-82 C Overshooting Top Precedes FED Lightning Jump

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 lighting 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

AllSky Layer CAPE Depicts Favorable Area for Additional CI

Additional convection was possible over southwest OK and/or northern Texas early this evening. AllSky product depicted a concentrated area of enhanced CAPE just south of the Red River, which is where the most robust CI took place right around 6pm.



Dave Grohl

GLM Predicting Strengthening Updrafts

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

Prob Severe Very Helpful Today

The Prob Severe Product has been very good for guidance today. See an example below.



Notice I have used an alternative color scale for the Prob Severe, but every cell with a Prob Severe of 80%+ (in black) was placed under some kind of warning. The prob severe was not the only tool used in the warning decision making process (as usual), but it was very effective in confirming the decision process using the base data.

Thorcaster

Verification of NUCAPS vs. Modified NUCAPS

NUCAPS data points from a polar orbiting NOAA-20 pass matched up with clear skies.  The following NUCAPS profiles were from the extreme southwest part of Missouri.



Unmodified NUCAPS profile from southwest Missouri, well south of Springfield.  Surface dewpoint was estimated at 57-58 F.  MUCAPE only up to 600 J/kg, with MLCAPE of 500 J/kg.



Modified NUCAPS data points from a NOAA-20 pass. Note data void through central Missouri....??? :(



Modified NUCAPS profile in same location as the unmodified sounding.  Surface dewpoint was estimated at 67-68 F.   High MUCAPE up to 3500 J/kg, with MLCAPE at 2900 J/kg.



Observed sounding from Springfield, MO at 18Z.  MUCAPE is 2500 J/kg, mixed layer down to 1000 J/kg.  The surface dewpoint was about the same as that of the modified NUCAPS. But the difference in MU/MLCAPE is significant.  I think the modified NUCAPS added value over the unmodified. Unfortunately, it seems a little overdone.  With that said, the instability probably increased between the observed sounding time of 18Z and the satellite pass near 1920Z.  An MUCAPE closer to 3000 J/kg is probably not too far off -- maybe by ~500 J/kg. -Roy

GLM flash rate, size, and RGB with IR

Loop on 22 May 2019, 21:36-22:06 UTC, showing a combined view of ABI Ch 1610.3 micron IR and GLM minimum flash area and flash extent density (top left). Other panels show the individual channels that contribute: FED (red), AFA (green) and IR (blue)

This pair of supercells near Tulsa, OK illustrates how flash rate and flash area information can complement one another. High flash rates and small flashes usually go together in a small updraft. However, at 2145 UTC the flash rate is much higher in the southern storm at the same time its minimum flash size is larger, with the opposite pattern in the northern storm. The northern storm was tornadic at this time. Shortly thereafter, the large flash rates decreased in the southern cell, and the average flash size became smaller, while cloud top brightness temperatures rapidly cooled and the extent of the anvil spread. The southern cell would soon go on to produce its own tornado.

The RGB panel in the top left combines the flash information together with the ABI 10.3 thermal infrared data: the coldest cloud tops and small flashes lead to a bright cyan color, and high flash rates push the colors further toward white. Early on the northern cell exhibits cyan colors while the southern cell is green and burgundy. Later, the southern cell becomes more cyan, while the northern cell takes on a more green hue.

Apparently, the jump in flash rate in the southern cell was an indicator of a strengthening updraft and the development of a mesocyclone. The drop in flash rate and minimum flash size might have been due to (1) a shift to small flashes that didn't make as much light, (2) extinction of light by an increasingly ice-rich, optically thick cloud, or (3) other instrument artifacts. While the explanation is less than clear-cut, synthesis of multiple sources of information improves the ability to understand the observations.

-deeplycloudy

ProbTor/ProbSevere Impressive Performance

There were 2 adjacent supercells heading into the Tulsa CWA and ProbSevere kept them as  separate objects (correctly) despite their proximity. This is a great sign. Additionally, the ProbTor product effectively differentiated between a tight couplet (north, 70% ProbTor) and a weaker couplet (south, 34% ProbTor).



This case shows the ability of ProbSevere to differentiate storms with distinct features despite close proximity. It also shows that ProbTor is doing what we think it should based on velocity features. -Atlanta Braves

NUCAPS availability maps

Working the SGF CWA this afternoon, I wasn't able to use the modified NUCAPS soundings, as there was a gap in the availability coverage right over that area. Below are maps of the modified sounding availability vs the reduced latency availability.




-64BoggsLites

ProbSevere handles intensifying storm well

The best storm so far went up in the far NE part of the OUN CWA and the ProbSevere model handled it well:



Note the lightning jump that occurs shortly after 21Z as well.



This is a nice supercell case! -Atlanta Braves

Comparison of NUCAPS modified and unmodified soundings at 19Z on 5/22

This post is going to compare the significant differences between the modified and unmodified NUCAPS sounding near Tulsa, OK at 19Z on May 22.



First a look at the unmodified sounding.  It actually shows a small temperature inversion near the surface in the boundary layer, with a surface temperature of 75, and a surface dew point of 61. This resulted in a computed surface-based CAPE of 362 J/kg, and a mixed layer CAPE of 148 J/kg. Now let's look at the NUCAPS sounding modified for the 19Z observed surface temp and dew point.



the modified NUCAPS soudning used the surface temp of 78 and surface dew point of 69. This caused a very large difference in the surface-based CAPE, with a value of 2277 J/kg (about 7X the unmodified).   The MLCAPE also more than doubled to 328 J/kg. Interestingly, the All Sky CAPE (which is designed to match the MLCAPE more closely then the SBCAPE) at the same time in the same area gave an estimate of  1627 J/kg (not shown). That would indicate that both the modified and unmodified versions significantly underestimated the instability, but the modified gave forecasters a much better idea of the potential based on the much higher SBCAPE.

I also noticed that the mixing process the modified NUCAPS used for the surface observation produces a rather unrealistic near surface profile. I think an improvement in the mixing scheme could improve the use of the modified NUCAPS soundings further. Despite that, the current modified does give a better indication of the convective potential in this case.

Thorcaster