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

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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.)

BRO Afternoon Forecast 1920Z

Forecaster comments from the EWP blog...

Synthetic WRF imagery was useful in making a convective forecast for Brownsville this afternoon.  At 13Z, the synthetic WRF depicted two areas of convection over TX with the south complex near Brownsville being slightly displaced to the south in location.  This convection was occurring in an area of high shear ahead of an upper level low progress slowly across the southwest U.S. (seen in synthetic and observed imagery).

13Z Synthetic:

13Z Observed IR/WV (top 2 panes):

At 19Z synthetic and observed IR/WV imagery matched up well with the southern complex, but over did convection to the south of the northern complex in TX.  Over Brownsville area, visible satellite imagery depicted a low broken cu field at 1914Z which matches low clouds in the synthetic IR imagery.

19Z Synthetic:

19Z Observed IR/WV (top 2 panes):

1914Z Visible Sat:

Conclusion:  The Synthetic WRF model seems to be doing an OK job overall so far today with a few issues.  However, it depicts the upper low driving convection today as well as 2 distinct areas of convection over TX.

For Brownsville area for the rest of the afternoon, synthetic images below predict convective initiation around 20Z with convection strengthening through the afternoon hours (22Z image), and then beginning to decrease in strength at 0Z.

20Z Synthetic:

22Z Synthetic:

0Z Synthetic:

BRO MESO desk @ 1834Z

Forecaster comments from EWP blog...

A few towering cu were present across BRO.   CTC centriods were present in LaSalle county (CRP) an immediately south of Starr county.  In fact, the LaSalle county CTC also showed a high strength of signal on the UAH-CI.

EWP: UW-CTC 45 minute lead-time on severe hail

Another day at HWT we are focusing on southern Texas.  An upper level low over northern Mexico is finally beginning to move eastward, this combined with humid low-level flow off the Gulf of Mexico is setting the stage for severe thunderstorms over southern Texas today.  There were numerous severe thunderstorms ongoing as of late morning.  One of the most recent developing storms is showcased below.  At 1632 UTC 10 May 2012, the UW-CTC product showed cloud-top cooling rates of ~ -6K / 15 min.  The following satellite scan at 1645 UTC the UW-CTC increased substantially to over -20 K / 15 min.  Later images of radar-based maximum expected hail size show estimated severe hail occurring at 1715 UTC and significant hail in excess of 3.00" at 1725 UTC. 

Figure 1.  Valid 1632 UTC 10 May 2012.  The UW-CTC product indicates initial substantial vertical growth of a developing thunderstorm (red circle).

Figure 2.  Valid 1645 UTC 10 May 2012.  The UW-CTC rate on the developing storm explodes into the strong category with cooling rates near -23 K / 15 min (red circle).

Figure 3.  Valid 1715 UTC 10 May 2012.  The bottom right panel shows radar-based maximum expected hail size exceeding severe thresholds (1.00", red circle), 45 minutes after the initial UW-CTC signal.

Figure 4.  Valid 1725 UTC 10 May 2012.  The bottom right panel shows radar-based maximum expected hail size of over 3.00 (red circle)", 55 minutes after the initial UW-CTC signal and 40 minute after the maximum UW-CTC signal.