Well, it appears that limited instability has again been an issue here... Current SPC Mesoanalysis at 23z indicates that sbCAPE remains in the 500-1000 j/kg range across central AL, southwestern GA, and the FL panhandle, and relatively nonextistant elsewhere. Widespread cloudcover has limited insolation. Yes, low-level warm air advection continues, but this has thus far been insufficient to build up much potential instability. The best moisture (and instability) remains over sw GA and the FL panhandle, though winds are veered to the south of that warm front.
Deep-layer shear continues to be very strong across the northern part of the mdt risk area, ranging from 60-85kts in the warm sector (or between the two warm fronts if you think of the situation as a double-warm front scenario). In addition, low-level shear appears to be quitte strong in GA, just where there is very little instability.
I do expect the instability axis to build into western GA with time as the cold front march across AL, though we'll have to see if the storms can be surface-based...
Nonetheless, I really do feel that the 15% torn prob in the northern part of the mdt risk area is a bit much given the very marginal surface-based potential instability in the risk area. So far, we've had several PDS tornado boxes (and other outlets, media and NWS alike, calling for significant tornadoes), and only 1 tornado report (yesterday) plus 3 tornado reports today (though all three were within a few miles of Montgomery). I'm not saying anything about the issuance of the watches or dogging on the SPC, but rather just that the models haven't been handling the near-surface environment very well at all. This isn't entirely uncommon, since the problems with convective parameterization are relatively well-known. It just makes forecasting that much more difficult when the near-surface model forecasts aren't very good, since it negatively affects other forecast elements, such as model forecast instability, etc.
EDIT: Not worth an additional post, but, as an update, SPC mesoanalysiss not indicating a shrinking area of 500 j/kg sbCAPE, so it appears that the tornado threat is shrinking, despite very impressive shear profiles (both deeplayer and low-level). In fact, the 0z FFC RAOB (central GA) shows ~1300 m2/s2 0-3km SRHelicity given a storm motion from 240 (west-southwest) at 44kts (which isn't entirely realistic, but noteworthy nontheless). The hodograph looks wicked to say the least.
At any rate, I did find it interesting the the TLH radar did a Tilt 1 scan at 0049z, 0051z, 0052z, 0052z, and 0058z. That's 5 scans in the course of 9 minutes... There were even two scans in the 0052z minute. I'm wondering if the TLH NWSFO is trying to see what it will feel like when (if, technically) the phased array radars are deployed next decade...
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