LBF HWT Blog Day 4

We didn’t have too many storms occur during operations today, but that allowed us to be able to focus more on CI.

LightningCast for CI

Was able to use LightningCast for convective initiation today as LBF was waiting for storms to fire back up for the afternoon and evening. Initially we were thinking storms would form first over the southern portion of the CWA based off of modeled convective parameters but at 2101Z, a 25% chance of lightning popped up via LC for the north-central portion of the forecast area. This 25% contour appeared a few minutes before radar reflectivity started showing up for the same area. Seeing even the 10% contour show up earlier on, clued me into the fact that we needed to shift our focus further north than we originally thought. These storms seemed to be forming along a shear gradient and weak boundary.
Of note, I am using the parallax corrected LC.
LC, GLM FED, and DCPD at 2100Z
LBF radar at 2109Z
By 2116Z, both GLM and ENTLN showed the first flash of lightning, allowing for around 15 minutes of lead time off of the 25% contour.
For comparison, these storms were forming ahead of the highest PHS CAPE and ahead of any of its stronger gradients.
As our day was winding down, LC continued to indicate areas to watch before it showed up on radar, but I did not grab additional images.


Tried to compare NUCAPS soundings today as we did have an overlap, but unfortunately ran into technical issues within my CAVE so was not able to do much with it. Another limiting factor was that the only “green” soundings from Aqua within our CWA fell within the far western scans which we were told by one of the developers they would next expect good data from, being on the limb. But for comparison, here are Aqua (1911Z) and NOAA-20 (1953Z) sounding from points NW of North Platte.
Points selected were both NW of the town of North Platte, circled below. The NE point of the two is Aqua and SW point is NOAA-20
– Matador

ILN HWT Blog Day 3


Did finally get a chance to check out NUCAPS for today’s case as the timing and location of the data was more compatible. It was good info ahead of the storms as it showed the low LCL values (mainly noticed in the modified soundings), below 1000 ft which is what you want to see for potential tornadoes. Overall, liked getting to dig into the NUCAP soundings, but given the finicky timing and data quality, it’s not something I could use on a regular basis for warning operations. Would be better suited for short term forecasting or possibly as the mesoanalyst.

GLM & LightningCast

For GLM, I set the max value at 130. I originally set it to 65 as I had been using in the high plains the past few days, but for these midwest storms it seemed too sensitive. 130 was a good value for today, likely because of the larger and more numerous storms than I dealt with today versus the previous days.
Also tried out the parallax corrected LightningCast today. Liked that it gave a more accurate location when using it for a specific location such as today’s DSS event. While it was made to pair with radar, it was still useful when using it with satellite products – just had to take a few seconds to make the mental adjustments at the beginning.


Prior to entering the ILN CWA, the PHS STP showed an area of high STP values in and near Rush County, Indiana. The actual IND office did issue a tor warning for this area at 4 PM ET.
Over time, I did notice that for STP, really just the current hour and the next couple of hours were useful. Jumping to 3 or 4 hours ahead it seemed that the data was missing for areas I expected to see higher values. Once the next run came in and I went back and looked, the data was much better. For an example below, there was a vast difference for 21Z between the 18Z run and the 20Z run where the 18Z run for that time did not seem realistic but the 20Z run was more what I expected to see.
08.18 run for 21Z


After talking with one of the ProbSevere people, was able to learn that the threshold for ProbTor is lower than that for Wind or Hail. For training purposes, it would be good to include this information to give a mental threshold for forecasters, such as an ongoing tornado would likely see a max of around 60% for ProbTor. It makes sense that the probs would be lower for tors just as they are for SPC outlooks where the tor percentages are also lower than that for wind or hail.
– Matador

Northeast Colorado Supercells

Nowcasting Supercell storm entering CWA: The loop of instability and SigTor highlight the southeast/south central CWA east of Colorado Spring, ahead of an already ongoing storm. North of this storm an environment of favorable instability exists up to about the latitude of Denver, with a significant drop off to the north.

