Category: OCTANE Speed Sandwich

MesoAnalysis Support and Lack of Radar

Posted in GREMLIN, OCTANE Speed Sandwich, SPG2024 on by Kevin Thiel.
More emphasis has been put on mesoanalysis in severe weather operations over the last several years and utilizing the OCTANE products has demonstrated that it has utility in confirming objective analysis. Scattered thunderstorms were developing across parts of the Carolinas today, but the mesoanalysis suggested that severe thunderstorms would be favored farther south and east of our area of concern through the late afternoon. A quick look at the SPC mesoanalysis of effective shear showed values of 40-50 kt to the south of our area of concern. As thunderstorms started to develop, we were able to use the OCTANE products to confirm that larger areas of shear were present with our southern storms.
Thunderstorms were ongoing across parts of northern SC and southern NC through mid afternoon. The OCTANE speed products clearly show slower wind speeds aloft to the north, while our southern storms show much higher wind speeds aloft and even some divergent signatures to the southwest of our event. A few of these southern storms would eventually become severe. This product will be beneficial to short term operations in confirming local objective analysis.

Our case also required us to look at information without utilizing radar. The GREMLIN product filled the role of radar data, but some notable issues were present. The GREMLIN latency approached 20 minutes at time, which really makes the product unusable for real time warning operations. However, discussion with the developers indicated that some of these latency issues could be overcome. The utility in the product comes from its visual representation. Forecasters are used to looking at radar data, and this product offers something similar. Latency issues must be overcome for it to be usable in operations. The product overlaid with real time lightning data would offer utility in areas with poor radar coverage or during times of significant radar outages. After working a few days with the other products, the GREMLIN utility really became evident in the absence of regular radar data. An example is shown below.

Tags: None

Octane Trying with Confirmed Tornado within QLCS

Posted in OCTANE Speed Sandwich, SPG2024 on by Kevin Thiel.

Day 1:

A NE-to-SW line of storms approaching the southern Texas/Louisiana border from the west with another W-to-E oriented line of scattered storms developing along a stationary front. The eastward moving storms starting to bow out with notch in the line starting to develop near the town of Starks, LA. Low-level rotation starting to show on SRV with a weak TDS showing up between 2115-2117Z and a stronger TDS at 2130Z. Radar starting to show what looks to be an embedded supercell within the line and several mesovortices beginning to develop just offshore along the southern half of the line.

 

  2117Z
 

2130Z
        Leading up to the development of the tornado, the Octane speed product indicated a decent speed decrease on the upshear side of the storm before tornadogenesis. The Octane speed product also showed higher speeds wrapping slightly back to the west just to the north of the main updraft. The Octane direction product also showed an interesting appendage developing just to the east of the speed min at the same time.

 

 
        As the storm cycled, and new updraft and meso developed, another speed min and direction changed was noted. The two products again showed higher speeds bending back to the west and the northern side of the updraft and another appendage developing on the direction product. While this storm did not produce a tornado, strong wind gusts of 55-60 mph and damage was reported.
 
– Vera Mae
Tags: None

HWT Day 2: Protecting the Quartet

Posted in LightningCast, OCTANE Speed Sandwich, SPG2024 on by Kevin Thiel.

Protect the Quartet!

Today we were charged with the noble task of watching over the the Quartet Festival located in Lawrenceburg TN. Gaps in the cloud coverage allowed us to utilize some of the satellite products a little more efficiently today. Our first sign of trouble came as convection began to form out in front of the main line moving WNW out of Alabama. LightningCast 60-min prob gave us our first initial heads up that lightning was possible with storms forming out ahead of the main line. A combination of Octane overlaid with GLM data was the primary source in our decision making to issue a notification to the event organizers. Thanks to our quick decision making, everyone is alive to sing again another day.

 

We combined lightning cast and ENTLN data with the radar to provide ground truth on when lighting was first scene within the 15 mile range ring which allowed us to issue follow up messages regarding the likelihood of ongoing lightning potential. Requesting a LightningCast point too also gave us confidence in issuing notifications to the event organizers.

