Lubbock, TX Mesoanalysis

Operating in the Lubbock, TX CWA to start today. At 2100 UTC, GOES-16 upper-level water vapor imagery (Fig 1) indicates a weak shortwave lifting to the northeast across SE Colorado/N Texas this afternoon, rounding the base of a broader upper trough over the western US. For viewing synoptic scale trends in water vapor imagery, I prefer to load the full disk imagery with CONUS imagery as an overlay. Time match to the full disk imagery allows for 15-min imagery which, for me, is ideal for longer term water vapor analysis. Meanwhile, loading the CONUS imagery allows for the full resolution (2km) to be displayed over the CONUS (full disk imagery has reduced resolution).

Figure 1

A GOES-16 1-min mesoscale sector was available over the forecast area today. In 0.64 um visible imagery (Fig 2), high to mid cirrus clouds mask much of the scene. A cu field has established itself across much of the southeast half of the state, on the eastern half of a dry line.

Figure 2

With the cloud cover in place, the LAP thermodynamic fields were missing significant data. The all sky products are useful in  filling in the cloud-induced gaps in data. The cloud type all sky product tells us whether a given pixel is derived from the GFS, cloudy sky retrieval algorithm, or clear-sky retrieval algorithm, allowing for comparison between the different algorithms and GFS first guess. Comparing adjacent pixels of different types for CAPE, the cloudy and clear sky pixels have lower values (~1800 j/kg) than the GFS first guess (~2400 j/kg). Comparing both with HRRR model runs and the SPC mesoanlysis, the lower values in the satellite retrievals seem to be more on par than does the GFS first guess. This leads one to believe the satellite is providing a correct adjustment to the model first guess. The LAP data indicates a max in instability through the center of the CWA along the dry line, decreasing east. LI values were also slightly lower in the retrievals compared to the GFS first guess, while TPW values were similar.

Figure 3: cw from top left: CAPE, LI, Retrieval Type, TPW. Sampling for clear sky pixel

 

Figure 4: cw from top left: CAPE, LI, Retrieval Type, TPW. Sampling for cloudy sky pixel

 
As for trends, the half-hourly all-sky LAP data indicates CAPE increasing steadily from around 1000 j/kg at 1728 UTC to around 1800 j/kg at 2028 UTC. A half-hour temporal resolution is adequate for analyzing trends in thermodynamic fields.

- Bucky