When it comes to high and northern plains – parallax becomes an issue. In this case lighting was occurring just on the other side of the border with the CWA, so here are the two LightningCasts (with/without parallax correction) for comparison:

ProbSevere v3 increases correlating to entering a favorable environment

PHI localized CAPE corridor

New area of MFA suggesting spitting storm with new updraft core of the established cell. (1950 UTC)

Storm cell split denoted by MFA with two distinct areas of MFA in upper right panel. (2000 UTC)

Focused on the cell east of Denver – this cell and subsequent others that developed are in the favorable area of instability. Just to the north of Boulder we spotted a few cells that attempted to develop, however in the lower instability environment movement off the higher terrain resulted in these cells falling apart. Through the rest of the afternoon this area remained convection free.

Sig Tor blip. A SRVE like feature was observed but at this time convergence associated with this feature wasn’t favorably located under the updraft.

Cell developing east of Denver, noted by the MFA  in the upper right panel. (2020 UTC)

Cell rapidly develops in an area of localized higher instability denoted by the PHS values discussed earlier on.(2034 UTC)

The LightningCast has identified the left turning nature of the storm(s) east of Denver

An interesting note was comparing the differences between GOES East (left panel) and GOES West (right panel). These subtle differences can  be effective in analyzing the strengthening of a thunderstorm.

In the middle of METWATCH – NUCAPS became available (about 1 hour latency). The sounding below is a modified NUCAPS profile, depicting the environment in which our storms developed. Storm mode was supercellular with frequent spitting of cells.

-Mr. Bean



LightningCast for storm approaching Scottsbluff

First instance of 50% contour 1831 Z
The lightning cast did build before backing off for a few frames, dropping below 50%, but jumps back up above at 1851 Z. From then until the first flashes of lightning, the probabilities continued to increase.
First instance of 75% contour 1906 Z
GLM denotes flash 1915 Z
So, lightningcast was able to indicate well ahead of time that we needed to keep an eye on that storm for lightning production as it approached the city.

GraphiCasts with ProbSevere and PHS

For today’s GraphiCast, decided to overlay ProbSevere V3 over visible satellite data to indicate the location of the stronger storms amongst all the clouds. The concern with using it for public graphics is whether the public will understand it. Went with a brief description that it indicates stronger storms for today, but would be curious to see how others message what probsevere means and then how the public may respond to it. I do like how it clearly shows the cells to watch out for.
To determine the time that storms would continue through, I only used the hourly PHS data which dropped off at 23Z. The images below show 20Z PHS vs 23Z. This timing for storms ending for the CYS CWA worked out well as the strong to severe storms exited the CWA by 2256Z with only a few isolated showers remaining for a short time afterwards.
– Matador

Potential LightningCast limitations under convective debris

The first day of familiarization with the tools for the hazardous weather testbed and we were assigned the Louisville CWA to test a number of products on. The synopsis of the area’s weather features a line of convection moving in from the west with a Severe Thunderstorm Watch in place and several storms had already been warned on.

On the other side of the CWA, a few weaker cells had developed under a mix of sun and high clouds. It’s this convection across the eastern CWA that became the focus for today’s blog. We chose to target the LightningCast product because we noticed that although the -10C MRMS data would suggest lightning, the LightningCast data was actually much lower than anticipated (below 10 percent). Why was this the case?

After speaking with John Cintineo about this, and looking at the training that was provided for this testbed, it was surmised that this may be a case where convective debris or high clouds could mask the signal of weaker convection.

Eventually LightningCast did highlight this area with a lightning risk, but this case is relevant because if we are using this tool to aid in DSS to our partners, we must also identify some potential limitations.

Noctilucent/Mr. Bean

LBF Day 1 HWT Blog

Day 1

Acting as LBF
This image was used in a graphicast to which we then added areas of concern over the next several hours and storm direction.

