 UTC (10 a.m. EST), Tropical Cyclone 15S was centered near 16.5 south latitude and 41.3 east longitude, about 349 nautical miles (401 miles/464 km) north-northeast of Europa Island. Maximum sustained winds were still near 35 knots (40 mph/62 kph), but are expected to increase over the next two days as it moves away from Mozambique and into the open waters of the Mozambique Channel, toward Madagascar. At 1500 UTC, however, it was moving slowly at 2 knots (2.3 mph/3.7 kph) to the west-northwest.

Tropical Cyclone 15S is expected to make landfall in west central Madagascar's Tsingy de Bemaraha Strict Nature Reserve and move across the island nation in a southeasterly direction, with its center expected to pass just south of the capital city of Antananarivo before exiting the east coast early next week.

Rob Gutro
NASA's Goddard Space Flight Center

S Indian Ocean: Storm Alert issued at 7 Mar, 2015 6:00 GMT (Final Warning)

Tropical Depression FIFTEEN (15S) currently located near 16.2 S 41.0 E is forecast to strike land to the following likelihood(s) at the given lead time(s):

Yellow Alert Country(s) or Province(s)
    Mozambique
        probability for TS is 60% currently
Yellow Alert City(s) and Town(s)
    Mogincual (15.6 S, 40.5 E)
        probability for TS is 60% currently

Green Alert City(s) and Town(s)
    Angoche (16.2 S, 40.0 E)
        probability for TS is 35% currently

Note that
    Yellow Alert (Elevated) is CAT 1 or above to between 10% and 30% probability, or TS to above 50% probability.
    Green Alert (Low) is TS to between 31% and 50% probability.
    CAT 1 means Tropical Cyclone strength winds of at least 74 mph, 119 km/h or 64 knots 1-min sustained.
    TS means Tropical Storm strength winds of at least 39 mph, 63 km/h or 34 knots 1-min sustained.

For graphical forecast information and further details please visit http://www.tropicalstormrisk.com/

South Indian Ocean: Tropical Storms - System 91S Formed today Along Madagascar's Western Coast

This visible image from NASA's Aqua satellite taken today at 11:10 UTC (6:10 a.m. EST) by the MODIS instrument aboard shows the storm riding the west coast of Madagascar. It is about 230 nautical miles west-southwest of Antananativo, Madagascar, near 20. 7 south and 43.3 east. The strongest thunderstorms are over the northeast quadrant, and there is weak fragmented curved banding of thunderstorms wrapping into the weak low-level center. System 91S is dealing with moderate vertical wind shear (20-30 knots), but half over the warm waters of the Mozambique Channel (water temps are as warm as 29C/84.2F. The Joint Typhoon Warning Center gives this a low chance for development over the next 24 days. Image Credit: NASA/NRL + EUMETSAT

Twin Tropical #Cyclones #tropicalstorms #southindianocean

In January 2015, two tropical cyclones swirled over the central Indian Ocean. Neither storm was particularly strong, nor were they expected to make landfall or cause significant damage. Rather, forecasters anticipate thatDiamondra and Eunice will weaken and dissipate over the coming days. But their close proximity offered striking views to satellites.

On January 28, 2015, geostationary satellites maintained by EUMETSAT and the Japanese Meteorological Agencycollected the infrared data used to make the composite image at the top of the page. The Visible Infrared Imaging Radiometer Suite (VIIRS) on Suomi NPP captured the lower image, another composite. Note that three separate swaths of data (acquired at 07:25 UTC, 09:05 UTC, and 10:50 UTC) were stitched together to produce the VIIRS image.

The two storms were about 1,500 kilometers (930 miles) apart on January 28, 2015, when VIIRS imaged the storm. Eunice, the stronger of the two, was located to the east of Diamondra. Eunice had maximum sustained winds of about 160 kilometers (100 miles) per hour, while Diamondra’s maximum winds topped out at about 100 kilometers (60 miles). Both storms were moving in a southeasterly direction.

If two tropical cyclones draw near each other, they begin to rotate cyclonically around an axis connecting their centers—something meteorologists call the Fujiwhara Effect. Such binary storms can even merge if their centers get close enough.

“But in this case, the centers of the two vortices appear to be too far apart,” explained Brian McNoldy, a meteorologist at the University of Miami. “As a rough rule of thumb, the centers would need to be at least 1,350 kilometers (840 miles) apart for the centers to start rotating about each other in some fashion. From the latest Joint Typhoon Warning Center forecasts, both storms are expected to move to the southeast at about the same speed, so they probably won’t get any closer to each other.”

