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

Comparison of NUCAPS and Observed Sounding at Corpus Christi

NUCAPS 19z soundings show a similar temperature and moisture profile as the special 18z observed sounding at Corpus Christi but there is some lack in detail in NUCAPS. For example, an elevated mixed layer just above the boundary layer is evident in the Corpus Cristi sounding but is not shown in the NUCAPS. Higher in the atmosphere there is a pronounced dry layer in the observed sounding that the NUCAPS captures fairly well. This could be important for synoptic patterns where dry air aloft advects into the region and the temporal and spatial resolutions of observed soundings are insufficient to show this. NUCAPS can supplement these observed soundings and provide a clearer picture. We noticed the mid level lapse rates are steeper in the observed soundings as compared to NUCAPS though with about 1C difference between the two. This has implications for analysis of how much instability is present and how the CAPE is distributed.

EDIT: Added images below. The first two are the nearest high quality NUCAPS soundings near Corpus. As mentioned above, the temperature discontinuity between the observed and NUCAPS sounding was operationally significant (~1.5C) at 500mb. However, the second NUCAPS sounding that we observed showed the 500mb temperature to be nearly the same as the observed sounding. We learned that these differences across small distances are typical near the coast due to land/sea surface emissivity and temperature differences.

-dryadiabat

2110z CRP Update:

2110z Update:

Interesting to see the difference between the observed 18z KCRP sounding and a 21z NUCAPS sounding south of the stronger convection.  The NUCAPS sounding implies a weakening of the earlier cap around 850 mb.  Is this weakening real, or is cloud contamination playing a role?  This detail would be key in determining plausibility of convection to become more surface-based.

                                                        18z CRP sounding

                                                        21z NUCAPS

Lightning Jump Algorithem

Is there a way to display the lightning jump algorithem with more transparancy?  I like to look at it however I do not like how it masks the relfectivity underneath.  Just a thought...

torman1