Author: Justin

Wrappin’ my head around some other GLM stuff

Posted in GLM, Live Blogs on by Justin.

Upper Left: 1-minute visible with 5 minute cloud flash (1-min update)
Upper Right: Total Optical Energy
Lower Left: GLM Average Group Area
Lower Right: Event Density

Bright yellow/orange colors on lower left depict a smaller average group area associated with a tighter concentration of flashes. We are intermittently seeing greater concentrations at the southern extent in an area otherwise associated with little activity. 

Now taking a look at a specific time below…

We see a single pixel of orange (lower part of lower left panel) corresponding with a small group area. This appears to be associated with two fairly isolated ENTLN flashes (upper left).  Total Optical Energy (upper right) and Event Density values (lower right) are not overly impressive, which is not surprising, given the limited activity.

Now for something else that’s rather striking (ha ha) in the eastern half of this area. ENTLN cloud flashes depict two active areas in the northeast corner but little if any activity to the southeast beyond that. Shown another way…

So, we see good connectivity in probable electrification from northwest to southeast that is not otherwise apparent in the flash data. So, I’m slowly coming around to the idea that this can be helpful for IDSS applications when lightning is a concern with multi-cell clusters featuring extensive anvil coverage.

#MarfaFront

GLM – Florida Coast

Posted in GLM on by Justin.

Convection off the coast of Florida developed into a few organized strong to severe storms over marine zones. GLM Flash Extent Density (upper left)  was far and away the most useful of the GLM products available for warning operations. The strongest storms were the most evident on this product compared to the others, and rapid lightning increases were most easily noted. This allows for quick use of the lightning data for situational awareness and setting priorities when there are numerous storms to interrogate. The other GLM products generally washed out any signal of which storms were the strongest, and didn’t provide as much information about overall storm trends.

 

The rapid 1-minute update times that can be linked with 1-minute meso sector satellite imagery and 2-minute MRMS data can allow for more rapid warning decisions (and thus more lead time) when all considered together with base radar data.

Compared to ENTLN 1km total flash data, there wasn’t much difference in warning utility between the two products. The same information can be derived from each product in terms of storm intensity and picking out the strongest updrafts. I would give a slight edge to the ENTLN in terms of product display as the smaller grid allows for better viewing of the background satellite imagery. However, the spatial extent aspect of the GLM has advantages for public safety messaging. So overall a very even match between the two products.

— warmbias —

 

AllSky vs. ProbSevere: Which MLCAPE is best and where?

Posted in HWT, Live Blogs, ProbSevere on by Justin.

When utilizing the AllSky CAPE image product (MLCAPE), and comparing it to the ProbSevere MLCAPE values for reliability purposes of both tools, it is noticeable the differences between the two when there’s precip. This is due to the fact that most rain areas will not be able to be sampled by the satellite (clear/cloudy), and will be utilizing the GFS data in these areas where ProbSevere is located.

One way around this difference reliability issue is to scan the surrounding areas that are utilizing satellite data (preferably a “clear” spot), and in those cases, the MLCAPE values sampled seemed more comparable to the ProbSevere MLCAPE (RAP) of the storm than that of the GFS sampled MLCAPE data. The GFS sampled locations almost always show a lower MLCAPE value than the ProbSevere MLCAPE. The downside of sampling farther away from the storms/precip areas is that you are sampling rather far away from the storm environment. It’s also difficult to say that the ProbSevere MLCAPE is more accurate or not and what the reliability factors may be.

Below is an example of a storm over TX that is sampling the MLCAPE of the GFS (green text) and of the ProbSevere RAP (white text). -shearluck

New Meso Detection Algorithm

Posted in NMDA on by Justin.

Tested out the legacy (upper left), digital (upper right) and new (lower left) meso detection algorithms on a supercell off the Florida Coast. Tracking of the NMDA performed admirably on this cell from scan to scan. However, I was not seeing elevated icon statuses (thicker circle, or cross haired circle) as the meso strengthened and became strongest in the low-levels. Perhaps this was just an Awips display issue, but overall I would give an edge to the DMDA in term of overall usefulness because of this issue.

— warmbias —

Fun 30 minutes of storms in Florida

Posted in AzShear, Forecaster Thoughts, GLM, HWT, Live Blogs on by Justin.

