Category: DSS

RADAR DOWN IN DULUTH CWA

Posted in DSS, LightningCast, OCTANE Speed Sandwich, SPG2024 on 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

Examining LightningCast Values Near Pierre SD

Posted in DSS, LightningCast, SPG2024 on by Kevin Thiel.

We have a Fishing Derby ongoing near Pierre, South Dakota. We observed some differences in the LightningCast probabilities within a 10 mile radius between the AWIPS contour plot and the dashboard.

Here’s an image from AWIPS at 2004Z (1504 local time), with the DSS point marked by a 10-mile radius near Pierre SD (white circle), and the LightningCast probabilities (60-min for 1 flash) contoured in blue and green.

 

Next, here is a look at the dashboard for the same DSS event. Of interest is the pink line, which shows the maximum probability for a flash within 10 miles of the DSS point within the last 5 minutes.

At the 1506 (local time) time slot on the dashboard, it shows the maximum probability of 47 percent. However, the AWIPS image above shows the greatest contour values within the DSS point radius for that same time minute span (at 1504 local time) and the value only barely exceeds 30 percent. It appears that the value on the dashboard is reading about 15% higher than the value that would be implied by the contour display in AWIPS.

Functionally, as long as the trends are consistent, this may not make much of an impact on messaging or forecasting for this DSS point. However, having the values more closely matching between the two sources is something that would likely increase forecaster confidence.

–Insolation

LightningCast and DSS

Posted in DSS, LightningCast, SPG2024 on by Kevin Thiel.

Monitoring convective development over the southwestern portion of the ABR CWA, where we are providing DSS support to a Fishing Derby (yellow range ring – 10 miles). From this data, I would be able to let an EM know that we’re noticing an uptick in lightning probabilities due to storm cells developing to the south/southeast of the Derby and moving northeast. These are not severe at this time and no lightning has been observed as of yet. However, currently, probabilities of lightning within 10 miles are between 40-50%. If I were to use LC while at an on-site deployment, I would have both the map view (first image/loop below) and the graph (second image below) up to show what I am looking at, but especially the map view to give context to the graph.

LightningCast in “map view” showing probabilities of one or more flashes (as an image, not contoured)
LightningCast Dashboard showing lightning probabilities at DSS point (Fishing Derby, Aberdeen, DS)

UPDATE # 1 – Lightning has been observed! From when the 10% contour (10% chance of 10 or more flashes) first popped up (red contour north of Lyman) at 2010Z, it was 10 minutes until GLM and the ground networks observed flashes. It was 5 minutes later when ground networks observed CGs.

LightningCast – time of first 10% contour (red) 2010Z

 

LightningCast – GLM and ground networks observe flashes 2020Z

 

LightningCast – Ground networks observe CGs 2025Z

In terms of lead time, I crafted a DSS message between 310-315pm (seen in the first paragraph above this update) and the first flashes were observed at 320p and CGs at 325p. Therefore, this gave a 10-15 minute lead time.

UPDATE #2 – Below is a snapshot of the LightningCast Dashboard showing the above mentioned GLM flashes within 10 miles.
Forecaster Cumulus

Analyzing Clusters, Anvils Carrying Charge North, Final Checkup on LightningCast

Posted in DSS, LightningCast, SPG2024 on by Kevin Thiel.

Working on the DSS for the PGA tournament, one of the more frustrating features was how thunderstorms well outside the range of the event produced lightning. About the time one DSS image was sent, there was a lightning flash that occurred well north of the primary cluster and near a very weak area of reflectivity.

However, this has been the story for much of the day, where intense convection has been to the south and weaker cells to the north are still managing to produce lightning. Below is the probability of exceeding 10 flashes on GLM, with GLM and MRMS at -10 C to highlight how weak the convection was to the north. The fact that reflectivity was barely at 25-35 dBZ would suggest little potential for lightning.

 

Analyzing the RGB channels for lightning, one can see this evolution well. With more intense updrafts producing several flashes on GLM, they appear yellow. To the north, where it appears the anvil is carrying charge north, the flashes are very long. From a DSS perspective, this can be frustrating when communicating the potential for high impact weather when all that one gets are sprinkles and rumbles of thunder. Still, the RGB channel can be very helpful in delineating these features, but would also be a helpful means to suggest that the northern convection may not develop quite as much. The 50dBZ echo tops are intended to help highlight the stronger storms. Note how a few pixels of 50dBZ echo tops at best appear in the blue, while the larger cluster of taller storms have the younger convection. This also helped me consider parallax as well. Overall, I really like the potential for lightning characteristics divided into this RGB would be helpful in pulse convection.
And then later, the LightningCast began to behave a bit more oddly. Perhaps these situations cause it to become bouncy. Although, you can almost see these dips in the flashes on the chart as well. At this stage, I feel like I could tell the poor folks playing above par at the PGA tournament and taking forever that they can pack up their clubs and head home, because at this stage, the lightning is here to stay.
Outside of the one flash of lightning that took place over the event about when values crept upwards towards 50 percent, there was a flash. However, values had been hovering around 30-40 percent for much of the day. Values crept even higher, and yet there were no flashes nearby. It seems whatever convective debris left the region, and then the forecast became better overall.
Kadic