PHS, ProbSevere

Enjoyed using PHS, especially getting the heads up at the beginning of today’s session to watch along the value gradients for stronger storms. That tip fit the bill for what we were seeing today and higher prob severe seemed to follow the gradient as well. I have not had much practice with version 2 of probsevere, so I cannot not really compare it to version 3. However, I did find version 3 useful today, especially with all the readout information breaking down the threat level for each type of severe hazard as well as mesh values.
2041 UTC
2141 UTC


From an IDSS standpoint, the Lightningcast is nice to use to give a heads up and see trends in lightning.
For GLM, I really liked decreasing the max value. Seems to work well in these smaller cells to highlight which cells to watch for.
– Matador

Greenville SC Observations

Synopsis: A deep upper low tracked slowly northeastward across Missouri today. The main cold front associated with this low moved across the Greenville, SC region. Along and ahead of the front, widespread showers and thunderstorms continued over western South Carolina for most of the afternoon and evening hours.

Our DSS messaging was for Softball Tournament Games located at Clemson University.

SPC Convective Outlook: Slight risk of thunderstorms over extreme northwestern SC, with marginal risk elsewhere.

Primary threat was wind flash flooding and wind with a chance of hail and a possible tornado.

Scattered showers and thunderstorms tracking northward across the forecast area.

IR imagery overlaid with lightning data.

Greenville ACARS sounding taken in 1910Z.

NUCAPS Sounding nearby Greenville.

Another NUCAPS Sounding nearby Greenville.

Mesoanalysis – Surface CAPE values ranging from 500 to 1,000 J/kg.

PHS showing similar instability parameters.

Watches/Warnings products issued throughout the day by WFO Greenville.

ProbSevere3: Low probability of severe weather, but sufficient enough for storm warning operations and convective maintenance situational awareness.

GLM Basic – Helped with operations as well as DSS.



Lightning Cast overlaid with satellite was helpful for enough lead time and confidence.

Lightning Cast overlaid with radar.

Lightning Cast overlaid with satellite.

Radar overlaid with Polygon Warnings issued throughout the day.

DSS update: A Flash Flood Warning was issued for Northwest South Carolina near Anderson county and remained in effect until 9:00 PM EDT.

Latest update on ProbSevere3 and tracking any nearby storms.

Latest update on GLM.

SPC Mesoscale Discussion. Thunderstorms intensified across northeast GA into upstate SC, near and south of a warm front that slowly lifted northward toward western NC.

Storm velocity showing gate-to-gate or small rotational couplets near Ware Shoals and Spartanburg.

Vortex Power

Louisville KY WFO Observations During DSS


Immediately after coming online, there was the potential for heavy showers in my area of concern and a storm heading toward an established DSS Event. Initially, LightningCast showed a 50%-75% chance of lightning within the next hour, but this was monitored in successive frames as the trend continued downward.
This product gave me the situational awareness to immediately know that I should be interrogating a storm heading toward my DSS event without an in-depth analysis across multiple radar/satellite products. I continued to monitor the product as I got the rest of my AWIPS setup and I noticed the downward trend continued for my storm of concern. This simple display along with GLM flash data (on a 0-50 scale for this storm mode) gave me confidence in analyzing this as a low-end threat. This has an application in the operational shift change where a new forecaster can have two simple products loaded on a screen with rapid updates indicating that a DSS area is increasing or decreasing its likelihood of seeing lightning within the next hour. These two products in tandem are not only useful operationally, but as a base situational awareness tool.
Initial LightingCast/GLM view of the storm moving toward the DSS event area.
Visually the trend decreased after this initial probability. It would be very useful to have these plots available in AWIPS to view the increasing/decreasing probabilities associated with perceived storm growth and decay.
After the initial spike (which occurred as I was logging on), you can see that with no observed strikes and the probabilities staying constant, there was no initial concern.
The trend continued with a subsequent steady decrease in probability.
Another storm the south became the main concern with a Significant Weather Advisory (SPS) issued for its growth and subsequent wind threat. In this case, I think LightingCast is doing a good job at highlighting the advection and limiting the probabilities over my area based on its current (pictured) motion.
LightningCast and GLM plotted with a current storm motion and Time of Arrival tool to show that it is expected to miss the DSS event at this current time. However LightningCast did put the area in the 75% contour at 20:26Z
Our DSS event was impacted by a separate storm just north of this main storm at 20:33Z. There were no cloud flashes ahead of the CG strike and LightningCast did a good job of highlighting the area as potential increased at 20:26Z, but this was only a lead time of 7 minutes. After this observed CG strike, LightningCast dropped the probabilities to around 50% despite observed strikes occurring within the previously outlined 75% area. Thick clouds around the area from previous and advancing convection were observed over the entire area.
Lightning has been observed near the DSS Event ahead of any observed cloud flashes at 20:33Z. LightningCast only gave a 7-minute lead time with this quick-pulsing storm.
With lightning ongoing and observed within the 75% contour,, LightningCast dropped the probabilities to ~50% at 20:45Z.
This was the LightningCast trend at the time of ongoing, observed, lightning.
The trend remained steady after the lightning was observed and continued through the next couple of hours as the storm following this one weakened and moved over the DSS event area.