There was a nice area of convection moving off the east coast of Florida with storms forming off an apparent outflow boundary moving to the south. As the storms moved off the coast they increased intensity exponentially. Focusing on these storms as they moved over water reflectivity showed max dBzs in the low to mid 60s with tops 45-50k ft high. GOES-16 Event density (5min-1min update) showed a value of 247 suggesting a nice updraft, which AzShear seems to further support with a bright white color and value of .007s^-1 exactly where the max dBzs/echo tops/GLM data is. In addition,prob severe did a good job of tracking the storms…but with the storms moving off the coast it is impossible to get any storm reports to verify its accuracy.

Utilizing all of this data I would most definitely want to issue a localized small craft or some sort of marine advisory or warning…if there was one for this are. -Desmond

AzShear .007s^-1

GOES-16 Event density (5min-1min update)

Max dBzs in the low to mid 60s

 

GLM detection efficiency over the Gulf of Mexico

Posted in Live Blogs on by Justin.

When life hands you lemons (or for that matter, a bleak, moisture-starved convective environment draped over the entire CONUS) we can still  make lemonade on this particular day by focusing on the Gulf of Mexico.

A question I’m asking all week when evaluating experimental products is: “How does this meaningfully improve upon what’s already operationally available?”  My initial impression of GLM was that it’s merely duplicating efforts of ENTLN (except of course over the ocean where it’s unquestionably important given the lack of ground sensors exist). One of the better examples of this I’ve seen is below. In the panels below, looking south of Mobile, we see a much weaker signal in ENTLN total lightning grids compared to off the TX coast, whereas Flash Extent Density shows much more similarity between the two areas.

Another thing that was pointed up during discussion this morning: ENTLN pulse detection efficiency is *highly* variable across even the interior CONUS. This is because sensors are more clustered around metropolitan areas  and therefore the number of pulse detections (and to a lesser extent, flash detections) can fluctuate quite significantly for completely non-meteorological reasons. So, I’m becoming increasingly convinced that GLM data might be a more useful sanity check than I previously thought.

Part of this experiment is to evaluate minimum flash area (botttom pane). To be continued…

#MarfaFront

MRMS Az Shear Product

Posted in AzShear on by Justin.

While MRMS Az Shear product is useful for situational awareness of stronger storms, the jumpy nature of the updates degrades its usefulness in storm interrogation. Would really like to see single radar Az Shear in real time, as it would greatly compliment the base radar data interrogation.

— warmbias —

This was interesting

Posted in GOESR, Live Blogs, Pseudo GLM on by Justin.

Since things were kinda boring over HGX today I had to look for things to blog about. Here is something interesting that I noticed with the Vis/IR Sandwich RGB. At the beginning of the loop the RGB didn’t show any IR brightness temperatures. As the TCU continued to develop we saw pixels of IR brightness temperatures starting to show up indicating cold cloud tops and the potential for glaciation to start. Low and behold, if we continue to watch the loop, more pixels start showing up…and a few minutes later both GLM and ground based networks picked up on a couple of CGs. As the thunderstorm developed, cloud tops cooled and more pixels started getting displayed we began to see more lightning.  This was something that I didn’t expect the RGB to pick up on and potentially helpful for situational awareness and IDSS in the west where most lightning tends to come from single cell thunderstorms. If you are able to pick up on these ahead of time you may be able to some lead time before lightning occurs.

Update…it happened again, pixels starting being displayed and then lightning occurred within a couple of minutes. If this generally hold true for single cell thunderstorms this would be awesome for outdoor IDSS.

Life and Death in One Loop

Posted in Live Blogs, Mesoscale Discussions, Total Lightning on by Justin.

Well, the convection is trying. And dying.  Case in point, the full life cycle of a pair of storms across the  northern suburubs of Houston.  Thoughts below:

You are looking at the 1-minute Mesoscale Sector scan with GLM Flash Extent Density, the Vaisala GLD dataset, and ProbSevere overlays.  Some things to look at:

ProbSevere struggled when the storms were most intense by merging two individual storm objects, splitting them apart, then re-merging back into one object.  Trends were a mess because of this.

GLM lightning activity ceased a full 10 minutes before ProbSevere dissipated the tracking associated with the cells.  However, it continued to show flashes taking place for 7-minutes after the last CG was detected in the GLD data.  Good use for IDSS to let people know that cloud-to-ground strikes are still possible.

The storms initially were moving northwest along a boundary then deviated to the northeast as they strengthened.  As soon as the moved off the boundary…bye bye!

-Dusty