Category: SPG2024

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

A Tale of Two Storms From OCTANE, LightningCast, and GREMLIN

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

 

 

This is an interesting comparison of two storms that show two initially different satellite and LightningCast signals that produce very different results on radar. The southern cell shows an initially much more consistent cloud top divergence signal from OCTANE with a more robust looking anvil shield and an above anvil cirrus plume. That aside, the northern storm consistently had a higher probability of >10 GLM flashes from LightningCast and eventually developed a far stronger radar signature and eventual severe thunderstorm. The southern storm struggled to even develop a 40 dBZ core. The animation below shows the same progression but with the OCTANE speed and direction RGBs. In this case if a severe decision was to be made with just the satellite presentation, the wrong decision may have been made (at least initially).

-Joaq

 

Finally, here is how GREMLIN handled the southern storm, which it understandably initially intruduced high reflectivity to the southern storm.

-Joaq

GLM Data Quality Under the Shadow of the Anvil

Posted in GLM DQP, SPG2024 on by Kevin Thiel.

As we are watching a cluster of thunderstorms develop across Nebraska, we’re in a region where GLM may not be able to most efficiently detect flashes in the region. However, underneath the shadow of the cirrus blow off, the flash detection efficiency increases, and the stoplight colormap begins to suggest that the data quality is better. Perhaps this offers a bit of hope when forecasting charge moving along with the anvil.

Kadic

OCTANE Trends for Ongoing Convection in ABR CWA

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

Taking a look at OCTANE – it seems like the IR/Nighttime data shows especially the directional details a bit more than the Visible/Daytime products. This has been a continuing trend this week. The CTD and CTC products have been useful with monitoring the strength of the storms (especially which may become severe) as well as with the newer convection/updrafts.

OCTANE – Visible (Daytime) vs IR (Nighttime)

 

OCTANE – Cloud Top Cooling and Cloud Top Divergence

Forecaster Cumulus

Update to PHS versus HRRR Convective Initiation

Posted in PHSnMWnABI, SPG2024 on by Kevin Thiel.

Looking at an update of the 19Z HRRR run and the 17Z PHS run, the more recent HRRR run is catching up to a sooner initiation solution. The 19Z HRRR is initiating cells as early as 21Z with a series of cells displayed above by 22Z, similar to the 17Z PHS. Another note is that the newer HRRR run has a higher SBCAPE value than the PHS at 1700-2700 J/kg compared to 1000-2000 J/kg from the PHS. Recent visible satellite trends look to favor an earlier initiation as well.

 

-Joaq

OCTANE Cloud Top Divergence and Cooling view of an Orphan Anvil

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

 

Here is a good example of the OCTANE product showing the transition from an updraft to a divergent anvil cloud, which then cuts off from the parent updraft. This “orphan” anvil is an indication of a convective initiation attempt, which can be a signal for upcoming successful initiation in the near future. The OCTANE product does well to highlight both the updraft and then the anvil in different color shades through the entire orphan anviling process.

Below is an additional animation of deepening cumulus development with the OCTANE cloud top cooling product highlighting the taller towers.

-Joaq

Waiting for CI – Looking at PHS

Posted in PHSnMWnABI, SPG2024 on by Kevin Thiel.

Anticipating most of the activity, should it develop, to begin in the next couple of hours in the western/southwestern portion of ABR’s CWA. However, I wanted to take a quick look at PHS to see some of the environmental parameters and how it relates to what’s going on now (and maybe later).

PHS Composite Reflectivity overlayed onto Visible Satellite (left) and MRMS Reflectivity (right)

For the above loop, PHS has perhaps the general idea of CI from the convection from earlier this afternoon, but struggled a bit with placement of some the stronger cells in the east. However, I think it may have a good handle of the lull we’re expecting until later this afternoon. It will be interesting to see whether we get storms in the line of pearls like it’s suggesting.

PHS MUCAPE at 20Z

 

SPC (RAP) MUCAPE at 19Z

Comparing the MUCAPE from SPC’s Mesoanalysis page (RAP) and PHS, it seems like both agree on ~2000 J/kg nosing into the southwestern portion of ABR’s CWA. This is the area that we are monitoring for initiation over the next couple of hours.

Forecaster Cumulus

PHS and HRRR for WFO ABR

Posted in PHSnMWnABI, SPG2024 on by Kevin Thiel.

As of 2030Z, storms have already initiated near Pierre SD in the KABR forecast area.

Both PHS and the HRRR appear to be too slow on forecasting convective initiation in this area.

The first image is PHS comp reflectivity (overlaid on PHS SBCAPE) valid at 22Z.

The image below is HRRR comp reflectivity valid at 22Z. Both PHS and HRRR are depicting convective initiation between 21Z-22Z, but as mentioned, storms have already initiated as of 2030Z. PHS and HRRR both show initiation in slightly different locations, but in real life, initiation occurred near both indicated locations.

Both PHS and HRRR also depict that stronger cells will develop near the SD/ND border in the 23Z-00Z time frame. The next two images show this in the parameter space. The first image shows Sig Tor Parameter on PHS (valid 23Z) and the second image is the same thing, but with PHS comp reflectivity overlaid on top.

Of most note is the simulated storm northwest of Ashley ND, which not only has the highest simulated comp reflectivity value, but also significantly impacts the storm-scale environment (as depicted in the model by an unrealistic significant localized bullseye of STP). As a forecaster, although I recognize these STP values (~10) are likely spurious, I can use their presence as a proxy to the fact that the storm simulated by PHS in this location is likely very strong and modifying its environment in a way that only significant supercells are able to do.

— 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

How is GREMLIN Doing? Storms Form Sooner Than Expected.

Posted in GREMLIN, SPG2024 on by Kevin Thiel.

Took a look at GREMLIN to see how it was handling the convection, as storms have developed a bit earlier than expected. It’s doing a great job with the overall picture of the line of discrete storms (formation and placement), but perhaps not as much with the intensity of those individual storms.

Reflectivity from KUDX on the left, GREMLIN in the center, and MRMS on the right

 

Forecaster Cumulus