Tropical Cyclone Gabrielle

[Somerset Squall]

TC 17S has formed, east of Cocos Island. Convection is still being sheared west of the LLC, but shear is expected to ease soon, allowing some modest intensification. 17S is currently heading southeastwards but should turn west away from Australia as a subtropical steering ridge forms to the south. Warm sea temps, lower shear and good outflow should see 17S intensify in the 24-48hr time period.

[Somerset Squall]

TC 17S has been named Tropical Cyclone Gabrielle. Intensity remains at 35kts, and it is clear, looking at latest satellite imagery, that Gabrielle is struggling against the shear. Shear has lessened to 20kts from 30kts, and is expected to become lower than 10kts in the next 24hrs. Coupled with warm seas and improving poleward outflow, this should provide a favourable environment for modest intensification. Beyond 36hrs, waters begin to cool so weakening is forcast to commence prior to 48hrs.

Gabrielle is currently moving south-southeastwards but as a ridge builds to the south of the system then a slow turn to the west-southwest is expected. This means that Gabrielle is unlikely to affect Australia. It also means Gabrielle will eventually track into the cooler waters southwest of the storm as mentioned above.

[Somerset Squall]

Gabrielle is losing the battle. Intensity is reduced to 30kts and convection is removed from the increasingly ill defined centre by the moderate to high shear impinging on the storm. Now the question is can Gabrielle survive the next 12hrs or so until the shear eases? Overall, I don't see Gabrielle becoming big, indeed it may dissipate if the shear doesn't let up soon.

[Cookie]

im just playing catch up

[Somerset Squall]

Gabrielle has made a small comeback since last night, and intensity has increased to 35kts. Moderate northeasterly shear continues to hinder further development of the storm. However, Gabrielle is now turning southwestwards and is expected to accelerate in this direction as a ridge to the south of the storm builds. This will have the effect of cancelling out the shear; convection will be blown southwestwards but the LLC will quickly follow it and forward speed should be enough to perhaps keep the LLC under the convection for more than a few hours at a time. Therefore, Gabrielle is still forecast to modestly intensify. Beyond 24hrs, shear really increases yet again to high levels, sea temps cool and the air becomes very dry eg. the ingredients for the dissipation of Gabrielle.

Edited March 3, 2009 by Somerset Squall

[Cookie]

thanks for the updates mate

[Cookie]

Gabriel has been downgraded to a tropical low based on overnight scatterometer data and Dvorak intensity assessments consistently below tropical cyclone intensity. Deep convection, although persistent in the southern semicircle, remains well removed from the LLCC identified on microwave imagery. The LLCC has become less well defined, indicating a slight weakening in the low-level circulation.

[Somerset Squall]

Well, Gabrielle decided to move westwards and the convection continued to be sheared southwestwards so the LLC and the convection didn't re-unite. As a result, the LLC has been exposed for too long to consider Gabrielle a tropical cyclone and as you rightly say cookie, the system has been declared a remnant low.

Edited March 4, 2009 by Somerset Squall