Adding Latitude/Longitude on Dashboard May Help Locate Mistaken Entry

Posted in DSS, LightningCast, SPG2024 on by Kevin Thiel.
While doing DSS for the PGA tournament, there was an instance where we were uncertain whether the dashboard was matching the values on the map. Below, the probability of 1 flash and 10 flashes are shown. Using the sampling tool within the 10 mile range ring, the values never exceeded 50 percent. However, on the dashboard for the PGA Attempt 3, there were values above 70 for a single flash.

Trying to find the reason why, the most likely situation is that the forecaster may have mistyped, either mixing up decimal points in the lat/lon, or swapping two digits around. It may be helpful to be able to go back and edit the entry if that occurs or be able to view the lat/lon point to be certain whether a typo occurred putting in the entry.

In this case it wasn’t a typo – It was parallax!

Kadic

Using GREMLIN for Time of Arrival

Posted in DSS, GREMLIN, LightningCast, SPG2024 on by Kevin Thiel.

LightningCast has been running high near the PGA Tournament today near Fort Worth as a result of several thunderstorms around the region, but not over the region. As a result, decided to swap over towards trying to use GREMLIN to find the time of arrival of the boundary noted earlier.

So an attempt was made to highlight this in the DSS image to provide an estimate of when these hazards would arrive. Perhaps another proofread would’ve caught the initial typo from copying it over. However, a value of about 40 percent was noted. Partners still had information that storms would become increasingly likely over a narrower time frame in addition to the probabilistic information from LightningCast.

But nature had other plans with a strike and a few pulses of lightning over the event at the time this was “sent out”. An area of weak convection was in the area, and so I would’ve thought that this would not produce lightning.
Sneaking in information on the RGB evaluation, you can see how this was not a young storm and likely something in decay, and that may track with a bit of the surprise element.

Kadic

Warning vs DSS – “WFO DMX”

Posted in DSS, GLM, GREMLIN, LightningCast, OCTANE Speed Sandwich, SPG2024 on by Kevin Thiel.

It was interesting when comparing the Warning side of the house today versus the DSS side. When we (Cumulus and Kadic) were discussing this and picked two of the tools we used the most, there were similarities and differences:

For Warning Ops: OCTANE and LightningCast

OCTANE proved very useful in interrogating convection. LightningCast was also a helpful diagnostic tool in highlighting the potential for and track of intense convection when used with ProbSevere.

OCTANE:

Here’s a look at 2 particular instances from OCTANE:

A combination of cloud top cooling in OCTANE and subsequent divergence aloft was a helpful clue in assessing the potential of a storm that was distant from the radar. It was caught a little later in analysis, but OCTANE proved helpful in diagnosing the storm and deciding to pull the trigger.

 

 

This next instance was a warning that was issued solely using OCTANE and seeing how well it lined up with radar. The warning targeted the center of where the maximum storm top divergence was taking place, and then stretched down towards the south to account for parallax. The warning decision was made for the impressive cloud top cooling and pronounced divergence that appeared in the scans leading up to the warning. The panel on the top left shows the OCTANE speed, and it transitioned to a blue color leading up to the event.

 

 

LightningCast and Radar:

As the line shifted east into the area, ProbSevere stood out, while the LightningCast steadily increased. The left hand panel depicts GREMLIN, and it properly highlights the southernmost storm as being the most intense. Unfortunately, not every storm that we issued warnings for got a specific screenshot, but when looking at LightningCast, areas that were likely to experience 10 or more flashes with a 70% probability seemed to correspond well with ProbSevere values would support issuing warnings.

Below is the example of what MRMS looked like the moment DMXSVR005 was issued solely based on OCTANE. Much of the SVR encompassed the highest LightningCast values with a probability of 10 flashes of 70% in yellow and the various ProbSevere contours. Again, this highlights how useful these tools can be in performing storm interrogation. However, when thunderstorms are numerous, this may be a lot to run through. They are definitely useful tools in the tool belt, though.

For DSS: LightingCast (especially the Dashboard) and GREMLIN/GLM.

– LightingCast: I REALLY like the form and Dashboard. It helps focus on the DSS site specifically and organizes the data really well to where I would feel comfortable explaining/showing an EM the graph of   lightning probabilities. Honestly, I could bring this back to my home WFO right now and use this for DSS events this summer. A couple things that could be added to make it even more awesome: adding more options for ranges (right now there is only 10 miles, perhaps adding 15 and/or 20 miles). Folks could then choose which to display in the graph. The other thing (fairly minor), perhaps reversing the size of the bubbles for the GLM data (smaller range, smaller bubble). But, this is personal preference – maybe if this could be customized by the user like the colors?

