The future torp probabilities here do not match my conceptual model given the current probability of 78%. I would think probabilities would remain high in the near term, and then possibly steadily decrease later on. Here, they decrease through 10 min and then increase again at 15 min. Not sure why.

The above two screenshots were taken one scan apart. In the time series, the probabilities remain high, but the red torp circle drops off from the screen as if the torp probabilities rapidly tanked.

Not that it was really needed, but divshear did show a strong signal with this TDS confirmed tornado.

Not much time to blog, but overall thoughts are I find myself defaulting to TORP and prob trends the most. Did notice a strong divergence signature in velocity and here is how it showed up in DivShear.

-dryadiabat

I issued a Tornado warning based on a sudden spike in TORP via KHPX, which contrasted with lower TORP values on KOHX. The history is short, too. It’s broad but strong and increasingly cyclonic-convergent. I might’ve held off without TORP but we’ll see what happens. 88% to start and now up to 94%. Of note, the velocity pattern was way less concerning on KOHX, and again TORP from OHX was relatively much lower.

-dryadiabat

Noticed TORP is having a hard time keeping the same tracking number on the same circulation in PAR. There was a storm where there was a consistent weak circulation and TORP should have been able to keep the same tracking number the whole way. Attached are two screenshots that are one scan right after the other (1 min difference). To a human the same circulation can easily be seen, but TORP assigns a new tracking number. The KTLX TORP on the same storm was able to keep the same tracking number. This in turn changes the history trend graphs and made it more difficult to follow.

-Gary

Quick initial thoughts on the mesoscale environment with limited data to analyze. Satellite shows residual PBL stability present with billow clouds immediately ahead of the convection that has developed, likely tied to residual capping EML. However, surface heating is resulting in steep low level lapse rates below this although midlevel lapse rates are poor at the moment, they should steepen and large scale ascent should begin to help lift/erode the cap soon. As we crest the peak of diurnal surface diabatic heating and enter early evening, the low-level jet should increase, just conceptually given upstream mid-latitude system over the central Rockies. I’m guessing (without model data) that as the trough approaches the hodographs should elongate in both the low and mid levels, resulting in greater shear values and more organized convective cells soon.

-dryadiabat

We noticed that there is a lot of “noise” in the velocity data from PAR. I think Charles mentioned this is due to a different dealiasing scheme relative to what we’re used to in the 88D. We don’t notice the noise in KTLX. This is impacting TORP, with values as high as 37% indicated on the back side of the storms associated with this signal, that clearly is false. Analysis of PAR and 88D data and conceptual models from storm structure give us confidence these probabilities are far too high and there’s no immediate tornado threat.

-dryadiabat

Quick note to say in the early stages of storm development, AzShear and DivShear seem noisy and not adding a lot of value without more clear mesocyclones and storm-scale velocity features. I’m sure that will change as the case evolves.

-dryadiabat

Continued jumping around of TORP objects chasing the bad data quality velocity due to the dealiasing strategy (re: post above). Meanwhile, we’re monitoring trends in intensity and character of the midlevel mesocyclones which are more steady using base data analysis to understand storm organization and as an indication of tornado protential trends.

-dryadiabat

I’m not sure I could’ve identified storm top divergence with DivShear along if just looking at that product without looking at velocity. In velocity it’s fairly clear although only a small area of outbounds, whereas in DivShear is more noisy. With time, I’m sure I could learn to pick this signature out more easily in DivShear, but for now it seems relatively difficult for me.

Also, another limitation is sometimes the (-) and (+) components are separated by one elevation, and not on the same scan, so it may not be as apparent using DivShear as compared to just standard base velocity.

-dryadiabat

Highest TORP probs of the day so far in northern Grady County seem to be associated with a storm that has anticyclonic rotation. But this may be more associated with noisy velocity data since TORP isn’t set to detect anticyclonic rotation, if I understand correctly.  Unsure what to make of this. Top image is PAR, bottom image is KTLX (slightly higher tilt).

