Satellite HWT Day 4 Carl

Satellite HWT Day 4 Thoughts

Octane Direction

During my initial afternoon analysis I noticed a good use case for the directional product in identifying how different air masses may be coming together over the CWA. In the directional product below, we can see the magenta showing the moist surface air mass that is advecting up from the SE into west Texas and western NM. A drier air mass that is creating a bit of a dry line is pushing from the west in the more yellow colors, with some glaciating cu noted within the Day Cloud Phase RGB. Elevated convection that is still persisting from overnight can be see pushing to the southeast in the lower right, giving the more green colors. This provided a very clear and quick way to pick out these different air masses that will be the main players later in the afternoon for potential convection.

MoistGradConv RGB ECONUS

Some really interesting features that stood out when looking at this imagery during the afternoon today. Notice the sharp gradient in the light vs dark greens running across Texas, starting in the southern pandhandle near the NM border and then running SE through central parts of TX. When overlaid with 24 hour MRMS precip, you can see a clear boundary between the areas that received rain last night (the panhandle, darker greens) and the area that did not (lighter green in the Big Bend areas). This clearly stands out in the Snow/Ice NIR band which makes up a portion of the RGB. Moisture can also be seen pooling in west Texas as it moves northwestard along the edge of the Mexican Plateau. Obs later in the day showed that the “brighter” area was mixing out a bit faster given the lack of soil moisture. Some good potential situational awareness being combined within the RGB, given the ability of this to also pick out things like the dry line a little bit easier.

ProbSevere v3

Issued a warning in an area of pretty poor radar coverage (lowest tilt height was around 15kft). MRMS was still capturing a good bit of the freezing level to -20C isothermal levels, so ProbSevere was running pretty strongly with hail probabilities. Additionally, there were some significant bursts of cooler cloud tops, and the Octane product began to show some of the stronger “divergent” signatures that we had seen throughout the week as well as highlighting a clear AACP, all signs of a stronger updraft capable of keeping hail lofted.

Given the environment, these products definitely gave me additional confidence and potential lead time, given these cores really grew tremendously about 15 minutes later, including an eventual split and right mover that likely produced some large hail (hard to verify in this area given lack of population).

More Octane (Speed)!

Another picture from later of how this storm grew and exploded. Octane was showing yet another AACP. A very interesting feature of this is that Octane speed algorithm does seem to be “tracking” the AACP in a way. There are a lot of research groups out there that have been looking at ways to track these features for injections of tropospheric moisture into the stratosphere among other things, so this could be a novel way at looking at that problem.

An hour or so later, we can see how the Octane product can be used to see that a storm was weakening. The deep blue divergent signature began to quickly fade, an indication that the updraft wasn’t as strong as it was previously. Given this is data flowing in from the mesoscale sectors on GOES 16, we are getting one minute updates, which will give some lead time over analyzing the core of the storm via the radar or MRMS which needs to get the radar data and then process it. This can be important for SVS or considerations for a downstream severe. I ended up still issuing a downstream severe, but was able to use what I was seeing in the product with the weakening trend to decrease the expected hail size. MRMS and ProbSevere trends closely followed, moving downward in severity.

Above: Weakening trend starts around 22Z for the Octane Speed product in the top left

Below: ProbSevere and MRMS trends begin to come down around 22:05Z or so, lagging the above by a few minutes. Every minute counts in lead time.

-Carl Coriolis

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Afternoon High Plains Convection in Southern Colorado

Today we focused on the Pueblo, Colorado  CWA for afternoon High Plains convection. Scattered convection developed across the CWA leading to large hail and damaging winds. The first Severe Thunderstorm formed on our CWA border with Albuquerque and drifting south into their CWA. A second Severe storm developed and tracked north towards our DSS Event in Pueblo, bringing the potential for large damaging hail and strong winds.

15Z PHS MUCAPE valid at 18Z showed around 2000  to 2500 J/kg for green areas while areas in blue had roughly 1000 to 2000 J/kg.
SPC MUCAPE Mesoanalysis valid at 18Z shows similar trends to the 15Z PHS MUCAPE values.

16Z PHS valid at 21Z showed a slight upward trend of MUCAPE in the eastern half of the CWA. 

21Z SPC Mesoanalysis showed increasing values of MUCAPE developing just south-southeast of the CWA, similar to the 16Z run of the PHS shown above. 


15Z PHS STP valid at 18Z showing little overall threat for tornado concerns through early afternoon, for the most part values were less than 0.25. 

SPC Mesoanalysis page showing 18Z STP values similar to the 15Z PHS forecast. 

The image below shows the Octane Speed product on the left and the Octane Direction product on the right, focusing on a cluster of activity near the Jefferson/Douglas County line in Colorado. Picked this screen capture as it showed a wide range in values, mainly for the Direction product. The Octane Speed product shows some speed shear present with the lighter speeds (darker blue, ~5 kts) transitioning to brighter green/a bit of yellow (~30 kts). The magnitude of directional shear was higher, showing direction of motion/divergence ranging from ~170 degrees (core of red area) to ~295 degrees (core of green area).
Below is a animated graphic showing the transition in both products. 


Chose to grab this Octane Direction product screen capture as it shows an elongated area of storm top divergence through central Colorado.  The red/magenta colors show direction generally from the 170-190 degree range, while the green/yellow colors show values from the 275-285 degree range. The black areas are spots of data dropout, which can occur when the speed shear product drops below 5kts.


