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

Lightning at the Chilé and Frijoles Festival

Our DSS event in Pueblo, Colorado today was at the Chilé and Frijoles Festival in downtown Pueblo (former HWT liaison Bill Line stated that the festival is very tasty). A severe storm approached slowly from the south, with LightningCast helping the DSS forecaster on the Pueblo desk provide simulated updates to event managers. In Figure 1, the "B" point in the middle of the images is the approximate location of the festival. 

Figure 1: LightningCast probabilities, GOES-16 day-cloud phase distinction RGB, and GOES-16 GLM flash-extent density.

Figure 2 shows the trend of LightningCast probabilities (for 1-min and 5-min sectors; top) and the trend in lightning observations for GLM and ENI (blue and orange; bottom). Forecasters have noted the utility of this capability in general, and one forecaster has noted that this capability could be a "game changer" when deployed on site to DSS events. For this advecting storm, a LightningCast probability of 50% provided about 50 minutes of lead time to the first flash within 5 miles of the festival site. 

We also had a good discussion about evaluating the lead time differences to the first nearby flash among initiating and advecting storms at given locations.

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.

-Champion

PHS SBCAPE Data in NV

 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.

-Champion

Octane Weakening Storm

 If we look at the cell on the border of Huerfano and Las Animas at the beginning of the loop has high speed (red and yellow) on the loop showing a mature thunderstorm. However, as the loop continues we notice the wind speeds quickly drop (green). This indicated the storm was starting to weakening which was verified on radar.  -Thunderstruck

Finding The Low Level Moisture Axis From The Octane Direction Product

  

The 19Z Octane Direction product depicts the low level southerly-flow  moisture axis well with the  the red/purple hues of the shallow cumulus from northeast New Mexico through the AMA and LUB CWAs. This clashes well with the westerly greens shown from the maturing convective towers and anvil clouds coming off the ABQ terrain, lining up with the westerly flow aloft. It's difficult to see the separation from where convection is rooted currently in north central New Mexico compared to where the southerly moist axis is to the east. That said, it's fair to expect a more favorable convective environment within that moist axis for thunderstorms to move into and strengthen later this afternoon or evening.

-Joaq

Storm Top Divergence Progression in a Severe Storm With Octane Products

 Shown is the progression of developing tower to severe storm with strong storm top divergence on the thunderstorm over the Colorado/New Mexico border. From around 1940Z to 1955Z  the Octane Speed showed the development of storm top divergence while both versions of ProbSevere increased in severe probabilities. The Octane Speed product then showed the upshear side of the storm become "stationary" as the storm top divergence strengthened even further after 20Z, lining up with ProbSevere V3's signal that the storm had become severe.

-Joaq

Differences in low level moisture between NUCAPS and guidance

 The NUCAPS sounding pass showed greater MLCAPE than the RAP sounding shown as well as the RAP output on the SPC Mesoscale analysis. A difference may be how the RAP is mixing out low level moisture, as it has a lower mean mixing ratio (8.4 g/kg) than both the NUCAPS pass and the NAM forecast sounding at the same point (10.1 g/kg and 10.4 g/kg respectively). The NAM is known to have an undermixing bias but may be closer to reality in situations like this where the surface isn't quite so hot and dry, giving more confidence to the NUCAPS instability.  Convection this afternoon is building into this area of instability, which makes the analysis important as it could play an impact on the magnitude of severe hazards.

-Joaq 

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.

-Champion

PHS PreStorm Environment

 Looking at the pre-storm environment using PSH we can see higher MUCAPE in the eastern most portion of ABQ CWA. We also looked at the SHIPS model on the PHS website and saw high number also in the eastern region of the CWA. That indicated to use the best chance of storms would be in the eastern most half of New Mexico and the biggest threat would be hail. PHS did excellent in this event. We have been seeing a few good hail cores in the area of the highest CAPE while areas to the west of of higher CAPE has see a storm or two but nothing close to severe.   .-Thunderstruck