-dryadiabat

Really liking the temporal resolution of PAR, especially trying to analyze/assess the northern Grady County supercell which displayed some weak low-level rotation embedded within the front flank of the cell to its south. Evolution on rotation magnitude and width were more easily seen in PAR than KTLX, even with SAILS3 enabled.

This has made the Prob trend graphics more complete and useful too (see below):

-dryadiabat

TORP probs increased from 38% to 63% as the tornado report came in and about the time the Tornado Warning decision was made. It peaked at 79% when Vrot was strongest, but as Vrot decreased TORP values fell quickly, despite likely tornado still ongoing given character of the velocity couplet. Probs dropped completely and the TORP object disappeared at 0007z despite weak couplet still present. Tornado threat seemed to completely end shortly after, but perhaps persisted a minute or two longer after TORP dropped.

-dryadiabat

Unsure if it’s just the color tables or other factors but the AzShear seems more useful in PAR than in the WSR-88D.

-dryadiabat

Noisy velocity not associated with tornadic rotation has 38% prob.

-dryadiabat

The “one more scan” dilemma is easier with the rapid updates of PAR. Rather than waiting for a new full volume of data, or even another SAILS cut, we have quicker updates to see the evolution of the RFD.

-dryadiabat

Noticed 87% TORP but there is some bad velocity quality within the TORP circle separate from the weak couplet that I’m wondering if may be contributing to these probabilities, since the couplet is fairly weak. It is tight though so that may be the primary impetus for the higher probabilities.

-dryadiabat

Also noticed higher (+) velocity on the north side of the circulation in KTLX compared to PAR. KTLX at the top, and PAR at the bottom below.

-dryadiabat

Stronger couplet and better AzShear and DivShear signal noted simultaneously.

-dryadiabat

~30 knot Vrot in central McClain County on KTLX. Stronger inbound maxima noticed on PAR too. Probs on TORP seem to be holding in mid-range a little more than I would’ve expected. 55% peak so far.

-dryadiabat

Spotter reported that there was nearly a tornado (X report), in a cell near Colby, KS.

AzShear picked up on this area, and DivShear was highlighting on it a couple of brief scans before.

KGLD velocity also indicated two brief potential couplets (just left of center in image).

As warning operator, I would have issued a TOR around 00:17z.

UPDATE: Further analysis indicates this cell was just on the north side of the boundary.

-Oppenheimer

Surface boundary (NE of DDC)  pretty evident in DivShear data. Less-so in AzShear.

When examining a TORP case in the western US, there were many detections that occurred along the mountain ranges. However, when “aggressive auto filtering” was turned on, all of these “bad” detections were removed:

In AWIPS, one thing that I found useful, at least as someone unfamiliar with the area and its terrain, was loading the HiRes Topo map beneath the TORP detections. I had to increase the line width of the TORP objections, but they displayed well on top of the HiRes Topo map:

Here is a signature that caught my eye, a bit of an elongated area of increasing convergence/divergence along a line segment in the northern part of the CWA:

Here is an example of how an AWIPS display looked around the time of a possible tornado. Velocity shows only a weak couplet. TORP had a weak track, but the current probability at the time of the tornado was just 30%.

I did not have a warning out at the time of the possible tornado (pictured above). But later at 2140z I decided to hoist a warning despite no TORP objection showing up. The same storm was producing weak rotation in velocity further south, and AzShear had a decent signal in those same locations:

In a subsequent scan at 2144z (not pictured) the velocity and AzShear signatures appeared to increase slightly, but TORP still did not have a detection for this area (this even after turning off any QC filters and reducing the probability filter to 10%).

-Orange Lightning

A look at DivShear six minutes before the tornado report (2128Z) did show a subtle tornado signature. I did note it in real-time, but it wasn’t clear enough for me to ultimately issue a warning.

UPDATE: SRV was actually the first thing that caught my eye at 2123Z.

-Sidney Crosby

Noticed a brief TORP object with no AzShear or DivShear from KBBX in the area. However, upon further investigation it likely came from KDAX farther south. -Sidney Crosby

Noticed this TORP object had been tracking probabilities for about 30 minutes in radar noise. This was also filtered out by the aggressive QC filter -Sidney Crosby