Convective Initiation in West Texas

Operations started earlier today, in part to give the chance to use some of the GOES-R products, such as convective initiation, before cirrus contamination.  The two initial locations were Ft. Worth and San Angelo.  The blog post “CI/CTC Identifying Developing Convection in a Favorable Environment” (http://goesrhwt.blogspot.com/2013/05/cictc-identifying-developing-convection.html) summarizes the use of CI earlier in the day in the San Angelo county warning area.

By mid-afternoon, one group shifted to the Lubbock county warning area to investigate the PGLM in that region.  The transfer to Lubbock occurred as storms were already firing, but we took a look back to see what had occurred previously.  

Flipping back we observed the GOES-R CI provide a probability of convection around 20 at 1930 UTC in northwestern Motley County (yellow arrow).

The GOES-R CI (upper left), IR (upper right) and visible satellite (lower left), and Lubbock, Texas radar reflectivity (lower right) at 1930 UTC.

The GOES-R CI remained at this level until 1945 UTC when an upper 70 value was observed at the junction of Motley, Floyd, and Briscoe Counties (yellow arrow).  The visible satellite imagery shows that the features are nearly stationary.

The GOES-R CI (upper left), IR (upper right) and visible satellite (lower left), and Lubbock, Texas radar reflectivity (lower right) at 1945 UTC.

By the next scan, the GOES-R CI had topped 90 for the probability of convection at 2002 UTC (yellow arrow).  Up to this point, the radar was showing now activity in this area.  Also take note of the GOES-R CI in Briscoe County (red arrow) showing moderate strength of signal values around the county.

The GOES-R CI (upper left), IR (upper right) and visible satellite (lower left), and Lubbock, Texas radar reflectivity (lower right) at 2002 UTC.

We then move ahead to 2022 UTC, where radar first observes reflectivities exceeding 35 dBZ and a developing cell can be seen in both the IR and visible imagery in Motley County (yellow arrow).  The GOES-R CI continues to trend upward in Briscoe County (red arrow, and there is no current radar observations of storms.

The GOES-R CI (upper left), IR (upper right) and visible satellite (lower left), and Lubbock, Texas radar reflectivity (lower right) at 2022 UTC.

The situation continues to be interesting by 2045 UTC.  The Motley County storm (yellow arrow) continues to slowly grow.  Also, in Briscoe County (red arrow), where the GOES-R CI was suggesting possible initiation, we are observing several cells in the county on radar, although none have exceeded 35 dBZ just yet.

The GOES-R CI (upper left), IR (upper right) and visible satellite (lower left), and Lubbock, Texas radar reflectivity (lower right) at 2045 UTC.

Finally, at 2115 UTC, the radar signature for the storms in Motley and Briscoe Counties is well defined.  Note that the GOES-R CI stops tracking mature cells.

The GOES-R CI (upper left), IR (upper right) and visible satellite (lower left), and Lubbock, Texas radar reflectivity (lower right) at 2115 UTC.

The GOES-R CI provided the first indication of a potential cell in Motley County at 1930 UTC, giving it a 50 minute lead time.  Even with waiting for a stronger probability of convection, the GOES-R CI provided 35 minutes of lead time (signal of 70+), and 20 minutes (signal of 90+), respectively.  The GOES-R CI followed that with roughly 40 minutes of lead time for the Briscoe County storms.  Once the storms got rolling in this region, they became the focus of the PGLM total lightning blog post “Warning Issued with only PGLM Lightning Jump” (http://goesrhwt.blogspot.com/2013/05/warning-issued-with-only-pglm-lightning.html).