• References

• Hong Kong Observatory What is the ‘Fujiwhara Effect’? Accessed January 28, 2015.
• Joint Typhoon Warning Center (2015, January 28) Current Northwest Pacifc/North Indian Ocean Tropical Storms.Accessed January 28, 2015.
• NASA Hurricane (2015, January 28) Diamondra (Southern Indian Ocean). Accessed January 28, 2015.
• Pacific Disaster Center (2015, January 28) Tropical Cyclone Activity Report. Accessed January 28, 2015.

Meteosat image Copyright EUMETSAT. VIIRS data from the Suomi National Polar-orbiting Partnership. Suomi NPP is the result of a partnership between NASA, the National Oceanic and Atmospheric Administration, and the Department of Defense. Caption by Adam Voiland.

Instrument(s): 

Meteosat

Suomi NPP - VIIRS

The Electric Eye of #Cyclone #Bansi #ISS #NASA

Though these images may look like they come from a science fiction movie, they are in fact photographs of tropical cyclone Bansi as seen at night by astronauts on the International Space Station (ISS). The images were taken when the ISS was east of Madagascar.

Bansi formed in the southwestern Indian Ocean on January 11, 2015. By the time this photo was taken on the following day, Bansi had achieved tropical cyclone strength, with sustained maximum winds over 185 kilometers (115 miles) per hour. The cyclone would reach category 4 strength before becoming a weak extra-tropical system on January 19.

The dim swirl of the cloud bands covers the ocean surface in both night images. The eye of the cyclone is brilliantly lit by lightning in or near the eye wall. The low-light settings of the camera used to take the image accentuate the contrast.

In the top image, the camera also accentuates the yellow-green airglow above the Earth’s limb, an atmospheric phenomenon frequently seen by astronauts. Stars appear above the airglow layer, and the solar panels of a docked Russian spacecraft jut into the image (upper left).

Astronaut photographs ISS042-E-135015 and ISS042-E-135030 were acquired on January 12, 2015, with a Nikon D4 digital camera using a 28 millimeter lens, and are provided by the ISS Crew Earth Observations Facility and the Earth Science and Remote Sensing Unit, Johnson Space Center. The image was taken by the Expedition 42 crew.They have been cropped and enhanced to improve contrast, and lens artifacts have been removed. TheInternational Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth. Caption by William L. Stefanov, NASA-JSC.

Instrument(s): 

ISS - Digital Camera - NASA

The Once-Powerful #Tropical #Cyclone #Bansi Stirred Up Ocean Sediment

On Jan. 19, NASA's Aqua satellite spotted sediment stirred up by Tropical Cyclone Bansi around the Cargados Carajos Shoals, Indian Ocean.

Image Credit: 

NASA Goddard MODIS Rapid Response Team

Tropical Cyclone Bansi reached a Category 4 status on the Saffir-Simpson Scale on January 15 and 16 as it moved through the Southern Indian Ocean. By January 19 as the storm was weakening over open ocean, NASA's Aqua satellite captured a picture of sediment stirred up from the storm around the Cargados Carajos Shoals.

On Jan. 15 at 0900 UTC (4 a.m. EST), Tropical Cyclone Bansi as a Category 4 hurricane on the Saffir-Simpson Scale with maximum sustained winds near 130 knots (149.6 mph/240.8 kph). At that time Bansi was centered about 451 nautical miles (519 miles/835 km) east of Port Louis, Mauritius.

On January 18 at 0900 UTC (4 a.m. EST) the time of the Joint Typhoon Warning Center's last bulletin on the system, Bansi's maximum sustained winds had dropped to 65 knots (74 mph/120.4 kph) and it was located 1,425 nautical miles (1,640 miles/2,639 km) southwest of Cocos Island. Later in the day, Bansi started extra-tropical transitioning and by January 19, it was a weaker extra-tropical cyclone moving over open waters of the Southern Indian Ocean.

On January 19 at 10:15 UTC (5:15 a.m. EST) when NASA's Aqua satellite passed over the Cargados Carajos Shoals, the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard captured a visible image of the results of Bansi's powerful winds. The image showed sediment stirred up from the ocean bottom around the Shoals had colored the ocean waters around them.

According to Mauritiusattractions.com, Cargados Carajos Shoals is also known as Saint Brandon and consists of more than 50 islands, coral ridges and vast sand flats on an extended reef. It is located in the Southern Indian Ocean about 268 nautical miles (308 miles/496 km north east of Mauritius.

Rob Gutro
NASA's Goddard Space Flight Center

Electrifying view inside a #cyclone from #ISS #Lightning

Tropical Cyclone Bansi on January 15, 2015. Image Credit: NASA

Samantha Cristoforetti, an Italian astronaut aboard the International Space Station (ISS), captured this view of Tropical Cyclone Bansi a couple of days ago (January 15, 2015), as the space station flew above the Indian Ocean. At the time, Bansi was a strong cyclone equivalent to a Category 4 storm with a symmetric eye and defined banding features. Now look below at Cristoforetti’s amazing pictures of this cyclone, via Twitter this weekend. Cristoforetti managed to catch lightning flashing within the eye of the storm. Simply amazing and breathtaking weather photos!

