EWP Blog – Page 13 – Spring Experiments & Beyond

Analyzing Differences Between OCTANE IR and Visible Speed and Direction Products

Posted in OCTANE Speed Sandwich, SPG2024 on May 22, 2024 by Kevin Thiel.

A number of features appear differently on IR and visible based OCTANE products this afternoon. First, the divergence of cloud top motion really stand out on the IR products, especially on the southwest storm in SJT’s CWA. The dark blues on the upshear side as well as the contrast of the red and green directional colors really appear well on the IR. In comparison, the visible based OCTANE speed product still shows shows the upshear values with the divergence signal, though it is a bit more subtle than IR. However the visible product allows us to see other features, like the above anvil cirrus plume on the southwest storm. In the cluster of storms to the northeast where this kind of feature isn’t visible, the visible OCTANE product still shows the strong cloud top divergence. OCTANE direction from IR shows divergence aloft a bit better than the visible product, though the difference isn’t huge. Finally, the color table adjustments done today to the Octane Speed IR product really help make the divergence stand out. Cloud top divergence in these products has been pretty well correlated with thunderstorm severity, so the IR based product seems like it would be very useful, especially at night.

-Joaq

SCP and SHIP from PHS is struggling in AWIPS

Posted in PHSnMWnABI, SPG2024 on May 22, 2024 by Kevin Thiel.

Not sure if something is going wrong with SHiP and SCP today, and it’s not a one off. Several cycles of the PHS are behaving strangely. Although STP and MUCAPE appear to be ingested fine.

The values on the website also appear a bit strange with strange jumping behaviors with lack of gradients. An example of the SCP is shown first, and then SHiP second.

Here are the values on the RAP Mesoanalysis.

So not entirely sure what has gotten into the PHS model.

Kadic.

Two Storms… to Collide?

Posted in GREMLIN, OCTANE Speed Sandwich, SPG2024 on May 22, 2024 by Kevin Thiel.

The storm in Reagan County, depending on the data you look at, looked like they may merge! When looking at OCTANE/Visible satellite, the cell moving out of Reagan actually seemed like it was moving fairly rapidly eastward towards the stronger cell in Tom Green County. But, when viewing radar data, it wasn’t moving quite that quickly. Interestingly, GREMLIN has been hinting that these may merge (or is this a smoothing effect?).

OCTANE

KMAF (left) and GREMLIN (right)

Forecaster Cumulus

PHS Environmental Parameters vs RAP and Radar for Warning Ops

Posted in PHSnMWnABI, SPG2024 on May 22, 2024 by Kevin Thiel.

For this case, we have a data outage for radar, so the closest radar we have to use is KMAF for WFO SJT (no MRMS data either). Was looking at the tornado probability for the storm moving out of Runnels County since the midlevel meso was strengthening. So, I took a look at the environmental parameters from PHS (namely, the SRH). It looked like the storm was ingesting 800-900 m2/s2 SRH, which is a bit high, but the idea that the storm was ingesting more SRH/modifying the environment to possibly increase the tornado potential was useful. Interestingly, the RAP from the SPC Mesoanalysis page shows an area of enhanced 0-3 km SRH (just to the NW of the storm).

PHS environment parameters at 1947Z


SPC Mesoanalysis 0-3 km SRH

KMAF 0.9 deg tilt indicating a very strong midlevel meso

Another thought – Perhaps having either 30 minute data or intervals (30 minute, 1 hour, 2 hour, etc.) might help from a mesoanalysis standpoint.

Forecaster Cumulus

Developing and Splitting Cells in Sterling County TX

Posted in GLM, GREMLIN, SPG2024 on May 22, 2024 by Kevin Thiel.

This lengthy post will cover a number of interesting observations with developing and splitting cells near Sterling County TX. This post will mainly focus on GREMLIN, but also a few other products.

Initially, we were focused on new updraft development Glasscock County TX. GOES-E GREMLIN (left panel) depicted Z values of about 57dBZ. KMAF comp reflectivity (right panel) was also picking up some 50+ dBZ. The 0.5 slice on KMAF (middle panel) was yet to really show anything of interest. This is evidence that GREMLIN is picking up on situations where echoes aloft have not yet started reaching near the ground. This has a degree of predictive value.

