Masters student in tropical meteorology at FSU. Raised in Alaskan blizzards, but drawn toward tropical cyclones by their superior PGF.
By: Levi32 , 4:46 PM GMT on June 27, 2009
Update 8pm eastern time:
During the course of the afternoon, a new area of convection has developed near and east of Cozumel, Mexico in association with Invest 93L. Visible imagery indicates that the tropical wave axis has become more amplified near or over the coast of the Yucatan Peninsula. The loops are also showing rotation with the area of convection but it looks mostly mid-level, and CIMSS maps show the 850mb vorticity maximum to already be well inland continuing on a NW course over the NE Yucatan. The upper low over the Bay of Campeche is backing away slower than expected and this is causing problems for 93L. The proximity of the upper low is causing the mid-upper steering flow to be towards the north, while the low-level flow is still to the NW. This is causing the mid-level circulation to try to run north but the surface center wants to deviate more to the west. That's a fancy way of saying 93L is getting severely inhibited by vertical wind shear, and is vertically skewed because of it. The new mid-level circulation may attempt to pull in the surface trough but only if convection persists, which it may not, and surface-feature domination seems to have been the rule so far with this system.
So for now we still have a very disorganized tropical disturbance that will be emerging in the southern Gulf of Mexico tomorrow, where there will be a more favorable environment for organization as the upper low gets out of the way. I will continue to monitor the situation.
Tropical Tidbit from 12:30pm EDT Saturday, June 27, 2009:
Turn up the volume, and click HD if quality is too low:
Invest 93L remains disorganized this morning without a closed low-level circulation. The location of the center was previously thought to be south of western Cuba earlier this morning before visible imagery came out, but it is just the mid-level circulation that came from the east Pacific and started this whole thing. The low-level center is actually somewhere south of Cozumel, Mexico, just east of the Yucatan if not already over the coast. The reason this didn't develop yesterday was because the energy didn't get bundled and consolidated because the mid-level low didn't interact very well with the tropical wave. So today as the mid-level circulation starts to weaken and move north the low-level center will have a chance to organize. We'll see convection try to cluster around it today, but it likely won't be able to do much while it moves over the NE Yucatan today and tonight.
Once north of the Yucatan though, is when we really have to watch this. The upper low in the Bay of Campeche currently shearing 93L a little bit from the south is going to continue moving west and allowing the upper ridge to build over the system, ventilating it and providing a low wind shear environment. SSTs in the gulf are very warm, and the only inhibiting factor I can think of is the moderate amount of dry air present in the western gulf. I still think this has a decent shot at becoming a tropical depression sometime in the next 2 days and possibly TS Anna. Right now I'd like to see a closed circulation develop and get the system into the gulf before speculating any more on the potential intensity. Keep in mind this could also dissipate just as easily as it could get named.
The GFS, GFDL, and HWRF still take this through the Yucatan channel and into Florida but they are initialized too far east. This isn't going through the channel. My idea over the last few days has been for this to move over the Yucatan and end up north of it near 88W 23N, and the 12z GFS that just came out has caught on and shifted west more in line with this track. The track forecast after that becomes more tricky. The upper high over Texas will be retrograding westward over the next 3 days and won't be able to grab the system and pull it into the western gulf, so I'm not really concerned about that possibility. However anyone from eastern Louisiana to south Florida could be staring this one in the face early next week. I'm currently leaning towards a scenario where 93L drifts around north of the Yucatan under weak steering currents and then eventually gets pulled north or northeast by the upper trough over the eastern US. This new trough coming in is going to be much more zonal (flatter) than previous troughs, as the pattern isn't quite as amplified as it was. The exact movement will depend on several things such as the strength of the system, the timing of the trough, and how deep the trough gets.
So the bottom line is that we still have an unorganized tropical disturbance that will be moving into the eastern Gulf of Mexico over the next few days with favorable conditions for development. Until or if we get classified system we can't speculate too much on strength and exact landfall locations.
We shall see what happens!
Invest 93L Visible Satellite: (click image for loop)
Invest 93L model tracks:
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