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Ongoing complex of thunderstorms pushing into south central MN this hour. Have a new set of thunderstorms forming in what AllSky is showing as a higher CAPE environment along the outflow pushing out from this complex. ProbSevere has picked up on this cell as well (near Milan)…showing a Hail chance of 55% now and growing quickly. Will monitor the downstream growth of both systems.
A storm just northeast of Amarillo developed quickly along a frontal boundary, and quickly showed supercellular characteristics with mid level rotation and a 65+ dbz core reaching about 35 kft MSL. 2 inch hail was reported with this storm during this time. GLM data again shows a decrease in both Flash Extent Density (top right) and Event Density (top left) show a notable decrease in GLM lightning activity while ground based radar remains fairly unchanged, and both the IR satellite presentation (bottom right overlaid on visible imagery) and radar data (not shown) indicate the storm maintained intensity and if anything, had strengthened a bit.
-64BoggsLites
A supercell moving northward along the dryline over the Texas Panhandle region underwent a split over the last 20 minutes or so. Preceding the split, there was a notable decrease in 5 minute GLM Flash Extend Density and Event Density. After the split, there were to notable maxes in both of these products. However, in the GLM Minimum Flash Area, this trend was not observed due to the more coarse resolution of the product. Better resolution may have helped identify both updraft regions within the 2 storms after the split. Additionally, a downward trend was noted in 5 Event Density and Flash Extent Density despite no real change in the ENTLN lightning activity. A loop of GLM data and IR/Vis depicting this storm split is below. 
-64BoggsLites
Comparing GLM flash extent density and GLM event density to ground based ENTLN data along the Kansas/Missouri border region, there is a notable minimum in GLM data with a couple of the large clusters of ground based lightning clusters, while the other ground based lightning clusters seem to correlate relatively well with GLM data. Very strange indeed
-64BoggsLites
Storms continue just after 7pm near the Oklahoma/Texas border. A currently severe-warned storm saw a substantial and rapid increase in lightning activity observed by the GLM Flash Extent Density product. However, the ground based lightning network did not follow the same trend and remained fairly steady. The ground based data is more reasonable considering the storm did not experience any sort of significant strengthening during this time period. Earlier discussions with lightning detection experts suggested the low GLM FED count may be due to the location of lightning within the storm updraft region, which could impact how well GLM can sense it. That is difficult for the typical operational meteorologist to consider in real-time since it goes well beyond current training, and leads to decreased forecast confidence in the lightning data.
Dave Grohl
GOES-16 10.3 um IR channel in the lower right panel captured an exceptionally cold overshooting top at -82 C. This occurred toward the beginning of the animation at 2311Z in far northern Oklahoma (south of Coffeyville, KS) and preceded a large jump in the flash extend density (upper left). The minimum flash area did not change much during this loop, so it may be advantageous for this component of GLM to have a higher spatial resolution than what is currently used. The GLM RGB product (upper right) merges the flash extent density, minimum flash area, and 10.3 um cloud top temperatures. A group of bright cyan and white pixels helped highlight where all three of the aforementioned components were maximized. In addition to a substantial increase in the flash extent density 5-10 min following the -82 C cloud top temp., ENTLN ground based lightning flash counts doubled during the same time.
Although the environmental conditions already supported warning on this storm prior to the overshooting top (OT), seeing the FED and ground based lightning double, likely in response to the intense OT, may push a forecaster to upgrade the severity of the warning (larger hail, higher winds etc.) -Roy
A loop of GLM products, particularly the Flash Extent Density and the Minimum Flash (top left and bottom right, respectively), appear to have depicted strengthening updrafts in the Tulsa area. In particular, notice the uptick in Flash Extent Density going from Creek to Osage Counties, as well as the area over northwestern Rogers County. The increases in FED coincided with low areas of Minimum Flash Area.
The MRMS -20C Reflectivity product shows the strengthening updrafts over the same time frame:
The GLM products increased confidence in a decision to issue two SVRs.
Ron Dayne
The first CI of the day occurred just after 19Z. The radar appearance of the storm remains healthy and the ground-based lightning networks are as strong as they’ve been, but the GLM strength has (erroneously) dropped off dramatically.
-Atlanta Braves
A semi-discrete cell tracked NNE of Little Rock, Arkansas. This storm developed a very tight reflectivity gradient on its southeast flank. A few other notable features were an inflow notch and hook-like appendage. Mitigating the severe potential with this storm was an outflow boundary displaced to the east of the updraft and low cloud flash counts (ground based) or cloud extent flash density (GLM).
The 0-2 km azimuthal shear generated what seemed to be a spurious bullseyes south of Searcy, Arkansas with values over 0.020 S-1. This data was input into the ProbTor algorithm, causing the spike to 72%. The 0-2 km azimuthal shear derived with the new dealiasing technique never plotted values over 0.008 S-1. In fact, the bullseyes which were located slightly to the NW of the primary rotation track, never showed up in the new azimuthal shear product. -Roy
The northern extent of a line of storms that has produced sporadic wind damage is approaching the LSX CWA from the south. One of these storms has good reflectivity structure with a tight front reflectivity gradient and a rear inflow notch. However, these storms appear to be entering a more stable airmass. This is reflected in the ProbSevere probabilities of the storm in question compared with one just a bit further north:
The northernmost storm with the cool contours has only a 22% ProbWind and is in an environment of only 715 J/kg MLCAPE (per the sampling feature). Meanwhile the storm in question to the south in the warmer contours has a 90% ProbWind with 1220 J/kg MLCAPE. These storms are moving to the northeast toward the more stable air. Incidentally, the All-Sky LAP CAPE does not depict as sharp of a gradient in the CAPE compared with the RAP-derived ProbSevere values:
I am not sure which is more accurate but I suspect the model-derived values are more accurate in this situation.
Furthermore, a weakening trend in the Flash Extent Density is observed on the northern end of the line:
This storm still deserves a warning, but we will see how quickly it weakens.
Ron Dayne