 

 

 

Discussing the LightningCast Probability data with Kilometers we were discussing ways to get more information out of it. We settled on loading the LightningCast as an image rather than contours. This combined with the sample tool and overlayed with Total Lightning products was more useful when forecasting for a specific DSS point. We also went ahead and limited the data being showed on the lower end of the GLM Flash Density. We didn’t want to exclude the Flash Density on the lowest end all together, but we wanted to highlight and compare the GLM Flash Density to the areas with the highest Octane SpeedSandwich. Our end result was this GIF below:

 

Today was a day to dive into GLM and Lightning probabilities. Once we settled on what we wanted to look at to make DSS related decisions, we realized that it wasn’t intuitive to the public. We needed a way to redesign the the Lightning Cast data to be easy to look at to the public. Because the NWS already has a color table for threats utilized by our National Centers, we decided to model our threat level based on the SPC’s convective outlook to create new colors for the contours. The following graphic is the end product of that:

As the system moved past, identifying areas that we could issue the all clear on was our next priority. The LightningCast created a nice looking bell curve that lined up with the time that the MCS moved over the event and showed the trends of the storm began to wind down.

 

 

Tags: None

Convective Initiation Failure

Posted in OCTANE Speed Sandwich, SPG2024 on by Kevin Thiel.

Watching a New Updraft Among ongoing Convection

Multiple supercell thunderstorms were ongoing across South Texas along and behind a southward moving outflow boundary within a strongly unstable airmass. At 2115Z, a new updraft began to develop near Realitos, TX to the southwest of an ongoing thunderstorm.

 

 

Fig 1: Notice the cooling cloud tops in the CTC image (top right) near Realitos, TX at 2114Z. This updraft is evident in the Day Cloud Phase Distinction RGB and Visible imagery.

About 5 minutes later, the cloud top cooling peaks near Realitos. The first faint radar echo become evident to the southwest of the ongoing supercell.

 

 

 

Fig 2: Cloud top cooling peaks at 2119Z near Realitos. The first weak radar echo is evident to the southwest of the ongoing supercell.

At 2127Z, the cloud top cooling product indicates that cooling has significantly decreased. Meanwhile the cloud top divergence product suggests little to no meaningful divergence is occurring. This suggests that the updraft has weakened and will not likely continue to develop. The latest CRP 0.3 degree reflectivity shows an intensification of the precipitation in this area, but the satellite derived imagery suggests that this intensification on radar is temporary and the updraft will continue to weaken.

 

Fig 3: Cloud top cooling has decreased and no notable cloud top divergence is observed. There is still considerable “texture” in the visible and daytime RGB. Notice the increase in reflectivity to the south of the ongoing thunderstorms.

 

The information from the derived products suggest that this updraft will likely not develop into an additional thunderstorm near the outflow boundary. There were several minutes of lead time over radar/visible imagery gained from these derived products to indicate that the updraft would not develop fully into a new thunderstorm. An animation of the updraft sequence is shown below.

 

 

 

wthrman

Tags: None

Lake Charles Radar Confirmed Tornado

Posted in OCTANE Speed Sandwich, SPG2024 on by Kevin Thiel.

 An MCS resulted in a number of TDS and TVS signatures on radar near Lake Charles today.

This one was capture to the WNW of Sulphur LA as an MCS surged east in an atmosphere that had 5000J/KG of SBCAPE. In addition to a TDS a LSR was submitted to the Lake Charles office regarding significant damage to the Walmart in Sulphur downstream of where these stills were taken. Radar was primarily used to determine that a tornado was on the ground. Looking at some of the Octane data, it was noted that this tornado formed on the leading edge of a speed minimum on the EMESO-1 Octane Speed Display.

As the storm moved toward Lake Charles, the line segment began to bow out. Numerous reports of wind damage came in with an Semi being flipped on I-10 and a 60MPH wind gust reported by the Lake Charles ASOS. Velocity data showed a strong signal for damaging winds, and the Octane Speed Sat Display again gave us a significant gradient between speeds as the storm passed over Lake Charles. This data could be useful in verifying the potential for damaging winds, especially when storms are close to the radar.

The Octane Sandwich display seems to be an upgrade to the Day Cloud Phase Distinction although both displays could serve different purposes, with Day Cloud being useful in watching storms develop, while Octane is useful once storms become more organized in identifying more distinct elements of the storm.

-Charmander

Tags: None

ProbSevere and LightningCast During Severe Warning Operations

Posted in LightningCast, OCTANE Speed Sandwich, ProbSevere, SPG2023 on by Kevin Thiel.

