Daily Summary: Week 1, Day 1 (April 18, 2016)

Today's activities took place in the Corpus Christi and Brownsville CWA's.

LAP
- A participant created a new colortable that was preferred over the default

CI
- An indicator of why probabilities dropped out would be nice
- We had good indicators from regular CI, but severe CI was very low. Despite lack of reports, some storms appeared to be severe.

ProbSevere
- I would show this on TV
- It did not provide much lead time to the intesification of the storm
- Storms that ended up being the strongest had strong glaciation rates

1-min imagery
-  Boundary sagging south across texas yesterday, storm developed on boundary, then started to lag behind boundary on cool side, when it started to rotate. 1 min imagery was helpful in showing that storm would stay on the cold side, didn’t seem like it had a good shot at tor potential. The 1min imagery was been helpful in showing that.

Lightning Jump
- Biggest complaint was that the display covered up other data; recommended to make it transparent.

NUCAPS
- Corpus had an 18Z sounding, so we did a comparison. For the most part it matched up, just lacked the vertical detail, could not tell if CAP was still in place. NUCAPS confirmed drier air was moving in.

Glaciation Rates

As a followup to the previous post on the Hidalgo County storm, there may be some value in glaciation rates. It's a small sample size but two of the storms that clearly were severe based on radar and confirmed by prob severe also displayed "strong". It may be worth exploring further the value of glaciation rates for these low shear / high CAPE environments where prob severe seems to offer little or no lead time.

-dryadiabat

LAP Layer PW Suggestion

Layered precipitable water suggestion:  It seems that the "upper-level" panel is far too broad/deep (700-300 mb).  If we can only show 3 layers, how about something like surface-850 mb, 850-700 mb, and 700-500 mb.  The more narrow, specific ranges between 850 and 500 mb would likely afford a better opportunity to see EML/dry regions, whereas 700-300 mb could wash these features out.

                                    Upper-right panel is too broad/deep.

First SVR warning in Brownsville CWA

Storms began to develop over the Brownsville CWA late Monday afternoon.  The NOAA/CIMSS ProbSevere model output was utilized by forecasters along with examination of all radar tilts.   As the Brownsville team noted a significant increase of reflectivity above the hail growth zone as well as a three-body scatter spike, ProbSevere values jumped from 38% to over 80% in 2 minutes (2250 to 2252 UTC; Figure 1).  The jump in ProbSevere values can be attributed to inputs of new satellite information--specifically strong vertical growth rates as well as a significant jump in the MRMS MESH.

Figure 1.  NOAA/CIMSS ProbSevere and MRMS composite reflectivity valid 2242-2254 UTC 18 April 2016.

This information was used to issue an experimental severe thunderstorm warning at approximately 2252 UTC.  A common theme noted in the limited sampling of storms today is the jump in ProbSevere values occurring at approximately the same time as seeing rapid reflectivity intensification in single radar site data.  See also:  Hidalgo Warning Decision

-Sieglaff

LAP Layer PW - New Color Curves

LAP Layered Precipitable Water Imagery:

New color curves are desperately needed to help better visualize moisture corridors.  The images below show how new color curves can help a forecaster key in on where the main moisture corridors are.

   Old Color Curve

   New Color Curve

Hidalgo County Warning Decision

Our warning decision for northern Hidalgo County was mostly based on radar observations. The 50 dBZ core significantly exceeded the height of the hail growth zone and a three-body scatter spike was observed. Prob Severe increased to 86% simultaneous with our decision to warn based on the above radar signatures. This was a substantial increase from the previous prob severe value two minutes prior of only 38%. Although prob severe didn't offer much lead time, it helped to confirm our analysis that the storm was severe.

-dryadiabat

CI And Prob Sever

Since we moved to Brownsville and nothing is cooking. We are looking at data over Mexico that may be moving up. Severe CI probability showed 100% prob for storm in Mexico at 22:00z. Comparision to Prob Severe shows 84% SVR Prob, 2.76" mesh and flash rate of 17.
Then at 2244 Prob SVR jumped up to 82%, mesh 1.72" and flash rate goes to 21. Storm most likely severe and was picked up in the Severe CI prob.

Thunder

Lightning Jump Suggestion

Lightning Jump suggestion:  Instead of having blocks/blobs of color that cover up radar and/or satellite imagery, why not have outline rings that are similar to what is displayed in ProbSevere, or at least something that is more transparent in nature?  - J-Money

SRSOR TOR

Tornado warnings have been issued for a supercell storm in far southwestern Texas.  The 1-min SRSOR VIS satellite data indicates this storm is elevated, as a well-defined boundary continues to track south of the storm in question.  As a result, this storm likely poses a very limited tornado threat.  

CI update

Additional elevated convection 22-23z farther east?

The attached CI panel shows textured, overshooting tops just north of the southward moving boundary in the eastern half of the CRP forecast area.  Higher probabilities of CI are also indicated.  Although large hail could develop, any downburst/tornadic development continues to look unlikely, as these storms should remain north of the boundary and elevated in nature.

                                                  2130z Severe CI