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Archive for Tropical Storms

Tropical Cyclone Bongani (02S) Expected to Track into Mozambique Channel

9.1S 49.9E

November 25th, 2009 Category: Tropical Storms

Tropical Cyclone Bongani - November 24th, 2009

Tropical Cyclone Bongani - November 24th, 2009

Track of TC 02S - November 24th, 2009 © Univ. of Wisconsin

Track of TC 02S

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Tropical Cyclone Bongani (02S), located approximately 560 nm north-northeast of Antananarivo, Madagascar, has tracked south-southwestward at 11 knots over the past six hours. The maximum significant wave height is 13 feet.

The forecast has been shifted south of the previous forecast based on a WSAT Coriolis 37h microwave image that shows a formative microwave eye south-of-track.

Despite the improved low level microwave signature evidenced in the aforementioned microwave image, deep convection has waned over the past 12 hours. Consequently, Dvorak intensity estimates from PGTW underestimate the current intensity.

The cyclone will continue to track just south of west along the western periphery of the mid-level subtropical ridge that is building east to west. Slow intensification is expected under the influence of generally favorable environmental conditions. However, the peak intensity has been decreased to 65 knots based on the latest intensity guidance.

The forecast track will bend increasingly poleward as the cyclone tracks into the Mozambique Channel due to the influence of an approaching upper level trough that will temporarily erode and re-orient the steering ridge. In addition, the trough will provide increased poleward venting before vertical wind shear elevates beyond TAU 72. After the trough passes the forecast track will flatten and the system will track inland over interior Mozambique, and will dissipate.

Tropical Cyclone Bongani (02S) Near Northern Madagascar

9.1S 52.0E

November 24th, 2009 Category: Tropical Storms

Tropical Cyclone Bongani - November 23rd, 2009

Tropical Cyclone Bongani - November 23rd, 2009

Track of TC 02S - November 24th, 2009 © Univ. of Wisconsin

Track of TC 02S

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Tropical Cyclone Bongani (02S), partially visible along the right edge, is located approximately 685 nm north-northeast of Antananarivo, Madagascar (below). The system has tracked west-southwestward at 6 knots over the past six hours.

Animated infrared satellite imagery indicates increasingly disorganized deep convection, however, a recent METOP-A image depicts a partially exposed but well-defined low-level circulation center (LLCC) with convective banding over the western semi-circle.

The current intensity of 45 knots is higher than the Dvorak estimates of 35 knots based on an ASCAT image (25-km) showing 40-45 knot unflagged winds.

TC 02S is forecast to track slowly west-southwestward through TAU 48 under the steering influence of a weak low- to mid-level subtropical ridge (STR) then is forecast to accelerate more southwestward after TAU 72 as the STR strengthens and shifts east of Madagascar. The majority of the model guidance indicates the system will likely turn poleward over water, while one model suggests the system could turn poleward later, as it tracks over Mozambique.

Bongani is forecast to intensify slowly but should strengthen after TAU 48 due to improved poleward outflow. TC 02S will likely weaken after TAU 96 due to increased vertical wind shear associated with the approaching midlatitude shortwave trough. Maximum significant wave height is 12 feet.

Tropical Cyclone 04A South-Southwest of Mumbai, India, and Tracking Northward

17.2N 72.9E

November 11th, 2009 Category: Tropical Storms

Tropical Cyclone 04A - November 10th, 2009

Tropical Cyclone 04A - November 10th, 2009

Track of TC 04A - November 10th, 2009 © Univ. of Wisconsin

Track of TC 04A

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Tropical Cyclone 04A, located approximately 245 nm south-southwest of Mumbai, India, has tracked northward at 11 knots over the past six hours. Maximum significant wave height is 13 feet.

The cyclone can be viewed best by opening the full image, in which convection associated with the system can be seen reaching northeastward towards the Himalayas and extending far south down the coast.

Animated multispectral satellite imagery and a TMI 37 ghz image depict a large monsoon-like circulation with improved convective banding over the north semi-circle and weak banding elsewhere.

The low-level circulation center has slowly consolidated under favorable poleward venting ahead of a midlatitude shortwave trough propagating over the western Arabian Sea, however, the current intensity has been held steady based on estimates of 35 knots and the 35-knot unflagged scatterometer winds.

