EWP Blog

An isolated convective cell just ahead of a line of thunderstorms became overrun by the line of storm and was absorbed by the line which resulted in an increase in the updraft and storm intensity.

The ProbSvr was showing increasing probabilities around 30% by 2216 UTC outlining an area that encompassed the storm merger as well as another cell to the north.

By 2220 UTC the ProbSvr had increased to 73% and now encompassed the merger as well as the storm to the north.  The base radar data was not very impressive and I had no thought for a severe thunderstorm warning despite the increased values of the ProbSvr.  This is another case where the ProbSvr has limitations and shows higher values when you have storm mergers and in these situations it should be used with caution.

The PGLM data began to increase at 2215 UTC and continued to to a max density around 31 flashes at 2218 UTC before slowly diminishing back to below 10 flashes by 2224 UTC.

I felt the PGLM data did provide me with improved situational awareness and help focus my attention to this area as these storms had been quite weak in the several scans leading up to this event.  I also can see where the one minute resolution of the PGLM data could provide an advantage to show a rapid increase in storm intensity between radar scans.

Jack Bauer

We have been tracking a multicell line of storms through the western CWA. Cell Flash rates and Cell Polygons were overlayed on radar data as well as DTA Alerts. Algorithm gave a zero flash rate?? Lynford

There appears to be another issue with ENI lightning double-centroid, this time with a double DTA for essentially the same cell. (Lamb County, 2230Z)

Issued warning for the sw CWA. Based on high dBZ well past the -20 level. Warning was issued at 2213z. Prob of svr increased to 51-53% from 2208z to 2216z.

Lynford

Have noticed several instances through the day today of the GOES LAP CAPE values looking very blocky across central Texas. This leads to very low CAPE values transitioning to a quick jump up to more realistic CAPE values. While this has been annoying, it was easy to interpolate between the lower values to get a better idea of the CAPE values in that area. -SRF

In the AMA area today, a double centroid was observed at 2203Z with one of the centroids going above 40 flashes/min, prompting the level 3 DTA, though probably erroneously as the before (2159Z) and after (2208Z) centroids were 20 flashes or less. Also, why did the algorithm produce two centroids of similar size at 2208Z?

Brick Tamland

While monitoring the storms just to the northwest of the SJT area, noticed a limitation of the ProbSevere tool, largely due to the processing time. At 2139Z on the KSJT radar, a TBSS was noted on several levels of the radar. With the time lag on the ProbSevere, it was still only outputting a 26% severe probability. But looking at the details below, you can see that the satellite growth around the same time was indicating both moderate and strong and leading to increased confidence in the strengthening storm.

Jumping ahead 2 minutes to 2141Z, the ProbSevere has jumped to 58% with the radar data being processed.

Now moving ahead to the next scan at 2144Z, the TBSS has moved closer to the surface and the ProbSevere has quickly jumped up to 94%.

While this jump has increased confidence, I felt that looking closely at the radar data I would have issued the warning (if it was in our area) before the ProbSevere had made the jump to 94% (would have probably been issued at the same time as the jump).

Finally, looking at the Lightning Cell Time Series data for that cell, a significant jump in the Total Lightning and Cell Area was seen around 2140Z, which matches the significant increase in the radar reflectivity data.

While our group is unable to use the lightning jump algorithm today, I find my self both wishing I was able to use that data but also glad it was able to utilize the time series data to pick up on the significant jump manually. -SRF

The Convective initiation product showed an area of 51% probability in the south central part of Parmer county in the far northwestern part of the LBB CWA at 2015 UTC after showing some 10% probabilities at 2000 UTC.  By 2030 UTC the convective initiation probability increased to over 60% and also identified another area with a 74% probability.

Looking back at the radar data in the loop below the first 10+ dbz reflectivity values appeared at 2037 UTC.

The first 35 dbz value occurred at 2048 UTC in the west central part of Parmer county.

I think the CI product successfully identified this initiation with over 30 minutes of lead time again highlighting it’s situational awareness value.

Jack Bauer

We moved over to SJT where we’re covered in pretty thick stratus. There was a promising looking boundary to the west of the CWA. The GOES CI showed 90% at the northern most part on this line. I was hoping this would be the beginning of a nice storm that would move into our CWA.

Apparently the environment did not agree…

The tiny little shower never amounted to anything and dissipated quickly. Fail.

-V. Darkbloom

At 2045Z, noticed a delay in gridded total lightning. Staff found out there is a 10 minute delay on the SBN.

Lynford