Category: OCTANE Speed Sandwich

Using OCTANE to diagnose three convective environments along the Missouri border

Posted in OCTANE Speed Sandwich, SPG2024 on by Kevin Thiel.
Currently monitoring OCTANE data in the vicinity of the Missouri border at about 1850Z on Tuesday, May 24.
North of the border (far southwest Iowa) there is mature convection, with a clear signal for changes in direction and speed on the anvil (top two panes). The mature convection shows cloud top divergence, with new convection on the southern flank showing a sharp signal for cloud top cooling (bottom left).
There is an area of banded cirrus moving through the region just south of this. This cirrus shows up on day cloud phase imagery (bottom right) but also in the OCTANE speed product. Looking at satellite data qualitatively, it’s clear the cumulus field is much less impressive in this area. Convection is not yet initiating here. Surface observations don’t show a clear signal for a less favorable air mass, so it’s possible the mid-level conditions are not as favorable.
South of all of this, we are looking at a new area of updraft initiation occurring just on the Kansas side of the border. On conventional satellite imagery we can see updrafts reaching upper levels and shearing off (orphaned anvils) indicating true convective initiation is still a little ways off, but we are getting very close. There is a consistent signal on OCTANE cloud top cooling for some of these spotty updrafts. Comparing with conventional imagery, the OCTANE cloud top cooling signals provided 5-10 minutes of lead time on the orphaned anvils. This is useful information, as once these storms begin maturing, they may provide a little more lead time on the initiation of lightning in addition to just the initiation of mature updrafts.
–Insolation
Tags: None

GLM Trends In A Warning Decision

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

Severe thunderstorm and tornado warnings were issued partially driven by the increasing intensity of GLM FED. With the indication of a strengthening updraft due to increasing lightning activity atop the convergence signature on radar, a warning decision was made for both damaging winds and a tornado threat.

OCTANE cloud top divergence also highlights the strongest thunderstorms in our CWA below.

 

-Joaq

Tags: None

Tracking Convective Development With OCTANE storm top divergence and LightningCast

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

Developing convection along a surface front in eastern Kansas was producing signals in the OCTANE storm top divergence product, signs of glaciation, in the day cloud phase product, and increasing LightningCast probabilities. Along northern areas of the surface boundary, the divergence product and visible characteristics were stronger, while updrafts further south still struggled to sustain themselves. This may be due to residual convective inhibition evident on MCI ACARS soundings. Even about 20 minutes after these screen shots were taken, the GLM activity was fairly weak, while the storm top divergence only really showed showed up on storms near and north of the KC metro. While severe convection is still likely downstream, the OCTANE divergence product definitely highlights where better synoptic forcing is overcoming any convective inhibition.

 

 

-Joaq

Tags: None

Warning vs DSS – “WFO DMX”

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

It was interesting when comparing the Warning side of the house today versus the DSS side. When we (Cumulus and Kadic) were discussing this and picked two of the tools we used the most, there were similarities and differences:

For Warning Ops: OCTANE and LightningCast

OCTANE proved very useful in interrogating convection. LightningCast was also a helpful diagnostic tool in highlighting the potential for and track of intense convection when used with ProbSevere.

OCTANE:

Here’s a look at 2 particular instances from OCTANE:

A combination of cloud top cooling in OCTANE and subsequent divergence aloft was a helpful clue in assessing the potential of a storm that was distant from the radar. It was caught a little later in analysis, but OCTANE proved helpful in diagnosing the storm and deciding to pull the trigger.

 

 

This next instance was a warning that was issued solely using OCTANE and seeing how well it lined up with radar. The warning targeted the center of where the maximum storm top divergence was taking place, and then stretched down towards the south to account for parallax. The warning decision was made for the impressive cloud top cooling and pronounced divergence that appeared in the scans leading up to the warning. The panel on the top left shows the OCTANE speed, and it transitioned to a blue color leading up to the event.

 

 

LightningCast and Radar:

As the line shifted east into the area, ProbSevere stood out, while the LightningCast steadily increased. The left hand panel depicts GREMLIN, and it properly highlights the southernmost storm as being the most intense. Unfortunately, not every storm that we issued warnings for got a specific screenshot, but when looking at LightningCast, areas that were likely to experience 10 or more flashes with a 70% probability seemed to correspond well with ProbSevere values would support issuing warnings.

