Day 3 Wrap Up

Wrap-Up and feedback from the day yesterday is listed below. Yesterday was a pretty slow day weather wise which gave the forecasters a good opportunity to explore more of the products.

GLM

A summation somewhere between 1 and 5 minutes would be perfect, not sure of the 2 minutes is the
perfect answer

Struggled to find a need to have the FED and the event density. FED and flash area seem to provide
the most use when using it within warning operations

Flashes and subsequently FED seems to be the most intuitive product

Hands on training would be the most imperative to get people up to speed on using GLM data in
operations and what and when the products are useful

Need to stick with simplicity, especially when presenting the information to the public or to EMs

It is important to use in conjunction with other lightning data to see CG strokes

GLM seems to provide a much larger coverage in stratiform areas or areas behind a line

ProbSevere

Environment yesterday was not conducive for ProbSevere to be real useful

Had some pulse storms and microbursts that weren’t detected

Still took a little while to catch on to the hail in the Texas storm as the background environment again
wasn’t real good

The object tracking was a little junky yesterday. It would combine cells and then split apart and then
combine again and so on.

Might be worthwhile to try to use reflectivity at -10C, even if it was a minute or so later

NUCAPS

Liked the lapse rate procedures to compare to models and see how well things were handled by the
models

Soundings would definitely be useful outside of the balloon times

Yesterday the modified had a substantially better boundary layer representation compared to the
unmodified version

Useful to have a background satellite image to understand which soundings are useful

The DB soundings seem to have a lot more yellow points than the operational version

CI

Continue to struggle with the fact that the severe CI is higher in a lot of cases that the non severe

The jumps in probabilities are inconsistent between the two products and don’t instill much confidence
in using the product

To use the product it needs to really draw my attention with a consistent higher value in a field of lower
values, especially in the summertime southeast thunderstorm environments

The data is very noisy and jumpy especially in the more discrete cloud areas

All-Sky LAP

Had some problems in the Arkansas area where there was quite a bit of cloud cover and the GFS data
seemed to be convectively contaminated and undercut the CAPE values

Did show a nose of more unstable air coming up into southern AR where storms did intensify slightly

Would be worth trying to have a CONUS “nest” using a little more high resolution model data to fill in the
cloudy regions

Like having the All-sky compared to the baseline product to fill in the cloudy areas, but some
improvements would be desired

Worked pretty well in Texas where there was very little cloud cover

GOES-16 Products

Loaded the Day Convection RGB, but need the higher resolution to be useful

Love using the Day Cloud Phase Distinction in initiation stages

Looking at the three WV channels on their own is still the most useful

Generally, the RGBs are difficult to understand and interpret without a lot of experience, even with
quick guides and training

The 1 minute updates are amazing

Lightning Shift

A severe thunderstorm developed over western Sterling County just within the SJT CWA. Hail was the main threat, with 1.5" hail expected. At the same time, and additional thunderstorm was developing over eastern Glasscock County immediately to the west of Sterling County.

A few minutes later, the most intense lightning began shifting to the west into Glasscock County. The storm began intensifying rapidly at that point.

Within a few more minutes, the Glasscock County storm became the dominant storm. hail up to 2" in diameter was expected. The Sterling County storm weakened a little as the Glasscock County storm took over.


Gary Cannalte

GLM Total Power

We had a brief discussion on the utility of Total Energy and what a "large" value may be. I noted this storm in southern Arkansas was indicating a 2 minute Flash Extent Density near 45  which is near the high end of the default color table. The Total Energy registered 240 fJ at this time, which is double the top end of that respective color table.

It makes me wonder what all factors contribute to high energy for a particular storm over another storm in a similar environment. What processes are at work in this instance?  It's all very fascinating and could have potential benefits in the warning environment should a correlation become evident.