First Severe Thunderstorm Warning issued for this area today came right after 20Z, based on ProbSevere values/time series as well as the Octane Speed Sandwich product.  Probabilities ramped up quickly for both ProbSevere and ProbHail on this storm at the edge of the PUB/ABQ CWA boundary. Octane around “peak” of the storm.Low Level SRM and ProbSvr (0.5 deg slice is about 10.8k ft AGL)Mesh showing 3 inch hail on the border of the Pueblo CWA.

ProbSevere and ProbHail maxed out at roughly 90% while the storm remained severe. This storm eventually moved into ABQ’s CWA.———————————————————-

2nd Severe Thunderstorm Warning – Huerfano County

ProbSevere values and time series for 2nd Severe Thunderstorm Warning of the day, readout is at its “peak”…around 2045Z.
Octane Speed/Direction at “Peak” of the storm,  around 2045Z. Directional shear varied from ~205 degrees (reds) to ~285 degrees (greens).
ProbSevere showing the weakening trend of the storm gave us confidence that the storm was in fact weakening.  Octane speed/direction further confirming the weakening trend as colors become more diffuse in nature.

ProbSevere showing continued weakening trend. We decided not to issue another severe thunderstorm warning on this storm based on the trend.

Though this storm showed a weakening trend, it was a short-lived trend, as it still had ~2000 j/kg of MUCAPE and effective shear around 30kts to work with as it tracked farther north.

The storm ended up re-intensifying, as shown by the ProbSevere output/time series below. We went ahead and issued another Severe Thunderstorm Warning for very large hail.  An increase in both storm top speed/directional shear was also shown by the Octane product.The level reflectivity images show an impressive core peaking in the 36-40k ft range, shown in the 12.5 deg. slice. MESH showing nearly 4 inch hail south of our DSS event in Pueblo. The event was notified about the potential for large damaging hail.


-Dwight Schrute/Bubbles

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LightningCast Over Eastern MT

This image shows Day Cloud Phase Distinction, LightningCast, and 5 Minute CG Flash Lightning Plots for NLDN and ENTLN across Eastern MT.  While LightningCast provides a lot of information, it’s easy for it to overwhelm forecasters in situations like what’s shown, especially if other colorful imagery is included.  A suggestion is to give forecasters the option to load LightningCast in 10% increments from 10-90% (10, 20, 30, etc).  Then, forecasters can turn the individual increments on or off depending on the situation (i.e. lots of severe weather can prompt the lower values to be turned off, or partners concerned with the initial start of lightning can prompt lower values to be turned on).  Having the ability to change the color, line style, and line width for each increment would also be nice.


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Octane Captures Intense Updraft Over NV

Here is a 1 hour loop (1-minute increments) of strong convection over NV.  The top image is Octane Speed with DMW overlayed.  The bottom image is MRMS 0.5 km MSL Composite Refl.  Notice an intense updraft develop in the center of the screen.  The blue indicates lower winds while green/yellow are higher.  Winds get as low as 2 kt in the anvil, while just downstream of it they are 30-40 kt!!!  The DMW confirm this as they are generally within 5 kt of the Octane speed.  Shortly after this happens, reflectivities rapidly increase.


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Here is what the PHS SBCAPE forecasted for 5/24, 20Z across NV.  (Some of the purple circles within the areas of blue hinted at ongoing convection).  This matches up well compared to the forecasted 20Z SPC Mesoscale Analysis SBCAPE.  How did it verify?

The 20Z SPC Mesoscale Analysis SBCAPE had an area that was 2,000 J/kg.  However, this appeared to be overdone as there  was widespread convection occurring across this area.

Remember, the PHS hinted at ongoing convection in some of these areas.


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PHS Comp Refl Data in NV

Here is what the PHS Comp Refl was forecasting for 5/24, 22Z across NV.  How did it verify a few hours later?

MRMS 0.5 km Comp Refl at 22Z showed a broad area of convection over NV.  What’s interesting is how some of the individual storms were very, very close to the locations where the forecast hinted at there being individual storms.  Keep in mind, the radar coverage in this part of the country is not very dense.


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ProbSevere_V3 Captures Hail

Severe storms developed over Hale County, TX on the afternoon of 5/22.  KLBB 0.5 Z reflectivity at 2109Z (top left image) indicated intense convection, especially just southeast of Hale Center.  ProbSevere V3 (the 4-Panel) did well at 2108Z.  The upper left has the ProbSevere Model at 84% with the MRMS 0.5 Comp Reflectivity peak value of 66 dBZ.  The upper right has ProbHail at 85% and MRMS Maximum Estimated Hail Size (MESH) peaking at 1.85″.  The lower right has ProbTor at 12% and MRMS Low-Level Rotation Tracks.  The lower left has ProbWind at 35% and MRMS Vertically Integrated Liquid (VIL) at 55.  Notice how the ProbSevere Time Series ProbHail was at 60% at 2020Z, nearly an hour before this.  What happened?  Here is the LSR…

County, State: HALE, TX
(marker location is approximate)
Lat.: 34.12, Lon.: -101.76
Time: 2023-05-22 21:09 UTC
Hail Size: 1.75 IN. DIA.


Since forecasters should consider warning with lower ProbSevere values for V3 compared to V2, these high values supported a warning.



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AzShear Effectively Detects Anticyclonic Rotation

Two supercells southwest of Lubbock produced perplexing base radar signatures with a clear right-mover reflectivity signature but anticyclonic rotation evident in storm-relative velocity. To its credit, the MRMS AzShear product picked up on the anticyclonic circulation effectively and should be able to detect the rare anticyclonic tornado!

None of the mesocyclone detection algorithms picked up on the anticyclonic rotation. Perhaps this is part of their design. The New MDA tried to detect a mesocyclone southeast of the main anticyclonic circulation on the gradient of the strong outbound velocities, but it is incorrect.

-Atlanta Braves