TPW Differences Along Dryline

The CIRA Merged TPW and All Sky LAP in the TX panhandle show some differences in the vicinity of the dryline at 19 UTC on 7 May.  This is a cloudy region so the retrievals are either GFS (All Sky LAP) or advected polar microwave (Merged TPW),  The All Sky LAP TPW shows a moist panhandle, with values in green / yellow (1″ or above).  The Merged TPW indicates lower values in green / purple, or about 0.7″.  Surface dewpoints range from 59-65 F, indicating moist air ahead of the dryline.

Surface GPS observations from Suominet at three TX stations in the panhandle (Amarillo – 1.0″, Borger – 1.0″, and Canadian – 1.1″) lean closer to the All Sky LAP analysis.  An hypothesis for the Merged TPW being low is dry retrievals from higher terrain to the west being advected into the moist sector.