SATCAST UAH CI Strength of Signal Provides Early Detection of Redeveloping Thunderstorms

Provided is a sequence of consecutive AWIPS-II display images highlighting the growth of new convective development on the south side of a thunderstorm complex that has just moved over this region.  The UAH CI "Strength of Signal" (SS) product shows very weak signals (< 30) of near-future CI likelihood early on       (Figure 1) from 1832 UTC, but then steadily increases its index values as new GOES satellite scans come in (Figure 2 through Figure 5).

Once the convective cloud top begins to approach the tropopause by 1932 UTC, its cloud top cooling rate (per the 10.7 um Brightness Temperature) decreases, which corresponds with a decrease in vertical growth.  As this occurs, the SS index values level off and even drop a little (Figure 6).  In the next GOES satellite scan at 1940 UTC, the UAH CI algorithm now begins to consider this convective cloud group as "mature" and ceases to consistently track and process it.  Our attention now turns to the radar, where the first appearance of an associated radar echo is expected in the near future (Figure 7).

Figures 8, 9, and 10 show the sequence of radar images leading to the eventual detection of convective rainfall by radar.  The first detected instance of a 35 dBZ or greater reflectivity associated with this convective cloud development occurs at 2012 UTC, about 1 hour and 40 minutes after the UAH CI algorithm began tracking and processing this convective development.

Figure 1.  UAH CI "SS" valid from 1832 UTC (Left).

Figure 2.  UAH CI "SS" valid from 1845 UTC (Left).

Figure 3.  UAH CI "SS" valid from 1902 UTC (Left).

Figure 4.  UAH CI "SS" valid from 1910 UTC (Left).

Figure 5.  UAH CI "SS" valid from 1915 UTC (Left).

Figure 6.  UAH CI "SS" valid from 1932 UTC... Notice that the index signal value has decreased as the cloud top has slowed its vertical growth and decreased its cooling rate as it has neared the tropopause (Left). At this time, there is still no radar echo associated with this new convective cloud development (Right).  

Figure 7.  At 1942 UTC... Still focusing on the region in the radar where new convective development is expected (Right).

Figure 8.  At 1948 UTC... Still focusing on the region in the radar where new convective development is expected (Right).

Figure 9.  At 2000 UTC... We are beginning to see the first semblance of a radar echo associated with the expected convective development, as highlighted by the UAH CI "SS" product (Right).

Figure 10.  At 2012 UTC... Now we see the convection increasing in intensity, per the radar reflectivity crossing above the 35 dBZ echo threshold (Right).