Tag: GLM

Long Flash via GLM in the Anvil / Stratiform Region

Posted in Live Blogs on by Michael.

GLM does a good job at capturing large flashes that appear in the stratiform region behind lines of storms. In this case looking at the Total Optical Energy for 5 minutes with 1 minute updates you can see the large flash show up (the yellows and the whites). Reflectivity from KMOB and Visible satellite are layers under the TOE data.

This large flash has Minimum Flash Area values between 1100-1700 km^2 with the Average Flash Area anywhere between 2700-3600 km^2. This is a large flash that extends back into the stratiform region (the Anvil) of the cumulonimbus clouds. You can see the lighter precipitation on the RALA (Reflectivity at Lowest Altitude) product below. The darker blocky outlined area is the Average Flash Size with other variables in the 4 panel.

One important operator note is to be careful what you time match with the GLM lightning data. In this case another forecaster had time matched with the 1 minute meso-sector of satellite and because of errors in that data the large anvil flash was skipped in the one minute GLM data. If the GLM data is the focus of your analysis always remember to time match with it and then use other data (like satellite or radar) on those time scales.

-Alexander T.

G16 and G17 Flash Extent Comparison

Posted in Live Blogs on by Michael.

Showing a quick comparison of G16  and G17 Flash Extent Density over srn Texas.

Takeaways – some “minor” changes in Flash Extent absolute values but trends are similar.  Quick look – had higher values than G17.  Also, parallax is different – but to be expected.  Overall – think both products could be used interchangeably across TX.

The Evolution of an Intensifying Cluster

Posted in Live Blogs, Mesoscale Discussions on by Michael.

Storms in the EWX CWA early in the shift were generally remaining sub-severe, with what looked to be heavy rain as the dominant threat. The first two loops (below), the storms were riding right along the gradient of the PWATs and CAPE. (continues below)

As the cluster of storms reached the eastern edge of a greater area of instability (below), the concern then turned to how much of the instability would be tapped into and how storms would react, with the thought that they’d likely become more robust. (continues below)

Attention was then turned to how the GLM was observing the evolution of the stronger cluster of storms within the northeastern portion of the CWA. I created a four-panel display, with MFA overlaid onto the mesosector visby imagery (upper left, below), clean IR with TOE overlaid (upper right; I had blinking enabled to capture the highest fJ, but is unseen in this GIF), Event Density with Group Centroid Density overlaid (bottom right, below), and FED with Flash Centroid Density overlaid (bottom right, below). It was fascinating to watch how the lightning unfolded with this particular cluster, and the MFA in particular immediately drew my eye to the storms moving toward the FWD CWA border. The smaller flashes began to blossom and expand out, which then had me look at the TOE and density products. The density products ramped up, but what I found the most interesting is that the MFA seemed to give me that initial clue that this storm was in fact tapping into some of the higher instability and allowing for the updraft(s) to intensify.

I then proceeded to take a look at the MRMS LL AzShear product (below), wistfully wishing I could look at the single radar version of this product. Sure enough, a clear signature developed, highlighting the amplifying wind within this cluster.

Last but not least, looking at ProbSevere, the ProbWind product picked up well on this signature, highlighted below.

Conclusion: I’m continuing to see some promise that there’s something to look deeper into with respect to these additional lightning products, particularly the MFA when used in combination of something like the Event or Flash Extend Density products. There seemed to be a good correlation with the TOE, as anticipated, but I’m still unsure about its utility as a stand-alone product. As for the Average Flash Area, I didn’t even pull it up given the limited amount of screen space I had and what I saw yesterday, with the AFA in particular not giving me hope of being able to gather good info/lead time in comparison to the MFA.

~Gritty

Side note: Had some excellent conversation with the GLM expert in the room and as we were talking and analyzing some of these products, it was noticed that there was quite an extensive channel, lightning that shot out well to the north of this cluster of focus. These GLM products could provide beneficial information when providing DSS to partners, such as letting partners and the public know not to go back outside just because there’s either light rain or the storm had already passed.

GLM Products Identify Hook Echo

Posted in Live Blogs on by Kristin C.

