Dry Signal East of Developing Dry Line?

 An interesting signal developed in the GeoXO synthetic Water Vapor Transmittance (WVT) imagery today across Texas. Higher reflectance values (brighter colors in the WVT) were sandwiched between lower values, both to the west and east, in Central TX.

Figure 1: 4-panel with GeoXO synthetic imagery (5.15 band - top left, WVT - top right) and GOES-19 imagery (IR - bottom left, VIS - bottom right) at ~1800 UTC 14 May 2026.

At first, this signal seemed a bit counterintuitive, as the dry line was expected to develop in western TX, based on today’s briefing and the SPC Convective Outlook. However, when taking a look at the Advected Layered Precipitable Water (ALPW) product at nearly the same time (1800 UTC 14 May 2026), there’s noticeably higher moisture in the 850-700 and 700-500 hPa layers across West TX and New Mexico, and to the east near the TX/LA border.

Figure 2: 4-panel CIRA ALPW at 1800 UTC 14 May 2026.

A 1700 UTC HRRR forecast run, valid for 1800 UTC, just southeast of the TX Panhandle, showed this sharp reduction in moisture in its sounding near 850 hPa. Farther west, this sharp reduction is not evident. Perhaps the dry air around 850 hPa resulted in this counterintuitive WVT signal in TX.

Figure 3: HRRR sounding over North-Central TX at 1800 UTC 14 May 2026.

Figure 4: HRRR sounding over the Texas Panhandle at 1800 UTC 14 May 2026.

-csmith70