Tropical Storm Iba Discussion Number 9

Wiki-Hurricanes Forecast Center

06:00 PM AST Mon Mar 25 2019

Not much change has occurred in association with Iba since the last advisory. The system remains encapsulated in a region of moderate to strong northwesterly wind shear, keeping the center of circulation exposed. A burst of convection that initiated in the early afternoon near Iba's center has brought the vortex closer to convection than this morning, briefly covering it. However, Iba's convective structure is quite deformed and the circulation has once again become exposed, and overall convecive intensity has been quickly decreasing this evening. SAB estimates remain at T3.0/45kt, but by previous rationale, recently received ScatSat data from 1030z indicating a swath of 35 kt winds without anything higher, and thus the intensity for Iba remains a possibly generous 40 kt.

No major changes to the track philosophy are introduced in this advisory. However, as the system weakens towards the end of the forecast window, the original vortex might enter a complex interaction with a developing trough axis which makes forecasting the initial disturbance's track rather ambiguous. Nonetheless, the same southward drift followed by southeastward trajectory is anticipated, with a possible slow down and equatorial drift caused by the shallowing cyclone moving with a low level ridging. Although slight intensification was previously forecast, the window of intensification is quickly closing and significant strengthening is becoming unlikely as conditions become increasingly hostile. At this juncture it appears that further intensifcation is unlikely. A slow weakening is projected through much of the forecast, with the possibility of some baroclinic enhancement in the late-term; this uptick in strength is likely more relevant from a system absorbing Iba rather than entirely resulting from Iba's original circulation.


INIT 25/2100Z 40 KT 45 MPH

12H 26/0600Z 35 KT 40 MPH

24H 26/1800Z 35 KT 40 MPH

36H 27/0600Z 30 KT 45 MPH

48H 27/1800Z 30 KT 35 MPH

72H 28/1800Z 25 KT 30 MPH...POST-TROP/REMNT LOW

96H 29/1800Z 25 KT 30 MPH...POST-TROP/REMNT LOW

120H 30/1800Z 30 KT 35 MPH...POST-TROP/REMNT LOW

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