GLM performed quite well over the area today, especially as the storms were strengthening. The MFA and FED were again useful in identifying potentially stronger storms and where to focus my attention. This was again useful outside of supercellular convection. I was surprised with how well GLM performed with dense cloud cover from ongoing convection to the south and debris clouds left over from convection earlier in the day.
In dense cloud cover, MFA and FED were able to recognize an area of convection pulsing once it left my DSS event area. This could be useful in a similar situation where the organizer of an event recognizes increased lightning in their area and is looking to return to operations (most of the EMs and organizers have lightning notifications from several ground-based detection networks and frequently interrogate us about ongoing trends). I would be able to use this as a tool to see that lightning near the event is a continued concern because of potential backbuilding around a strengthening storm.
GLM suite showing a pulse in a storm near my DSS event area.
Overall, GLM was very useful in tandem with the LightningCast products for showing growth and decay in ongoing thunderstorms.
A strengthening storm to the south of my event area shows not only FED increasing, but also sees the LightningCast 75% contour expanding northward likely due to advection of the storm. The scale in this image is FED on a range of 0-50.


PHS again performed well on the 0-2 hour timeframe. The primary fields of interest were instability (CAPE, LI) and the SigTor parameter.
PHS model data with instability, LI, and SigTor. This is a model forecast of 1-hour for the 19Z time period which was initialization in our DSS simulation.
PHS was already highlighting the area of concern along a tongue of instability where storms were ongoing as of the 19Z 1-hour forecast. In subsequent frames, it shows the instability being maintained as storms move toward my DSS area despite thick cloud cover overhead. Based on previously discussed trends in observed lightning, it seemed it was accurately showing areas of marginal but sufficient instability.
One impressive feature of the PHS model was a thin line of instability on the back edge of convection. This area was a focus for several isolated thunderstorms behind the main line advancing through northern KY as of 21Z. This was a 3-hour forecast pictured above with highlighted areas of instability by low STP, highlighting an insufficiently sheared environment.
It is worth noting that within this study/testbed, we are looking in areas of Slight Risk or higher as highlighted by the SPC as our area of interest. In an operational setting, it is fairly uncommon to have severe weather events only when the area is highlighted in the Slight or higher category. Therefore, it is unlikely that the SigTor parameter would be useful outside of high-profile events. For example, at my local WFO, we have many severe weather days where we have very high CAPE, but very little in the way of shear. Since our primary concern is usually wind, I don’t think SigTor would be useful. It may be worth adding additional parameters highlighting various threat potentials (wind, hail, etc.).

ProbSevere v3

I was not the warning forecast in this instance, but I did notice that a couplet of rotation was observed on the MRMS rotation tracks. Based on radar data (it is worth noting that this storm was at a large distance from the radar), the couplet was well within the bounds of a rotating couplet with vertical continuity and frame-to-frame consistency.
However, ProbSevere only had a tornado probability of around 10% which should have been higher given the available radar data. This couplet was short-lived, but survived for a few frames after its initial detection. Probabilities did increase, but were not high enough for what I would have expected to be a weak tornado given the surrounding data.
ProbSevere 4-panel showing overall severe potential, hail, wind, and tornado probabilities. According to the data, all of the probabilities remained low, including TOR which should have been higher in this case. This is also supported with MRMS rotational measurements and KLVX radar data.