A moderate risk for severe storms was forecast for the Southern Plains with hail, wind, and tornadoes as significant threats.  Storms quickly initiated in southwest Kansas (See Figure 2) and were ongoing when the testbed started at around 19z. Primarily used during warning operations were ProbSevere, LightningCast, and radar. Thrown in for good measure I used OCTANE to aid in storm motion and direction.  ProbSevere was helpful in issuing warnings but was vital in assisting in the hail size mentioned in the warning text.

Figure 1: SPC Day 1 Outlook for June 15, 2023.

Figure 2: 2011z showing ProbHail with a MESH of 2.17” provided the confidence to mention 2-inch hail in the text.  There were two separate storms that eventually merged later in the afternoon.

Figure 3: storms were beginning to merge and ProvSevere was as well and thus prompted just one warning instead of two.

Figure 4: New warning with ProbSevere now depicting just one storm.

Figure 5: Storms continued to merge and evolved into a wind signature more than a hail producer.  Thus the ProbWind had a nice uptick to 68% at 2133z.  Before this time it never rose bout 40%.

Figure 6: Once the convection evolved into a linear wind producer, LightningCast became helpful in how far east to extend the polygon.  I used the 75% contour and issued a 60-minute warning.

Figure 7: Captured much of the event to show the evolution of convection and ProbSevere.

Figure 8: OCTANE aided in determining the area of cell merger in southern Grant and portions of Stevens Counties. 

– Podium       

Tags: None

6/15/23 HWT – AMA

Posted in NUCAPS, OCTANE Speed Sandwich, PHSnMWnABI, ProbSevere, SPG2023 on by Kevin Thiel.

What appears to be a nice distinction between sheared / lesser sheared convection across the Octane window. Stronger shear across SW OK producing much different appearance versus SW KS convection.  Nice quick visual distinction for operational use. The idea of a quantifiable divergence contour and/or grid would be welcome also.

Octane data from Goes west meso sector was zoomed in along the inflow region across the SW OK supercell (not our CWA but I had to look). The upper right panel is the directional component and the color scale was changed to highlight approximately 210 – 150 degree range. The increasingly warm colors represent a backing of flow at approximately 4.5 kFt. This level of storm integration (if appropriate) would be advantageous to warning operations.

ProbSevere time series plots do not sample. I would like sampling tied to the cursor as in the parent CAVE window. The element assignment within ProbSevere did cause a problem with the time series information with a storm that strengthened on the southern end of a developing line. The storm initially had a defined area for the region of interest but once ProbSevere assigned it to the larger line the probabilities became much less representative. This impacted ProbTor values which were being monitored ahead of an eventual tornado warning in the Tx Panhandle. I was the warning forecaster today and used ProbSevere extensively for my decisions. It is not the deciding factor but it certainly weighs into the decision process.

PHS model output was interesting and the Updraft Wind element was noted as something not usually seen with model output. It was viewed initially but I didn’t monitor the model output once storms developed and warnings were being issued.

NUCAPS forecasts were unavailable until the very end of the operational window. I did view the 19z overpass soundings and found the familiar  trends of errors at the boundary layer when compared to nearby surface observations. This limitation continues to impact my confidence in the product.

– jbm

Tags: None

6/15 HWT OUN SuperCell

Posted in OCTANE Speed Sandwich, PHSnMWnABI, ProbSevere, SPG2023 on by Kevin Thiel.

A very intense supercell formed across western portions of OUN CWA. This cell underwent many transformations including splitting and merging at other times. Octane was very interesting to watch as this cell went through the various processes before eventually producing a tornado. Octane was able to show the storm splitting before it occurred on radar.  PHS was also showing corridors of stronger 0-3 and 0-1 SRH; SPC Mesoanalysis was showing this as well but I did like how the PHS was able to highlight exactly where these occurred. Seeing that and a near stationary boundary did increase my confidence that if a storm was able to latch on it would become tornadic. Probsevere/MESH did struggle to catch on to how large the hail actually was initially before finally picking up on the hail size.

4 Panel with Octane on the top row; appears to be two distinct divergence signatures occurring

Radar Loop of storm splitting shortly after Octane signature…. Notice how the left mover dissipates.

