EWP Blog

Noticed how a storm may briefly increase to 40 flashes/min, yielding a level 3 DTA for a cell. See the images below which highlight that although the DTA threshold was met for briefly for a few minutes, the successive flash rates dropped below the 40 flash/min threshold for minutes thereafter. The DTAs may be more useful for operational forecasters if the valid time were reduced from 45 mins to 30 mins. This would reduce the amount of products that may clutter up the radar interrogation process.

Brick Tamland

Now that we have a verified severe storm in Midland’s area, let’s see how the lightning jump and probability severe algorithm worked.

At 1945Z, the algorithm showed a severe probability of 27%. The lightning jump was nothing to jump about.

With the next 0.5 deg scan at 1950Z, the probability skyrocketed to 83%.

At 2031Z, a 3 sigma lightning jump occurred. Severe probability was 93% at this time.

By 2049Z, the cell grew into this beast. Max reflectivity on the 0.5 deg tilt was 75.5 dBZ @ 16000 ft MSL/12230 ft AGL. A prominent TBSS had developed on the storm by 2040Z.

The LSR associated with this storm is shown here. Severe hail was observed beginning at 308 PM CDT/2008 GMT. In this case, the lightning jump occurred over 20 minutes after the storm began to produce severe hail. However, the probability severe did provide a lead time of about 20 minutes.

-V. Darkbloom

Below is an image where the western cell was in the western US section of the thunderstorm alert area and the eastern cell was in the eastern US section of the thunderstorm alert area. Both sections are in the Midland CWA. Note the long lift of products loaded to have both cells in a Level 1 thunderstorm alert. Why was there no Level 2 alert on the eastern cell? It had 12 or more flashes for 2 to 3 minutes.

This set up with a set boundary will be cumbersome when it crosses through any CWA.

-Lynford

With the main convection still to the south of the area, decided to test out the 1900Z NUCAPS sounding. With clouds and convection closer to the KS/NE border, went a little farther south into Kansas for the sounding, which conveniently lined up the KFOE site.

Clicking on that point came up with the sounding shown below.

This sounding provided a good first guess, but looking at the surface data (75/56 on the sounding) indicated that it needed to be adjusted to match the ob at KFOE (84/59).

Making that adjustment to the surface conditions increased the CAPE values from around 1350 J/kg to 2660 J/kg. That put the values better in line with the initial values see on the RAP initial conditions. -SRF

First severe storm warning issued at 2002 UTC for a storm over northern Pottawatomie county along strong instability gradient, just southeast of a weak surface low and in the vicinity of weak surface boundary.

Looking at the all-tilts products we noticed 60 dbz values above the -20C level and the ETN displayed a DTA with a significant increase in flash rate from around 30 to 60 to over 100 flashes in consecutive scans.  This coincided with GOES-R overshooting top detection as well as the lightning jump algorithm showing a 2 sigma jump followed by a 6 sigma jump.

The probability of severe increased to over 90% shortly after the warning went out and the PHI also was showing values in the 70s preceding the warning and was above 80% at the warning issuance.  This particular case in my mind really builds my confidence in the potential of the lightning jump, PHI and prob severe algorithms as it relates to warning operations and potentially improving lead time, of course after proper studies have been done in both verifying and null events.  It would be helpful to have some sort of threshold values for PHI and Prob severe as general guidance (based on geographical location).

DTA track was not very representative of the actual storm motion as it had a northern bias.  This could be due to the storm favoring the instability gradient and local boundary as the actual storm motion was more east of the DTA track.

Jack Bauer/Brick Tamland

Overlayed cell tracking with Thunderstorm alert Level 2 and Alert Level 3 on KMAF reflectivity. Also had points (editable). I wanted to get the cell lightning trend. However, number of cell flashes per minute was not displayed and clicking on the point had no response.

Tiffany reloaded all of these images and then was able to successfully get a graph of lightning trends.

-Lynford

The excitement at the moment is in the Texas Panhandle. A quick look at one of the cells in Amarillo’s CWA:

(note: this is LBB radar data as we’re not pulling in AMA data at the moment)

The ENI Lightning Jump algorithm shows a 2 sigma jump. The contours are the NOAA/CIMSS highly experimental probability severe, coming it at 47%.

It had peaked slightly earlier around 60%.

19Z temp and moisture profiles from JPSS came in just after 20Z. I picked a point sounding in the relatively clear area of the eastern OK Panhandle…

And the resulting temp/dewpoint profile:

Surface based CAPE was 1016 J/kg with an LI of -4C. This is comparable to the approx 1100 J/kg and -5C shown on the GOES-R LAP algorithm in this area at 19Z.

WFO AMA ended up issuing a severe thunderstorm warning for this storm. Now we wait for verification.

-V. Darkbloom

With convection largely staying south of the OAX area, have been watching convection in the TOP area. Saw a really good use of the Lightning Jump Detection Algorithm showing a rapid increase in lighting with the cell in northeast Kansas. At 1941Z, the cell was fairly weak with modest lightning.

As the initial cell weakened and a second cell developed to the east the lightning diminished and then rapidly increased at 1951Z producing a significant lightning jump (6 sigma).

The ProbSevere product was trailing at this time due to the rapid increase (<5%), but within 15 minutes it rapidly increased to over 90% at 2005Z.

While I wasn’t looking closely at the radar data while producing a previous blog post, that rapid increase shown in the lightning jump algorithm really caught my attention and showed me that it was something to checkout. -SRF