The GLM data, specifically the FED data, was used to provide DSS to the Riverfest in La Crosse, WI. After my first contact with the event POC, I noticed that the FED data was off by roughly a county from the ground-based lightning data. This was my first time witnessing the parallax issue from the GLM and why ground-based lightning networks are a key component in confirming that the GLM location is accurate. In Figure 1, notice the intense concentration of the lightning just southwest of the event (20 mile and 5 mile radius rings) depicted by the GLM while the ENTLN/NLDN say that concentration is about a county south. The parallax is evident in other lightning concentrations in and around the event circle. I know it’s something being worked on to have the GLM data corrected to avoid this parallax issue, but it would be nice to have a map of the locations where the parallax is more evident in case you may not need the corrected version. Obviously, the further north, the larger the parallax, but not quite sure at what latitudes it really starts to show its hand. On a side note, for aviation purposes, the parallax could become problematic if the GLM lightning data is off by a factor of a county or two, especially if re-routing aircraft is occurring.
Figure 1: GLM Flash Extent Density compared with ENTLN data on June 15, 2022.
Figure 2: FED and ENTLN animation showing the GLM parallax.
I utilized the Lightning Cast to provide a probable end time of the lightning threat for the Riverfest event in La Crosse, WI. This was a valuable tool as it provided some added confidence when the storms would exit the event area. I did my best to line up the TOA tool with the 25 percentile contour. Once I got my estimated time that the end of the lightning threat would reach the event, then I added about 30 minutes to ensure it was well east of the event circle.
A large portion of the MKX CWA was included in a MDT severe risk, so by the start of the operational period, we had to assess the evolving severe threat spreading in from the west. Meanwhile, our DSS event was the Madison Jazz Festival, which entailed a focus specifically on south central Wisconsin. The PHS CAPE forecast appeared to be a noteworthy improvement from the CAPE fields on the SPC Mesoanalysis, along with the short-term forecast on that page.
Below are the 18z through 20z plots of MUCAPE, MUCIN and effective bulk shear from the SPC Mesoanalysis page.
Compare the above images with 4000 J/kg of uncapped MUCAPE to the PHS MUCAPE initialization at 18z and 2-hour forecasts (19z and 20z) below.
As you can see, while the SPC mesoanalysis was indicating 4,000 J/kg of uncapped MUCAPE, the PHS forecast showed CAPE decreasing across central and south central Wisconsin. This was an important and helpful piece of information for our DSS content for the Madison Jazz Festival.
The Day Cloud Phase RGB images below back up the PHS forecast vs the SPC mesoanalysis, as relatively flat Cu field over our area of interest actually dissipated between 20z and 22z.
Based on the PHS forecast combined with satellite analysis, we were able to focus the convective threat for the Madison area toward 6PM and onward, tied to the stronger forcing and better moisture arriving from the west where the ongoing convection resided closer to the cold front. It appears that the PHS sampling of moisture in the column applied to the near-term forecast strongly outperformed the SPC/RAP Mesoanalysis model background and OA algorithm.
Differences between the LightningCast (LC) CONUS and LC Mesos
Note below the CONUS scale (1st image) and Mesos (Meso Sector 2 on 6/15) had a different depiction of the lightning probability over northeast Iowa at 1911z 22Jun15. This was due to the time for a CONUS GOES-East scan to complete, vs. the much shorter time for a Meso sector, which in turn affects the LightningCast model. This is something to keep in mind when using the product.
ProbSevereV3 Trends for Severe Convection in Western/Southwestern Wisconsin
At 2106z, the ARX office had recently issued a Tornado Warning (2102z) for the northern cell with a high % on PSV3 and PTV3, per the noted superior calibration of the updated model vs. the V2. Could the PSV3 and PTV3 trend on this storm have assisted the radar operator in an increased lead time? As you can see below, starting at 2045z, there was a sharp upward trend in the ProbTor, to near 40% prior to 21z. At the least, this tool appears to be an excellent situational awareness tool, and may even be able to help lead time in some cases. It helped us in the MKX CWA regarding downstream warning issuances. In the event of an unexpected radar outage in a sparse radar coverage area, environmental analysis plus satellite interrogation with the utility of PSv3 could support successful radar warning ops in a less than ideal scenario.
Today’s experience landed us in MKX monitoring convective development potential across the western portion of the CWA, with a line of storms ultimately moving in from the west, and some risk of discrete cells persisting even after we ceased the experiment.
I took the opportunity today to set up procedures overlaying PHSnABI indices (CAPE) with satellite imagery (e.g. Day/Cloud Phase or Viz), to see how well it corresponded with convective development. Unfortunately I didn’t grab a screenshot, but it was a nifty display that I hope to use again. PHSnABI suggested that CAPE in some areas of the CWA was not as high as the SPC mesoanalysis or RAP suggested. We tried to investigate this using a combination of NUCAPS and model soundings and RAOB, but couldn’t figure out a reason for the CAPE depression before incoming storms grabbed our attention. Notably, the indices derived only from GOES agreed with PHSnABI about this depression, though we couldn’t figure out if it was correct. It seems likely the GOES ABI was driving the PHSnABI result.
My main takeaway the rest of today is how useful ProbSever, ProbTor, and LightningCast can be with approaching/developing convection.
