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

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Learning the Ropes – GLM DQP Applications!

Posted in GLM DQP, News, SPG2024 on by Kevin Thiel.

GLM DQP: learning about its application – where data might be suspect or questionable. Where convection/GLM is along the line/boundaries could be such areas. Although not in Cheyenne’s CWA, saw an example over Cuba of pink pixels (at or near saturation), but could see lightning detection around it. This was an area near one of the boundaries (pink pixels were right along the line).

GLM DQP 1949Z over Cuba 20 May 2024 – pink (at or near saturation) pixels along boundary line

 

Forecaster Cumulus

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GLM Glint in South America / Panama

Posted in GLM DQP, SPG2024 on by Kevin Thiel.

A glint was observed on various data sources tracking westward across northern South America and Panama between about 1630Z and 2000Z on May 24.

The glint is plainly evident on visible imagery (bottom right) and GLM Background (top right). On the GLM Data Quality, you can witness pixels that reach saturation over South America (directly related to the glint) — but there is also an area of convection that gets to near saturation over Panama. It appears that the most direct sun angle roughly coincides with the mature phase of these thunderstorms over Panama, leading to a period of near-saturation that eventually fades as the convection weakens. Convection can be confirmed by the presence of GLM flashes, but there does appear to be a relative min in GLM flash detections coincident with the near-saturation area.

 

–Insolation

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Terraced SBCIN PHS Product in SW Kansas

Posted in PHSnMWnABI, SPG2024 on by Kevin Thiel.

At 22Z (5hr forecast) the PHS SBCIN product was showing a terraced appearance in SW Kansas. Maximum values were above 350, dropping to around 100 (blue/purple) a couple counties to the north. Between the two, there is the appearance that SBCIN decreases then increases again. Wanted to document this to see if there is a known cause for this appearance in the PHS data.

 

–Insolation

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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

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PHS Forecast For Supercell in Northeast Colorado

Posted in PHSnMWnABI, SPG2024 on by Kevin Thiel.

Have been looking at PHS data and forecasts in northeastern Colorado. In simulated composite reflectivity (bottom right), there is an indication of a supercell (perhaps right-moving) tracking eastward toward the CO/NE/KS triple point. PHS indicates that this supercell will be tracking into an increasingly favorable environment, and by 02Z, it will be entering an area with much larger CAPE and a nearby local maxima in STP.

 

Using more traditional mesoscale analysis (such as SPC) there are indications that this forecast is sound. For example, the 6hr SPC mesoanalysis forecast (valid 04Z) shows a supercell riding the northern gradient of an STP bullseye. Knowing that it’s often not the bullseye of a parameter to be concerned about, but rather the northern gradient, this has raised my interest as a forecaster.

 

To me, the PHS data provides additional confidence in the potential for this storm to become quite strong a few hours from now. Based on mesoanalysis, this storm could be capable of producing all hazards, with hodographs (SPC meso) and STP (both SPC meso and PHS) suggesting a tornado threat is absolutely there. I would probably use this information to start adjusting messaging, in sort of that in-between watch-and-warning paradigm.

–Insolation

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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

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Identifying potentially stronger thunderstorms with IR OCTANE divergence and LightningCast

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

 

Displayed here are OCTANE products built from both visible (right panel) and IR (left panel). What caught my eye is the characteristic of the OCTANE direction in the IR panel, where directional divergence is showing up much more clearly than in the visible OCTANE product. This is especially showing up in the northern set of storms, where LightningCast is also highlighting for a probability of >10 flashes in the next 60 minutes (shown below). These both highlight an area with a higher probability for more intense convection in the near-term.

-Joaq
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LightningCast and DSS

Posted in DSS, LightningCast, SPG2024 on by Kevin Thiel.

Viewing CI and LightningCast (LC). LC probabilities on the SW portion of the storm (in the center) at 1958Z ranged between 70-75%. Just before GLM signatures pop up at 2007Z, LC probabilities jump up to around 82%. Not included in the animation, but at 1951Z, LC probabilities were around 50%. The overall trend upward would give me confidence that I can use this product to tell an emergency manager the potential for lightning is medium to high within the next 10-20 minutes (using this case, hypothetically starting at 1951Z).

Lightning Cast product overlaid on Cloud Phase Distinction on the left and radar reflectivity on the right. 20 May 2024

Forecaster Cumulus

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