OCTANE Speed Sandwich – Page 5

San Antonio Waiting Game

Posted in LightningCast, OCTANE Speed Sandwich, PHSnMWnABI, SPG2024 on June 5, 2024 by Kevin Thiel.

San Antonio: broad cu field is still fighting substantial dry aloft despite extreme instability in the Great Bend region. No notable cooling or anything of note in the OCTANE data. Residual outflow boundary from earlier MCS is acting as a mechanism for a lone strong-severe thunderstorm just north of our CWA. Strong OCTANE divergence and cooling seen along the nose of PHS instability gradient with 3500+ CAPE; shear is essentially zero across this region. PHS composite reflectivity clearly did not forecast this outflow and thus the convection.

2100z: Strong-severe lone thunderstorm with very clear and strong divergence signal in both divergence field and speed fields. Rainbow signal seen in the direction field due to the very limited shear.

Orphaning anvils in the cooling OCTANE fields to the west of the primary convection suggest the PSH fields for instability are just displaced to the east at 2100z.

Nice depiction of the PHS being wrong but right at the same time. Clearly slightly displaced with instability gradient to the east, but accurately showed the single cell or two behavior that we have seen.

Impressive single cell continues as of 2130z, and some notable cloud top cooling and divergence is now seen in the cell to the southeast. Instability axis is clearly ~50 miles to the north of the PHS.

Lightningcast is bullish on both the southeast and south newly developing convection. Very broad contours however, possibly too much false alarm area here (?).

Broad persistent divergence in OCTANE fields in the southern cell. DHX radar shows 50 dbZ core over 30k feet within an extreme instability zone of 4000+ j/kg. Issued a severe

Large jump in cooling seen above the divergence field in OCTANE, expecting further intensification shortly in the next.

DHX Radar Divergence maxing out around ~90-100 knots as of 2150z. OCTANE cloud top divergence is generally sitting between 25-40 knots.

Double Rainbow!

Deep persistent OCTANE divergence in speed and direction, core weakening slightly based on DHX radar but still likely warranted a second warning. No signs of real weakening in any of the satellite products, but radar not quite as tall with 50 dbZ core.

-Hellothere

Application of Octane, LightningCast and GREMLIN across western Maine

Posted in GREMLIN, LightningCast, OCTANE Speed Sandwich, SPG2024 on June 5, 2024 by Kevin Thiel.

Maine has an overall weaker radar coverage compared to many other CWA’s across the CONUS. This made it a great place to test out some satellite convective products such as Octane, LightningCast, and GREMLIN. The first image shows the confidence of LightningCast in the development of thunderstorms across parts of north central Maine. Shading shows >75% confidence of seeing 1 or more lightning strikes within the next hour. This was supported by Octane, which showed increased cloud cooling occurring over this area along with large areas of cloud top divergence. What happened nearly an hour later was for the most part on point. GREMLIN and reflectivity showed patchy storms developing across the region; this was also shown on ENTLN lightning plots. GREMLIN did a great job of highlighting the stronger storms with higher reflectivity although those were lower than the actual reflectivity. The lightning plots showed large clusters of lightning, which was nearly identical to where LightningCast had drawn contours nearly an hour before. Overall, the use of all these products together in my opinion would greatly improve convective forecasting as I feel they work great together. This was once again shown today across Maine by highlighting areas with potential convective development and eventual patches of high density lightning strikes.

-Sven The Puffin

OCTANE CAN ENHANCE SITUATIONAL AWARENESS

Posted in OCTANE Speed Sandwich, SPG2024 on June 5, 2024 by Kevin Thiel.

Thunderstorms formed over portions of New England (Maine and New Hampshire) along the periphery of an exiting upper level low. This convection was primarily diurnally driven with a lack of forcing.

With marginal storms that developed I wanted to take the approach that I was without certain data, like some radar tools and probsevere. There were two storms that were showing a little promise of getting near Severe limits. One storm developed south of Portland in which we warned on which was very close to the radar cone of silence. A second cell developed further to the west with some dialesing and some poorer radar quality. When going through the various experimental data since the storms were marginal I attempted to see if I could qualify relative storm intensity with the use of OCTANE.

Below you can make out the first cell which weakened towards Portland, however a second cell has ticked up showing 60 dbz reflectivity for this scan at 21:18z.

I began examining this second cell a few minutes earlier with satellite products. I noticed earlier with visible satellite data and along with the CTC (Cloud Top Cooling OCTANE product) that there was convective initiation. But then use of the CTD (Cloud Top Divergence -see purple shading in OCTANE bottom left of 4 panel below) also indicated divergence aloft, and in subsequent scans speed divergence was increasing (upper left panel). You can make out on the upper left panel the Octane Speed which shows a second area of speed divergence with activity off to the west. I played with the color table to draw out this feature a touch just as the cloud top divergence indication began to increase in order to attempt to see a visual trend.