Capturing lightning in itself is a difficult feat. Taking images of the lightning from outer space? How cool is that?

Sam Cristoforetti        ✔ @AstroSamantha

Follow

And a look from above into the eye of the cyclone! E uno sguardo dall'alto nell'occhio del ciclone. #Bansi

1:03 AM - 18 Jan 2015

- NASA + EarthSky

Final Update - #TropicalStorms: Cyclone Banzi (05 S) and Tropical Storm Chedza (06 S) - South Indian Ocean #cyclone #tropicalstorms

SO. INDIAN OCEAN - Chedza Now a Depression and Fizzling Tropical Storm Chedza crossed Madagascar from west to east and is now east of the island nation in the open waters of the Southern Indian Ocean. Maximum sustained winds have dropped to 25 knots. The center of Chedza is located near 22.9 south and 51.6 east, about 248 nautical miles west-southwest of La Reunion Island. Chedza is moving to the east-southeast at 12 knots. Satellite imagery shows a ragged and fully-exposed low-level circulation, and wind shear has pushed the bulk of clouds and showers east of the center. Wind shear is expected to increase and the system is expected to dissipate. The Joint Typhoon Warning Center issued their final advisory on this system today. This infrared image from the MODIS instrument aboard NASA's Aqua satellite shows most of the high clouds and thunderstorms pushed east of center. Madagascar is left (west) of the storm.

SO. INDIAN OCEAN - Bansi Holding Hurricane Status... for Now Tropical Cyclone Bansi continues to maintain hurricane status but is headed for adverse conditions. On Jan. 17 at 2100 UTC (4 p.m. EST), Bansi's maximum sustained winds were near 75 knots. It was centered near 25.0 south and 73.3 east, about 867 nautical miles southeast of Port Louis, Mauritius. Bansi is speeding eastward at 20 knots. It is headed toward strong vertical wind shear which is expected to weaken it to a tropical storm on Jan. 18 over open ocean. This visible image is from ESA's METEO-7 satellite on Jan. 17.

- NASA Hurricane Centre

Update 5 - #TropicalStorms: Cyclone Banzi (05 S) and Tropical Storm Chedza (06 S) - South Indian Ocean #cyclone #tropicalstorms

Chedza (Southern Indian Ocean)

NASA Spots Newborn Tropical Storm Chedza Making Landfall Tropical Storm Chedza rapidly intensified from a tropical low pressure area to a tropical storm during the morning hours on January 16 near Madagascar's southwestern coast. NASA's Aqua satellite passed overhead and captured an image of the newborn storm's quick landfall. The Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard Aqua took a visible picture of Chedza on Jan. 16 at 11:20 UTC (6:20 a.m. EST). At that time, Chedza's center was along Madagascar's southwestern coast, and the eastern half of the storm was over the island nation while the western half was over the Mozambique Channel. The MODIS image also showed what appeared to be a developing eye. At 0900 UTC (4 a.m. EST), Tropical Storm Chedza's maximum sustained winds were near 50 knots (57.5 mph/92.6 kph). Chedza was centered near 20.0 south latitude and 44.2 east longitude, about 650 nautical miles (748 miles/1,204 km) west of St. Denis, La Reunion Island. Chedza was moving to the east-southeast at 6 knots (6.9 mph/11.1 kph) and is expected to continue moving in that general direction. The Joint Typhoon Warning Center (JTWC) looked at animated multispectral satellite imagery today, January 16 and noted that it showed "a continued consolidation of the system with a more defined low-level circulation center with deep convective banding (of thunderstorms) wrapping in as the system is beginning to make landfall across western Madagascar." JTWC forecasts take Chedza on an easterly track over Madagascar and back into the Southern Indian Ocean where it is expected to re-intensify and pass south of La Reunion Island early next week.

Bansi (Southern Indian Ocean)