Below is the example of what MRMS looked like the moment DMXSVR005 was issued solely based on OCTANE. Much of the SVR encompassed the highest LightningCast values with a probability of 10 flashes of 70% in yellow and the various ProbSevere contours. Again, this highlights how useful these tools can be in performing storm interrogation. However, when thunderstorms are numerous, this may be a lot to run through. They are definitely useful tools in the tool belt, though.

For DSS: LightingCast (especially the Dashboard) and GREMLIN/GLM.

– LightingCast: I REALLY like the form and Dashboard. It helps focus on the DSS site specifically and organizes the data really well to where I would feel comfortable explaining/showing an EM the graph of   lightning probabilities. Honestly, I could bring this back to my home WFO right now and use this for DSS events this summer. A couple things that could be added to make it even more awesome: adding more options for ranges (right now there is only 10 miles, perhaps adding 15 and/or 20 miles). Folks could then choose which to display in the graph. The other thing (fairly minor), perhaps reversing the size of the bubbles for the GLM data (smaller range, smaller bubble). But, this is personal preference – maybe if this could be customized by the user like the colors?

– GREMLIN/GLM: GREMLIN followed the storms a lot better today (seems to do better with more intense storms versus run of the mill/sub-severe ones). I used a two panel display with GREMLIN on the left and MRMS on the right with GLM and LightningCast and compared the two. I used time of arrival for the storms to 10 miles outside the DSS event and also at the site itself. GREMLIN was able to keep up with MRMS really well! I am becoming more and more convinced that this could be a really great product to help if a radar goes down or there is a radar hole (in data).

Overall, it seems as though OCTANE was used more for warning ops versus DSS, but LightningCast was used by both the warning operator and DSS forecaster.

Forecasters Cumulus and Kadic

Tags: None

Collection of Day Two Thoughts

Posted in GLM DQP, GREMLIN, OCTANE Speed Sandwich, PHSnMWnABI, SPG2024 on by Kevin Thiel.

Day 2 has featured more convection, and has been a helpful day testing these products and how they help in warning operations. Although I might not feel confident making warning decisions solely based on any of these tools, I think that each tool provides a valuable piece of information.

Pre-Storm

To keep things short here with all the observations, PHS was very helpful today in showing how the QLCS situation would evolved with several areas of embedded rotation. Having CAPE with SRH together showed how these came together, and in conjunction with velocity highlighted rotation updrafts within PHS. This proved to be a helpful pre-storm evaluation. A few storms began rotating, and then everything began rotating as the PHS model indicated.

 

Observations Related To Warning

The developing squall had a linear appearance at first. As time progressed with more embedded areas of rotation, this became a lot less neatly organized.

Here is a look pre-warning for a tornado warned cell with ProbTor increasing up to almost 40 before moving off the point.

 

 

A zoom in on an impressive overshooting top. Sorry for the reverse loop.

 

Here is a V-notch like structure. Though it doesn’t correspond with a radar V-notch, it does indicate how strong an updraft this was.

 

 

And here’s the radar look of that, which appears to somewhat match the configuration seen aloft.
Interesting Signals

 

One thing to note early was that the PHS forecast had a lot of convective debris lingering in Iowa that was not present in reality. This does not appear to have impacted the instability parameters very much.

We’d mentioned looking at the dewpoints for the tendency for aggressive convection. But it only seemed slightly high compared to reality.

We did have a blob near Sioux City on Gremlin that didn’t really correspond with any signal on radar, and it didn’t seem to have satellite signal to go with it. Not sure where it came from, but we were able to see it was erroneous.

 

Here’s a look at GREMLIN with waves and wobbles following the GLM lightning.

 

 

Here’s another fun look at where it seemed the convection on the northern flank may have affected GLM quality with values decreasing on the north side. Note the reversed image loops.

Here’s an instance where GREMLIN’s max intensity happened before a lightning jump. Unfortunately this is reversed, but GREMLIN struggled to resolve an intensifying storm in the middle of the line.
Here is an example of GREMLIN losing a cell in 3 surrounding cells.

Kadic

Tags: None

OCTANE CTC/CTP Near St Joseph MO

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

Examining the qualitative appearance of OCTANE Cloud Top Divergence (CTD) and Cloud Top Cooling (CTC) products with storms near St Joseph MO.