TC 04A is forecast to continue tracking northward along the western periphery of the low- to mid-level subtropical ridge and should track under increasing vertical wind shear (VWS) associated with the aforementioned midlatitude shortwave trough. Available model guidance are in good agreement through TAU 48 and support this northward track philosophy.

The system should intensify 10-15 knots over the next 24-36 hours but is likely to weaken quickly after TAU 24 due to strong VWS in excess of 50 knots and interaction with land after TAU 36. TC 04A is expected to dissipate over land between TAU 48 and 72.

Ida Upgraded to Category 2 Hurricane, Moving Into Southern Gulf of Mexico – November 9th, 2009

21.7N 87.1W

November 9th, 2009 Category: Image of the day, Tropical Storms

Hurricane Ida - November 8th, 2009

Hurricane Ida - November 8th, 2009

Track of Ida - November 8th, 2009 © Univ. of Wisconsin

Track of Ida

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As of 3:00 PM CST (2100 UTC), the center of Hurricane Ida was located near latitude 22.2 north, longitude 86.3 west, or about 95 miles (155 km) west-northwest of the western tip of Cuba and about 510 miles (815 km) south-southeast of the mouth of the Mississippi River.

Ida is a category two hurricane on the Saffir-Simpson scale, although the system is forecast to gradually weaken on Monday. Here, the hurricane is visible near the coast of the Yucatan Peninsula, with part of the shoreline of Florida visible to the north.

Ida is moving toward the north-northwest near 10 mph (17 km/hr). A gradual turn toward the north and an increase in forward speed are expected during the next 24 to 36 hours. On the forecast track, Ida is expected to cross the Gulf of Mexico Sunday evening and Monday and be near the northern Gulf coast on Tuesday.

Maximum sustained winds are near 100 mph (160 km/hr) with higher gusts. Hurricane force winds extend outward up to 35 miles (55 km) from the center, and tropical storm force winds extend outward up to 140 miles (220 km). The minimum central pressure is 976 mb (28.82 inches).

Ida is expected to produce total rain accumulations of 3 to 5 inches over portions of the Yucatan Peninsula and western Cuba, with possible isolated maximum amounts of 10 inches. Rains will be increasing well in advance of Ida across the central and eastern Gulf coast, but will become steadier and heavier by Monday into Tuesday. Total storm accumulations of 3 to 5 inches with isolated maximum storm totals of 8 inches will be possible through Tuesday from the central and eastern Gulf coast northward into the eastern portions of the Tennessee Valley and the southern Appalachians.

A storm surge could raise water levels by as much as 3 to 4 feet above ground level along the coast of the Yucatan Peninsula. Near the coast, the surge will be accompanied by large and destructive waves.

A hurricane watch remains in effect for the northern Gulf coast from Grand Isle, Louisiana to Mexico Beach, Florida, and the Yucatan Peninsula of Mexico from Tulum to Playa del Carmen. This watch does not include the city of New Orleans. A hurricane watch means that hurricane conditions are possible within the watch area, generally within 36 hours.

A hurricane warning remains in effect for the Yucatan Peninsula of Mexico from Playa del Carmen to Cabo Catoche, meaning that hurricane conditions are expected somewhere within the warning area within 24 hours. Preparations to protect life and property should be rushed to completion in the warning area.

A tropical storm warning remains in effect for the Yucatan Peninsula Punta Allen northward to Playa del Carmen and from Cabo Catoche westward to San Felipe, as well as for the Cuban province of Pinar del Rio. A tropical storm warning means that tropical storm conditions are expected within the warning area within 24 hours. Finally, a tropical storm watch remains in effect for the Isle of Youth.

Tropical Storm 25W Tracking Northeastward

24.5N 158.9E

November 9th, 2009 Category: Tropical Storms

Tropical Storm 25W - November 6th, 2009

Tropical Storm 25W - November 6th, 2009

Track of TS 25W - November 7th, 2009 © Univ. of Wisconsin

Track of TS 25W

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Tropical Storm 25W is now located near 22.2N 159.5E, or approximately 435 nautical miles west-northwest of Wake Island. The system has tracked northeastward at 13 knots over the past six hours. Maximum significant wave height is 13 feet.

Maximum sustained winds are at 45 knots, with higher gusts of up to 55 knots. The radius of 34 knot winds extending outward from the eye of the storm is 30 nautical miles in the southwest and northwest quadrants, 35 nautical miles in the southeast quadrant, and 40 nautical miles in the northeast quadrant.