TCS 025 Continues to develop
This small unorganized system has continued to develop. Attached below is the animated IR image with AMVs and analyzed divergence overlayed:
MTSAT-IR image, upper level AMVs and analyzed divergence of TCS025. Valid 13Z 28 August, 2008.
As seen in the animation, TCS025 has decent outflow to it’s north. The convection isn’t organized or symmetric, but it’s fairly wide-spread. It seems to be interacting with a fairly strong upper-level low to it’s north and northwest. This low may be the key to it’s forward motion.
What about surface circulation?
Here is the same IR with a quickscat analysis valid on 07 Z on the 28th of August along with low-level AMVs.
MTSAT-IR image with low-level AMVs and recent quickscatt analysis. Image and AMVs valid 13Z, 28 August, 2008. Quickscat Valid 07Z.
From the image, you can see an almost complete low-level circulation, missing a northerly component on the system’s west side. There is however, one ship report at 20 N, 145E of a fairly weak northwesterly wind.
The water underneath is fairly warm (around 30C). It’s survival is most likely related to the interaction with that trough to it’s northwest.
Tags: divergence, intensity, TCS025
August 28th, 2008 at 12:48 pm
Posted on behalf of Derrick Herndon:
The shear North of the LLCC is certainly associated with the cold core system. However this system has been slowly spinning down and the shear is far enough North to not impact the sfc system in the short term. Certainly there seems to be a broad area of divergence S and E of the u/l low and this may be leading to weak pressure falls there. So there is likely troughing SE of the u/l low a weak surface reflection of the cold core system directly beneath the cold core low and of course our 025 system that appeared to be convectively initiated. Given the troughing SE of the cold core system and it’s weak surface reflection I suspect that inflow on the North side is weak if existent at all, decreasing low-level convergence (and thus vorticity). Also the air quality to the North is likely not as good owing to weak subsidence in the cold core system. Perhaps the TPW minimum we see there is a reflection of that. Ingestion of any of that air is also not going to help. So a couple of things going for the system and a couple against. Enough to maintain a weak LLCC but not enough maybe to intensify?