Optical Flow Winds

With the widespread convection across my area and the long-term cloudiness, I did find some correlation between the Optical Flow Winds and the strongest storms over my CWA (LMK). This was similar to the Birmingham area yesterday, but the stronger storms were not as pronounced in yesterday’s case. CAPE profiles were a little more pronounced today across central KY which likely contributed to this advantage. However, it was still hard to pick out the exact divergence value with these storms, but there were obvious hot spots that helped with situational awareness.
The strongest divergent cells were more obvious on the OFW display today and they lined-up with the strongest cells across the LMK CWA.


NUCAPS data was unavailable today and the passes did not line-up with our area. Even if we had some data available, there would have likely been too many red-retrievals to make use of the soundings due to widespread thick cloud cover.
– Overcast Ambience

ILX Ramblings

A comparison of NUCAPS at 19Z with observed/analysis products from SPC showed good comparison for both modified and unmodified data. Below shows the unmodified NUCAPS sounding that was “green” over the north-central portion of the ILX CWA. The MLCAPE was around 500 J/kg, with DCAPE around 690 J/kg, freezing levels just below 10,000 feet, and PW’s around 1.1 inches.

A modified NUCAPS sounding for the same location showed an uptick in MLCAPE to around 600 J/kg, along with similar PW’s, DCAPE and freezing level.

A comparison with SPC mesoanalysis at 20Z showed very comparable PW values, between 1.1 to 1.2 inches over north-central IL, and freezing levels between 10 to 11 kft. As for MLCAPE, it appeared that for both modified and unmodified NUCAPS, the observed was higher than NUCAPS, around 1000-1500 J/kg, perhaps not having a high enough surface dewpoint. As for 850 mb temperatures, they were comparable to those observed, in the 12-14 degC range. DCAPE was also comparable in NUCAPS with what the SPC mesoanalysis page was showing, between 600-700 J/kg.

With regards to lightningCAST, ProbSevere, and GLM, around 1932Z, once again the LightningCast was showing good lead time for areas downstream of storms. The main cell at this time I was watching was in the southeast Part of our CWA, which had a nice contour of 75% to the north and east of that cell extending well north of the storm core.

At 20Z, the Optical Flow divergence field appeared to match up well with observed convection at this time. It thus showed quite well with the shear field.

ProbSevere’s time series graph continues to show added value, allowing the forecaster to see the trend in a storm’s severity and probability of severe potential. This image was at 20:40Z.

Around 21Z, I noticed a jump in GLM FED for the area of storms in the northwest part of the CWA. Alongside this, the GLM TOE also increased, along with a decrease in MFA with the same storm cell. This area corresponded with increased flash rates in the EarthNetworks. I modified the GLM FED scale to 20-25 as a maximum to see the activity better, as well as lowering TOE to 50 as a maximum.

Around 22Z, the GLM TOE showed a good correlation with the 3 strongest storms based on dBZ and ProbSevere, one to the north, and two in the far southeast, bordering Indiana. For this display of TOE, I lowered the contours to a max of 50, which seemed to work well.

Around 22:12Z, the LightningCast showed an uptick in probabilities of 75% north of a cell that was starting to show towering CU on the day cloud phase. This was before GLM and ground-based radar showed uptick in lightning activity.

Are the edges of LightningCast contours related to the detection of GLM? See below image…The contours do not close off.


DSS in the Birmingham CWA


The initial outlook on the PHS model shows limited potential in the CAPE and STP in this area around the DSS at 20Z. However, it shows an increased potential for 21-22Z which may be the time of most concern for my DSS area.
The initial 20Z model showing limited instability and the contoured ProbSevere to show ongoing convection.
PHS shows a tongue of instability and associated STP as the main convective line lifts northward. This would indicate that the main concern would occur around 22Z.
Based on the line of storms to the west of our DSS event and the associated shower activity lifting northward ahead of the line, the PHS model was accurately representing the convective potential. LightningCast also shows a decrease during this time period which increases consistency and confidence in what the forecaster is seeing.
This lack of convection was observed as showers moved through the area without any lightning or wind potential. There was some redevelopment behind the line and to the south of our event that indicated some concern. At 22Z, you can see the line of storms already being analyzed by ProbSevere lining up nicely with modeled instability and other plotted severe weather parameters.
ProbSevere contours and PHS model line up nicely in the 22Z 2-hour model forecast and show consistency in where the area of greatest concern is likely to be.