Tropical Cyclone Bansi's eye was wide open as NASA's Terra satellite passed overhead on January 15. As Bansi strengthened on Jan. 16, the eye decreased in size. On January 15 at 06:15 UTC (1:15 a.m. EST), the Moderate Resolution Imaging Spectroradiometer or MODIS instrument that flies aboard NASA's Terra satellite captured a visible picture of Tropical Cyclone Bansi when it was east-northeast of the island of Mauritius. The satellite flew directly over Bansi and the image clearly showed the wide eye all the way down to the blue ocean surface. Powerful thunderstorms circled the storm, which was at Category Four strength on the Saffir-Simpson scale at the time of the satellite's overpass. According to the Joint Typhoon Warning Center, Bansi's eye was 32 nautical miles (36.8 miles/59.2 km) wide, down from 46 nautical miles (53.9 miles/85.1 km) wide on Jan. 15. At 0900 UTC (4 a.m. EST), Tropical Cyclone Bansi's maximum sustained winds increased to 130 knots (149.6 mph/240.8 kph), still making it a Category 4 storm. Just 24 prior, those winds were near 120 knots (138.1 mph/222.2 kph). Bansi was centered near 20.5 south latitude and 65.8 east longitude, about 451 nautical miles (519 miles/835 km) east of Port Louis, Mauritius. Bansi was moving to the southeast at 15 knots (17.2 mph/27.8 kph) and is expected to continue moving in that general direction. Heavy ocean swells are expected for Mauritius through Jan. 19 as the tropical cyclone passes to the north and east of the island. The Mauritius Meteorological Services noted "The sea will be very rough with easterly swells of the order of 4 meters, peaking to 7 meters that will continue to break mainly along the eastern and southern coasts. The public is strongly advised not to venture at sea." For updated warnings from Mauritius Meteorological Services, visit: http://metservice.intnet.mu/. Bansi is forecast to weaken and being transitioning into an extra-tropical storm by Jan. 18 and 19 over open waters of the Southern Indian Ocean.

-  Rob Gutro NASA's Goddard Space Flight Center

Update 4 - #TropicalStorms: Cyclone Banzi (05 S) and Tropical Storm Chedza (06 S) - South Indian Ocean #cyclone #tropicalstorms

152100Z POSITION NEAR 18.6S 63.3E. TROPICAL CYCLONE (TC) 05S (BANSI), LOCATED APPROXIMATELY 335 NM EAST- NORTHEAST OF PORT LOUIS, MAURITIUS, HAS TRACKED EAST-SOUTHEASTWARD AT 12 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY INDICATES A SLIGHT WEAKENING TREND WITH A 30-NM RAGGED EYE AND A MORE ASYMMETRIC APPEARANCE TO THE EYEWALL AND CONVECTIVE BANDING. THIS WEAKENING TREND IS CLEARLY EVIDENT IN A 151732Z METOP-B 89 GHZ IMAGE, WHICH SHOWS EROSION OF THE CONVECTIVE BANDING AND EYEWALL OVER THE SOUTHWESTERN SEMI-CIRCLE WITH DEEP CONVECTION DISPLACED OVER THE NORTHEAST SEMI-CIRCLE. UPPER-LEVEL ANALYSIS SHOWS INCREASED SOUTHWESTERLY VERTICAL WIND SHEAR (VWS) ASSOCIATED WITH AN UPPER-LEVEL SHORTWAVE TROUGH IMPINGING ON THE SYSTEM. ADDITIONALLY, TC 05S IS NOW EMBEDDED WITHIN A BROAD AREA OF UPPER-LEVEL TROUGHING, WHICH SHOULD INHIBIT FURTHER INTENSIFICATION. THERE IS GOOD CONFIDENCE IN THE INITIAL POSITION BASED ON THE EYE. THE INITIAL INTENSITY IS ASSESSED AT 115 KNOTS BASED ON T6.0 (115 KNOTS) DVORAK ESTIMATES FROM ALL AGENCIES. TC 05S IS TRACKING EASTWARD TO EAST-SOUTHEASTWARD ALONG THE POLEWARD PERIPHERY OF THE NEAR-EQUATORIAL RIDGE BUT IS FORECAST TO TRANSITION TO THE STEERING INFLUENCE OF THE SUBTROPICAL RIDGE NEAR TAU 36, WHICH WILL ACCELERATE THE SYSTEM EAST-SOUTHEASTWARD TO SOUTHEASTWARD. DYNAMIC GUIDANCE REMAINS IN GOOD AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK. THE SYSTEM IS EXPECTED TO BEGIN EXTRA-TROPICAL TRANSITION (ETT) NEAR TAU 48 AS IT INTERACTS WITH THE BAROCLINIC ZONE AND SHOULD COMPLETE ETT BY TAU 96. TC 05S IS EXPECTED TO WEAKEN SIGNIFICANTLY AFTER TAU 24 AS IT ENCOUNTERS INCREASING VWS AND COOLER SST. AFTER TAU 48, TC 05S WILL RAPIDLY WEAKEN AS IT UNDERGOES ETT. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 151800Z IS 35 FEET.

