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ProbSvr readout is becoming so long it is hard to fit within a 4_panel. It is not usable as a readout in a 9_panel due to the number of parameters being shown. Perhaps combine the LLAzShear into a single line such as (Max,LLA,MLA) (0.004/s,0.0002/s,0.005/s) to save space???
— S Coulomb
While it is very easy to plot forecast soundings from whatever model you may choose, NUCAPS provides yet another resource as an alternative to NWP. A strong thunderstorm formed in Mexico around 22z today, almost due west of Del Rio, TX. SPC mesoanalysis showed approximately 2000-3000 J/kg of MUCAPE in the vicinity prior to convection initiation (CI). A quick look at a 20z modified-NUCAPS sounding corroborated the SPC analysis, with ~2400 J/kg of MUCAPE at 20z. The NUCAPS data allow for a detailed analysis of the resulting profile and can be a useful alternative to model soundings, especially the modified products as they attempt to more accurately represent the boundary layer based upon RTMA data. The 20z NUCAPS had ample CAPE in the hail growth region along with 700-500 mb lapse rates in excess of 7C/km. Effective bulk shear in excess of 40 knots coupled with favorable thermodynamic environment likely resulted in this storm producing large hail as KMAF radar sampled greater than 60 dBZ at greater than 32K feet. ProbSevere hail output peaked at 97% (MRMS Mesh = 1.87″) roughly 40 minutes after CI.
–Stanley Cupp
20z NUCAPS sounding near storm in Mexico
20z SPC Mesoanalysis MUCAPE and 0-6km shear (dot indicates point of CI)
Loop showing the evolution of a strong cell west of Del Rio in Mexico. Prob Severe values were dominated by Prob Hail in this case. This hail threat makes sense given mesoanalysis and storm mode, supported by 12z Del Rio sounding. Peak values around 97% occurred before the storm split, but after peak dbz values observed on radar. This makes sense considering the beam height at this range (165 mi from MAF) was showing the mid-level core at 30kft MSL – hail would likely have needed time to fall out from this height. This case could be useful for offices with high radar beam heights distant from isolated thunderstorms. Prob Tor did nudge up around the time of the storm split enough to show the ‘double contour’, however V data at low levels was not present.
Same storm now with GLM Event Density. This data showed a lightning decrease around the time that the storm split. Following the split, almost 0 lightning was observed in the southern cell, while the left split saw a spike in event density. The left split reinvigorated shortly after the split while the right mover weakened.
This is the same loop with radar overlaid that shows the storm split and this time flash extent density. Almost 0 lightning data seen in the south cell.
The modified NUCAPS sounding over Brewster Co TX was more representative of the actual conditions at 20Z versus the regular NUCAPS. A dryline was positioned very near the point of interest and convective initiation eventually occurred near the boundary in ~1000 ML CAPE air around 22Z. 
Modified NUCAPS sounding w/ surface Td near 47F. MLCAPE ~ 1000 J/kg.
Regular NUCAPS sounding w/ surface Td near 54F. ML CAPE ~2000 J/kg.
RTMA Td analysis. Point H is where the NUCAPS sounding was taken from.
GOES-16 RGB at 2150Z showing CI occurring near the dryline.
Below is an example of a case where prob severe my offer the best option for a warning decision. This storm is outside of the best RADAR coverage available; however, strong development has been seen on Satellite imagery for an extended period of time. In a case like this, the PROB Severe Algorithm may be the best option for a warning decision, based on the data available.
South Beach
Figure A
Figure B
Best Practice: Look at lower left image on both Figure A and B (GLM Minimum Flash Area), notice Figure B has interpolate turned on which makes the product less useful since outer edges also have minimum values. The GLM Minimum Flash Area of interest jumped out much better on Figure A without interpolate turned on.
Figure C
Blending both All Sky Sfc-900mb PW and Visible satellite imagery together for convection initiation in western TX panhandle.
Photo above shows a double maximum in AzShear. One of these is clearly colocated with a TOR on ground via CC. However, velocity shows two very different situations, possible strong tornado on ground versus convergence along the RFD gust front. If you were just looking at the AzShear product, both of these areas would be cause for concern, when in fact the impacts are extremely different. Would be nice to be able to differentiate between extreme high values of AzShear near a tornado versus more broad convergence on any wind shift area.
This next image shows a region where the AzShear maximum is too broad. This may simply be a color table issue, but clearly there is an area within the white region where a tornado is on the ground, and other regions within that max where only general convergence is occurring.
This image shows a location where some ground clutter is producing a false positive and negative AzShear couplet. Mathematically it makes sense to see this here given the V data, however to an untrained eye or someone just solely depending on AzShear you could be led astray.
A positive of AzShear is that it can highlight areas of potential concern down the road. The above frame was just one of several frames showing strong convergence and high AzShear values preceding a second tornado from the main cell 10 minutes later. This could be particularly helpful in QLCS storm modes where convergence and shear increases in a broad sense along the main line prior to tornadogenesis. Also in this particular case, the V data was not entirely conclusive that convergence was increasing. AzShear was very conclusive here.
Dusty Davis
First impression of the single radar AzShear……display is rather noisy with lots of couplets…many not associated with any storm. Perhaps if had the option to filter out negative values (blue) so can focus on positive values only would make for easier digestion of data and enhance SA. IN current state of product, would have have to be sure to compare to base velocity data, etc.
Azshear did help draw my attention to potential cyclic nature of the storm and picked up on increasing shear to northeast perhaps a little sooner than if I had not been looking at it. Pickup up on second circulation and locked on to it very well as second tornado(?) developed.
Azshear also seemed to highlight the shear along the RFD/Flanking line rather well.
0-2 km merged product provided similar information. Did not have good feel for 3-6 km product yet.
Again, biggest drawback is the noisiness of Azshear. I could see where this could distract from true area of shear associated with developing mesocyclone. Color enhancement could be improved as well.
Quik TWIP
Az shear while noisy can be used to quickly draw you attention to features of interest. It can point you to the center of strongest rotation very quickly helping a forecaster determine the area under the greatest threat from a tornadic circulation or where it is most intense.
South Beach
AzShear helped identify a new developing circulation ahead of the reflectivity signature. This provided added SA in watching for new meso development. It also “might” help identify quick spin-ups along a surging bow echo or RFD. At first glance, false alarms appeared to be minimized but this was a fairly classic supercell case with at least one strong tornado and clear debris signature.
— S Coulomb