Using the 4 panel with Octane, IR and Day Cloud Phase it was also beneficial to see the upper divergence signature on Octane correlate with the cooling cloud tops of IR and Day Cloud Phase. Although it didn’t seem to create any additional lead time with that aspect; at least that I was able to notice. It was overall a very interesting storm to watch for this experiment.

4 Panel Intensification of storm.  Note the rapid color gradient to blue (upper level divergence)on Octane towards the end of the loop.

Radar loop around the same time as the 4 panel above   

– Tor Nader

Tags: None

6/15 Feedback for AMA

Posted in LightningCast, NUCAPS, OCTANE Speed Sandwich, PHSnMWnABI, ProbSevere, SPG2023 on by Kevin Thiel.

PHS

The surface based CINH at 20z lined up rather well with the satellite imagery showing the slightly more stable clouds over the eastern CWA.

When sampling an image versus contours, the contour sampling has the entire product name in the readout

PHS captured the initial convection just east of AMA well, even though the convection started an hour earlier than PHS indicated.  Image on right is PHS SB CAPE and contours are PHS SB CINH.  Home is roughly where the storm is located.  Satellite image is around 1930z and PHS forecast is 21z when CINH dropped from 80j/kg to 40 j/kg.

PHS did a reasonable job predicting the general storm coverage by 21z from the 16z run.

Toward the end of the exercise, the storm coverage was well captured by the PHS 16z run.  Should have taken this into account for my public graphics when describing the storm evolution.

NUCAPS

This is a NUCAPS sounding in the TX panhandle near AMA vs. a RAP40 sounding at the same point.  The RAP has the same trend in the dew point profile as NUCAPS, but is lower.

Noticed the NUCAPS sounding didn’t have the lower dew points around 400 mb as shown in the special sounding.  NUCAPS did have a hint of the weak cap near the surface though.

NUCAPS 700-500mb lapse rates from the gridded data was a constant 34.17 C/KM across the map.

NUCAPS forecast for ML CAPE was slightly less than what SPC mesoanalysis had at the same time of 20z.

NUCAPS ML CINH was higher than SPC Mesanalysis for 20z, with some parts of the CWA having almost 90j/kg of CINH south of Liberal, KS.

The 700-500mb lapse rates matched well with SPC meosanalysis for 20z.

OCTANE

OCTANE showed the cumulus developing along the dry line and warm front well.  Can also distinguish which clouds are becoming taller.

OCTANE highlighted where convection was taller, and Lightning Cast started to show probabilities for those same updrafts.

ProbHail

Noticed what could be an above anvil cirrus plume with the storm in question.  Prob Hail only had a 35% chance for severe hail at the time.

Prob Tor

Noticed the Prob Tor jumped up depending on what cells it was encompassing.  Took three screen shots to denote the trend.  Seemed reasonable for it to increase since the end cell was ingesting the dry line at the time the probabilities increased.

-Rainman

Tags: None

Day 4 Review of Products & Operational Applications

Posted in LightningCast, OCTANE Speed Sandwich, PHSnMWnABI, SPG2023 on by Kevin Thiel.

Today, I took on the role of mesoanalyst during operations. I first looked at PHS fields (mainly MUCAPE and bulk shear) and compared them to the SPC mesoanalysis of said fields. The two agreed well, though I do have a suggestion – PHS bulk shear fields are given in m/s, but knots or mph would be better for quick comparison to SPC mesoanalysis and most model output.

I then looked at OCTANE imagery and immediately took note of the divergence signature associated with an especially robust storm over western DDC (Figure 1). This signature was easy to identify as the environmental winds aloft were relatively light.

Figure 1

As the operational period wore on, LightningCast indicated a high likelihood of convection over the southwest portion of DDC well before any radar returns actually appeared (Figure 2). My group used this information to create a DSS graphic that highlighted this area for likely storm development later (which did in fact end up happening).

Figure 2

OCTANE Direction later captured what at first glance appeared to be a couple divergence signatures over southwestern DDC (Figure 3). Upon closer inspection, however, these signatures were co-located with relative minima in OCTANE Speed. The proximity of these signatures to areas of missing pixels (where winds are likely <5 kts) in OCTANE Direction suggests very light winds and/or lower quality data, per the developer.

Figure 3

– Vort Max

Tags: None