We didn’t have too many storms occur during operations today, but that allowed us to be able to focus more on CI.
GLM & LightningCast
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.
LightningCast for storm approaching Scottsbluff
GraphiCasts with ProbSevere and PHS
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.
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
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.