In our NWS Corpus Christi Warned Storm (ACTUAL NWS CC) The GLM did a fantastic job of identifying the rain wrapped hook echo. I’ve attached visuals and corresponding velocity. Just thought it was pretty neat. The satellite and radar imagery was a little too busy to define it as nicely as the GLM did.

-lakeeffect

HGX Mesoanalysis

Posted in Live Blogs, Mesoscale Discussions on by Michael.

Storms are approaching the HGX CWA. GOES-16 imagery shows amply cumulus development across much of the CWA. With temps in the upper 70s and dew points in the upper 60, I expect there to be ample instability in this environment.All Sky LAPS retrievals indicate ML CAPE just shy of 1000 J/kg, but with this environment, I would expect instability to be higher. The modified NUCAPS shows a profile more in line with what I would expect to see. In this profile, the surface dew points were close to what surface obs show, but the surface temp did need to be adjusted up a bit. This sounding, coupled with analyzed deep layer shear, leads me to think severe weather is a possibility in this area.Sandor Clegane

GLM Assist In DSS

Posted in Forecaster Thoughts, Live Blogs, News on by Michael.

The below image shows GOES-16 day cloud convection (DCC) beneath GLM Minimum Flash Area (MFA). Point F is a DSS event. DCC shows clouds glaciating a county upstream of our DSS event, with the storm becoming electrified shortly after glaciation per MFA. This prompted a call to the emergency manager providing support for the DSS event letting them know that lightning was imminent.

ENI total lightning also shows lightning (white points), but the point data fails to show the extent of the lightning, which may lead decision makers to think that they have more time to react to the approaching lightning than they actually do.Sandor Clegane

GLM MFA for Storm re-generation

Posted in Forecaster Thoughts, GOESR, Live Blogs on by Kristin C.

GLM Minimum Flash Area showed some utility in boosting lead time for storm re-generation. The storm in the center of the first image had started to weaken a bit after moving off of the outflow boundary that initiated it.

The storm continues to show no new updraft development in the sat imagery as well as MFA product.

At 20:29 GLM MFA begins to indicate that there may be a new updraft forming as it interacts with a differential heating boundary/outflow from the leading storm.

Over the next 20 minutes the updraft continues to strengthen as the storm becomes more robust. The MFA led the visible satellite depiction of the new updraft by 2-4 min. This could be useful when trying to decide whether to continue warnings or not.

 

 

 

Waiting on convection – diagnosis and investigation of products

Posted in Forecaster Thoughts, Mesoscale Discussions on by Kristin C.

Corpus Christi —

In investigating the environment we’ve deemed the convection to be more or less dependent on synoptic forcing via the cold front dropping southeast.

A

In A, plotted is Total Precipitable Water along with SPC Convective Outlook and analyzed fronts. A couple of things can be noted: TPW is very high under the Slight Risk, and it is displayed very nicely with good resolution contained within the gradient. This is a good example without going into too much detail about how our environment is primed for severe weather. However, NUCAPS Gridded Data has not come into our area as of 20z. This makes it hard to test the product and how it captures the boundary layer. 

Now, we wait.

B

As we wait for the cold front to drop SE, our attention is focused on convection happening in NE Mexico (pictured in B). These cells popped up right along the CAPE boundary between values of 300 j/kg to 1500 j/kg.

C

As can be seen in C, the GLM has indicated these storms contain lightning, thus they are intensifying in nature. We will now be monitoring the hail threat.

 

-lakeeffect

More Lightning Analysis…

Posted in Live Blogs on by Michael.

So far, the MFA is following the previous logic of using it as a way to identify vigorous updrafts. Below, the progression in a 15-minute period follows that correlation between the smaller flashes increasing in area indicating a strengthening cell(s). However, I could see its utility degraded in a larger-scale multicell environment with clusters close together, especially as the areas of smaller flashes increases, given the low-resolution of the grid itself. As for Total Optical Energy (TOE, at the bottom), I think there is benefit in using this product as well to monitor trends, but I had to use a different color curve for it to stand out to me more (last animation, below).

~Gritty

2146Z:

2155Z:

2200Z:

TOE Loops: