Placed beneath the left exit region of an approaching mid/upper jet from the SW, scattered storms evolved in a weakly sheared environment. Latest reflectivity scans reveal a few 60 dBz scans with strongest cores and MRMS MESH pointing to some small hail…still sub-severe. With SBCAPE already exceeding 1500 J/kg in many places, the overall hail and wind gust risk constantly increases during the following hours…however scattered initiation likely causes messy clustering of storms with decreasing diabatic heating. The focus for more severe storms will be east of the Midland area, when storms finally evolve in a stronger shear environment. We’ll look for current storms to send outflow boundaries to the east for initiation in SPC’s SLGT risk area next to forced initiation as the upper trough further approaches.

Radar reflectivity with MESH atop.

Helge

Gabe, the OUNWRF PI, showed us an interesting way to monitor a few model output fields simultaneously.  The display here includes the model derived radar reflectivity as a background image, with the green contours showing updraft helicity and the salmon contours the maximum hourly column hail.  The display here is consistent with the expected mode of convection over the next few hours…namely, pulse storms or multicell clusters.  With marginal bulk shear values, we aren’t expected a lot of deeply rotating storms, but there will be a large hail and/or damaging wind threat with some of the stronger cores.  I will continue to watch this display through the evening to see how it all pans out.

CL

This is a image of LAPS_OUN_3 km run from 15 UTC 05/14/13 for 18 UTC compared to actual 0.5 Degree reflectivity from KMAF at 18 UTC.  The LAPS data were nearly dead on with the location, coverage, intensity, and storm mode with the storms southwest of Midland with perhaps a slight underestimation of activity near the NM/TX border.

This is a image of the OUNWRF 16 UTC run 05/14/13 for 1845 UTC 1 km AGL Derived Radar Reflectivity compared to 0.5 Degree Reflectivity from KMAF at 1845 UTC.  They compared well with the OUNWRF doing a fine job with the location and storm mode (isolated cells/multicell clusters) near and just southwest of Midland.  The OUNWRF underestimated unorganized convection across SE NM.  Michael Scotten

At 2226z a storm in the LUB CWA had 1 flash on the pGLM and 10 minutes later the number was up to near 40 flashes.

An experimental warning was issued based only on this and without any other data. About 5 minutes post warning, the HSDA algorithm hit for large hail.

Several minutes later the MESH hit at 1.02″

The pGLM was the first hit of possible severe weather and gave 5-10 minutes more lead time to when the MRMS products hit for severe hail.

Hampshire

A supercell thunderstorm developed north of San Angelo TX at about 2030Z, and became severe as it moved east. After the storm made a hard right turn and began moving southeast, it grew to an extreme level of intensity, especially with regard to hail potential.

About a half hour later, t he storm continued to strengthen, now showing a TBSS with > 30 dBZ and a 70 dbZ core that extended to over 25k feet.

The HC product showed giant hail at numerous slices throughout this period of very high storm intensity. Here are examples from the 2210Z volume scan.

At the time of these images, we received reports of baseball size hail, and numerous reports of golf ball size hail.

Here is a look at a plethora of MRMS products at 2210Z.

MRMS at 2210Z (part 1).

MESH showed a maximum hail size of over 2.75″ in this image (and actually peaked at over 3″ near the same time). This is in the top left of the first MRMS image.

POSH (which is directly proportional to MESH) reached values of 100% when MESH indicated about 2.5″ or greater. This is in the top left of the second MRMS image.

Reflectivity at -20 degrees C (top right in the second MRMS image) is over 70 dBZ. The 60 dBZ echo reached over 20k feet above the freezing level (bottom left in the second MRMS image). Vertically Integrated Ice (bottom right of the second MRMS image) is over 50 kg/m2, too high for the default color scale.

This data helped provide forecaster confidence in the fact that hail was extremely large in this particular supercell.

–Hatzos

We finally had storms develop within the West Texas LMA.  The strongest updraft this evening showed marked ramp up of flashes to 40 just as the storms 50 dBZ core reached 26.25 kft briefly before coming back down about 10 minutes later with the flash density also subsiding back to 15 to 25 flashes. Although the storm didn’t reach severe criteria, it was beneficial that the Flash Extent Density updates in 1 minute intervals, which lets the warning forecaster monitor for rapid updraft development between radar volume scans.  This storm resulted in a report of dime size hail.

Kurtz