160300Z POSITION NEAR 19.6S 42.7E. TROPICAL CYCLONE (TC) 06S (CHEDZA), LOCATED APPROXIMATELY 736 NM WEST OF ST DENIS, HAS TRACKED EAST-SOUTHEASTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY INDICATES RAPID CONSOLIDATION WITH IMPROVED DEEP CONVECTIVE BANDING. A 152336Z SSMI IMAGE DEPICTS A WELL-DEFINED, PARTIALLY-EXPOSED LOW- LEVEL CIRCULATION CENTER POSITIONED ON THE NORTHWEST EDGE OF A DEEP CONVECTIVE BAND. RECENT SCATTEROMETER DATA INDICATES 35 TO 40 KNOT WINDS. UPPER-LEVEL ANALYSIS REVEALS A FAVORABLE ENVIRONMENT WITH GOOD EQUATORWARD OUTFLOW AND A DEVELOPING POLEWARD CHANNEL OVER THE SOUTHERN SEMI-CIRCLE OF THE LLCC. THERE IS GOOD CONFIDENCE IN THE INITIAL POSITION BASED ON THE AFOREMENTIONED SSMI IMAGE. THE INITIAL INTENSITY IS ASSESSED AT 40 KNOTS BASED ON AN AVERAGE OF DVORAK ESTIMATES RANGING FROM 35 TO 45 KNOTS. TC 06S IS TRACKING ALONG THE PERIPHERY OF THE NEAR-EQUATORIAL RIDGE (NER) AND IS FORECAST TO CONTINUE TRACKING EASTWARD THROUGH TAU 72. THE SYSTEM IS EXPECTED TO INTENSIFY, PRIOR TO LANDFALL NEAR TAU 12, TO A PEAK INTENSITY OF 50 KNOTS. THEREAFTER, THE SYSTEM WILL WEAKEN AS IT TRACKS OVER LAND. GRADUAL INTENSIFICATION IS EXPECTED AS THE SYSTEM RE-EMERGES OVER WATER AFTER TAU 40. DYNAMIC GUIDANCE IS IN TIGHT AGREEMENT THROUGH TAU 72. AFTER TAU 72, THE SYSTEM WILL SLOW DUE TO COMPETING STEERING INFLUENCES, NAMELY, THE NER AND A BUILDING SUBTROPICAL RIDGE TO THE SOUTH. DYNAMIC GUIDANCE DIVERGES DUE TO UNCERTAINTIES IN THE STRENGTH AND ORIENTATION OF THE STEERING INFLUENCES. OVERALL, THERE IS LOW CONFIDENCE IN THE JTWC FORECAST TRACK DUE TO THE LARGE MODEL SPREAD IN THE EXTENDED TAUS. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 160000Z IS 10 FEET. NEXT WARNINGS AT 161500Z AND 170300Z. THIS WARNING SUPERSEDES AND CANCELS REF A JOINT TYPHOON WRNCEN PEARL HARBOR HI 151621Z JAN 15 TROPICAL CYCLONE FORMATION ALERT (WTXS21 PGTW 151630). REFER TO TROPICAL CYCLONE 05S (BANSI) WARNINGS (WTXS31 PGTW) FOR TWELVE-HOURLY UPDATES.// NNNN

- JTWC

Update 3 - #TropicalCyclone 05S (#Bansi) - South Indian Ocean #cyclone #tropicalstorms

S Indian Ocean: Storm Alert issued at 14 Jan, 2015 18:00 GMT

Tropical Cyclone BANSI (05S) currently located near 17.4 S 59.6 E is forecast to strike land to the following likelihood(s) at the given lead time(s):

Red Alert City(s) and Town(s)
    Port Mathurin (19.7 S, 63.4 E)
        probability for CAT 1 or above is 50% in about 36 hours
        probability for TS is 80% in about 36 hours

Note that
    Red Alert (Severe) is CAT 1 or above to between 31% and 100% probability.
    CAT 1 means Tropical Cyclone strength winds of at least 74 mph, 119 km/h or 64 knots 1-min sustained.
    TS means Tropical Storm strength winds of at least 39 mph, 63 km/h or 34 knots 1-min sustained.

For graphical forecast information and further details please visit http://www.tropicalstormrisk.com/

-  Eumetsat, Cyclocane and TropicalStormRisk

Update 2 - #TropicalCyclone 05S (#Bansi) - South Indian Ocean #cyclone #tropicalstorms