Fig 1. Note the Total Energy in the bottom left panel is 2 times the color table maximum.

wall_cloud

NUCAPS Soundings and Imagery

The first image below shows the afternoon NUCAPS soundings over AR and vicinity, displayed over the GOES CH2 Vis and NUCAPS 850-500mb lapse rate imagery. The image has data only for the "green" soundings, i.e., those for which both the IR and MW retrievals were successful. This results in a lot of "holes" in the NUCAPS images. Taking away the NUCAPS image (second screen capture below), it's not exactly clear why some of the soundings are green and some adjacent ones are yellow, e.g., over southern AR, as the cloud fields below look very similar. Perhaps the QC process could be modified so that more sounding are included in the creation of the NUCAPS images, as these are much quicker to examine than looking at each individual sounding. BTW, the NUCAPS lapse rates over southern AR are only about 6.5 deg C per km, not particularly impressive. The t-storms in AR today have been mostly sub-severe.  A.Cope

Odd ProbSevere Cell ID

A cluster of several distinct storm cores were identified by ProbSevere moving across west Texas this afternoon. However, for a brief period of time, the cores were combined into one storm ID, event though the cores still looked distinct.

2254Z-2312Z ProbSevere/MRMS RALA Loop

Alex Brown

CI/CI-Severe in West Texas Convection

I was able to watch the CI and CI-Severe products in some convection that developed over Glasscock county just west of the San Angelo CWA.

This image was taken at 2147Z on Wednesday, with CI in the upper left, CI-Severe upper right, Goes-16 Visible lower right, and SJT 0.5 degrees reflectivity lower left. While satellite has started to show buildups in the cumulus field in the county, no precipitation or lightning has developed. CI is in the 30-50% range over southeastern parts of the county, while CI-Severe was higher for the central area.

At 2157Z, precipitation developed over the northwestern part of the county, with low CI probability over the eastern part. The CI-Severe jumped up to 80%+ over the northeastern part of the county.

By 2212Z, 4 areas of precipitation had developed. Some lightning was occurring withe the easternmost and northwesternmost cells. Since convection was occurring, the CI and CI-Severe dropped almost completely.

The CI product was useful for anticipating where the showers and thunderstorms would develop, but did not provide a clue as to their intensity. All of the cells were producing lightning by around 2245Z.

Gary Cannalte

Convective Initiation over Arkansas

Looking at another example of the Convective Initiation Product over western Arkansas, from earlier this afternoon. The loop below shows the general CI product overlaid on the "sandwich" VIS/IR imagery, for the period approximately 18Z to 19Z. Looking at the cu or towering cu field over SW AR, the CI values vary considerably from one time to the next. Values are generally around 50 percent or less (green/blue), but sometimes jump up to 60-70 percent (yellow). Thunderstorms did develop over this area shortly after 21Z.  A. Cope

Overshooting top with Flash Extent Density

I found it interesting to watch the Flash Extent Density increase concurrently with the development of an overshooting top.The FED increased from a count of 2 at the onset of the overshooting top to a maximum of 11 at its peak.

Fig 1. Overshooting top detected by Day Cloud Phase Distinction RGB, overlayed with Flash Extent Density (5 minute with 1 minute update) from the GLM.

wall_cloud

Update to Earlier Blog Post on CAPE spread between AllSky/NUCAPS

In an earlier blog post today I showed that considerable spread existed between the AllSkyLAP CAPE and the NUCAPS Improved Latency CAPE values over northern SJT forecast area. While it was not available at the time of the previous blog post, the NUCAPS Modified sounding showed CAPE values that were in the ballpark of what AllSkyLAP was showing.

1941Z NUCAPS Modified sounding

Alex Brown

Other GLM Products

The 4-panel image below shows lightning over western AR. Upper-left is flash extent density (FED), which is scheduled to be the initial operational GLM product in AWIPS. Upper right is Event density which seems to show similar patterns to FED, but the values are 5 to 10 times higher. Not sure if this adds any significant value to FED.

The bottom two panels are Group Centroid Density and Flash Centroid Density. All the centroids are just single points, so each one highlights a single grid cell in the 2x2 km ABI grid, leading to a much finer "pixelated" appearance. At this point it's hard to see what operational use they might have.  A.Cope