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Real-time posts made during testbed nowcast and warning operations.
NearCAST guidance continues to support the enhancement of thunderstorm development from Jim Hogg and Starr counties. It’s appears the model indicated a weak disturbance increasing Theta E across forecast area between 01Z and 04Z, which will add to the existing unstable conditions. Severe thunderstorm potential remains high. Emergency managers and other decision makers are strongly encouraged to prepare for the threat of severe weather through 05Z. Isolated tornadoes are still possible. rn/ams
23Z HRRR output projected strong convection with a better handle on the Webb Co. storms. It didn’t pick the storm approaching NW Zapata county. It did handle the coverage between isolated and scattered. rn/ams
Severe storm west of SW Webb/NW Zapata counties continue to paint a CTC -20 to -22C/15min between 2210Z-2255Z as the storm tracks east. rn/ams
The image below shows the 1km composite updraft maximum (top left), 0.5 z, 1km surface maximum vorticity (bottom left), and the 1-5km updraft helicity (bottom right). Although the 0.5 velocity data is not shown, it is contaminated and not very useful. This makes the 3DVAR data extremely useful in identifying where the strongest low level rotation is located and the potential for a tornado.
CI continues to show promising results in terms of providing significant lead for strong/severe t-storms.
The first image below at 2115Z shows a strength of signal around 99 (red) in UAH-CI in the upper left pane for a developing storm west of Laredo.
The next image at 2125Z depicts -14C/15 min UW-CI (lower left) for the developing storm.
Radar imagery continued to show storm growth and the storm reached 50 to 55 dbz at 2208Z as shown in the upper right pane of the image below. Also, MESH reached 1.18 inches at this time as well.
With these figures in mind, the lead time from initial CI detection on UAH-CI was around 55 min. and the lead time from UW-CI was around 45 min. It would be great to put a product out conveying the possibility of strong storms when we first see these CI signals with an actual warning coming later.
AMS/Nunez
We noticed a good comparison of the CTC at 2210Z occurring 18 minutes before the 1″ hail indication by MESH. rn/ams
Focusing on the newly developed storms over Mexico and west of Laredo, the synthetic satellite appeared to capture the progression of these storms as they move east. Projections have these storms moving into Texas between 00Z-01Z. Latest radar trends may be a bit faster though. rn/ams
These two nearCast screen captures depict the main axis of theta e/PW that was translating east of the BRO. Ample moisture remains over the eastern and southern parts of the BRO CWA and support thunderstorm development. Sadly, convection continues to be inhibited and is reflected on the 3DVAR sim. comp. reflectivity. RN/AMS
The below image at 22Z depicts nearcast theta-e at 780 mb in the upper left pane, synthetic WRF IR in the upper right, nearcast theta-e at 500 mb in the lower left, and nearcast vertical theta-e difference low-mid in the bottom right.
Looking at the 780 mb theta-e, it shows areas in yellow of best moisture/instability predicted for this afternoon which matches up with storms predict in synthetic IR imagery. Because the 2 products derived off of different model projections are in decent agreement, this lends more confidence to this convective scenario for this afternoon.
AMS/Nunez