140900Z POSITION NEAR 17.4S 58.6E. TROPICAL CYCLONE (TC) 05S (BANSI), LOCATED APPROXIMATELY 181 NM NORTH-NORTHEAST OF PORT LOUIS, MAURITIU, HAS TRACKED EAST- NORTHEASTWARD AT 03 KNOTS OVER THE PAST SIX HOURS. RECENT ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS SPIRAL BANDING WRAPPING INTO A 12-NM CLOUD-FILLED EYE. THE CURRENT POSITION IS BASED ON THE MSI LOOP WITH HIGH CONFIDENCE. A 140523Z METOP-B MICROWAVE IMAGE GIVES HINT OF A POSSIBLE EYE-WALL REPLACEMENT CYCLE, WITH A LIMITED MOAT VISIBLE IN THE MICROWAVE. AS SUCH, THE INITIAL INTENSITY HAS BEEN DECREASED TO 90 KNOTS TO REFLECT THE WEAKENING TREND DURING THE CYCLE. UPPER-LEVEL ANALYSIS INDICATES TC 05S REMAINS IN FAVORABLE ENVIRONMENT WITH LOW (05 TO 10 KNOTS) VERTICAL WIND SHEAR (VWS) AND AGGRESSIVE POLEWARD OUTFLOW. TC BANSI IS CURRENTLY TRACKING ALONG THE SOUTHERN PERIPHERY OF A WEAKENING AND ELONGATING NEAR-EQUATORIAL RIDGE (NER). SLOW OR NEAR QUASI- STATIONARY MOVEMENT IS EXPECTED OVER THE NEXT 36 HOURS DUE TO A WEAK STEERING ENVIRONMENT BETWEEN THE NER TO THE NORTH AND A DEVELOPING SUBTROPICAL RIDGE (STR) TO THE EAST. OVER THE NEXT 48 HOURS, SLIGHTLY FAVORABLE CONDITIONS ARE EXPECTED TO PERSIST ALLOWING THE SYSTEM TO SLOWLY REGAIN SOME OF ITS FORMER INTENSITY, LEADING TO A PEAK OF 115 KNOTS BEFORE STARTING TO WEAKEN. BEYOND TAU 48, TC 05S IS FORECAST TO TRACK SOUTHEASTWARD AND ACCELERATE UNDER THE STEERING INFLUENCE OF THE STRENGTHENING STR. TC BANSI WILL CONTINUE TO WEAKEN AS VWS INCREASES AND OCEAN HEAT CONTENT DECREASES ALONG ITS EXPECTED TRACK. AVAILABLE MODEL GUIDANCE IS IN OVERALL GOOD AGREEMENT LENDING TO HIGH CONFIDENCE IN THE JTWC TRACK FORECAST WHICH IS POSITIONED CLOSE TO MULTI-MODEL CONSENSUS. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 140600Z IS 30 FEET.

In a previous update I asked weather observers to keep an eye on System 93 in the Mozambique channel. This system already dumped heavy rain in parts of Mozambique and Malawi resulting in flash flooding. Thousands had to literally run for their lives while others were't so lucky to escape.

System 93S has no developed further. Although most people are watching  Tropical Cyclone Bansi in the Southern Indian Ocean, a new tropical low pressure area has intensified about 489 nautical miles west-northwest of Antananarivo, Madagascar, in the Mozambique Channel. System 93S is actually straddling the coast of Mozambique. System 93S is centered near 17.7 south and 37.9 east. Satellite imagery shows that there is flaring "deep convection" - rising air that forms thunderstorms that make up a tropical cyclone - associated with this slowly-consolidating area of low pressure. The warm sea surface temps in the Mozambique Channel will help the tropical low develop. Currently maximum sustained winds are estimated between 20 to 25 knots. Despite the good conditions, at least over the next day, this system has a low chance for development into a tropical depression, but keep an eye on it.

- JTWC, SAT24 and NASA

Update1 - #TropicalCyclone 05S (#Bansi)now active in the South Indian Ocean #cyclone #tropicalstorms

Very Intense TC BANSI (05S) currently located near 17.6 S 56.8 E is forecast to strike land to the following likelihood(s) at the given lead time(s):
Yellow Alert Country(s) or Province(s)
    Mauritius
        probability for TS is 70% in about 24 hours
Yellow Alert City(s) and Town(s)
    Port Louis (20.2 S, 57.5 E)
        probability for TS is 70% in about 24 hours
    Port Mathurin (19.7 S, 63.4 E)
        probability for CAT 1 or above is 10% in about 72 hours
        probability for TS is 35% in about 72 hours