The loop from here shows that this storm then proceeds to split as it moves into Sterling County TX. The storm split is apparent on the KMAF lowest slice and comp reflectivity, as early as 2020Z. On GOES-E GREMLIN, the split does not start to show up until 2040Z, and is not readily apparent and clear until 2100Z.

So, let’s look a little closer into why GOES-E GREMLIN may have struggled with picking up the split. The loop below compares GOES-W satellite imagery (left panel) with GOES-E satellite imagery (right panel). While GOES-E data masks the updraft of the left-mover under the anvil from the right-mover, GOES-W has a better view of the left-mover updraft.

Comparing GOES-W GREMLIN and GOES-E GREMLIN, it’s clear that GOES-W had the better view of the left-mover updraft, and picked up on the split much more accurately (though it was low on dBZ values). On the contrary, GOES-W GREMLIN did a much less consistent job in handling the right-mover.

–Insolation

From a GLM perspective, it’s clear that GOES-West GLM sensor had a better view of the left split updraft and lightning activity than GOES-East. The flash extent density product shown below detected an increase in activity much quicker on GOES-West than its east counterpart. This may be due to the less inhibited view GOES-West had of the updraft looking at it from an angle compared to a more top-down view GOES-East had, which may have been blocked by water droplets or hail near the top of the thunderstorm.

-Joaq

Adding Latitude/Longitude on Dashboard May Help Locate Mistaken Entry

Posted in DSS, LightningCast, SPG2024 on May 22, 2024 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

OCTANE… the GOAT for Warning Ops Today!

Posted in OCTANE Speed Sandwich, SPG2024 on May 22, 2024 by Kevin Thiel.

On the warning desk today, I’ve noticed that I have been using OCTANE the most out of the newer tools (besides an adjacent radar). It has really helped with confidence with warning decisions – are the storms maintaining strength… are newer ones growing? The storm in the eastern portion of this loop (below) has been going and going for a handful of hours (originally SVR in our area). OCTANE has kept right along with it and showing its evolution aloft (in both IR and Visible).

Also learning to use the CTP and CTD portion of OCTANE – it’s been helpful to keep track of the newer updrafts (shows up really well to the west with the outflow, but also in the green where there is more anvil/cirrus overflow). Also, it’s been a great tool to see where storms are maintaining strength (where the divergence signature in the pinks/purples hold on).

These products have aided in confidence in warning ops, especially with lack of primary radar.

Forecaster Cumulus

Comparing GREMLIN Across Two Storms

Posted in GREMLIN, SPG2024 on May 22, 2024 by Kevin Thiel.

The GREMLIN radar product is shown above in the top left while MRMS composite reflectivity is on the top right. The two storms in question have severe warnings on them in this loop. The thunderstorm in the southwest is more isolated from other convective cloud debris, while also displaying a more intense thermal couplet and cloud top divergence signal than the thunderstorm to the northeast. It seems likely that this is the reason why the northeast storm has a lower ceiling for GREMLIN reflectivity than the southwest storm, even though the MRMS composite includes a 60 dBZ core in the northeast storm.

-Joaq

OCTANE Cloud Top Divergence and Cooling to Analyze Thunderstorm Severity

Posted in OCTANE Speed Sandwich, SPG2024 on May 22, 2024 by Kevin Thiel.

The distribution characteristic of the derived cloud top divergence product has been helpful in highlighting potentially severe thundretsorms. Here the purple/pink colors are fairly consistent compared to the more “broken” distribution of colors to the east. Additionally, cloud top cooling is appearing as an overshooting top (and continued to reappear after this animation ended). Even if radar data was absent the severity of the thunderstorm would be apparant. A warning was issued on this storm (shown below).

-Joaq

Comparing PHS Reflectivity with the HRRR and MRMS Reflectivity

Posted in PHSnMWnABI, SPG2024 on May 22, 2024 by Kevin Thiel.

In this animation we track the progression of MRMS composite reflectivity (right) hourly over the previous three hours compared to the PHS (left) and HRRR (center) reflectivity. This morning convection allowing models were slow to initiate convection compared to reality and it seems that trend is continuing this afternoon with the southeastern progression of ongoing convection. The PHS has been slowest today with the southeastern movement, while the HRRR is a bit closer to reality but still behind (especially in the in the northeastern portion of the CWA.

-Joaq