– GREMLIN/GLM: GREMLIN followed the storms a lot better today (seems to do better with more intense storms versus run of the mill/sub-severe ones). I used a two panel display with GREMLIN on the left and MRMS on the right with GLM and LightningCast and compared the two. I used time of arrival for the storms to 10 miles outside the DSS event and also at the site itself. GREMLIN was able to keep up with MRMS really well! I am becoming more and more convinced that this could be a really great product to help if a radar goes down or there is a radar hole (in data).

Overall, it seems as though OCTANE was used more for warning ops versus DSS, but LightningCast was used by both the warning operator and DSS forecaster.

Forecasters Cumulus and Kadic

Using GREMLIN and LightningCast for Warning Ops and DSS

Posted in DSS, GREMLIN, LightningCast, SPG2024 on by Kevin Thiel.

GREMLIN continues to perform well with regards to the overall picture of precipitation and convection. In fact, in the example below, GREMLIN seems to be catching on to the northern extent of the line breaking apart and the southern portion becoming more intense. However, it seems to be a bit slower than the MRMS data.

LightningCast could be more useful in this case if the thresholds were modified (25 flashes versus 10) to better identify and focus on the more intense convection.

LightningCast overlayed on GREMLIN emulated radar (left) and MRMS Composite Reflectivity (right)

Looking at the LightningCast dashboard for our DSS event, probabilities of lightning are increasing. I found that this is actually an easier way of being able to communicate lightning probabilities for a site (or a range around the site) versus using the map (seen above). This would allow me to let an EM or site official know that probability of lightning is near 80% for 10 miles form the site (within the next hour) and 50% at the site itself.

 

LightningCast Dashboard for Belin Quartet Summer Concert Series (Des Moines, IA)

We provided valuable support. A message was sent nearly 45 minutes ahead of time following the issuance of a Severe Thunderstorm Warning to the west.

If our partners are simply looking to delay, LightningCast may also prove helpful in giving the all clear if you don’t see anything upstream on radar. The values react well as convection clears the site. This is also great in helping you know for sure when the last lightning flash took place, and it can help us give better information.

 

Forecasters Cumulus and Kadic

LightningCast and DSS

Posted in DSS, LightningCast, SPG2024 on by Kevin Thiel.

Viewing CI and LightningCast (LC). LC probabilities on the SW portion of the storm (in the center) at 1958Z ranged between 70-75%. Just before GLM signatures pop up at 2007Z, LC probabilities jump up to around 82%. Not included in the animation, but at 1951Z, LC probabilities were around 50%. The overall trend upward would give me confidence that I can use this product to tell an emergency manager the potential for lightning is medium to high within the next 10-20 minutes (using this case, hypothetically starting at 1951Z).

Lightning Cast product overlaid on Cloud Phase Distinction on the left and radar reflectivity on the right. 20 May 2024

Forecaster Cumulus

Columbia SC: Trucks with Food

Posted in DSS, GREMLIN, OCTANE Speed Sandwich, PHSnMWnABI, SPG2024 on by Kevin Thiel.

Protecting the Foodies

A Severe Thunderstorm watch that covered most of Columbia’s CWA was where we concentrated our forecasting efforts today. We found ourselves with no radar and were forced to make decisions on warnings with satellite only. As a result we made some modifications and combined the power of GREMLIN and OCTANE. Here’s what that love child looks like:

 

 

 

One of the issues we had in making decisions based on GREMLIN data was the lack of information it provided. GREMLIN provides a radar emulation and given that it’s a satellite based product it would be nice to see more information in the sample tool of what’s being shown. Values like temperature at highest reflectivity and echotops could be inferred by GREMLIN to help forecasters make better decisions if radar wasn’t available. The other issue we had with GREMLIN was the latency. Products were running anywhere from 15-20 minutes behind the rest of the satellite products that we were using.

A few minutes later we issued our first SVR warning for the eastern edge of CAE CWA for winds over 60MPH and nickle sized hail (sub severe).

 

As our storm moved out of the CWA we allowed the SVR to expire and took a look at the PHS Forecast model and compared it to the HRRR to prepare for the next round of thunderstorms. But both models seemed to agree that more TSRA was unlikely:

 

Storms in GSP came together and eventually created a good line of thunderstorms from GREMLIN’s point of view. GREMLIN was picking up some areas of higher DBZ and a lightning jump through the line was consistent with what we’d expect to see on radar for a SVR. A warning was issued on a line of storms:

 

The line started to fall apart as soon as it hit the CWA border. We allowed the warning to expire without feeling the need to re-issue downstream. After that, storms no loner had access to some of the peak daytime heating that allowed them to become sub-severe during the afternoon.
-Charmander