LightningCast & GLM for DSS

Initially the LightningCast for our DSS event surged to near 50% or slightly above. This was an initial concern for the DSS area.
As these storms weakened, the probabilities of lightning also fell to under 25%. I liked that these probability decreases were not rapid, but a gradual fall after the initial peak. GLM and LightningCast both had a consistent drop in probability and lightning activity as the “storms” weakened.
It is becoming clear that the rate of change of all of these satellite products is the most important information that a forecaster can gain. While an initial picture of the probabilities looks concerning, pairing this with other satellite products for context and seeing the overall trend of this data led to an easy decision to wait for additional data. Taking this at face value would lead to a quick (and potentially unnecessary) reaction.
Initial threat of lightning as illustrated by the LightningCast product.
The showers on the SE side of this line have decreased in intensity and have lost most of their lightning potential. The probabilities have decreased accordingly.
LightningCast, GLM, radar, and satellite showing the decreasing trend in lightning threat and the approach of moderate to light showers on the DSS event.
Showers are expected within the next 30-40 minutes and the trend in lightning appears to be going down consistently. GLM has also been helpful in showing that no cloud flashes have been observed at this stage.
There were some minor inconsistencies that I noticed since the Meso-sectors were both over our CWA. These were mostly minor, but I noticed at one point, a location had a probability of >50% or 0% and did not intersect with GLM measurements.
Inconsistencies in GLM and LightingCast Meso1/Meso2 probabilities. It seems the accurate probability here was 0% based on the lack of ground-based lightning network reporting.
As PHS indicated there was a second and more concerning wave of convection moving from the SW toward the DSS event area later in the afternoon. GLM and LightningCast probabilities both show the strengthening of this pulse and the increased lightning activity as it moved into the BMX CWA.
21:26Z, the storm indicated a 10% chance of lightning at the DSS event area.
21:36Z, the storm indicated a 50% chance of lightning at the DSS event area.
The 45-minute warning was given at 21:50Z to the event coordinator that a storm with the potential of producing lightning and winds in excess of 30 mph was approaching the event area. GLM was a key part in this decision as it continued to show strengthening with lightning pulses indicating that the storm was at least maintaining its strength. The LightningCast probabilities were also increasing as they approached the area with the 75% contour moving into the area by 21:52Z.
GLM (top) and LightningCast at the 45-minute DSS decision point.
The pulses weakened significantly as it approached the area and this was consistently evident in the GLM display and the LightningCast probabilities.
GLM (top) shows the MFA increasing and the FED decreasing. This was consistent with radar data and observed lightning pulses. The LightningCast probabilities also decreased.
Lightning occurred in the area around 22:38Z with GLM showing another pulse beginning as the storm moved through our DSS area.
In general, I found GLM to be much more useful today outside of the supercellular mode with more multicellular convection observed over central and southern AL and especially so for identifying strong cells within a linear structure.

ProbSevere v3

In a DSS setting there isn’t a real reason to use ProbSevere v3 because winds far below the 50-knot threshold could cause problems at our DSS events. That being said, there was great information in the trend graphic as I could see the growth and decay of storms that were already in progress. This allowed me to focus my attention on the strongest storms.


Ongoing convection ahead of the line of storms limited the NUCAPS ability to produce good data. Availability of soundings was also an issue as the data came in between 19-20Z with storms ongoing near my area of interest.

Optical Flow Winds

For the optical flow winds, there wasn’t much in the way of DSS that I could find a use for. The divergence field again could be useful, but with the suite of GLM I was seeing the divergence and strengthening of the storms in multiple products. Visualization is still the main hurdle with OFW.
Once the anvil for some of these storms developed it was difficult to use. Especially as debris clouds developed and overspread the area in advance of additional convection behind the initial line.
– Overcast Ambiance