BRO MESO Desk @ 0010Z

EXPERIMENTAL forecaster discussion from EWP blog...

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.

EWP: EXPERIMENTAL Severe Thunderstorm Warning Based on UW-CTC and Environmental Parameters

Another thunderstorm was developing along an outflow boundary over southern Texas.  The NWS forecaster working the KCRP WFO made note of the UW-CTC  -20 K / 15 min at 2310 UTC 10 May 2012 on the newly developing thunderstorm.  Given the experiment is designed for out-of-routine thinking, he decided to issue a severe thunderstorm warning "a radar volume scan earlier" based upon the mesoscale environment, previous thunderstorm development along the boundary, and the fact the storm was exhibiting cooling rates in the strong category from the UW-CTC vs. NEXRAD study presented for training.

Figure 1.  Valid 2310 UTC 10 May 2012.  The UW-CTC rate of ~ -20 K / 15 min (top right panel) combined with the environmental conditions and previous thunderstorm development in the vicinity allowed for an experimental severe thunderstorm warning at EWP/HWT (bottom left panel).  **NOTE THIS IS AN EXPERIMENTAL WARNING**

We are continuing to monitor the storm via the KCRP radar for further intensification.
UPDATE 1:  2340 UTC 10 May 2012 - radar is estimating just over 1.00" hail (severe hail threshold); for a 30 minute lead-time for UW-CTC.

UPDATE 2:  2350 UTC 10 May 2012 - the NWS forecaster has upgraded the severe thunderstorm warning to an EXPERIMENTAL tornado warning, 40 minutes after the intense UW-CTC signal.   The radar estimated hail size has increased to 1.40".  The storm is highlighted in the image below.

Figure 2.  Valid 2350 UTC 10 May 2012.  The storm warned on in Figure 1, now upgraded to an EXPERIMENTAL tornado warning highlighted by the red circle.

EWP: UAH SATCAST and UW-CTC Provides 40-50 minute lead time on EXPERIMENTAL Severe Warning

Thunderstorms continued to develop along an outflow boundary over southern Texas Thursday afternoon.  The satellite-based convective support algorithms (UAH SATCAST and UW-CTC) captured the early growth of the latest thunderstorm along the outflow boundary.  Shown in the figures below, SATCAST and UW-CTC provided 40-50 minutes of lead-time ahead of severe thunderstorm issuance and approximately 1 hour ahead of tornado warning issuance.  Additionally golf ball size hail was reported with this storm 1.5 hours later.

Figure 1.  Valid 2140 UTC 10 May 2012.  The UAH CI Strength of Signal product detects early rapid growth on a newly developing storm in south Texas (top-left pane).

Figure 2.  Valid 2145 UTC 10 May 2012.  The UW-CTC algorithm identifies the same developing storm with cooling rates of approximately -12 K / 15 min (top-right pane).

Figure 3. Valid 2155 UTC 10 May 2012.  The UAH CI Strength of Signal product continues to indicate rapid redevelopment on the tail end of the existing thunderstorm complex (top-left pane).

Figure 4. Valid 2229 UTC 10 May 2012.  The base reflectivity from KCRP with severe thunderstorm warning polygon issued by NWS forecasters at the EWP/HWT.  This warning was later upgraded to a tornado waring at the EWP/HWT.  **NOTE THIS IS AN EXPERIMENTAL WARNING**

Sieglaff/CIMSS
Walker/UAH
Barnes/WFO OUN

BRO/CRP West Radar Analysis 2240Z

Forecaster comments from EWP blog...

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.

BRO MESO Desk @ 2250Z

Forecaster comments from EWP blog...

We noticed a good comparison of the CTC at 2210Z occurring 18 minutes before the 1″ hail indication by MESH.

BRO/CRP West Meso Desk @ 2220Z

Forecaster comments from EWP blog...

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.

MESO Desk update @ 2150Z

Forecaster comments from the EWP blog...

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.

 

Mexico! CTC shows a rapidly developing thunderstorm

Forecaster comments from the EWP blog...

Top image – IR Satellite with CTC rates of -40C/15 min (dark looking region) ~25 minutes before
+60 dBZ @ ~32Kft (bottom image) were observed.

BRO Meso Analysis with Nearcast/Sythetic WRF at 2030Z

Forecaster comments from the EWP blog...

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 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.

 

BRO MESO Desk @ 20Z

Forecaster comments from EWP blog...

The following four screen captures depict several favored areas of UAH-CI strength of signal along the outflow boundaries that exist immediately north of CWA and north-south along a line from Los Angeles-Realitos-Encino-Raymondville.   Knowing were the boundaries were located,  UAH strength of signal allowed us to focus on the most favored areas between 20Z-21Z.   (Synthetic Sat showed the most likely CI would take place between 20-21Z, particularly with storms along the Rio Grande.  It didn’t capture any activity over the northern extent of the outflow boundary.)