Severe thunderstorms developed across central Texas on 22 May 2024 in associated with a surface cold front/trough and dryline further south.
The precise location of the dryline across west Texas was captured well in GOES-East Split Window Difference Imagery. Recall, the SWD captures low level moisture gradients well, particularly in the presence of steep lapse rates and clear skies, filling in spatial gaps between sfc obs. The imagery in Figure 1 overlays IR for cold cloud tops (-40C to -80C) as color on top of split window difference imagery (grayscale), showing the evolution of the dryline and areas of convective initiation along it. The latest TOWR-S RPM included a menu item for the grayscale split window difference. Of note is the pinching off of the dryline in the center of the image, along which one of the areas of convection developed later in the animation.
Figure 1: 22 May 2024 GOES-East Split Window Difference (gray) and clean window IR for cold BTs (color).
GOES-East Geocolor Imagery, which includes Rayleigh corrected true color imagery during the daytime, provided a great view of smoke trapped in the moist airmass east of the dryline (Fig 2). The aerosols were depicted best toward sunset as forward scattering increased for GOES-East.
Figure 2: 22 May 2024 GOES-East Geocolor Imagery.
Focusing on one of the storms in central Texas, 1-min visible imagery depicted rapid convective initiation, as well as the development of notable storm top features like overshooting tops and a large and long lived above anvil cirrus plume (Fig 3).
Figure 3: 22 May 2024 GOES-East 1-min VIS.
The CIRA OCTANE speed sandwich product colors visible imagery by optical-flow-derived speed (Fig 4). The product helps highlight relevant convective features, such as convective initiation (increasing speed as the cloud grows into faster wind speeds), the above anvil cirrus plume (slower speed compared to surrounding anvil), and cloud top divergence (couplet of slow speeds (upwind of updraft) and fast speeds (downwind of updraft)).
Figure 4: 22 May 2024 GOES-East 1-min VIS/OCTANE-Speed Sandwich.
More satellite imagery and products from this event can be found in this CIMSS Satellite Blog post.
Bill Line, NESDIS/STAR