This was a storm that ticked up briefly. I pretended that I did not have probsevere, along with radar reflectivity and velocity. As it turns out ProbSevere did tick up to 20 percent around 21:18z

The decision was made not to warn on this cell. It turned out to be a good thing as afterwards I inspected various radar features and MESH did not indicate a severe hail threat as it only ticked up to under a half inch. And radar reflectivity briefly ticked up to 60 dbz but with no velocity core and thus no severe hazard threat.

What OCTANE provided here was a guide as to where to look next. OCTANE can be helpful, at least it was in this case in terms of where to look next, especially when you get the speed divergence and cloud top divergence (CTD) signatures. IF speed divergence signatures values decreased (lower down the color curve) on the upshear side of the cell, then perhaps that may have been a signal to warn, but they did not increase and this was the proper decision as available radar tools suggested not to warn on this cell.

– 5454wx

Monitoring Convective Trends across WFO MPX

Posted in OCTANE Speed Sandwich, SPG2024 on June 4, 2024 by Kevin Thiel.

This scenario began at WFO MPX with a broken line of strong thunderstorms approaching from the west. Many small-scale features were identified using OCTANE and radar trends, with focus on a DSS event ongoing “Fishing Derby” in Wright County, MS.

Doppler radar and Day Cloud Phase Distinction both illustrate new development ahead of the main activity to the west, ahead of an eastward surging outflow boundary. This led to the first DSS notification giving the event a heads up for >30mph winds and lightning in the next 1 to 2 hours. LightningCast was helpful showing probabilities increasing from the west.

One specific updraft noticed around 20:00Z, with the decision for a warning to follow along with 40dbz around 40,000ft ARL. OCTANE products were specifically helpful, especially by modifying the colorbar settings for OCTANE Speed. Decreasing the MAX from 200 to 100 and increasing the MIN from 0 to 15 gave a greater contrast and “bullseye” to help diagnose strengthening divergence.

Several additional DSS notifications were sent to the site to alert them of not only the approaching activity, but how long the activity might last over the next following hour.

A TSTM Wind Dmg LSR followed with this storm that led to an injury.

LSR: *** 1 INJ *** Corrects previous tstm wnd dmg report from 7 N Hutchinson. Relayed report from sheriffs office of a shed with roof blown off and sides collapsed

Again, OCTANE gave great situational awareness to support alongside with radar to lead to proactive warning decision.

– RED11248

Tracking convection across DLH CWA with Octane, LightningCast, and GREMLIN

Posted in GREMLIN, LightningCast, OCTANE Speed Sandwich, SPG2024 on June 4, 2024 by Kevin Thiel.

Forecasting in DLH today was challenging due to the radar being made unavailable. However, some of the satellite convective products were able to create accurate forecasts regarding the location of storms and lightning. Firstly, looking at Lightningcast there were gradients of ~25% appearing 1 hour out around the DSS point indicating the possibility of lightning developing within the next hour. This was also supported by Octane, which was showing storms initiating to the south with early signals of cloud top cooling and divergence occurring. Around 1 hour later this seemed to mostly come to fruition, which can be seen on the 4 panel image with GRMLN data on it. Lightning seemed to be mainly concentrated east of the DSS point which was shown in lightningcast. Also these storms originated from the south which Octane began to hint on early out. Overall, it looks as if all three of these satellite convective products did a good job in forecasting possible convection without the use of a radar.

-Sven The Puffin

RADAR DOWN IN DULUTH CWA

Posted in DSS, LightningCast, OCTANE Speed Sandwich, SPG2024 on June 4, 2024 by Kevin Thiel.

Without the use of radar out of Duluth more reliance was given to Satellite derived observations and satellite derived output.

Below is the OCTANE cloud top cooling and cloud top divergence product. You may notice in an area of moderate but increasing instability there is convective initiation ahead of the main line of convection. However, you can notice early in the loop that there is convective cooling indicated in the south-central portion of the CWA and the far SE portion of the CWA. Notice how in the far SE portion of the CWA there is the purple shading indicating cloud top divergence. And in south central portions there are “hotter” yellow and tiny red(s) (may be hard to notice due to scale) pixels indicating cooling cloud tops, but with no purple shading and thus no meaningful divergence at the cloud top. This is indicative of orphan anvils. The moral of the story here is that without radar the OCTANE product heightens your attention to the cells in the far SE portion of the CWA, and this would be where to consider SVR or SPS product release, with the activity across South Central portions of the CWA failing to produce significant convection at this point in time despite moderate to strong instability.

Further southeast however notice that there is stronger instability over SE portions of the CWA, thus the OCTANE product is giving you a result which coincides with where there is higher instability (higher MLCAPE – see SPC mesoanalysis).