LightningCast, combined with GLM data, was useful for IDSS imagery to depict position and potential of lightning (example DSS slide using these graphics provided below). Storms never made it to our decision point prior to leaving the experiment, but lightning threat was usefully communicated to the simulated JazzFest event.
As convection developed, we also practiced relying on probSevere and probTor for lead time in anticipating warnings. The following shows an example where the probTor trends corresponded well with ARX’s actual decision to issue a tornado warning.
SImilarly, intensification of the convective line appeared to be well detected. In fact, depending on what threshold of the probSevere parameters is relied on (probably depends on environment and other factors), the escalating value could have given useful lead time for a severe issuance decision.
Although the main mode appeared to be a line of convection, there were positions along the line where tornado risk seemed to increase (evidenced by radar velocity). It was reassuring to see probTor pick up on the gradually increasing risk of tornadoes as well.
And one final note… lightningCast is fairly impressive in how it produces calibrated estimates of lightning occurrence using only a single time step of satellite imagery (though it uses several bands of the ABI). Naturally lightningCast has difficulty where a developing tower is obscured by an anvil overhead, as we saw in this example. But it was neat to see lightningCast immediately respond with a broader swath of high lightning probabilities the very first time that a tower poked above the anvil that previously obscured it. The fact that it was hidden probably means lightning could have been occurring below the anvil with lower than ideal lightningCast probabilities (though non-zero, to its credit), but it was neat to see the immediate adjustment to the probability contours with new imagery.
– Buzz Lightyear
On June 15th 2022, a dynamic setup was unfolding across Iowa, Minnesota, and Wisconsin with multiple hazards that NWS forecasters would have had to message and warn. For this case, we were on watch for a DSS event representing the Cranberry Blossom Festival in Wisconsin Rapids in the GRB CWA. The main concerns with the event were lightning and any severe storms, both of which seemed certain for this case and the name of the game was timing the oncoming convection.
LightningCast uses machine learning with numerous satellite inputs that yields the probability of lightning occurring at a location within the next hour. This product immediately jumps to the front of a forecaster’s mind to apply for decision support services (DSS) or assessing lightning probability for airport forecasting. Below is a table showing the probabilities from LightningCast versus the “time of arrival” tool that estimated storm timing based on the movement of storms:
Utilizing the GLM data for DSS and severe weather operations is vital in providing timely and quality information to our partners and the public. In this instance on Tuesday, June 14, 2022, we were monitoring storms near a DSS event (baseball tournament) located in Panama City Beach, FL. You can see the location marked as Home on the following animations. Two main forecast concerns, isolated convection along the beach due to the sea breeze and a line of storms moving south west out of SE Georgia into northern Florida heading toward the DSS event.
The first, and most imminent concern, was focused on the isolated storms developing along the sea breeze front throughout the FL Panhandle. The main threat with these isolated storms was lightning and brief heavy rain. Utilizing Day Cloud Phase Distinction RGB overlaid with GLM Flash Extent Density, Minimum Flash Area, and Total Optical Energy was used for the DSS provided. A line of CU developed to the east of the event moving westward. Again, the main concern was with lightning but certainly with the amount of instability (DCAPE present), downbursts could pose a threat as well. Utilizing the GLM data, they were able to contact the event POC to notify them of the lightning threat to the east and if held together could reach the 10 mile radius within next 1-2 hours (21-22z). What helped with the lightning briefing was the short intensity shown on the TOE and MFA within that storm to the east of Home. It quickly weakened and we were able to notify the event coordinator of this information providing them with further confidence to not have to evacuate their facility during the tournament.
The second concern for the event was the line of storms to the northeast in GA/northern FL moving southwest toward the event. The great news about this storm was the very very slow movement southwest. Thus, the threat of lightning and gusty winds would hold off for a considerable time frame.
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.
Optical Flow Winds
LightningCast & GLM for DSS
Optical Flow Winds
I decided to submit a quick DSS briefing for the Fort Wayne Tin Caps with DCPD indicating glaciation and weak echoes on radar. LightningCast was starting to increase over northern IN for that weak developing convection. Additional convection is spreading in from the south, and higher LightningCast contours are also spreading in. PHS shows increased CAPE over the next hour.
Left: DCPD with GLM and LC. Right: Base reflectivity with LC
Loop of base reflectivity and LC from 1938 to 2014Z:
Left: PHS forecast CAPE at 20Z. Right: PHS LI at 20Z
First GOES flashes a little after 20Z. DCPD with GLM FED and LC
However, by 21Z, lightning is limited pretty much to cells to the northwest and E/NE of Fort Wayne.
Happily, LightningCast called the lightning flash east of Fort Wayne about 10 minutes out (small pink circle east of Fort Wayne)
Why is barely anything happening? Convection looks to be “firing” now on an instability gradient. Indicated by PHS at 21Z:
Am I confident that things will ramp up at all for our area within the next couple of hours? So-so. Here is PHS CAPE and LI for 21Z.
And gridded NUCAPS 850-500mb lapse rates at 1730Z, ranging from around 4.5-6C/km
However, zooming out, there is an area of convection across central IN that should begin approaching our southern CWA boundary within the next half hour. Here is the GLM 4 panel with GOES clean IR underlaid with the FED, at 2130Z.