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3-6km AzShear shows the cell that had caused an earlier short-lived tornado to the west starting to tighten up again. The SRM shows another convergence zone lining up perpendicular to the shear vector.
The 0-2km shear merged product may not be bad to use in this region between MXX and EOX.
A few minutes later that product shows a strengthening meso there, coupled with a broad couplet.
Charley
The next few minutes saw AzShear MXX 0.5 degree cycle up and down…pictured above is an up cycle. A look at the 3-6 km AzShear doesn’t show much happening aloft.
You still can see the tornadoes tracking to the south in that image though.
Charley
The northern line breaks still have some higher base tilt AzShear, but the couplets are not as strong. 
Looking at the 3-6km AzShear, the southern of the two breaks has a higher value aloft, but the northern one is more shallow.
A few minutes later, the MXX 0.5 Tilt AzShear has a couple of maxima right in the reflectivity breaks mentioned earlier…and a little more in the way of couplets. If I had a SVR out on this part of the line, I’d be tempted to upgrade to TOR possible, given my history with weaker EF0-1 tornadoes along a line of storms.
Again a few minutes later, the AzShear product maxima have weakened as well as the couplets on SRM.
For analysis sake…I tend to like the Single Radar AzShear product over the merged products for low-level rotation…but did like the 3-6 km shear to see stronger cells rotating aloft. Figure the latter would be sampled well by multiple radars across the region, whereas the 0-2 km region is better for a single radar.
Charley
The MXX radar showed more of a ramp up ahead of the touchdown of tornado 2…evidenced in part from this MergedAzShear0_2km image. The white color started showing up about 5 minutes ahead of touchdown for this cell.
Meanwhile, Tornado 1 keeps tracking along nicely, maintaining a pretty strong intensity, indicated by the Rotation Track map.
Charley
Meanwhile, south of the two tornado tracks, a couple of smaller supercells have developed. They too show ZDR arcs, but AzShear is not as pronounced, either at the 0-2km or 3-6km ranges. In addition couplets on SRM/Velocity are much less noticeable.
Charley
The 0-2km product still highlighted all three parts of the line, and reflectivity still shows the line breaks up north, but the velocity product itself is not showing much gate to gate tight mesos there, despite the higher AzShear numbers.
Charley
The merged 0-2km AzShear product shows threat more areas of interest along a north/south line crossing MXX. The southern one obviously is the strongest, but one just north of the radar and one farther north of the radar has reflectivity and velocity tags indicate some potential for tornadogenesis. Reflectivity shows line breaks and a convergence zone at enough of an angle to the 0-3km shear vector to induce some stronger mesos.
The 3-6km shear vector focuses more on the southern one of those three.
Charley
AzShear product for EOX, showing higher elevation rotation, was strong for this cell as it was getting organized. MXX was lower, but the merged shear product picked up on the high value.
Other Dual Pol factors indicated the supercell was starting to get ready to drop a TOR…with ZDR arc forming on the MXX radar. 
A few minutes later, the MXX AzShear on the base tilt still didn’t show the high values until right at tornado time. 
Then at time of touchdown, it showed a better max in the lowest tilt.
The merged 0-2km Azshear product then cycled down after that max, despite continued higher values from the EOX radar…in fact the trend was getting stronger from that radar, with peak values near 0.03 at touchdown time. Sampling indicated the AzShear on the base tilt was at 1.7-1.8 km AGL at this time, so I would think it still would factor into the 0-2km AzShear product.
Charley
Today’s operations will be begin with their focus over the Twin Cities/Chanhassen (MPX) county warning area. Severe storms have already developed and are approaching the Twin Cities area from the northwest. The Storm Prediction Center current has a mesoscale discussion out for the area highlighting potential watch issuance within the next few hours with the main threat being damaging winds but large hail is also possible.
Other potential regions of operation include the low-country region of South Carolina, where there is currently a severe thunderstorm watch, and extreme west Texas into southern New Mexico. We’ll monitor the weather situations in these locations and adjust our operations area as needed.
Single-radar AzShear does a really good job of identifying preferred locations of circulation along a QLCS. The bullseye started as an elongated area of enhanced AzShear and then converges into a more concentrated area. This product provides a helpful heuristic for identifying tightening circulations in the midst of noisy velocity data with less-clear signatures.
One can easily see the congealing AzShear bullseye before the circulation tightens the tornado starts.
On the contrary, the Merged AzShear product demonstrated some latency issues that would lead to less confidence in circulation tightening.
This image, taken at the same time as the KEOX AzShear product, shows several unorganized areas of enhanced rotation right before the tornado started in the merged AzShear product. The tightening circulation is an important precursor to tornadogenesis and the merged product seems to struggle. -Atlanta Braves