Lightning Cast continued to show high confidence of lightning over the next 60 min with the linear MCS moving into western portions of the CWA. This lead to high confidence in forecasting lightning for a DSS location (Solana State Forest) during this event.

Steady behavior with the greater than or equal to 10 flashes in the next hour.

High probability of 1 flash of lightning in the next hour, increasing then holding steady

Here (below) is the Lightning Cast and GLM dashboard output comparing the forecast to the GLM flash count. Note: the dashboard was down initially but came back online

Thus we were able to give a high confidence lightning forecast for DSS.

Here is the GLM Flash Extent Density at the time of the Lightning Cast 1 hour forecast.

– 5454wx

OCTANE Speed Product Shows Weakening Trend in Storm Well

Posted in OCTANE Speed Sandwich, SPG2024 on June 3, 2024 by Kevin Thiel.

A strong storm with a well defined mid-level mesocyclone entered the western portion of the MKX CWA at around 4:00 PM CDT. At the time, the OCTANE speed product showed a well defined gradient and the divergence product showed fairly high values, indicating that the updraft was quite strong. We decided to issue a severe thunderstorm warning with a tornado possible tag on this cell as a result.

Not long after the warning was issued, we noticed a significant weakening trend in the reflectivity signatures. This weakening trend was supported by the OCTANE products as well, with a much more diffuse gradient in the speed product and lower values in the cloud top divergence. An interesting thing to note, though, is that the Day Cloud Phase imagery looks nearly identical to when we issued the warning, so it did not capture the weakening trend.

Another interesting thing to note is that the IR imagery did not seem to indicate that there was as much weakening either. One image from around the time of warning issuance and one from around the time when the warning expired are shown below.

In all, the OCTANE products seem to be very useful in assessing the strength of a storm’s updraft. Looking forward to gaining more experience with it and the other products throughout the rest of the week.

– EI2018

Severe thunderstorm warning issued for South Central Wisconsin

Posted in OCTANE Speed Sandwich, PHSnMWnABI, SPG2024 on June 3, 2024 by Kevin Thiel.

Solid signature from both nearby radars but the beam height was at least 8k feet. PHS environmental fields were supportive of a primary wind hazard. OCTANE divergence fields distinctly noted this cell with persistent strong divergence as it moved into the CWA. Low level wind fields were not as impressive with widespread STP of less than 0.2, despite strong instability in the PHS fields.

-Hellothere

High Confidence in Progressive/Weak MCS

Posted in GLM, LightningCast, OCTANE Speed Sandwich, SPG2024 on June 3, 2024 by Kevin Thiel.

KSHV radar trends illustrate a cold-pool dominated, weak MCS approaching the NW corner of the CWA. Many satellite products illustrated a consistent mainly sub-severe weather episode unfolding giving increasing confidence in the near-term forecast and expected impacts. Focus would be on any stronger individual updrafts for potential isolated severe thunderstorm warnings.

Overall, there was high confidence in approaching thunderstorms per radar and LightningCast data pinpointed the ongoing widespread nature of the convection, given several embedded impulses of GLM spikes behind the leading southeastward surging outflow boundary:

East Octane SpeedDirCTD-CTD_4Pan procedure provides more calculated parameters on top of RGB and ABI products to quickly diagnose convective strength/intensity.

The top 3 panels below (OCTANE speed, direction and Cloud-top Cooling and Divergence) identify a large-scale cirrus canopy with embedded updraft impulses.

Situational awareness was enhanced by adding on local KSHV and KLZK radar which helped to identify a SSW to NNE boundary and associated CI ahead of the main line, which OCTANE products began to illustrate (see center of each product, identifying increasing speed/directional divergence colocated to the convection along the boundary)

Given the environmental parameters, this would have been a location to examine for the potential of a severe thunderstorm warning, especially if associated radar trends (RIJ via radial velocity) indicate increasing downdraft wind potential.

– RED11248

Finding Boundaries in OCTANE Direction and Comparing to Satellite

Posted in OCTANE Speed Sandwich, SPG2024 on May 23, 2024 by Kevin Thiel.

As a forecaster, I’m most accustomed to pulse severe conditions, and I work in an area where there tends to be abundant cloud cover. So being able to find boundaries is really helpful. So I decided to review some of the low-level cumulus fields in OCTANE and looking how accurate they are compared to current derived GOES East winds. From what I sampled, they were within 5 degrees of OCTANE.

Now zooming out, we see that there will be an area of confluence in the wind field based on the low-level cu field. Further aloft, you can see some of the diffluence along the warm conveyor belt. Sometimes, wind barbs are really useful tools to assessing an environment, and I think a similar function in OCTANE could be useful for mesoanalysis.

Kadic

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Spring Experiments & Beyond

Category: OCTANE Speed Sandwich