First image: 2001Z. A series of updrafts is noted, several with mature CTD signals in blue/purple/red. Most notably is the signal over Leavenworth/Platte counties (largest CTD signal, near the bottom). The CTD signal here is large and mature, which implies a very strong updraft relative to the other storms in the area. The size of this feature does matter, as it implies the updraft (and thus the outspreading of the anvil) is very strong relative to the others. To add on to this, there is a CTC signal (green dot) associated with an overshooting top. This indicates that even though this storm has already produced a significant updraft, it continues to produce an overshooting top, implying the updraft is still strong and mature.

10 minutes later, things have changed. The image below is from 2011Z. Now, the CTD signal has spread out considerably and it appears the storm has past maturity. The more fragmented / strung-out appearance of the OCTANE CTD signal is a sign that the storm is likely weakening. There is also no longer a CTC signal associated with that particular anvil. Rather, it appears a new CTC signal (a new updraft) is going up on the southern flank. This is a sign that these storms are cycling and have more of a multicellular mode than a supercellular mode at the moment.

 

 

–Insolation

Tags: None

Using OCTANE cloud top divergence for severe development situational awareness

Posted in OCTANE Speed Sandwich, SPG2024 on by Kevin Thiel.
The OCTANE cloud top divergence product offered situational awareness in the development of a severe thunderstorm north of Kansas City. While the pink and purple values in the cloud top divergence increased, radar data at the base tilts showed little signal of intensification. There were signs of intensification aloft on the KEAX radar, but the OCTANE product allowed for a more easily available signal of growth aloft if the forecaster wasn’t moving through the radar tilts at the time. About 10 minutes after the first image below, a warning was issued as the storm aloft fully matured.

 

 

Tags: None

OCTANE Speed Assignments in Montana

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

An area of thunderstorms over southern Montana was examined using OCTANE and other satellite imagery.

Of interest in particular is the storm over western Big Horn County. The day cloud phase loop (bottom right) shows that this is a slow-moving thunderstorm, but there is also a bunch of patchy/streaky high cirrus moving much faster over top of it. Looking at the OCTANE speed sandwich (top left), it appears that the convective updraft was assigned the speed of the faster cirrus (yellow/orange, ~80kts). In reality, this updraft is moving much slower. For the sake of comparison and verification, notice the two updrafts over Stillwater County. These updrafts appear similar in nature based on the day cloud phase imagery, but the Stillwater County storms do not have any high cirrus contaminating the signal. As such, they are assigned a proper velocity on the OCTANE speed sandwich (green, ~30kts). There are also some artifacts in the divergence (bottom left) with the Big Horn County storm.

–Insolation

Tags: None

End of Day 1 Thoughts

Posted in GLM DQP, GREMLIN, LightningCast, OCTANE Speed Sandwich, PHSnMWnABI, SPG2024 on by Kevin Thiel.

Thoughts at the end of Day 1…

The LightningCast product I think would be VERY useful for DSS. Overall, when seeing it perform in real-time, the increasing LC probabilities seem to eventually correlate well with GLM flash density. I look forward to using the DSS form this week and seeing how that works for specific sites.

The GREMLIN product seems to be a great way to see the overall picture of precipitation (say, for a region). I think it struggles with precipitation intensity a bit (>45 dbZ) both for storm cells and for heavy stratiform precipitation. At the “storm” level, I have seen instances of the model not following the evolution well (either too intense or not enough).

For OCTANE, it was easier to pick out an example of CI and divergence with the IR versus the Visible products. I could use the direction product on its own in operations, but I really like having the speed, direction, and cloud top divergence all together in a 3 panel to identify convection.

PHS did a great job today identifying convective initiation when overlayed on visible satellite imagery. I look forward to seeing how this performs in other areas of the country this week.

Still learning how best to utilize the GLM DQP; but, when looking over Cuba, I was able to better understand how it locates areas where the data might not be the best. I hope to learn more about this product through the week and see more examples of its application.

Forecaster Cumulus

Tags: None

OCTANE Signal With New Convection Near Chicago

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

At 1910Z on May 20, OCTANE picked up a good signal on convection developing just northwest of Chicago, IL. On the Speed Direction product, there was a well-defined difference in direction vector on the southeast flank of the anvil (250deg) versus the western flank of the anvil (200deg).

 

There is also a subtle signal on the OCTANE speed sandwich product, though not as pronounced. Regardless, for a fresh storm just reaching severe levels, it was worth noting.

 

–Insolation

Tags: None