Note that
    Yellow Alert (Elevated) is CAT 1 or above to between 10% and 30% probability, or TS to above 50% probability.
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SOUTH INDIAN OCEAN AREA (135E WEST TO COAST OF AFRICA): A. TROPICAL CYCLONE SUMMARY: (1) AT 120600Z, TROPICAL CYCLONE 05S (BANSI) WAS LOCATED NEAR 17.2S 55.9E, APPROXIMATELY 191 NM NORTH- NORTHWEST OF PORT LOUIS, MAURITIUS, AND HAD TRACKED EASTWARD AT 07 KNOTS OVER THE PAST SIX HOURS. MAXIMUM SUSTAINED SURFACE WINDS WERE ESTIMATED AT 100 KNOTS GUSTING TO 125 KNOTS. SEE REF A (WTXS31 PGTW 120900) FOR FURTHER DETAILS. (2) NO OTHER TROPICAL CYCLONES. B. TROPICAL DISTURBANCE SUMMARY: (1) AN AREA OF CONVECTION HAS PERSISTED NEAR 16.7S 38.9E, APPROXIMATELY 489 NM WEST-NORTHWEST OF ANTANANARIVO, MADAGASCAR. RECENT ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS FLARING DEEP CONVECTION ASSOCIATED WITH A SLOWLY-CONSOLIDATING LOW- LEVEL CIRCULATION CENTER STRADDLING THE COAST OF MOZAMBIQUE. THE MSI AND A 121118Z NOOA-19 MICROWAVE IMAGE ALSO REVEAL THE LLCC IS WITHIN A BROAD AREA OF TURNING THAT SPANS ACROSS THE MOZAMBIQUE CHANNEL. A 120653Z ASCAT PASS PARTIALLY SHOWS 20 TO 25 KNOT WINDS OVER THE EASTERN SEMI-CIRCLE. THE DISTURBANCE IS LOCATED IN A MARGINALLY FAVORABLE ENVIRONMENT WITH MODERATE TO STRONG (20 TO 30 KNOTS) VERTICAL WIND SHEAR OFFSET BY GOOD POLEWARD OUTFLOW. ADDITIONALLY, WARM SEA SURFACE TEMPERATURES IN THE CHANNEL ARE CONDUCIVE FOR DEVELOPMENT. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1004 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS LOW. (2) NO OTHER SUSPECT AREAS.// NNNN

Images and Info: TSR, JTWC, Eumetsat, SAT24 and NOAA (Click on images for larger view.)

#TropicalCyclone 05S (#Bansi)now active in the South Indian Ocean #cyclone #tropicalstorms

TROPICAL CYCLONE 05S (BANSI) HAS FORMED AND WAS LOCATED NEAR 16.3S 54.7E, APPROXIMATELY 254 NM NORTH OF ST DENIS.

BANSI Current Status: Current Wind Speed 80 knots / MPH
Max Predicted Wind Speed 120 knots / 138 MPH at Tuesday, 13 Jan 2015 8:00 PM

BANSI Land Hazards:   Maurice / Mauritius / Rodrigues / Agalega /La Réunion

112100Z POSITION NEAR 17.3S 55.3E. TROPICAL CYCLONE (TC) 05S (BANSI), LOCATED APPROXIMATELY 219 NM NORTHWEST OF PORT LOUIS, MAURITIUS, HAS TRACKED SOUTH-SOUTHEASTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A RAPIDLY CONSOLIDATING SYSTEM WITH A 25- NM RAGGED EYE. TC 05S HAS RAPIDLY INTENSIFIED 35 KNOTS OVER THE PAST 24 HOURS FROM 30 KNOTS TO THE CURRENT INTENSITY OF 65 KNOTS. A 111611Z GPM 36 GHZ MICROWAVE IMAGE INDICATES A WELL-ORGANIZED LOW- LEVEL CIRCULATION CENTER (LLCC) WITH FRAGMENTED, MULTIPLE BANDS WRAPPING INTO THE LLCC. UPPER-LEVEL ANALYSIS REVEALS A VERY FAVORABLE ENVIRONMENT WITH DUAL CHANNEL OUTFLOW. THERE IS HIGH CONFIDENCE IN THE CURRENT POSITION BASED ON THE EYE FEATURE. THE CURRENT INTENSITY IS BASED ON DVORAK ESTIMATES OF T4.0 (65 KNOTS) FROM ALL AGENCIES. TC 05S IS TRACKING SLOWLY SOUTH-SOUTHEASTWARD BUT IS FORECAST TO TURN EASTWARD THROUGH TAU 36 AS THE NEAR-EQUATORIAL RIDGE SHIFTS EQUATORWARD OF THE SYSTEM. AFTER TAU 36, TC 05S SHOULD BEGIN TO STEER UNDER THE INFLUENCE OF THE SUBTROPICAL RIDGE POSITIONED TO THE EAST AND IS EXPECTED TO MAINTAIN A SOUTHEASTWARD TRACK THROUGH TAU 120. THE DYNAMIC GUIDANCE IS IN FAIR AGREEMENT, SUPPORTING THE GENERAL TRACK, HOWEVER, GFDN AND EGRR DEPICT AN UNLIKELY EAST-NORTHEASTWARD TRACK THROUGH TAU 36. IN DIRECT DISAGREEMENT, SATELLITE IMAGERY THROUGH 111930Z CONTINUES TO SHOW A SOUTHWARD TRACK MOTION. AFTER TAU 36, DYNAMIC GUIDANCE REFLECTS SIMILAR TRACK MOTION AND SYNOPTIC STEERING ENVIRONMENT. OVERALL, THERE IS LOW CONFIDENCE IN THE JTWC FORECAST TRACK DUE TO THE SPREAD IN MODEL GUIDANCE. TC BANSI IS FORECAST TO CONTINUE RAPIDLY INTENSIFYING THROUGH TAU 48 TO A PEAK OF 120 KNOTS DUE TO VERY FAVORABLE OUTFLOW AND WARM SST (GREATER THAN 29C). AFTER TAU 48, ENVIRONMENTAL CONDITIONS WILL GRADUALLY DETERIORATE AS SST AND OCEAN HEAT CONTENT DECREASE TO MARGINAL LEVELS. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 111800Z IS 18 FEET. NEXT WARNINGS AT 120900Z AND 122100Z.// NNNN

