Mon Nov 09 2009 08:33 PM
Ida Making Her Final Approach as a Strong Storm

Tropical Storm Ida is maintaining itself as a force still to be reckoned with as she makes her final approach towards immenent landfall, perhaps in the Mobile area.

Although much of Ida's circulation has long been sheared away towards the NE, and in the process steadily weakening it from a Cat 2 hurricane just yesterday down to a strong tropical storm, she's been very tenacious in hanging onto that maximum tropical storm status for quite a few hours now, despite the ever-present shear.

Complements of a strong and sustained burst of very strong thunderstorms (see above) over a low circulation center that had been previously exposed after the upper half had been sheared off, Ida was then able to, despite the shear, begin to rebuild it's inner core structure and nearly succeeded in doing so, redeveloping an inpressive looking eyewall feature as best displayed in the 85 GHz Microwave frequency band, one of my favorite tools for analyzing tropical cyclone structure.

You can easily see a fairly decent eyewall in the NW semicircle, presumably where the strongest thunderstorms are located, and the eye was nearly able to close off into a complete circular eyewall. Were it not for the continuing shear, it's likely Ida could well have regained hurricane strength.

But, as of this moment, Ida is still a solid top-of-the-line tropical storm with some inner-core characteristics of a low end hurricane. If you look closely at the image, you can also see Ida being tilted towards the NE, in the direction of the shear. The surface low (concentric light blue lines) appears to be lagging behind by some distance the very obvious pseudo-eyewall feature (bright red). The center of the surface low appears to be just SW of the strong convective band, and that would imply considerable tilt. And this is another deterrent from Ida being able to strengthen significantly, despite the large flare-up of bursting convection earlier in the day. So the shearing effect works in various ways to diminish the strength of cyclones.

Even though Ida is being strongly sheared and looks to be decidedly sub-tropical, she is still a true tropical storm, and likely won't make extra-tropical transition until sometime well after landfall.

It's worth repeating here that we can all be very thankful here in November that the shear once again came to our rescue and prevented Ida from becoming a major hurricane that might have targeted New Orleans. But the shear knocked it down in strength, ripped the top half off and sent it streaking away and gently pushed her away and to the right of the Mighty Mississippi.

So while this will be quite a good blow and some coastal flooding for Mobile and the Panhandle area, I do believe we dodged, yet again, what could have been a much more destructive situation. And it's a good thing there will be more Ida's to churn the oceans again one day, as this Ida will certainly not have her name added to the infamous list of retired hurricane names. And that's something we can all be thankful for.

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