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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
I noticed that when the “Aggressively-Filtered” TORP objects (likely sampling mountain peaks) were displaying the 5,10,15-min tornado probabilities, they would decrease or jump around or increase. In all of the other cases, the probability seemed to only increase with the greater amount of time. Once we finally got a TORP object sampling a real storm off KBBX, the probabilities only increased as you got closer to the 30-minute time frame, matching what I would expect and what I was seeing in all of the other cases.
Kilometers
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
Noted a DivShear increase along that thin line of precipitation as it increased in intensity and started to produce several lightning strikes.
Kilometers
It was interesting to see a Torp object identified due west of the BBX radar around 21 UTC with really weak reflectivity and what looks like suspicious velocity data with AZshear in the high category for almost 20 min. This is interesting that this one persists even with the “display aggressive filtered objects” off.
Flash
In the morning supercell case set in OUN CWA, I looked at the pretornado probabilities on the second warning I issued and found it interesting and encouraging that the 5-30 min pretornado probabilities showed increasing values at all 5 min time steps and were higher than the observed Torp probability which added some confidence in the detection and confirmed what I was seeing in the base radar data.
Flash
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
In this case which involves significant terrain on each side of the valley, Torp objects were identified for many areas where poor velocity data in the higher terrain was observed when turning on the “Display aggressive filtered auto objects”. However, when this is turned off almost all of the Torp objects are removed so it appears the filtering technique being employed is working as intended at least early on in the case.
Flash
Noting that the aggressive TORP filter is filtering out numerous TORP objects that don’t appear to need them. -Sidney Crosby
Comparison of TORP object markers in Central California.
First image is the PHI tool with “Display Aggressive Filtered” turned off.
Second image is the PHI tool with “Display Aggressive Filtered turned on.
Most of the object markers align with the edges of the mountains and it’s highly likely terrain blockage clutter is resulting in these erroneous markers.