SAWXREP and MSBWX  is also monitoring a tropical low for further development.  Invest area 93S is currently situated in the Mozambique channel. (See image underneath)

Latest satellite image via SAT24 of both TC Bansi and the TLP 93S:

Observers need to keep a close eye on both these systems.

Images: JTWC, NOAA, CIMSS, SAT24, Cyclocane and Eumetsat

#TropicalStorm Potential for the next 48 hours: Southern Indian Ocean #Cyclones #tropicalstorms

There are currently two tropical disturbance areas that needs constant observation for the possible development of tropical cyclones in the next 24 - 48 hours. The one area N/West of Madagascar has a high potential while the other area in the Mozambique Channel has a low potential. (See images below)

Latest Satellite Images of the two disturbance areas:

Here is the text for the area NW of Madagascar:

WTXS21 PGTW 110200 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE FORMATION ALERT// RMKS/ 1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN 140 NM EITHER SIDE OF A LINE FROM 15.9S 53.0E TO 17.4S 56.5E WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME. WINDS IN THE AREA ARE ESTIMATED TO BE 25 TO 30 KNOTS. METSAT IMAGERY AT 110130Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 16.2S 53.7E. THE SYSTEM IS MOVING NORTHEASTWARD AT 03 KNOTS. 2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 16.4S 53.5E IS NOW LOCATED NEAR 16.2S 53.7E, APPROXIMATELY 325 NM NORTH- NORTHWEST OF LA REUNION. ANIMATED INFRARED SATELLITE IMAGERY DEPICTS DEEP CONVECTIVE BANDING WRAPPING OVER A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC). A 102252Z MHS MICROWAVE IMAGE REVEALS DEEP CONVECTIVE BANDING ALONG THE NORTHEASTERN PERIPHERY WRAPPING INTO A CONSOLIDATING LLCC. THE UPPER LEVEL ENVIRONMENT IS FAVORABLE FOR DEVELOPMENT WITH DUAL CHANNEL OUTFLOW AND LOW VERTICAL WIND SHEAR (10 TO 15 KNOTS). MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1003 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS HIGH. 3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY 120200Z.// NNNN

The potential for the development of a significant tropical cyclone in this area in the next 24 hours is high.  

Observers need to keep a close eye on both these systems.

Images: JTWC, NOAA, SAT24 and Eumetsat

Final Update: #SevereWeather, #HeavyRain #Flashflooding expected during the period 26 - 29 December 2014 in SA

This morning the Tropical Low Pressure system appeared to have fizzled out with only a few convective storms and cirrus clouds around in parts of Limpopo, Mpumalanga and Gauteng. Please note that their is still plenty of moist air around and with enough instability could still result in thunderstorms, heavy rain and flooding in the above mentioned areas. The system appear to weaken at night time and strengthen during the day, with some isolated developing convective cells mainly appearing in the afternoon.

Severe weather is expected with damaging results if this system intensifies again this afternoon. A word of advise to holidaymakers near rivers, low water bridges, ravines, estuaries, low lying area and areas prone to flooding or flash flooding: Be on high alert for the above period (27 - 29 December 2014)

What can we expect from this system:
1. Always the possibility of Severe Weather
2. Moderate to heavy rain (50mm or more in places)
3. Strong winds
4. Possibility of Flooding or flash flooding
5. Colder weather conditions
6. Possible Severe thunderstorms
7. Possible Hail
8. Possible storm or flood damage 

Finally: As always do not underestimate any weather system. MSBWX will monitor this system closely and will bring you updates as this system moves across the country.

SAWXREP need your real time weather observations i.o.w. if you observe heavy rain, flooding, strong wind, rough seas, storm damage etc. Please inform the SAWXREP so that we in turn can keep the public informed. Tweet us at @SAWXREP . Do not assume that SAWXREP knows for certain that severe weather has occurred. Help us to spread the word about severe weather and NEVER assume that your weather observation report is not important.

SAWXREP would like to hear from you.

Images: Eumetsat, NCEP (Click on images for larger view.)

 - MSBWX + SAWXREP